Saturday, August 26, 2017

Myomonitor: The Original Sphenopalatine Ganglion Stimulator Has a Fifty Year History of Safety Treating Pain, Migraines, Headaches and TMJ Disorders

The Spenopalatine Ganglion (SPG) Block was first discussed in the literature in 1908.  It was described by Sluder for treatment symptoms that may have been a TMJ disorder, possibly migraine or cluster headaches.  These disorders were named Sluder's Neuralgia.

SPG Blocks are the most common method of treating the Ganglion but Stimulation is currently where there is also a great deal of cutting edge research.

The Sphenopalatine Ganglion or SPG is also known as the Pterygopalatine Ganglion, The Nasal Ganglion, Meckels Ganglion or simply Sluder's Ganglion.

The Ganglion is found in the Pterygopalatine fossa and is accessible by many means for blocking with anesthetic solutions.  The Maxillary branch of the Trigeminal nerve and the maxillary rtery are also found in the fossa.

The most effective method is an injection into the pterygoid fissue a relatively easy when a supra-zygomatic approach is utilized.  Dentists are very familiar with palatal injections at the greater palatine foramen for dental anesthesia but can also block the SPG utilizing an injection deep into the greater palatine canal.

There have recently been many new devices developed for performing SPG Blocks including the Sphenocath, The Allevio and the TX360.  The TX360 is is the specific device described for use with MiRx protocol for prention of cluster headaches and migraines.   All three devices are effective and are used to deposit anesthetic into the posterior nasal cavity on the nasal mucosa over the anterior wall of the pterygopalatine fossa.

My preferred method of doing SPG Blocks that I have taught to hundreds of clinicians and patients is with cotton-tipped nasal catheters that offer continual capillary feed of anesthetic to the nasal mucosa over the ganglion.  This is the ideal method to for teaching self administration to patients, the most successful way to address the ganglion.

This method is so extremely successful because patients can do it as needed to control and prevent pain, anxiety and depression.  It has an added advantage of being extremely affordable and cost effective for both patients and insurance companies.

Stimulation of the Sphenopalatine Ganglion is currently a very high interest for many medical devices manufacturers however there a SPG  stimulator on the market that is non-invasive and has a fifty year record of safety and efficacy for treatment of Headaches, and Migraines as well as TMJ disorders but one company, Myotronics  has manufactured a device that utilizes ultra-low frequency TENS to stimulate the Sphenopalatine Ganglion for over 50 years.
The Myomonitor is the device and it is specifically designed to stimulat trigeminal nerves bilaterally and simultaneously.  However, while not marketed as a SPG stimulator it may be one of the best available.

Chicago Cluster Headache Prevention: Sphenopalatine Stimulation With Myomonitor combined with SPG Blocks



Neuromuscular Dentistry, Myomonitior and Sphenopalatine Ganglion Stimulation to Enhance Healing and Address Neurological Disorders and Diseases Including Stroke.


The utilization of the Myomonitor (ULF-TENS) change dentistry creating a new method of treating TMJ and MPD disorders. Doctors utilizing neuromuscular dentistry have an extremely high success rate in treating both TMD, Headaches and Migraines.
The Serendipitous Stimulation of the Sympathetic and Parasympathetic nervous system via the Sphenopalatine Ganglion is a probable reason for their amazing success.
Much of dentistry has been unable to achieve the results seen in neuromuscular dentistry in treating pain. This has caused many practitioners to say that TMJ disorders are Axis 2 disorders concerning the H-P-A complex or Hypothalamus-Pituitary-Adrenal System. The Myomonitor is a ULF-TENS that relaxes the muscles and simultaneously stimulates the Sphenopalatine Ganglion.
A recent cover article in Neurology Reviews (December 2016 Volume 24, Number 12 discussed the effects of Sphenopalatine Ganglion Stimulation.
Stimulation is a safe and effective method of temporarily allowing the Blood-Brain Barrier to deliver therapeutics to the brain whether they are pharmaceuticals or naturally occurring substances.
It has also been shown to enhance delivery of Mesenchymal Stem Cells and improve functional outcomes according to research presented at the 141st Annual Meeting of the American Neurological Association.
They found that this treatment does not entail unwanted systemic effects and could be potentially applied in the treatment of other Neurological Disorders.
This is not new to Neuromuscular dentists who have followed the work of Dr Bernard Jankelson for over 50 years. Dr J as we affectionately called him originally began his work to help his wife who had MS.
I had the great privledge of lecturing on the use of SPG Blocks in conjunction with Neuromuscular Dentistry. My lecture was originally scheduled for 60 minutes but was increased to 90 minutes. I was blown away as my research showed that I Sphenopalatine Ganglion Stimulation had been used by myself and all neuromuscular dentists for over 50 years!
According to Lorraine Iacovitti PhD of the Jefferson Stem Cell and Regeneration Neuroscience at Thomas Jefferson University in Philadelphia. They are currently investigating the mechanisms responsible for the response to SPG stimulation.
They are looking at the effect of different frequencies on the effect.
They feel that this could “improve treatments for many neurological diseases and disorders. In 2004 Yarnitsky et al found that stimulating the Sphenopalatine Ganglion caused a transient reversible increase in Blood-Brain permeability.
Michael Lang MD led a research project under Dr Iacovitti’s group studying SPG stimulation in rats with occlusions of the Middle Cerebral Artery. Using this stimulation with stem cells they could reduce infarct size and decrease proinflamatory factors in stroke.
Amazingly, Electron Microscopy showed that most tight junctions in the rat’s brain appeared normal after stimulation of the Sphenopalatine Ganglion.
They used a study that stimulated the Sphenopalatine Ganglion at a slow rate of 10 Hz and 5 volts. This is very similar to the Myomonitor that utilizes a .66 Hz also in the low frequentcy range and actually set to match physiologic recovery of nerve cells after stimulation.
In a three leg study stroke recovery was evaluated in a untreated group, stem cell treated group and stem cells with SPG stimulation.
At day 14 the Modified Neurologic Severity Score was 50% lower in the group receiving SPG Stimulation and stem cells compared to control untreated rats.
According to Dr Iacovitti Stem Cells moved into the brain in a similar manner as to after tumor-necrosis-factor-alpha stimulated inflammation.
Unlike mannitol administration SPG Stimulation showed NO ADVERSE SID EFFECTS.
The ICCMO or International College of CranioMandibular Orthopedics is the scientific organization founded by Dr Barney Jankelson to support Neuromuscular Dentistry.
INTRODUCTION TO TENS (Reprinted form LVI global)
A major player in teaching Neuromuscular Dentistry.
T.E.N.S. modalities are designated into three distinct categories based on technical parameters and physiologic action. (Mannheimer, J. Clinical Transcutaneous Electrical Nerve Stimulation. F.A. Davis, Philad., 1986).
A T.E.N.S. mode that uses high rate (50 to 100 Hz), asymmetrical biphasic wave (40-75 usec) is referred to as Conventional. High Frequency T.E.N.S. This mode is designed to selectively actuate the large myelinated afferent fibers. Muscle fasciculization is not apparent. Conventional high frequency T.E.N.S. is characterized by fast onset of relief, short therapeutic effect, generally not exceeding length of stimulation. There is little or no endogenous opiate liberation and no reversal by naloxone. The high frequency T.E.N.S. is primarily a local CNS (segmental effect).
Additional added information: The MYOMONITOR is an ULF-TENS operating at .66HZ a physiologic established rate. It is included in low frequency range.
A second T.E.N.S. mode is Low Frequency Acupuncture-like T.E.N.S. with a pulse rate of 0.5 Hz to 10.0 Hz using a asymmetrical biphasic wave form of 150-500 usec. It produces muscle contraction, slow onset (20 mm. or more), long therapeutic effect and activates small pain afferent and motor efferent fiber stimulation. There is endogenous opiate liberation, naloxone reversal and long therapeutic effect. The Low Frequency T.E.N.S. allow a period for muscle recovery between pulses with stimulation by surface electrodes in segmentally related myotomes being most efficacious. The Myo-monitor is a low frequency acupuncture-like T.E.N.S.
The third type of T.E.N.S. is a Electrogalvanic Stimulator (E.G.S.) It is characterized by having a monophasic, twin peak wave for each pulse of 10-20 msec utilizing direct current. E.G.S. is designed for local tissue effect, not pain control.
Both low and high frequency T.E.N.S. have ample and specific documentation in the medical literature regarding local histochemical and endorphin effects. The following articles address the mode of action of conventional high frequency T.E.N.S. and low frequency acupuncture-like T.E.N.S.
1. Ersek, R. (1977) Transcutaneous neurostimulation: A new therapeutic – modality for controlling pain. Clinical Orthopedics and Related Research. Vol. 128:314-324.
2. Eriksson, M.D., and Sjolund, B.H. (1978) Pain relief from conventional versus acupuncture-like T.E.N.S. in patients with chronic facial pain. Pain Abstracts. 2nd World Congress on Pain, Montreal: IASP, p 128.
3. Takakora, K., et al. (1979) Pain control by transcutaneous electrical nerve stimulation using irregular pulse of 1 Hz fluctuation. Applied Neurophysiology. 42:314.
4. Murray, W., and Miller, J. (1960) Potency differences of morphine-type agents by radiant heat and „cramping‟ analgesic assays provide evidence for potentializing substance from the posterior pituitary gland. J. *pharmocologic Exp. Ther. pp 128-380.
5. Goldstein, A., Lowney, L., and Pal, B. (1971) Stereospecific and nonspecific interactions of the morphine narcotic congener leurophanol in subcellular functions of rat brain. Proc. Nat. Acad. Science USA. 68:1742.
6. Moyer, D.J., Price, D.D., and Rafii, A. (1977) Antagonism of acupuncture analgesis in man by the narcotic antagonist nalaxone. Brain Research. pp 121-368.
7. Akil, H., et al. (1978) Encephalin-like material elevated in ventricular cerebrospinal fluid of pain patients after Analgesic facial stimulation. Science. 201:463.
8. Simantor, R., et al. (1976) The regional distribution of a morphine-like encephalin in monkey brain. Brain Research. 106:189.
9. Sjolund, B., and Eriksson, M. (1979) Endorphins and analgesia produced by peripheral conditioning stimulation. Advances in Pain Research And Therapy, vol. 3, Bonica, et al., eds. Raven Press, N.Y.
10. Wall, P.D. (1980) The role of substantia gelatinosa as a gate control. Pain. Research Ed. Bonica, 58:205.
11. Kerr, F.W. (1975) Neuroanatomical substrates of nociception in the spinal cord. Pain. 1:325.
12. Loeser, J.D., et al. (1975) “Relief of pain by transcutaneous stimulation.” J. Neurosurg. 42:308.
13. Arcangeli, P., and Galleti, R. (1974) Endogenous pain producing substances. Recent Advances on Pain: Pathophysiology and Clinical Aspects. Ed. Bonica, p 36.
14. Thorsteinsson, G., et al. (1977) Transcutaneous electrical stimulation: A double-blind trial of its efficacy for pain. Arch. Phys. Med. Rehab. 58:8.
15. Long, D., and Hagfors, N. (1975) Electrical stimulation in the nervous system: The current status of electrical stimulation of the nervous system for relief of pain. Pain. 1:109.
16. Dooley, D.M., and Kasprak, M. (1976) Modification of blood flow to the extremities by electrical stimulation of the nervous system. S. Med. Journal 69: 1309.
17. Abram, S.E. (1976) Increased sympathetic tone associated with transcutaneous electrical stimulation. Anesthesiology. 45:575.
18. Abram, S.E., et al. (1980) Increased skin temperature during transcutaneous electrical stimulation. Anesth. Anaig. 59:22.
19. Rowlingson, J., et al. (1978) The effect of transcutaneous nerve stimulation on blood flow in normal extremities. Pain Abstr. Vol. 1, 2nd World Congress on Pain, mt. Assoc. for Study of Pain, Seattle, p 155.
20. Murphy, T.M., and Bonica, J.J. (1977) Acupuncture analgesia and anesthesia. Arch. Surg. 112:896.
21. Andersson, S.A., and Holmgren, E. (1977) Analgesic effects of peripheral conditioning stimulation parameters. Acupunct. Electro. Res. 2:237.
22. Sjolund, B.H., and Ericksson, M.E. (1976) Electro-acupuncture and endogenous morphines. Lancet. 2:1085.
23. Voll, R. (1975) Twenty years of electroacupuncture therapy using low- frequency current pulses. American J. of Acupuncture. 3:291.
24. Kosterlitz, H.W., and Hughes, J. (1976) Possible physiologic significance of enkephalin on endogenous ligand of opiate receptors. Advances in Pain Research and Therapy. Ed. Bonica, Raven Press, N.Y., p 641.
25. Terenius, L. (1978) Significance of endorphins in endogenous antinociception. Advances in Biochemical Psychoparm. Ed. Costa and Trabucchi. Raven Press, N.Y., p 31.
26. Adams, J.E. (1976) Naloxone reversal of analgesia produced by brain stimulation in the human. Pain. 2:161.
27. Hosobuchi, Y., et al. (1977) Pain relief by electrical stimulation of the central grey matter in humans and its reversal by naloxone. Science. 17:183.
28. Burton, C., and Marrer, D.D. (1974) Pain suppression by transcutaneous electrical stimulation. IEEE Trans. Biomed. Eng. 21:81.
29. Andersson, S.A., et al. (1976) Evaluation of the pain suppression effect of different frequencies of peripheral electrical stimulation in chronic pain conditions. Acta Orthop. Scandia. 47:149.
30. Wolf, C.J., et al. (1980) Antinociceptive effect of peripheral segmental electrical stimulation in the rat. Pain. 8:237.
31. Malow, R.M., and Dougher, M.J. (1979) A Signal detection analysis of the effects of transcutaneous stimulation on pain. Psychosom. Med. 4:101.
32. Ebersold, M.J., Laws, E.R., and Albers, LW. (1977) Measurements of autonomic function before, during and after transcutaneous stimulation in patients with chronic pain and in control subjects. Mayo Clin. Proc. 52:228.
33. Pert, A., and Yaksh, T. (1974) Sites of morphine induced analgesia in the primate brain: Relation to pain pathways. Brain Research. 80:135.
34. Sjolund, B.H., Terenius, L., and Ericksson, M.B, (1977) Increased cerebrospinal fluid levels of endorphin after electro-acupuncture. Acta Physiol. Scand. 100:382.
35. Mayer, D.J., Price, D.D., and Raffii, A. (1977) Antagonism of acupuncture analgesia in man by the narcotic antogonist naloxone. Brain Res. 121:368.
36. Schien, H., and Bentley, G.A. (1980) The possibility that a component of morphine induced analgesia is contributed indirectly via the relase of endogenous opioids. Pain. 9:73.
37. Mao, W., et al. (1980) High versus low intensity acupuncture analgesia for treatment of chronic pain: Effects on platelet serotonin. Pain. 8:331.
38. Cheng, R.S., and Pomeranz, B. (1981) Monoaminergic mechanism of electroacupuncture analgesia. Brain Res. 215:77.
39. Cheng, R.S., and Poneranz, B. (1980) Electroacupuncture is mediated by stereospecific opiate receptors and is reversed by antagonists of type I receptors. Life Science. 26:631.
40. He, L. (1987) Involvement of endogenous opiold peptides in acupuncture alangesia. Pain. 31:99-121.
41. Chen, B.Y., and Pan, X.P. (1984) Correlation of pain threshold and level of beta-endorphin-like immunoreactive substance in human CFS during electroacupuncture analgesia. Acta Physiol. 36:183-187.
42. Chan, C.W., and Tsang, H. (1987) Inhibition of the human flexion reflex by low intensity, high frequency transcutaneous electrical nerve stimulation (TENS) has a gradual
onset and offset. Pain. 28:239-253.
43. Facchinetti, F., et al. (1981) Concomitant increase in nociceptive flexion reflex threshold and plasma opioids following transcutaneous nerve stimulation. Pain. 11:49-63.
44. Hansoon, P., and Ekblom, A. (1983) Transcutaneous electrical nerve stimulation (TENS) as compared to placebo TENS for relief of acute oro-facial pain. Pain. 15:157-165.
The medical literature is clear and unequivocal – low frequency T.E.N.S. (0.5 – 10 Hz) is both safe and efficacious for muscle relaxation and pain control. It is also clear that low frequency T.E.N.S. has a high degree of specificity when utilized for craniofacial pain (Andersson, 1979; Eriksson et al., 1984; Chapman et al., 1979; Andersson et al., 1977; Andersson and Holmgren, 1975; Sjolund et al., 1975; Reichmanis and Becker, 1977; Hansoon and Ekblom, 1983; Tereshalmy et al., 1982; Phero, 1987; Lasagna et al., 1986; Thomas, 1986; Pantaleo et al., 1983; Wessberg and Dinhani, 1977; Konchak et al., 1988).
Choi and Mitani at Osaka Dental University in 1973 applied the Myomonitor to 15 subjects and monitored the evoked response using wire EMG electrodes. The study concluded “The evoked EMG was recorded from the anterior portion of the temporal, the masseter, the anterior ventral of the digastric, and obicularis oris and the buccinator muscles. . . The Myo-monitor pulse stimulates the nerve trunks of the fifth and seventh cranial nerves at the superior mandibular notch percutaneously and it appeared to have afferent and efferent effects.”
Using accepted intensity-duration methodology Jankelson, et al., 1975 demonstrated that the chronaxy values for Myo-monitor generated curves were well below those for direct muscle stimulation. Further verification of neural mediation resulted from the study of Williamson and Marshall, 1986 using succinylcholine. The study concluded “Succinylcholine acts by competing with acetyicholine at the myoneural end plate and, therefore, no neurally stimulated muscle contraction under such conditions is by direct depolarization of the muscle itself. With the Myo-monitor evoking electrical impulses, there was no muscle contraction in either instance. This information would support the conclusion that the Myo-monitor stimulus is transmitted neurally.”
Fujii 1977 at the University of Osaka used multiple site monitoring to distinguish M wave and H wave response. Using multiple anatomically separate recording sites the study concluded “Two kinds of response were obtained with latencies of about 2.0 msec. and about 6.0 msec. respectively. The former was assumed to be a direct potential (M wave) and the latter a monosynaptic reflex potential (H wave).” The use of recording sites anatomically distant from the input stimuli is essential for valid conclusions using this methodology. In a 1988 study of Myo-monitor stimulation, Dao, Feine and Lund for unexplained reasons placed the recording needle proximate to the electrode stimuli site
McMillan et al., 1987 at the University of Hong Kong concluded that “Contraction of muscles of the upper and lower eyelids, the lateral aspect of the nose and the upper lip indicates stimulation of the facial nerve, in particular its zygomatic and buccal branches. The results of our anatomic investigation indicate that this effect is produced by the stimulation of the branches of the upper division of the facial nerve as they pass in a more or less direct anterior course over the preauricular region. These branches will then be directly beneath a surface electrode placed according to the standard protocol. Propagation of the Myo-monitor stimulus along branches from the buccal anastomotic loops of the nerve would ensure contraction of muscles of the upper lip and angles of the mouth. . . This observation supports electromyographic evidence and results of intensity duration tests that indicate muscle contraction resulting from Myomonitor stimulation is neurally mediated.”
Goodgold and Eberstein examined eight individual investigative studies and found that normal distal latency and conduction velocity of peripheral motor nerves ranged from 2.1 to 5.6 msec. and 44.8 to 67.9 msec., respectively. They concluded that the latency to the obicularis oris which is innervated by the facial nerve in response to stimulation at the angle of the jaw, averages 2.5 to 3.0 msec. Basmajian summarized the results of six studies conducted by separate authors on peripheral nerve conduction velocity and found a range of conduction velocity between 37 and 73 meters/sec. Assuming the distance between the stimulation electrode and the wire recording electrode was approximately 2 cm, it should have taken 0.27 to 0.54 msec. for the pulse to travel this distance if the muscles were stimulated directly. This time interval is much less than the 1.80 to 4.4 msec. measured in the Dao study. This suggests the pulse must have traveled a much longer distance. A neurally mediated pulse would have: 1) 0.5 msec. charging the dermal capacitance, 2) neural conduction time of 0.7 msec. assuming a neural conduction pathway of 4 cm and conduction velocity of 55 meters/sec. which is the average of Basmajian‟s review, 3) residual latency (delay at the myoneural junction) of 0.6 msec., 4) intermuscular delay of approximately 0.4 msec. depending upon electrode placement. Adding the sum of these phenomena we find the latency of 1.80 to 4.04 msec. as measured by Dao, et al. is well within the range of neurally mediated response, despite their electrode placement.
ARTICLES REVIEWED IN THIS PUBLICATION
SECTION 1: STUDIES THAT DOCUMENT EFFICACY OF LOW FREQUENCY TENS
1. Andersson, S. Pain control by sensory stimulation. Advances in Pain Research and Therapy. Vol. 3, Ed. Bonica et al. Raven Press, N.Y., 1979. p. 569-585.
2. Eriksson, M., Sjolund, B., and Sundbarg, G. Pain relief from peripheral conditioning stimulation in patients with chronic facial pain. J. Neurosurg. 61:149-155, 1984.
3. Chapman, C.R., Chen A.C., and Bonica, J.J. Effects of intrasegmentalelectrical acupuncture on dental pain: evaluation by threshold estimation and sensory decision theory. Pain. Vol. 3, Biomedical Press, pp 213-227, 1977.
4. Sjolund, B., and Eriksson, M. Endorphins and analgesia produced by peripheral conditioning stimulation. Advances in Pain Research and Therapy. Vol. 3, ed. Bonica Raven Press, N.Y. 1979.
5. Chapman R., Wilson, M., and Gehrig, J. Comparative effects of acupuncture and transcutaneous stimulation on the perception of painful dental stimuli. Pain. Vol. 2, p 265-283, Amsterdam 1976.
6. Andersson, S.A., Holmgren, E., and Roos, A. Analgesic effects of peripheral conditioning stimulation – II. importance of certain stimulation parameters. Acupuncture and Electro-Therapeut. Res. mt. J. Vol. 2, No. 3, pp 237-246. Great Britain 1977.
7. Andersson S.A., and Holmgren, E. Analgesic effects of peripheral conditioning stimulation – III. Effect of high frequency stimulation; segmental mechanisms interacting with pain. Acupuncture and ElectroTherapeut. Res. mt. J. Vol. 3, pp 23-36, Great Britain 1978.
8. Andersson, S.A., and Holmgren, E. On acupuncture analgesia and the mechanism of pain. American J. of Chinese Medicine. Vol. 3, No 4, pp 311-344, 1975.
9. Sjolund B., Terenius, L., and Eriksson, M. Increased cerebrospinal fluid levels of endorphins after electro-acupuncture Acta Physiol. Scand. 100: 382-384, Sweden 1977.
10. Cheng, R.S., and Pomeranz, B.H. Electro-acupuncture analgesia is mediated by stereospecific opiate receptors and is reversed by antagonists of type I receptors. Life Sciences. Vol. 26, pp 631 -638, 1980.
11. Reichmanis, M., and Becker, R.O. Relief of experimentally induced pain by stimulation at acupuncture loci: a review. Comparative Medicine East and West. Vol. 5, No 3-4, pp 281-288, 1977.
12. Andersson, S.A., Pain control by sensory stimulation. Advances in Pain Research and Therapy. Vol. 3 Ed. John J. Bonica et al, 1979.
13. Mannheimer, J.S., and Lampe, G.N. Clinical Transcutaneous Electrical Nerve Stimulation. Philadelphia: F.A. Davis, p 341, 1984.
14. Hansson, P., and Ekblom, A. Transcutaneous electrical nerve stimulation (TENS) as compared to placebo TENS for the relief of acute oro-facial pain. Pain. Vol. 15, pp 157-165, 1983.
15. Terezhalmy, G.T., Ross, G.R., and Holmes-Johnson, E. Transcutaneous electrical nerve stimulation treatment of TMJ-MPDS patients. Ear, Nose, and Throat Journal. Vol. 61, pp 22-28, December 1982.
16. Phero, J.C., Raj, P.P., and MacDonald, J.S. Transcutaneous electrical nerve stimulation and myoneural injection therapy for management of chronic myofascial pain. The Dental Clinics of North America. Vol. 31, No. 4, pp 703-722, October 1987.
SECTION 2: STUDIES THAT DOCUMENT NEURAL MEDIATION OF MYOMONITOR STIMULUS
1. Jankelson, B., Sparks, S., and Crane, P., Neural conduction of the Myo-monitor stimulus: A quantitative analysis. J. Prosthetic Dentistry. Vol. 34, No. 3, pp 245-253, September 1975.
2. Fujii, H. Evoked EMG of masseter and temporalis muscles in man. J. of Oral Rehabilitation. Vol. 4 pp 291-303, 1977.
3. Fujii, H., and Mitani, H. Reflex responses of the masseter and temporal muscles in man. J. of Dental Research. Vol. 52, No. 5, pp. 1046-1050, 1973.
4. Choi, B. On the mandibular position regulated by Myo-monitor stimulation. J. Japanese Prosthetic Dentistry. Vol. 17 pp 73-96, 1973.
5. Williamson, E., and Marshall, D. Myomonitor rest position in the presence and absence of stress. Facial Orthopedics and Temporomandibular Arthrography. Ed. Williamson, Vol. 3, No: 2, 1986.
SECTION 3: STUDIES THAT DOCUMENT HISTOCHEMICAL EFFECT OF LOW FREQUENCY TENS
1. Dixon, H.H., and Dickel, H.A. Tension headache. J. Northwest Medicine. Vol. 66, pp. 817-820, Sept. 1967.
2. Dixon, H.H., and O‟Hara, M. Fatigue contracture of skeletal muscles. J. Northwest Medicine. Vol 66, pp-8l3-8l6, Sept. 1967.
3. Rodbard, S., and Pragay, E.B. Contraction frequency, blood supply, and muscle pain. J. of Applied Physiology. Vol. 24, No. 2, Feb. 1968.
4. Rasmussen, O.C., Bonde-Peterson, F., Christensen, L.V., and Moller, E. Blood flow in human mandibular elevators at rest and during controlled biting. J. Oral Biology. Vol. 22, pp 539-543, 1977.
5. Lasagna, M., and Orland, C. Modificazione die flussi ematici muscolocutanei indotta dollo stimulazione neurale transcutanea isichemia e dolore nella patologia occlusale. J. Odotostomatologia e Lymplantopratessi. 1986.
6. Thomas, N.R. Spectral analysis in the pre- and post-TENS condition. Presented International College of Cranlo-Mandibular Orthopedics, Oct. 1986.
SECTION 4: STUDIES DOCUMENTING MYO-MONITOR EFFICACY
1. Pantaleo, T., Prayer-Galletti, F., Pini-Prato, G., and Prayer-Galletti, S. An Electromyographic study in patients with myo-facial pain-dysfunction syndrome. Bull. Group. mt. Rech, sc. Stomat. et Odont. Vol 26, pp. 167-179, 1983.
2. Wessberg, G.A., and Dinham, R. The Myo-monitor and the myo-facial pain dysfunction syndrome. J. Hawaii Dental Assoc. Vol. 10, No. 2, pp. 10-13, 1977.
3. Wessberg, G.A., Carroll, W.L., Dinham, R., and Wolford, L.M. Transcutaneous electrical stimulation as an adjunct in the management of myofascial pain dysfunction syndrome. J. of Prosth. Dent. Vol. 45, No. 3, pp. 307-314, 1981.
4. Boschiero, R., Fraccari, F., and Pagnacco, O. Analysis of the results of the use of the myo-monitor in patients with reduced mouth openings. J. Mm. Stomatologica. Vol. 35, pp. 857-864, Sept. 1986.
5. Konchak, P., Thomas, N., Lanigan, D., and Devon, R. Freeway space measurement using mandibular Kinesiograph and EMG before and after TENS. The Angle Orthodontist. Oct. 1988, pp. 343-350.
6. Bazzotti, L. Electromyography tension and frequency spectrum analysis at rest of some masticatory muscles, before and after TENS. Electromyogr Clin Neurophysiol. 1997 Sep; 37(6):365-78.
7. Eble, O.S., Jonas, I.E., and Kappert, H.F. Transcutaneous electrical nerve stimulation (TENS): its short-term and long-term effects on the masticatory muscles. J. Orofac Orthop. 2000; 61(2):100-11.
STUDIES THAT DOCUMENT THE EFFICACY OF LOW FREQUENCY TENS
LOW FREQUENCY (ACUPUNCTURE LIKE) TENS = MYO-MONITOR
LOW FREQUENCY T.E.N.S.
INTRODUCTION
The A.D.A. draft status report on Devices for the Diagnosis and Treatment of Temporomandibular Disorders sites a single study by Block and Laskin as evidence that TENS and a placebo effect elicited similar results. Block and Laskin used a pulse generated stimulator with peak amplitude from 0-76 ma (500 ohm load) and a pulse rate of 12-100 pulses/sec. Block and Clark clearly state that the modality employed in their study is based on the concept of stimulation that increases input into the spinal gate, thereby altering pain awareness by inhibiting pain sensation.
It must be noted that this is an entirely different modality than low frequency, 0.5 Hz-4 Hz, acupuncture-like TENS. The well controlled studies of Chapman, Anderson, Erickson, Sjolund, Bonica, Chang, Holmgren and others clearly support the preference of low frequency TENS for treatment of chronic pain disorders. Low frequency acupuncture-like modalities such as the Myomonitor have ample and specific documentation in the medical literature regarding local histochemical and endorphin effects.
Following are controlled studies from the medical and dental literature supporting the efficacy of low frequency (acupuncture-like) TENS. Low frequency TENS has a 0.5Hz • 10Hz frequency parameter. However, most of the studies utilize 0.5Hz to 9.0Hz in the investigations.
Andersson, S.A. Pain control by sensory stimulation. Advances in Pain Research and Therapy. Vol 3, ed. John J. Bonica et al, Raven Press, N.Y. 1979.
Transcutaneous nerve stimulation (TNS) and acupuncture are the main methods for sensory stimulation used in medical practice.
In contrast to acupuncture, TNS is usually given at high frequency (50 to 100 Hz) and with low intensity which is kept well below that giving pain. The subjective sensation is different from that during acupuncture and is described as tingling or vibration. There are no phasic muscle movements, but a slight tonic contraction may occur in muscles close to the stimulating electrodes (Andersson, S.A. 1979). The afferent nerve fiber discharge consists of a continuous firing in low and high-threshold afferents depending on the intensity.
Another relevant parameter of the sensory stimulation is its frequency. Pain threshold measurements have shown that low frequency (1 to 4 Hz) gives a gradual and slow increase of the threshold which remains elevated during a long-lasting stimulation and returns slowly in the poststimulation period. These effects contrast strongly the transient pain threshold increase observed during stimulation at high frequency (100 Hz). In spite of a continuous stimulation at high intensity, the pain threshold declines to the control level. It should also be noted that the effect is more localized than that at low frequency. Thus low-frequency stimulation of the cheeks increases the threshold of the teeth in both the upper and lower jaws, whereas high-frequency stimulation at the same location and intensity gives a transient effect only in the incisive and canine teeth of the upper jaw.
It should also be noted that the most common type of conditioning stimulation TNS, often has a pronounced effect on chronic pain, but the pain threshold (is) unchanged or increased only transiently at the start of the stimulation. The pain threshold measurements refer to experimental pain mediated via A delta fibers, at least when electrical stimuli are used as tests. Chronic pain may be due to activity in C fibers, and it remains to be determined whether the threshold for C fiber-mediated sensations is increased during high-frequency stimulation.
When the low frequency, high-intensity stimulation is modified into repetitive, high-frequency bursts, the conditioning is less distressing and pain conditions not relieved by high-frequency stimulation can be alleviated. (Eriksson, M. 1976.)
Substances with morphine-like effects, endorphins, appear to be transmitters in the descending control systems, and morphine exerts its analgesic effect partly by activation of such systems (Mayer,D.J. 1976), but it has also a direct action on the spinal cord (Besson, 1973, Fields, 1978, Kitahata, 1974, LeBars, 1976, Zieglgansberger 1976). Administration of naloxone, a specific narcotic antagonist, inhibits the analgesic effect both of electrical stimulation of the brainstem and of morphine. (Fields 1978)
There is evidence that low-frequency stimulation (acupuncture) activates descending control systems. Naloxone decreases or eliminates the analgesia produced by classic needle acupuncture in healthy subjects (Mayer, 1975) Moreover, naloxone inhibits the pain relief elicited by low-frequency electrical stimulation in patients with chronic pain but it does not counteract analgesic effects produced by high-frequency sensory stimulation. (Sjolund 1976) A low concentration of endorphins is often found in the cerebrospinal fluid (CSF) of patients with chronic pain of somatic origin as compared to pain of psychogenic origin (Almay 1978). Low-frequency electrical stimulation producing pain relief increases the CSF concentration of endorphins. (Sjolund 1977). The counteraction by naloxone of the pain relief after acupuncture could thus be due to an effect on the endorphin release by the stimulation.
A pain inhibition center, possibly including the brainstem structure producing analgesia by direct stimulation, receives input from a variety of afferents ranging from large non-pain fibers to pain afferents. Stimulation of these afferents increases the output from the pain inhibition center with blockade of the transmission at different levels of the pain pathway. The pain inhibitory mechanism has endorphins as transmitters in some link. The differences in the characteristic of the pain relief elicited by different types of sensory stimulation appears to reflect at least two different pain inhibitory mechanisms.
Eriksson, M., Sjolund, B. and Sundbarg, G. Pain relief from peripheral conditioning stimulation in patients with chronic facial pain. J. Neurosurg., 61:149-155, 1984.
Departments of Clinical Neurophysiology and Neurosurgery, University Hospital, Lund, Sweden.
In a prospective study, 50 consecutive patients, referred to a pain treatment unit for surgery to alleviate various forms of facial pain, were all given transcutaneous nerve stimulation (TNS) therapy and followed for 2 years. Of the 44 patients remaining at the 2-year follow-up review, 20 (45%) reported satisfactory analgesia from conventional or acupuncture-like TNS. The latter technique markedly improved the overall results. No serious side effects were seen. Atypical facial pain of known etiology responded best to treatment, but satisfactory relief was often produced with tic douloureux. Duration of the pain condition as well as sex of the patient were predictors of treatment results. It is concluded that TNS therapy represents a valid alternative to surgery when pharmacological therapy fails, especially in the elderly and in patients with atypical facial pain.
Patients with chronic so-called intractable facial pain may present management problems. This is true for typical trigeminal neuralgia (tic douloureux) as well as for atypical forms of facial pain. (Anthony, M 1974, Loeser, J.D. 1977, Rasmussen 1965)
A different line of therapy has developed from the hypothesis that trigeminal neuralgia is a result of vascular compression of the trigeminal nerve root. (Dandy, W.E. 1934)
In cases of atypical facial pain, (Gregg, J.M. 1978, Rushton, J.G. 1959) with or without an identifiable organic cause, antiepileptic drugs are generally ineffective. Alcohol injections or surgery, even if giving temporary relief, may later result in a considerable worsening of the condition. (Gregg, J.M. 1975, Rasmussen, P. 1965). Conventional analgesics may be useful when there is an organic cause for the disorder, and tricyclic antidepressant drugs may help when there is not. (Anthony, M. 1974) The available therapeutic methods, however, leave many patients unaided and substantially handicapped by their chronic facial pain.
During the last decade, treatment by conditioning stimulation of peripheral nerves has become increasingly used for patients with acute and chronic pain conditions. (Loeser, J.D. 1975, Long, D.M. 1976, Wall, P.D. 1967) A long-term follow-up study of the effect of two types of transcutaneous electrical nerve stimulation (TNS) showed that, after 2 years, 31% of patients referred to a neurosurgical department still experienced useful analgesia from daily TNS treatment. (Eriksson, M.B.E. 1979) Among these successfully treated patients with chronic pain were several who had previously had intractable facial pain, some of whom had to use a newly developed TNS technique (acupuncture-like TNS)(Eriksson, M.B.E. 1976) to obtain pain relief.
Apart from the need for alternative therapeutic methods among patients with intractable facial pain, it seemed of great interest for the evaluation of the TNS techniques to test and follow a group of patients suffering from chronic pain that was less varied as to type and location than in previous studies. We therefore initiated a prospective long-term follow-up study of 50 patients with intractable facial pain, treated with conventional (Ihalainen, U., 1978, Wall, P.D. 1967) or acupuncture-like (Ericksson, M.B.E. 1976, Eriksson, M.B.E., 1979). The facial pain conditions treated represent two types of pain: namely, acute intermittent (tic douloureux) and chronic continuous (atypical facial pain). The study and the results obtained are the subjects of this report.
The series included 50 consecutive patients with intractable facial pain who were referred to the Department of Neurosurgery at Lund University Hospital for surgery. Twenty-one patients had been classified as having tic douloureux. To comply with the diagnostic criteria, the pain had to be: 1) truly paroxysmal; 2) unilateral; 3) provocable by non-nociceptive facial stimuli; 4) confined to the innervation area of one, two, or three trigeminal branches; and 5) not associated with sensory or other neurological deficit.
Twenty-nine patients did not fulfill the criteria . . . tic douloureux and will be considered here as having “atypical facial pain.” In 18 of these patients the pain resulted from accidental or surgical trauma (11 patients), cerebrovascular disease, (five patients), or herpes zoster oplithalmicus (two patients).
If after the first 2-week trial period, there was no significant pain relief, the patient was instructed how to use the stimulator for acupuncture-like TNS. The positive electrode was then placed in front of the ear and the negative electrode over the forehead, cheek, or chin. The stimulator was set for a train (7 pulses at 100Hz) given at a repetition rate of 1.5 to 2 Hz. (Eriksson, 1976, Eriksson, 1979) and the electrodes adjusted so that visible muscle contractions were produced in the area of pain (Fig. 2). If, after another 2-week trial period at home, there was still no report of significant pain relief, the TNS trial was recorded as a failure. If stimulation treatment was reported to reduce the intensity and frequency of pain paroxysms, or produced useful relief in patients with non-paroxysmal atypical intractable facial pain, the patient was instructed to continue with the treatment and was seen again 2 months later.
After 3 months of treatment, 16 (32%) of the 50 patients experienced successful or moderately successful pain relief with conventional TNS only. (Fig. 3) Of the 34 patients who did not benefit from conventional TNS, acupuncture-like TNS proved to be satisfactory in 13 patients. Thus, in all, 29 (58%) of the 50 patients experienced pain relief from TNS. Twenty patients used stimulation only and were considered a success, and nine patients who added small amounts of adjuvant pharmacotherapy were considered a moderate success.
There was no significant difference in treatment success between patients with tic douloureux (11 of 21 patients) and atypical facial pain (18 of 29 patients). However, significantly (0.025
0.05. These findings indicate that the increase in pain threshold that occurred with acupunctural stimulation did, in fact, reflect a decrease in sensory sensitivity to tooth pulp shocks. Response bias played a trivial role in the treatment-induced threshold increase.
DISCUSSION
In spite of differences in equipment, procedure, site of acupunctural stimulation, and cultural context, we have replicated the dental acupuncture analgesia phenomenon reported by Andersson and Holmgren (Andersson 1973). Intense electrical stimulation at 2-3 Hz over an 😯 min period yielded a gradual increase in dental pain thresholds which reached a relatively stable state after approximately 20 min. An SDT analysis of the discrimination tasks involving high intensity, low intensity, and blank stimuli demonstrated that the pain threshold increase reflected a reduction in sensory sensitivity. There was no significant change in response bias or willingness to call the stimulation experienced painful.
The apparent proclivity of dental structures to respond to acupunctural stimulation when cutaneous tissues do not, may be due to morphological or neurological differences in skin and teeth or to unique properties of the trigeminal system or its projection to the brain stem.
Sjolund, B.H., and Eriksson, M. Endorphins and analgesia produced by peripheral conditioning stimulation. Advances in Pain Research and Therapy. Vol 3, ed. John J. Bonica, et at. Raven Press, New York, 1979.
ACUPUNCTURE – LIKE TNS
Chiang et al. (Chiang 1973) claimed that impulses from deep afferents were necessary to elicit acupuncture analgesia. Andersson and co-workers (Andersson 1973, Andersson 1976, Sjolund, this volume) found that a stimulation strength giving forceful muscle contractions in the facial musculature was necessary for the rise in tooth pain threshold. They also found that the pain threshold increase was induced even more readily with stimulation via surface electrodes than via needles, probably because the surface electrodes allowed more current to be passed (Andersson 1973).
This type of stimulation, acupuncture-like low-frequency TNS, reduced the current necessary to elicit muscle contraction to half or two-thirds of the single shock values and was tried whenever our chronic pain patients did not experience analgesia from conventional high-frequency TNS. The compiled long-term results of stimulation treatment we then improved by about 40% (Eriksson 1976, Eriksson 1979).
INFLUENCE OF NALAXONE
From the present results it thus seems as if the acupuncture-like (lo-) TNS acts through links utilizing endorphins whereas conventional (hi-) TNS produces analgesia via some other mechanism.
ENDORPHIN MEASUREMENTS
When the concentrations of these endorphin fractions were measured in the cerebrospinal fluid of our chronic patients before (Fig. 3, C) and after (Fig. 3, EAP) acupuncture-like TNS, there was a systematic increase of the fraction I concentration in lumbar cerebrospinal fluid of those patients receiving stimulation of lumbar afferents (Sjolund 1977, unpublished; Fig. 3). This confirms the results on naloxone administration and in addition points to a local release and action of the endorphins at the spinal level during acupuncture-like TNS (see Duggan 1976, Yaksh 1976). With conventional TNS, no increase of endorphin concentrations has been seen in pilot experiments (L. Terenius, personal communication).
Chapman, C., Richard, W., Michael, E., and Gehrig, J.D. Comparative effects of acupuncture and transcutaneous stimulation on the perception of painful dental stimuli. Pain, 2:265-283, 1976.
SUMMARY
The effects of acupunctural stimulation on the perception of induced dental pain were compared with those of placebo acupuncture and transcutaneous electrical stimulation (TES) at an acupuncture site. Each of 4 groups of 15 subjects received one of the following treatments: acupuncture, placebo acupuncture, TES, or control conditions. Every subject was tested twice, once in a baseline session and on another day in a test session. Four levels of painful dental stimuli were delivered repeatedly and in random order to each subject in each session, who rated the perceived intensity of each stimulus on a pain category scale.
All three treatment groups showed a significant reduction in magnitude of stimulus ratings after treatment. A Sensory Decision Theory analysis of the data was employed to assess the sensory sensitivity of each subject to each of 4 levels of dental stimulation and the willingness of the subject to label the strongest stimulus as painful. Acupuncture and TES groups showed a small but significant sensory analgesic response to treatment and a significant reduction in willingness to identify the strongest stimulus as painful when contrasted to controls, but placebo acupuncture subjects failed to show significant change on either of the response measures. The effects of acupuncture were most pronounced at the lowest level of stimulation, while TES affected the perception of all levels of dental stimuli. The observed effects appeared to be small, reliable, and dependent on the stimulation of a particular anatomical locus.
METHODS
Four treatment groups were established: acupuncture, transcutaneous electrical stimulation (TES) at an acupuncture site, placebo acupuncture, and control. Subjects in each of these groups were tested twice on two separate days to provide a separate set of baseline and test measurements for each group.
It has been argued convincingly that acupuncture analgesia studies cannot be run double blind (Mark 1973), but is nonetheless desirable to reduce experimenter expectation effects as far as possible. Accordingly, a pseudo-double blind procedure was established in which a visual screen was used to ensure that neither the subject nor the experimenter could see which treatment was being administered to the subject during the test session. Of course, tactile cues were still available to the subject.
RESULTS
While SDT analyses are of intrinsic value, it is of interest to relate them to observable pain behavior. In this study, the perceivable behaviors were the ratings assigned to the dental stimuli, and the analgesic effects evident to an observer were the reductions in the magnitude of rating judgments given to the stimuli. In order to relate changes in d‟ and C4 to decreases in rating values, multiple regression methods were employed.
Since change scores indicated behavioral changes over sessions, they reflected treatment effects in the acupuncture and TES groups. It was of interest to ask how much of the treatment-induced change in pain ratings could be accounted for on the basis of change in sensory sensitivity and response bias. Multiple regression methods provided a way of estimating this and of evaluating the relative importance of sensory and bias factors.
In brief, this was done by using d‟ and C4 as predictors in order to create hypothetical estimates of mean rating change values for each subject. The accuracy of such predictions was evaluated by comparing the values predicted on the basis of d‟ and C4 with the actual mean rating measures. The results obtained indicated that the two SDT measures taken together were meaningful as predictors of the mean rating changes in the treatment groups. This implied that the observable behavioral changes in ratings reflected unobservable changes in sensory abilities and attitude toward reporting the stimuli as painful, in addition to inevitable measurement error.
In order to evaluate whether d‟ or C4 was most influential in determining the rating behaviors of the subjects, the proportion of variability among the rating change scores which could be accounted for by d‟ changes measures was estimated, and the same calculation was followed for the C4 values.
DISCUSSION
The data obtained from the acupuncture subjects have provided a general replication of the sensory hypalgesic effect reported by Chapman et al. (Chapman 1975). However, in the first study the d‟ analgesic effects appeared to be consistent in magnitude across stimulus levels but this was not replicated here. In Table II it is evident that such changes were greatest at the lowest level of stimulus intensity, and small or negligible at the higher levels. The results of the multiple regression analyses have supported this observation, indicating that acupuncture‟s effects were minimal for higher levels of stimulation. As a check, a multiple regression analysis similar to that described above was carried out on the acupuncture data collected by Chapman et al. (Chapman 1975). The essential results, reported in Table V, are highly consistent with those obtained in this study. Thus, while d‟ scores changed substantially at all levels of stimulus intensity in the earlier study, only the changes at the lower intensity were significantly related to changes in pain ratings. These findings indicate that acupuncture‟s analgesic effects were in fact quite similar to those of 33% nitrous oxide.
Interestingly, a similar result was obtained for subjects undergoing TES at an acupuncture site, and this agrees with the report of Andersson et al. (Andersson 1973) who observed a slightly greater increase in pain threshold with TES than with acupuncture. These observations suggest that the analgesic effects reported here were not dependent on the stimulation of deeper structures. Since the placebo acupuncture group showed no positive responses to treatment, it would seem that acupuncturally induced dental hypalgesia requires stimulation of specific loci.
Andersson, S.A., Holmgren, E., and Roos, A. Analgesic effects of peripheral conditioning stimulation – U. Importance of certain stimulation parameters. Acupuncture & Electro-Therapeut. Res. mt. J., Vol 2, No. 3 & 4, pp. 237-246, 1977.
ABSTRACT
The pain threshold effects in teeth, generally described in a previous paper, are related to certain parameters of the conditioning stimulation. A strong low frequency stimulation (2/see) giving pronounced beating sensations and powerful muscle contractions is needed to produce any significant threshold increase and no changes of the threshold were found at low intensities.
DISCUSSION
The present results show some important features of the pain threshold effects produced by low frequency conditioning stimulation. Thus, the degree of the threshold increase is mainly related to a relatively segmental location of the stimulating electrodes and to the intensity of the conditioning stimuli. If these parameters are kept constant the effect is also reproducible.
It can, however, be stated that conditioning stimulation of the maxillar branch of the trigeminal nerve influences the pain threshold of the teeth similarly in both the upper and lower jaw, the latter being innervated by the mandibular branch of the trigeminal nerve and thus not strictly segmental to the location of the stimulation electrodes.
The results of the present study give further support to the idea that basic physiological mechanisms are involved in the pain threshold effects of the conditioning stimulation (Andersson et al, 1976). If psychological suggestive components were most important, certain effects on the pain threshold would have been expected already at low intensities of the stimulation (levels A-C). The absence of effects, in spite of the sensations evoked by the electrical pulses, indicates that a suggestive component is not of any significant importance in the present experimental situation. This conclusion is also supported by the reproducibility of the effects at constant stimulation intensities and by the possibility of also producing threshold increases in primarily unresponsive subjects when they have been sufficiently acquainted to the experimental situation to allow an appropriate intensity of the conditioning stimulation.
The above mentioned observations suggest that the activation of large diameter afferent fibres conveying the information from low threshold cutaneous afferents is not sufficient to influence the pain threshold at a low stimulation rate. The pain threshold seems to increase only when the subjective magnitude of the beating and observed muscle contractions exceed a certain level. Apparently the conditioning stimulation must activate not only low threshold afferents but also fibres with higher thresholds. The present finding of a pronounced increase of pain threshold only at intensities giving rise to powerful muscle contractions, suggests that activation of muscle afferents is of importance in obtaining an increase of the pain threshold.
Andersson, S.A., and Holmgren E. Analgesic effects of peripheral conditioning stimulation – IL Effect of high frequency stimulation; Segmental mechanisms interacting with pain. Acupuncture & Electro-Therapeut. Res. mt. J., Vol 3, pp 23-36, 1978.
ABSTRACT
The effects on the pain threshold of teeth during conditioning stimulation with different frequencies were studied in volunteers. High intensity stimulation of the cheeks at 100/sec produced at onset a transient increase of the pain threshold essentially restricted to teeth of the upper jaw. No increase of the pain threshold was obtained by stimulation at 100/sec of the hands. Conditioning with 10/sec of the cheeks gave a rapid rise of the threshold followed by a gradual increase, but during prolonged conditioning the threshold declined. Stimulation with 2/sec produced a slow gradual increase of the threshold which remained at high level throughout a longlasting period. The after-effect was more pronounced at stimulation with 2/sec as compared to 10/sec. The segmental mechanisms of pain are discussed and it is suggested that the pain afferents should be considered as a subgroup of the flexor reflex afferents and that the segmental connexions of the pain afferents are subject to similar pre- and postsynaptic segmental and supraspinal inhibitory mechanisms as those known to exist with regard to the transmission from the flexor relex afferents to the flexor motoneurones. The effect of low frequency, high intensity conditioning stimulation on the pain threshold and on acute pain is discussed in relation to an increased inhibition at the input stage by feedback systems via the brain stem. High frequency stimulation is suggested to influence the pain threshold and chronic pain mainly due to pre and postsynaptic inhibition elicited by activity in primary afferents at the segmental level.
INTRODUCTION
A method of low frequency (1-3/sec) conditioning stimulation has been developed for Chinese acupuncture. Stimulation can be applied either through manipulation of needles of through low frequency high intensity electrical stimulation via either needles or surface electrodes. Both Chinese (cf. Kaada et al, 1974) and Western reports (Holmdabl, 1973; Mann et al., 1973; Omura, 1973, 1975) argue that this method of stimulation has a relieving effect in acute as well as chronic pain conditions. Electrical stimulation via needles or surface electrodes also produces a marded increase of the pain threshold (Andersson et al., 1977a). In contrast to the almost immediate effect of high frequency stimulation, the onset of the pain relief is gradual, lasting 15-20 min, and the after-effect is longlasting with a slow gradual return of the pain. The pain threshold also showed a gradual increase during low frequency electrical stimulation and a gradual decline in the post-stimulation period (Andersson et al., 1977a). Thus, there is a marked similarity between the time course of the clinical analgesia and the pain threshold increase during low frequency conditioning stimulation. Another similarity between the analgesia and the pain threshold increase is found in the high intensity required to obtain these effects during low frequency stimulation (Anderson et al., 1977c).
A pronounced pain threshold increase is obtained only by an intensity just below that producing pain. The importance of intense stimulation has abs been stressed in reports of surgical analgesia induced by conditioning stimulation (Peking Acupuncture Anaesthesia Co-ordinating Group, 1973; Section of Thoracic Surgery, Peking 1973). Thus pain relief during low frequency stimulation appears to be produced by recruiting another type of afferent fibres as compared with high frequency stimulation which is already effective at a moderate intensity activating low threshold mechano-receptors. The Analgesic effects of high and low frequency conditioning stimulation also differ with regard to their distribution. During low frequency conditioning, non- segmental effects have been stressed, particularly in Chinese reports, and it has been claimed that a generalized analgesia and pain threshold increase can be obtained by manipulation of needles at certain points. This effect contrasts strongly with the closely segmental pain relief found during high frequency stimulation and is also in conflict with the results in a previous report (Andersson et al., 1977c) which showed that the pain threshold increases mainly in regions related to those exposed to conditioning stimulation, i.e. mainly cheek stimulation increased the pain threshold of teeth. Some Chinese reports emphasize, however, the segmental stimulation is of importance to obtain analgesia sufficient for surgery (Hua Shan Hospital of Shanghai, 1973; Shanghai First People‟s Hospital, 1973).
Thus, large differences are found in the Analgesic effects of conditioning stimulation with high and low frequencies which suggests that the mechanisms interacting with the sensations of pain are different.
DISCUSSION
GENERAL CONSIDERATIONS
The slowly increasing and longlasting pain threshold changes produced by a conditioning stimulation of 2/sec were completely different from those produced at high frequencies. Stimulation at 100/sec induced an increase of the threshold almost exclusively in teeth into which the sensation of dull pain projected, and the threshold decreased rapidly during the continued conditioning. The threshold effect was obtained only at a high intensity. During continuous stimulation at a constant intensity the test subjects reported a decrease in the sensation of dull pain which approximately paralleled the decrease of the tested pain threshold. Stimulation at 10/sec appeared to produce changes of the threshold with characteristics of the effect from stimulation at 2/sec and at 100/sec. The rapid increase and fall of the threshold at the start and end of the 10/sec conditioning may be related to the transient effect at 100/sec. These threshold changes were followed by a slow increase and decrease respectively at the onset and end of the conditioning which are typical characteristics of the effects of stimulation at 2/sec.
SUPRASPINAL CONTROL
The transmission from the FRA both to flexor motoneurones and to ascending pathways, which may be involved in the transmission of pain, is tonically depressed from supraspinal structures as revealed in acute experiments in decerebrate cats (Holmquist et al., 1960). One such pathway is the dorsal reticulospinal pathway which arises in the brain stem and inhibits the transmission in the FRA pathways at an early stage in the interneuronal chain (Engberg et al., 1968a,b). A similar inhibition appears to be exerted on the FRA pathway by a serontoninergic descending system (Engberg et al., 1968c,d) arising in the dorsal raphe nuclei (Dahlstrom and Fuxe, 1965). It has been shown in behavioural experiments that stimulation of certain brain structures, especially in the mesencephalic central grey and in the dorsal raphe nuclei, induces analgeia without other behavioural changes. This holds true for different species such as rat (Mayer et al., 1971; Balagura and Ralph, 1973) and cat (Oliveras et al., 1974). These Analgesic effects may be due to the above mentioned descending inhibitory influences since the brain stem stimulation inhibits discharges, evoked by stimuli considered to be painful, in spinal neurones of lamina V (Oliveras et al., 1974). Stimulation of the orbital cortex also gives inhibition of these cells, an effect assumed to be mediated via the brain stem (Wyon-Maillar et al, 1972). The dorsal raphe nuclei are known to contain serotoninergic neurones (Dahlstrom and Fuxe, 1965) and further support of their descending Analgesic influence is the fact that analgesia induced by brain stem stimulation is antagonized by the serotonin synthesis inhibitory p-CPA (Akil and Mayer, 1972). A particularly interesting finding is the need for a long induction time (15-20 min) of this brain stem- induced analgesia (Melzack and Melinkoff, 1974). It is not known at present how the activity in these descending control systems varies during different conditions, neither is the functional significance of the input to these systems established. One possibility is that certain descending pathways are parts of a system which controls the level of excitability at an early stage of certain ascending pathways excited from FRA, including the pain afferents. The similarity in the characteristics of the Analgesic effects elicited by electrical stimulation in certain brain stem nuclei (Meizact and Melinkoff, 1974) and by low frequency conditioning stimulation suggests that essentially the same mechanisms are utilized. As a working hypotheses we assume that 2/sec conditioning stimulation induces a slowly increasing activity in descending control systems which inhibit the transmission of impulses both postsynaptically and presynaptically in the pain pathway. A certain topographical arrangement in the descending system is also required to account for the close relation between the regions of conditioning stimulation and the pain threshold although some general increase of the efficiency of the inhibitory effect may be present as suggested by the effect on the pain threshold of teeth due to conditioning stimulation of hands (Andersson et al., 1977c).
Support for the hypothesis that low frequency conditioning stimulation interferes with the transmission of activity in the FRA system has been obtained in animal experiments. After conditioning with 2/sec of forelimb nerves or the infraorbital nerves in awake cats the jaw opening reflex, elicited by electrical stimulation of the tooth pulp and considered as an analogue to the spinal flexion reflex (Sherrington, 1917), is depressed in parallel with reduced aversive reactions (Andersson, 1973; Andersson and Holmgren, in preparation). This observation is consistent with a Chinese report that low frequency (1/sec) electro-acupuncture depresses the jaw opening reflex and reduces the cortical potential evoked by electrical stimulation of teeth (Peking Acupuncture Anaesthesia Co-ordinating Group, 1973). In addition, it has been shown that brain stem stimulation at locations known to induce behavioural analgesia also increases the threshold for the jaw opening reflex (Oliveras et al., 1973)
RELATION TO CLINICAL PAIN
The discussed mechanisms of interaction with the sensation of pain are of interest in relation to clinical pain conditions. It is apparent from clinical reports that low and high frequency conditioning stimulation have different influences on acute and chronic pain. Acute pain seems to be relieved by low frequency conditioning stimulation. The time course of this effect is similar to the observed increase of the pain threshold with a long induction time (15-30 ruin) and longlasting post-stimulation effect. The analgesia is often sufficient to allow surgery. Our findings of an effect on the pain threshold mainly from areas with innervation relatively closely related to that receiving the pain stimulus, are in agreement with a number of recent reports on clinical analgesia during low frequency conditioning. Thus, large similarities seem to exist in the effect on the pain threshold and on clinical pain during conditioning stimulation with low frequencies. It is concluded that the same general pain blocking mechanisms give rise to the pain threshold increase and the clinical analgesia.
Andersson, S.A., and Holmgren, E. On acupuncture analgesia and the mechanism of pain. American Journal of Chinese Medicine. Vol 3, No. 4, pp. 311-334, 1975.
ABSTRACT:
The effect on the experimental tooth pain threshold of conditioning electrical stimulation via needles or surface electrodes applied to the hands and cheeks was studied in 34 dental students. Conditioning stimulation with 2/sec. gave a slowly increasing pain threshold followed by a slow return to the control level in the post-conditioning period. In each individual the amplitude of the threshold increase was reproducible. It was concluded that these effects are not due to motivational but to more basic neurophysiological mechanisms. The pain threshold was increased mainly by segmental conditioning stimulation; segmentally unrelated stimulation gave usually only small effects. Conditioning stimulation with 100/sec. produced only a strict segmental short-lasting effect. Effects with characteristics of both 2/sec. and 100/sec. were obtained by conditioning at 10/sec.
It is suggested that the transmission of impulses from the pain afferents to ascending pathways is controlled at the segmental level by (a) presynaptic inhibition within the group of afferents giving rise to the flexion reflex of which the pain afferents are assumed to be a part; (b) postsynaptic inhibition between alternate pathways excited by flexion reflex afferents; and (c) descending control from supraspinal systems which may utilize similar segmental mechanisms as the primary afferents.
The studies (Andersson, et al, 1975, Andersson, Holmgren and Roos, 1975, Andersson and Holmgren, 1975) summarized in this paper were initiated in order to experimentally elucidate whether a low frequency, electrical peripheral conditioning stimulation can influence the perception of pain. During the initial survey of such effects (Andersson, et al., 1975) using the tooth pulp as a pain test system, it was found that a pain threshold increase could be objectively demonstrated with several characteristics resembling the above mentioned “acupuncture analgesia.”
This paper also includes an extensive discussion regarding possible neurophysiological mechanisms underlying the pain threshold effects reported. These mechanisms are also discussed in relation to clinical pain.
MATERIAL AND METHODS
SUBJECTS
The present studies were performed on a group of students in the age group of 21-29 years. In order to avoid a biased selection a full class of 42 dental students was requested to participate in this investigation and all but two volunteered. Six students were excluded because of diseases or pregnancy. The remaining 34 students (15 females and 19 males) were all healthy and did not use drugs.
RESULTS
GENERAL PAIN THRESHOLD EFFECTS
The primary question in this study was: Can electrical conditioning stimulation increase the tooth pain threshold? The initial part of the investigation consisted of a standardized test procedure in which 30 students were studied, 18 with needle electrodes and 12 with surface electrodes (Andersson, et al., 1975). Each threshold value represents the mean value of several measurements of one of the six tested teeth. The control threshold was established two times with and interval of 15 to 30 minutes. The needles or surface electrodes were then applied and the stimulator connected to the electrodes but no electrical conditioning stimulation was given. The pain threshold was measured 15 to 20 minutes later. At time zero condition stimulation started with 2 impulses per second to hands and cheeks and the intensity was slowly increased during the following 10 minutes to a level just below that tolerable to the subject. The pain threshold was measured at intervals of 15 minutes. The stimulation was usually discontinued after 75 minutes, and the threshold was measured several times during the post- conditioning period. Since the duration of the conditioning stimulation period varied slightly, the time scale was reset when this stimulation was discontinued.
SUPRASPINAL CONTROL
The transmission from the FRA both to flexor motoneurones and to ascending pathways, which may be involved in the transmission of pain, is tonically depressed from supraspinal structures as revealed in acute experiments in decerebrated cats (Holmquist, Lundberg and Oscarsson 1960). One such pathway is the dorsal reticulospinal system which arises in the brain stem and inhibits the transmission in the FRA pathways at an early stage in the interneuronal chain (Endberg, Lundberg and Ryall 1968a,b). a similar inhibition appears to be exerted on the FRA pathway by a serotoninergic descending system (Endberg ,Lundberg and Ryall 1968c,d) arising in the dorsal raphe nuclei (Dahlstrom and Fuxe 1965). It has been shown in behavioral experiments that stimulation of certain brain structures, especially the mesencephalic central grey and the dorsal rephe nuclei, induces powerful analgesia without other behavioral changes. This holds true for different species such as rat (Mayer et al., 1971; Balagura and Ralph 1973) and cat (Oliveras, et al., 1974). These analgesic effects may very well be due to the above mentioned descending inhibitory influences, since the brain stem stimulation inhibits discharges evoked by stimuli considered to be painful in spinal neurones of lamina V (Oliveras, et al, 1974). Stimulation of the orbital cortex also gives inhibition of these cells, an effect assumed to be mediated via the brain stem (Wyon-Maillard, Conseiller and Besson, 1972). The dorsal raphe nuclei are known to contain serotoninergic neurones (Dalstrom and Fuxe, 1965) and further support for their descending analgesic influences is the fact that analgesia induced by brain stem stimulation is antagonized by the serotonin synthesis inhibitor p-CPA (Akil and Mayer, 1972). A particularly interesting finding is the need for a long induction time (15-20 minutes) of this brain stem induced analgesia (Melzack and Melinkoff, 1974). It is not known at present how the activity in these descending control systems varies during different conditions; neither is the functional significance of the input to these systems established. One possibility is that certain descending pathways are parts of a system which controls the level of excitability at an early stage of certain ascending pathways excited from FRA, including the pain afferents. The similarity in the characteristics of the analgesic effects elicited by electrical stimulation in certain brain stem nuclei (Meizack and Melinkoff, 1974) and by low frequency conditioning stimulation suggests that principally the same mechanisms are utilized. As a working hypothesis we assume that 2/sec. conditioning stimulation induces a slowly increasing activity in the descending control systems which inhibits the transmission of impulses both postsynaptically and presynaptically in the pain pathway. A certain topographical arrangement in the descending systems is also required to account for the close relation between the regions of conditioning stimulation and the Analgesic effect, although some general increase of the efficiency of the inhibitory effect may be present as suggested by the slight influence on the pain threshold of teeth due to conditioning stimulation of hands.
Some further support for the hypothesis that low frequency conditioning stimulation interferes with the transmission of activity in the FRA system has been obtained in experiments in awake cats after conditioning with 2/sec. of forelimb and/or infraorbital nerves. The jaw opening reflex, considered analogous to the spinal flexion reflex (Sherrington, 1917), elicited by electrical stimulation of the tooth pulp was depressed in parallel with reduced aversive reactions (Andersson, 1973; Andersson, 1975). This observation is consistent with a short Chinese note indicating the low frequency elector-acupuncture (1/sec.) simultaneously depresses the jaw opening reflex and reduces the cortical potential evoked by electrical stimulation of teeth (Peking Acupuncture Anaesthesia Co-ordinating Group 1973). Consistent results have also been obtained in experiments on cats where brain stem stimulation, previously known to induce analgesia, increased the threshold to jaw opening elicited by tooth pulp stimulation (Oliveras, Woda, Guilbaud and Besson, 1973).
Sjolund, B., Terenius, L., and Eriksson, M. Increased cerebrospinal fluid levels of endorphins after electro-acupuncture. Acta Physiol. Scand. 100, 382-384, 1977.
In modern Chinese acupuncture, low frequency electrical stimulation of the inserted needles is often used instead of the classical method of manual twirling (Kaada et al. 1974, Bonica 1974). As confirmed in Western investigations (Andersson et al.1973, Chapman et al. 1975) the pain threshold of healthy volunteers is increased with the procedure. Moreover, electro-acupuncture performed via surface electrodes has been found to be more effective than that via needles (Andersson et al. 1973), probably because the amount of current passed can be larger and the seemingly necessary muscle twitches in adjacent regions therefore are stronger (Andersson et al. 1976b). Despite these results, attempts to use acupuncture for the long term relief of chronic pain have been largely unsuccessful (Andersson et al. 1976a, Gaw et at. 1975). However, by modifying the stimulation technique to reinforce muscle contractions, electro-acupuncture via surface electrodes can give satisfactory relief of chronic pain (Eriksson and Sjoluad 1976).
The mechanism behind acupuncture analgesia remains unclear. However, naloxone, a specific opiate antagonist (Martin 1967), counteracts the increase in pain threshold in healthy individuals found after classical needle acupuncture (Mayer et al. 1975) as well as the analgesia from electro-acupuncture in patients with chronic pain (Sjolund and Eriksson 1976). A similar effect has recently been reported with mice receiving electro acupuncture (Pomeranz and Chiu 1976). These results suggest the activation of an inhibitory mechanism releasing endogenous morphinelike substances (endorphins; Hughes et al. 1975, Terenius and Wahlstrom 1975a). Since it is now possible to determine the concentrations of several endorphins in human cerebrospinal fluid (CSF; Terenius and Wahlstrom 1975b), we have investigated whether electro-acupuncture via surface electrodes (Eriksson and Sjolund 1976) changes the endorphin content of the CSF during the period of analhesia experienced by the patients.
The two chromatographic fractions (I and II) account for more that 75% of the total endorphin activity of the human CSF as measured in the receptor binding assay (Wahlstrom et al. 1976). In patients with no pain and apparently healthy, the CSF concentrations of these fractions, express as picomoles of Met-enkephalin/ml are 1.4+/-0.4 (mean +/- S.E.) pmol/ml (I) and 5.2/-+1.8 pmol/ml (II) respectively (Terenius et al. 1976). From the present results it appears that the lumbar CSF content of fraction I is very low in all patients while experiencing pain, confirming earlier observations on patients with trigeminal neuralgia (Terenius and Wahlstrom 1975b). No systematic change is seen with fraction II. During stimulation analgesia a marked rise of endorphin fraction I in lumbar CSF is seen in patients no. 1-4, while this is not the case in the other patients.
Cheng, R.S., and Pomeranz, B.H. Electroacupuncture analgesia is mediated by stereospecific opiate receptors and is reversed by antagonists of type I receptors. Life Sd. Vol 26, pp. 631-638, 1980.
SUMMARY
Dextronaloxone, a recently synthesized stereoisomer, which was shown to possess much less opiate receptor affinity than levonaloxone, produces no reversal of electroacupuncture analgesia (EAA) in mice. Since levonaloxone completely reverses EAA, this proves that stereospecific opiate receptors are involved. It has been reported that there are two classes of opiate receptors: Type I and Type II. Type I opiate receptors may be responsible for opiate analgesia. Antagonists of Type I receptors, levonaloxone, naltrexone, cyclazocine and diprenorphine, all block electroacupuncture analgesia at low doses. All together, these results strongly support the hypothesis that electroacupuncture analgesia is mediated by opiate receptors. Possibly Type I receptors are the major components of this system.
Type I opiate receptors are found mostly in the brain areas which mediate analgesia (Pert, C.B., Taylor, D.P. and Pert, A 1979). They are most likely the receptors responsible for exogenous or endogenous opiate analgesia.
However, it is highly unlikely that Type II receptors are involved in EAA since Type I antagonists completely reverse EAA. These results (the stereo- specificity data, and the effects of Type I blockers) strongly support the hypothesis that opiate receptors are involved in electroacupuncture analgesia.
Reichmanis, M., and Becker, R.O. Relief of experimentally-induced pain by stimulation at acupuncture loci: a review. Comparative Medicine East and West. Vol V., No. 3-4 pp. 281-288, 1977.
24 recent studies on acupuncture analgesia for the relief of experimentally- induced pain are reviewed. Negative or equivocal results are reported in 7 of these. The remaining 17(71%) report significant analgesic effects during manual or electrical stimulation (particularly at very low frequencies on the order of 2 Hz) at acupuncture loci. Many investigators note that the full analgesic effect is attained only after about 20 minutes of stimulation. Further investigation of the analgesic effects of stimulation at acupuncture loci, particularly the effect of very low frequency electrical stimulation, is fully warranted by these preliminary findings.
Several studies have been conducted on the effects of stimulation at acupuncture loci for the relief of dental pain, notably by Andersson et al. In a preliminary report, they stated that electrical stimulation at point Li-4 (dorsum of the hand) and other points in the area of the infra-orbital nerve significantly increased pain thresholds in 30 subjects. The analgesic effect reached a maximum about 30 minutes upon cessation (Andersson et al 1973). Surface electrodes were more effective than subcutaneous electrodes, and low frequency constant current stimulation (2 Hz) was more effective than higher frequencies (10 Hz, 100 Hz) in inducing analgesia (Andersson, S.A., and Holmgren E. 1975). Omura (Omura, Y., 1975) has also noted that longer-lasting effects are obtained with very low frequency electrical stimulation. Further tests showed that a fairly strong stimulus was needed for any significant increase in pain threshold (Holmgren, E., 1975).
Andersson, S.A. Pain control by sensory stimulation. Advances in Pain Research and Therapy. Vol. 3 Ed. John J. Bonica et al, 1979.
TNS developed from the hypothesis of pain-controlling gates (Melzack, R., and Wall, P., 1965) according to which an increased activity in large afferent nerve fibers could produce pain relief by blocking of the transmission in the pain pathways.
In contrast to acupuncture, TNS is usually given at high frequency (50 to 100 Hz) and with low intensity which is kept well below that giving pain. The subjective sensation is different from that during acupuncture and is described as tingling or vibration. There are no phasic muscle movements, but a light tonic contraction may occur in muscles close to the stimulating electrodes. The afferent nerve fiber discharge consists of a continuous firing in low-end high- threshold afferents depending on the intensity.
FREQUENCY OF STIMULATION
Another relevant parameter of the sensory stimulation is its frequency. Pain threshold measurements have shown that low frequency (1 to 4 Hz) gives a gradual and slow increase of the threshold which remains elevated during a long- lasting stimulation and returns slowly in. the poststimulation period. These effects contrast strongly the transient pain threshold observed during stimulation at high frequency (100 Hz). In spite of a continuous stimulation at high intensity, the pain threshold declines to the control level. It should also be noted that the effect is more localized than that at low frequency. Thus low-frequency stimulation of the cheeks increases the threshold of the teeth in both the upper and lower jaws, whereas high-frequency stimulation at the same location and intensity gives a transient effect only in the incisive and canine teeth of the upper jaw.
RELATION TO TRADITIONAL ACUPUNCTURE
Activation of high-threshold afferents is a common feature in needle manipulation and in electrical low-frequency stimulation. An obvious difference is, however, that needle stimulation has effects on receptors and afferents only in a limited region at the site of the needling whereas electrical stimulation must activate receptors in a much larger area in order to influence the pain.
Andersson et al. (Andersson, S.A., Block, F., and Holmgren E., 1976) tested low-frequency stimulation applied via surface electrodes. Stimulation a 2 Hz and with an intensity which elicited strong muscle contractions was given at the low back region bilaterally. The pain relief was very good or good in 48% of the women and some analgesia occurred in 37%. The results suggested a relation between high suggestibility and good analgesic effect. However, the study did not indicate that the pain relief was due to the suggestibility only since both suggestion and hypnosis had been used prior to the sensory stimulation without producing paid relief. Probably there are some factors which predispose for both hypnosiblity and analgesic effect during sensory stimulation.
When the low-frequency, high-intensity stimulation is modified into repetitive, high-frequency bursts, the conditioning is less distressing and pain conditions not relieved by high-frequency stimulation can be alleviated (Eriksson, M. and Sjolund, B. 1976).
There is evidence that low-frequency stimulation (acupuncture) activates descending control systems. Naloxone decreases or (?) eliminates the analgesia produced by classic needle acupuncture in healthy subjects. (Mayer, J.D., Price, E.R., Rafii, A., 1975). Moreover, naloxone inhibits the pain relief elicited by low- frequency electrical stimulation in patients with chronic pain but it does not counteract analgesic effects produced by high-frequency sensory stimulation (Sjolund, B., and Eriksson, M.,1977). A low concentration of endorphins is often found in the cerebrospinal fluid (CSF) of patients with chronic pain of somatic origin as compared to pain of psychogenic origin (Almay, B.G. et al., 1978). Low frequency electrical stimulation producing pain relief increases the CSF concentration of endorphins (Sjolund, B., Terenius, L., and Eriksson, M. 1977). The counteraction by naloxone of the pain relief after acupuncture could thus be due to an effect on the endorphin release by the stimulation.
Mannheimer, J.S., and Lampe, G.N. Clinical transcutaneous electrical nerve stimulation. Philadelphia: FA. Davis, p. 341, 1984.
STRONG, LOW -RATE (ACUPUNCTURE – LIKE) T.E.N.S.
Electrical parameters adjusted to provide a low rate 1 to 4 Hz), wide pulse width (150 to 250 usec), and high intensity are know as strong, low-rate (acupuncture-like) T.E.N.S. To be effective, this mode of T.E.N.S. requires an induction period of at least 20 to 30 minutes and must produce strong, visible muscle contractions in segmentally related myotomes. In those experiments comparing the effects of needle or surface stimulation (percutaneous versus transcutaneous), similar results were obtained and in many cases they were somewhat better with surface stimulation.
This mode of stimulation provides a definite prolonged aftereffect of pain relief, which seems to be related to the long onset.
Hansson, P., and Ekblom, A. Transcutaneous electrical nerve stimulation (TENS) as compared to placebo TENS for the relief of acute oro-facial pain. Pain. Vol 15, pp. 157-165, 1983.
SUMMARY
The present paper describes the effect of high frequency, low frequency and placebo TENS on acute oro-facial pain in 62 patients, attending to an emergency clinic for dental surgery; they had all suffered pain for 1-4 days. The patients were randomly assigned to one of three groups receiving either high frequency (100 Hz), low frequency (2 Hz) or placebo TENS. In the two groups receiving TENS (42 patients) 16 patients reported a reduction in pain intensity exceeding 50%; out of these 16 patients, 4 patients reported complete relief of pain. In the placebo group (20 patients) 2 patients reported a pain reduction of more than 50%; out of these 2 patients, none reported a complete pain relief
METHODS
The effect of TENS and placebo TENS was studied in 62 patients aged 19- 54 years (26 males and 36 females) admitted to an emergency clinic for dental surgery for treatment of oro-facial pain. The most common causes for the pain were pulpal inflammation, apical periodontitis (including facial abscesses) and postoperative pain following removal of a tooth. Patients with these diagnoses were represented in equal numbers in the test groups and in the placebo group. All patients suffered from acute pain; most of the patients had experienced pain for 1- 4 days. None of them had taken analgesics within 6 h before submitted for treatment. All of the patients were examined, told the diagnosis and asked if they would take part in the experiments. Those willing to participate were informed about their role in the experiment. Furthermore the subjects were told that they might or might not experience pain relief as well as aggravation of pain during stimulation. Every effort was made to avoid suggestion. The patients were told that they could stop the stimulation at any time and all the patients were informed that they would get a conventional dental treatment after termination of the stimulation.
The patients were assigned randomly to one of the three groups, high frequency, low frequency or placebo TENS. They were asked to rate their pain intensity before they received any stimulation, by using a 5-graded verbal scale.
DISCUSSION
Previous studies concerning the pain reducing effect of TENS in acute (Augustinsson, et al 1977, Hymes, et al 1974, Rosenberg, et al, 1978, and Van der Ark, et al 1975) and chronic (Ihalainen, et al 1978, Loeser, et al 1975, Long, et al 1975, and Picaza, et al 1975) pain of different origin are consistent in showing temporary alleviation of pain in about 50% of the patients. It must be pointed out, however, that different authors use different criteria in evaluating the pain reduction obtained by TENS, which makes it difficult to compare results in various reports.
The findings in the present study clearly show that TENS of either 100 or 2 Hz may reduce or abolish acute oro-facial pain. On the basis of our results, no significant difference could be observed between the pain relieving effect of high frequency and low frequency TENS. However, it should be noted that most patients found the muscle twitches produced by the low frequency TENS uncomfortable. This was in contrast to high frequency TENS which most often produced a pleasant sensation and a feeling of warmth. Sixteen of the 42 patients treated with TENS experienced a pain relief exceeding 50%, which in the placebo group 2 out of 20 patients reported a similar degree of decrease in pain intensity. The magnitude of the placebo effect in this study, if considering all patients in the placebo group who reported some relief of pain (i.e., 8 out of 20 patients), is similar to that reported in other studies (Thorsteinsson, et al 1978), i.e., a 40% placebo effect. The difference between the pain alleviating effect of TENS as compared to placebo TENS suggests that the reduction of pain obtained in the present study is unlikely to be due to placebo effects.
In studies of any method of treating pain it is important to compare the pain alleviation obtained with that of other modes of treatment. We did compare TENS and placebo TENS to the pain relief obtained from pharmacological substances used by the patients before visiting the clinic. It is interesting to note that only 1 of the 5 patients receiving placebo TENS rated this superior to the analgesic medication used, while 12 out of 23 patients receiving TENS rated the TENS effect higher than analgesics used. All patients rating TENS and placebo – TENS superior to the specific analgesic medication used, experienced a pain relief from TENS or from placebo-TENS exceeding 50%
In conclusion, the observations in the present study suggest that acute oro – facial pain can be effectively reduced by TENS, either at 100 or at 2 Hz. The results of the present study and previous findings (Ottoson, et al 1981) further suggest that vibratory stimulation in some cases is superior to TENS.
Terezhalmy, G.T., Ross, G.R. and Holmes-Johnson, E. Transcutaneous electrical nerve stimulation treatment of TMJ-MPDS patients. Ear, Nose and Throat Journal. Vol 61, pp. 22-28, December 1982.
Correct diagnosis and selection of the most effective therapeutic approach for the management of TMJ – MPDS require not only knowledge of the etiology, physiopathology, symptomatology, and affective qualities of the pain syndrome but also an awareness of the availability of different modes of therapy. The purpose of this study is to examine the effect of transcutaneous electrical nerve stimulation (TENS) on patients with TMJ-MPDS and to analyze factors that might influence patient response to transcutaneous stimulation.
TRANSCUTANEOUS ELECTRICAL NERVE STIMULATION
The Panel on Review of Neurological Devices of the Food and Drug Administration concluded in its 1976 report that (1) TENS is progressing in technical sophistication, (2) a reasonable and acceptable degree of efficacy has been documented in long-term trials, (3) TENS is being accepted by many members of the health care community as a safe and simple therapeutic means of alleviating pain, and (4) TENS provides a meaningful alternative to other types of pain therapy that are known to have a higher degree of risk (FDA Report, 1976)
MATERIALS AND METHODS
Twenty-five patients suffering from pain associated with TMJ-MPDS participated in this study. These patients were selected on the basis of one or more of the following criteria: (1) intrajoint pain associated with muscle tenderness and ear symptoms; (2) muscle spasms related to fatigue and tension due to sudden or chronic stretch; (3) a combination of intrajoint pain and muscle spasms; (4) referred pain from trigger points within a muscle in spasm, and (5) limitation or loss of mandibular function without evidence of systemic or neoplastic disease. Informed consent was obtained from all patients.
A Pain Rating Index was developed on the basis of the McGill Pain Questionnaire‟s intensity scale in the sensory temporal, constrictive pressure, dullness, and miscellaneous categories; evaluative category; and two supplementary miscellaneous subclasses. Each subclass has an intensity scale ranging from 1 to 5 in order of increasing intensity. The intensity scores in each subclass were added to determine the Pain Rating Index for each patient
DISCUSSION
Our study indicates that TENS offers a rapid, noninvasive, and generally predictable means of pain suppression. It can be a valuable alternative to other modes of therapy in the treatment of TMJ-MPDS. If TENS therapy is successful, no other treatment would appear to be necessary. When TENS therapy is less than effective or does not give the desired pain relief, other treatment modalities must be considered. Correction of minor and major dental occlusal discrepancies, pharmacotherapy, and surgery are invasive procedures and are therefore not without risk. As such, we believe that biofeedback techniques and psychological counseling may appropriately take precedence in the treatment of the patient with TMJ – MPDS.
Although comparisons of TENS treatment with a placebo were not done in this study, two separate investigators have shown that the placebo effect with TENS is in the range of 32 to 33 percent (Loeser, et al 1975, Thorsteinsson, et al, 1977). In both of these studies, the placebo effect appeared to be brief and gave little evidence to support the contention that the effect persists for any significant period of time. Our findings of 72 percent long-term responses were considerably greater than the accepted placebo effect.
The McGill Pain Questionnaire appeared to be sufficiently sensitive to provide the clinician with important information concerning patient response to TENS. It has the potential for providing qualitative and quantitative data that can be analyzed, and it should be useful in distinguishing among the effects of different methods of controlling pain
CONCLUSION
TENS is an effective, noninvasive means for suppressing pain caused by TMJ-MPDS. Patient responses to treatment may be evaluated with the McGill Pain Questionnaire. The MMPI provides important information concerning the patient‟s emotional equilibrium and is a valuable prognostic tool. Our data suggests that TMJ-MPDS is multifactorial and that no single discipline or therapeutic approach should necessarily be considered the only method for patient management.
Phero, J.C., Raj, P. P., and McDonald, J.S. Transcutaneous electrical nerve stimulation and myoneural injection therapy for management of chronic myofascial pain. The Dental Clinics of North America. Vol. 31, No. 4, October 1987.
TRANSCUTANEOUS ELECTRICAL NERVE STIMULATION
The present-day use of TENS began after the 1965 publication of Melzack and Wall‟s classic paper “Pain Mechanisms: A New Theory” (Meizack, et al 1965). Two years later, it was found that external application of electrical stimulation was effective in relieving pain. This technique was used to determine if a patient was a suitable candidate for the surgical implantation of dorsal column electrodes (Shealy, C. 1972). These researchers laid the foundation for the current utilization of TENS to manage acute and chronic pain.
TENS has been used in a variety of health care settings including pain control centers, emergency rooms, operating rooms, postanesthesia care units, and labor rooms. There is a need for health professionals to develop knowledge and expertise in this noninvasive method of providing patient analgesia. Of key importance is the area of patient education in the use of TENS. With proper training and equipment, the patient can learn to utilize a TENS unit at home with satisfactory results often giving them a significant degree of self-control over their chronic pain.
THEORIES ON MECHANISM OF ACTION
The placebo effect noted with the use of TENS has been a subject of study by many researchers. The placebo effect is believed to be minimal (Long, D. 1974). If it occurs during a trial of TENS it will not be sustained.
INDICATIONS FOR TENS
TENS has been demonstrated to be effective in relieving both acute and chronic pain. TENS therapy alone may be sufficient to modulate pain, but it is most often used in conjunction with other modalities of therapy to maintain relaxation and relief of pain
GOALS OF TENS THERAPY
The goals of TENS therapy as a single modality or in conjunction with other modalities are as follows: a 50 per cent decrease in pain, a 50 per cent increase in function and mobility, and a SO per cent decrease in medication with the elimination of agents with addictive potential. These results have been obtained using TENS on patients experiencing acute pain and chronic pain (Hymes, et al 1974, Long, D. 1977, Shealy, C. 1972, Shealy, C.N. 1974)
MODES OF STIMULATION
ACUPUNCTURE MODE (HIGH WIDTH, LOW RATE)
This setting is often the second mode of choice and is very effective for deep, aching chronic pain. It is useful when previous nerve damage has occurred (3M: TENS, 1983). This mode stimulates the cutaneous, subcutaneous and deep nerve fibers. A low rate, <10 -0.6599="" -337="" -35="" -scand.="" -t="" .="" 0.001="" 0.01="" 0.02="" 0.059="" 0.05="" 0.084="" 0.125="" 0.152="" 0.158="" 0.180="" 0.249="" 0.26="" 0.2="" 0.31.o="" 0.3="" 0.46="" 0.58="" 0.5="" 0.7="" 0.9="" 0.ll7ms="" 0="" 1-109="" 1-2="" 1-353.="" 1-36="" 1.01="" 1.0="" 1.3="" 1.5-second="" 1.5="" 1.6="" 1.8mm="" 1.="" 100:258-264="" 100:382-384="" 100="" 1012.s="" 1046-1050="" 106="" 109="" 10:1065-1077="" 10:13-35="" 10:37-45="" 10="" 11.67="" 11.="" 113:293-310="" 115:111-128="" 115="" 117:492-499="" 1187-="" 1194="" 11:109-115="" 11:445-454="" 11:61="" 11="" 121-158="" 123:214-224="" 123:553-564="" 123="" 125="" 125hz="" 127:393="" 127:508-510="" 12:107-112="" 12:255-261="" 12="" 13.5="" 130-187="" 130:338-340="" 132:="" 133="" 135-154="" 135:439="" 13:365-371="" 13:37-45="" 141="" 144="" 146="" 147-156="" 148-153="" 14:359-383="" 14="" 14c10="" 14c20="" 150:2067-2071="" 150:971="" 154="" 155:108-109="" 15="" 15mm="" 15uv="" 1600="" 161="" 166="" 167-179="" 168:168-169="" 16:1759-1764="" 16:210-217="" 16:447-456="" 16:59="" 16="" 171:545-548="" 173:295-301="" 174:1351-1354="" 178:311-327="" 17:147="" 17:303-312="" 17:79-96="" 17="" 185-193="" 185="" 187:173-189="" 187:239-245="" 1883.="" 1883="" 189:66="" 18:122-129="" 18:167-178="" 18:169-178="" 18:169="" 18="" 19.="" 1912.="" 1912="" 1917.="" 1921.="" 1921="" 1927.="" 1927="" 1928="" 1929.="" 1929="" 192:1356-1358="" 192:518-525="" 1931.="" 1931="" 1934.="" 1934="" 1935.="" 1935="" 1939.="" 1939="" 193="" 1942.="" 1942="" 1948="" 1949.="" 1949="" 194:201-223="" 194:225-236="" 1951.="" 1951="" 1952.="" 1952="" 1953.="" 1953="" 1954.="" 1954="" 1955.="" 1955="" 1956.="" 1956="" 1957.="" 1957="" 1958.="" 1958="" 1959.="" 1959="" 1960.="" 1960="" 1961.="" 1961="" 1962.="" 1962="" 1963.="" 1963="" 1964.="" 1964="" 1965.="" 1965="" 1966.="" 1966="" 1967.="" 1967="" 1968.="" 1968="" 1968a.="" 1968b.="" 1968c.="" 1968d.="" 1969.="" 1969="" 1970.="" 1970="" 1971.="" 1971="" 1972.="" 1972="" 1973.="" 1973="" 1974.="" 1974="" 1975.="" 1975="" 1975a.="" 1975b.="" 1975c.="" 1976.="" 1976="" 1976a.="" 1976b.="" 1977.="" 1977="" 1977a.="" 1977c.="" 1978.="" 1978="" 1979.="" 1979="" 1980.="" 1980="" 1981.="" 1981="" 1982.="" 1983.="" 1983="" 1985.="" 1985="" 1986.="" 1986="" 1987="" 1988.="" 1988="" 1997="" 19:1757-1762="" 19:262-278="" 19:353-359="" 19="" 1:1.8="" 1:109-123="" 1:14-16="" 1:157-181="" 1:16-="" 1:2="" 1:51-141="" 1:607-622="" 1="" 1mm="" 1st="" 2.0.="" 2.0="" 2.2="" 2.6mm="" 2.77="" 2.9mm="" 2.="" 20-30="" 20-minute="" 20.30="" 2000="" 203:735-738="" 206="" 209-210="" 209-320="" 20:32-44="" 20="" 20th="" 219:1324-1329="" 21:257-268="" 21:269-277="" 21="" 22-37="" 220:1-18="" 220="" 221="" 225:1532="" 229="" 22:589-592="" 22="" 23:157="" 23:419-421="" 23:917-920="" 24-45="" 2421-2423.="" 243="" 245-="" 246:="" 247="" 24:142-145="" 24:447-455="" 24:725="" 24:="" 24="" 25-27="" 253:31="" 253="" 258:577-579="" 25:222-224="" 25="" 26-27="" 260="" 261:302-321="" 264:456-458="" 26:379-392="" 26:547-553="" 26="" 273-281="" 276="" 280="" 287="" 28:297-301="" 28:43-51="" 28:45-46="" 28="" 291-303="" 293="" 29="" 29th-oct.="" 2:1085="" 2:13="" 2:16="" 2:17="" 2:20="" 2:237-246="" 2:265-283="" 2:307-322="" 2:379-404="" 2:405="" 2:564="" 2:57-60="" 2="" 2a61="" 2mm="" 2nd="" 3-32="" 3.0="" 3.1="" 3.4mm.="" 3.61="" 3.6="" 3.84="" 3.8="" 3.="" 30:19-24="" 30:559="" 30="" 319-323="" 32:594-598="" 32="" 33.33="" 33.4="" 331.="" 331="" 33="" 343-350.="" 34:245="" 34:3="" 34:75="" 34="" 350-352="" 35:66-71="" 35:837-857="" 35:9-10="" 35="" 36:632="" 36:763-768="" 375-378="" 37="" 381-420="" 38:3="" 38="" 3:12="" 3:133-142="" 3:151-157="" 3:155-162="" 3:157-162="" 3:271-281="" 3:311-334="" 3:57-58="" 3:587-591="" 3="" 3a74="" 3m:tens:="" 3m="" 3rd="" 4.6="" 4.79="" 4.7="" 4.="" 40:217-248="" 40="" 410="" 41:203-214="" 41:39-48="" 41:456="" 41:548="" 41="" 42:308-314="" 42:532-537="" 42="" 43:137="" 43:369-374="" 448="" 44:438="" 44:656="" 44:692-697="" 44="" 45.4="" 45.55="" 45:307-314="" 45="" 46:71-83="" 47:149-162="" 483="" 49-56="" 4:105-114="" 4:187-194="" 4:59-65="" 4:761-767="" 4="" 4th="" 5-a.="" 5-bd="" 5.97="" 5.="" 500="" 50="" 51:394="" 51:404-431="" 52:1046-1050="" 52="" 539-543="" 549-569="" 54a:165="" 55:684-690="" 565="" 569-585="" 56="" 57-62="" 575-581.="" 575-581="" 58:8-13="" 58="" 59="" 5:129-133="" 5:153-162="" 5:31-="" 5:399-407="" 5="" 5a="" 5b="" 5e="" 5f="" 5th="" 6.06="" 6.0="" 6.28="" 6.5="" 6.67="" 6.78="" 6.89="" 6.98="" 6.9o="" 60-90="" 60:327-330="" 60:369-379="" 60="" 619="" 61="" 62="" 63:19-26="" 63:393-396="" 64:445-456="" 64="" 65="" 66:538-556="" 66:813="" 66="" 677-681="" 67:625-646="" 67="" 68:412-419="" 69:244-247="" 69="" 6:119-136="" 6:25="" 6:335-347="" 6="" 7.0="" 7.2="" 7.6="" 70:701-720="" 70:707-708="" 70="" 71:1171-1181="" 71:156="" 72:115-122="" 72:123-133="" 73-96="" 73="" 74:175-182="" 74:351-354="" 74:86-90="" 75:385="" 75="" 75hz="" 761-678="" 77-109="" 77:679-688="" 78:404-="" 78="" 79:131="" 79:93="" 79:="" 79="" 7:251="" 7:31-53="" 7:35-51="" 7:360="" 7="" 7th="" 8.1="" 8090="" 80="" 813-816="" 817-820="" 818="" 81:12="" 81:272-275="" 81:290-292="" 82:468="" 82:61-70="" 857-864="" 86:312-319="" 86="" 87.87="" 8:207-215="" 8:481-484="" 9.9="" 90:834-840="" 90="" 94:417-442="" 94:74-81="" 95="" 97:44="" 98:60-80="" 9:139-147="" 9:183="" 9:35-39="" 9:47-52="" 9="" a.="" a.c.="" a.e.="" a.g.="" a.h.="" a.i.="" a.k.="" a.l.="" a.s.="" a.w.="" a="" able="" abnormal="" abnormally="" abolish="" abolishment="" abolition="" about="" above.="" above="" abraded="" abs.="" absence="" absent.="" absent="" abstr.="" abstract="" abstracts.="" abstracts="" abundant="" abuse="" ac="" acad.="" academic="" academy="" accepted="" accompanied="" accompanies="" accompanying="" accomplished="" accordance="" according="" accordingly="" accounted="" accumulated="" accumulation="" accuracy="" accurate="" acetylcholine="" achieve="" achieved.="" achieved="" achievement="" acid="" acoustic="" across="" acrylic="" act="" acta="" acting="" action.="" action="" actions="" activa="" activated="" activates="" activities.="" activities="" activity.="" activity="" acts="" actually="" acupunct.="" acupuncture-like="" acupuncture.="" acupuncture:="" acupuncture="" acute="" adaptive="" added="" addition="" additional="" adequate="" adhesive="" adjacent="" adjunct="" adjunt="" adjust="" adjustable="" adjusted="" adjustment="" adjustments="" administration="" adopted="" adv.="" advance="" advanced="" advances="" advantage="" aetiology="" aetiopathogenetical="" affect="" affected="" affections="" affects="" afferent="" afferents.="" afferents="" affords="" after="" again="" age.="" age="" agents.="" agents="" aging="" agitated="" agladery="" ago="" agonist="" agree="" ahlgren="" aid="" aide="" ailing="" aillard="" aim="" air="" ak="" akil="" akupunktur.="" akupunktur="" al.="" al="" alabama="" aladjemoff="" alarm="" albe-fessard="" albeit="" alerted="" algic="" alginate="" algoceptor="" algren="" alium="" alive.="" all="" alleviate="" allow="" allowance="" almay="" almost="" alone="" along="" alpha="" already="" also="" alter="" alteration.="" alteration="" alterations:="" alterations="" altering="" although="" always="" am.="" am4b="" am="" amer.="" american="" amfjord="" amine="" among="" amount="" amp="" amplification="" amplified="" amplifier="" amplifiers="" amplitude="" amsterdam="" an="" anaesth.="" anaesthesia.="" anaesthesia="" analgesi="" analgesia.="" analgesia:="" analgesia="" analgesiants="" analgesic="" analisi="" analyses.="" analyses="" analysing="" analysis.="" analysis="" analyzed.="" analyzed="" anat.="" anat="" anatomic="" anatomical="" anatomically="" anatomy="" ancherz="" and="" anderson="" andersson="" andrews="" anesthesia.="" anesthesia="" anesthesiology="" angina="" angle="" animals="" ankelson="" ann.="" annals="" annu.="" anong="" anordnung="" anossia="" another="" anoxia.="" ansigtssmerter="" anson="" answer="" antagonism="" antagonists.="" antaleo="" anterior="" anteroinferior="" anteroposterior="" anthony="" anthropoiden.="" antidromic="" antidromically="" antithesis="" anwendung="" anxiety="" any="" anz.="" apanese="" apfelbaum="" apparatus.="" apparatus="" apparently="" appeared.="" appeared="" appears="" appl.="" applicability="" applicate="" application="" applications="" applied.="" applied="" applying="" appointment:="" appointments:="" approach="" approached="" approaches.="" approximately="" ara="" arbitrary="" arc.="" arc="" arch.="" arch="" arches="" archiv="" archives="" archs="" arcs.="" are="" area="" areas="" arethrography="" argued="" aris="" arise="" arisen="" ark="" arlsoo="" arm="" around="" arrest="" arrison="" arrived="" arthritis="" arthrography.="" article="" articles="" articular="" articulator="" as="" ascend="" ascending="" ash="" asked="" askin="" aspects="" ass.="" asser="" assess="" assessed="" assessing="" assist="" assoc.="" associated="" association.="" association="" assumed="" assumes="" assuming="" assumption="" assured="" astrom="" asymptomatic="" at="" atelectasis.="" atkins="" atp-adp.="" attained="" attainment="" attempt="" attempts="" attention.="" atypical="" audiomonitor="" aug.="" aug="" augustinsson="" author="" authors="" av="" availability="" avelow="" average="" averaged="" averages.="" avoid="" away="" awson="" axon="" ayer="" azarbal="" b-115="" b.="" b.a.="" b.b.="" b.e.="" b.g.="" b.g.l.="" b.h.="" b.m.="" b.n.="" b.r.="" b.w.="" b="" back="" bag.="" balagura="" balance.="" balance="" balanced.="" balanced="" baltimore:="" baltimore="" basbaum="" base="" based="" basel="" baseline="" basis="" basmajian="" bassett="" bayerl="" bays="" bazzoti="" bazzotti="" be="" beam="" bear="" became="" because="" become="" becomes="" bedovningseffekter="" been="" beers="" before="" behavioral="" being="" believe="" bell="" below="" beneficial="" benoist="" berlin.="" besonderes="" bessette="" besson="" beta-lipoproteins="" better="" between="" bevaegesystem="" bias="" bigland="" biglund="" bilaterally="" biochemical="" bioelectric="" biol.="" biol="" biology.="" biology="" biomed="" bipolar="" bite="" biting.="" biting="" black="" block="" blockade="" blocked="" blood="" body.="" body="" boever="" bohlin="" bonde-petersen="" bonde-peterson="" bone="" bonica="" bonikos="" bonvallet="" book="" boone="" borne="" boschiero="" both="" bottom="" bourke="" bourne="" bowsher="" boyd="" br.="" brachial="" brain="" brainstem="" branches="" bratzlavsky="" breakdown.="" breakdown="" breathed="" breathing="" brignolio="" brill="" brings="" bristol="" brit.="" brussels="" bruxism.="" bruxisme.="" bstract="" bstracts="" buccinator="" buchthal="" builds="" built="" bulbospinal="" bull.="" bundsen="" burton="" but="" by="" byproducts="" c.="" c.a.="" c.b.="" c.c.="" c.i.="" c.j.="" c.n.="" c.p.="" c.r.="" c.s.="" c.v.="" c.w.="" c4.="" c="" cadaver.="" cademy="" calculate="" calculated.="" calculated="" calculating="" calculation="" calculations.="" calibration="" called="" came="" camera="" can="" cannot="" cannow="" capability="" capable="" capacity="" capillary="" carder="" cardiac="" cardiol.="" cardiovascular="" cardle="" care.="" care="" careful="" carlsoo="" carlsson="" carried="" carroll="" case="" cases.="" cases="" cast="" casting="" casts="" cat.="" cat="" categories.="" categories="" causal="" cause="" caused="" causes="" causing="" ccles="" cells="" cent="" center.="" center="" centers="" central="" centric="" centrically="" centro="" cephalographs="" cephalometric="" cephalometrics.="" cerebrospinal="" certain="" certainly="" cervical="" chaco="" chaffin="" chage="" chair="" chalmers="" chang="" change="" changes="" changing="" chap.="" chapman="" character.="" character="" characteristic="" characteristics="" characterization="" characterized="" charging="" charles="" check="" checked="" checking="" chem.="" chemical="" chemistry="" chewing="" chex="" chez="" chiang="" chicago="" chiefly="" children:="" children="" chin.="" china.="" chiu="" choi="" chosen.="" christensen="" christman="" chronaxies="" chronaxy.="" chronaxy="" chronic="" chu="" chuanliao="" chudy="" cintyre="" circle.="" circle="" circulation="" circulatory="" cited="" clarified="" clarify="" class="" classic="" classification.="" classifications="" claudicatio="" claudication.="" claudication="" clear-cut.="" clear-cut="" clear="" clearance.="" clearance="" clearly="" clemente="" clench="" clenching:="" clenching="" clin.="" clin="" clinic="" clinical="" clinician="" clinicians="" close="" closed="" closing="" closure.="" closure="" closures.="" cluster="" cm.="" cm="" co-ordinating="" co.="" coincided="" coincident="" collaborators="" college.="" college="" combined="" comfortable="" common="" commonly="" communication.="" communication="" company="" comparaison="" comparative="" compare="" compared="" comparison.="" comparison="" comparisons="" compatible="" compensation="" competing="" complained="" complaints="" complete="" completed.="" completely="" complex="" component.="" composed="" compounds="" compression="" comprised="" compromise="" compute="" computer-aided="" computerized="" concentrations="" concepts="" concern="" concerned="" concerning="" concluded="" conclusion="" conclusions:="" conclusions="" condition.="" condition="" conditioned="" conditioning="" conditions.="" conditions="" conducted="" conducting="" conduction-="" conduction-velocity="" conduction="" condylar="" condyles="" confidently="" configuration="" confirm="" confirmed="" confirming="" confirms="" conflict="" conflicting="" confronted="" cong.="" congr.="" congress="" conjunction="" conn.="" connection="" connections="" conseiller="" consent="" consequence="" consequent="" consider="" consideration.="" considerations="" considered="" consisted="" consistent="" constancy="" constant-current="" constant-voltage="" constant="" constantcurrent="" constantly="" consultation="" contact="" continually="" continue="" continued="" contract.="" contract="" contracted="" contracting="" contraction.="" contraction="" contractions.="" contractions="" contracts="" contracture.="" contracture="" contractures="" contralateral="" contrary="" contrast="" contribute="" control="" controllable="" controlled="" controls="" conventional="" converts="" cooper="" coordinating="" coordination="" copenhagen:="" corbin="" cord.="" cord="" core="" corp.="" corporation="" correct="" corrected="" correction.="" correction="" corrections.="" corrections="" correlate="" correlated.="" correlated="" correlation="" corresponded="" correspondence="" corresponding="" cortex="" cortical="" cosenza="" cost="" costen="" could="" coupling="" course="" crane="" cranial="" cranio-mandibular="" cranio="" craniocervial="" craniodentofacial="" craniomandibular="" cranium-mandibular="" creased="" creation="" crepitus="" criteria:="" criteria="" criterion="" critical="" critique="" cross-bridge="" cross="" csf.="" csf="" ct="" cup="" current="" currents="" curtis="" curve-fitting="" curve="" curves:="" curves="" cutaneous="" cycle.="" d.="" d.d.="" d.e.="" d.f.="" d.g.="" d.h.="" d.j.="" d.l.="" d.m.="" d.p.="" d.s.="" d="" dahlstrom="" dandy="" dao="" data.="" data="" date="" davenport="" dawson="" days="" de="" deals="" debiasi="" decerebrate="" decided="" declenche="" decompression="" decrease="" decreased="" decreases="" deep="" defect="" deficiency="" defined="" definite="" definition="" definitive="" deformation="" degeneration.="" degree="" dei="" delay.="" delay="" delayed="" deliver="" delivering="" delivers="" delivery="" demonstrated="" demonstrates="" den.="" den="" dennis="" denominated="" density="" dent.="" dent="" dentaire="" dental="" dentistry.="" dentistry="" dentition.="" dentition="" dentitions="" dentofacial="" denture="" dentures.="" dentures="" deny="" departure="" dependent="" depending="" depletion="" depolarization="" depolarizations="" depressed="" depressor="" dept.="" der="" derangements="" derijk="" derived="" dermal="" des="" descended="" descending="" describe="" described.="" described="" describes="" describing="" description="" descriptive="" designed="" detailed="" detect="" detectable="" detected="" detection="" determination="" determine="" determined.="" determined="" determines="" determining="" deutsche="" develop="" developed.="" developed="" development="" developments="" device="" devices.="" devices="" devoid="" devon="" di="" diagnosis="" diagnostic="" diagram="" diameter="" diameters="" diathermy="" diazepam="" dickel="" did="" didn="" die="" diencephalon="" differ="" difference="" differences="" different="" differential="" differentiate="" differentiated="" differing="" difficultly="" difficulty="" digastric="" dilemma.="" dimension.="" dimension="" dimensions.="" dimensions="" dinham="" diphasic="" direct="" directed="" directly="" disappear="" disappearance="" disappeared="" disappears.="" discharge="" discharged="" discharges="" discontinued="" discontinuities.="" discreetly="" discrepancies="" discrepancy="" discrimination="" discussed="" discussion="" disease.="" disease="" diseases="" disfunction="" disnociceptive="" disorders:="" disorders="" displacement="" displayed="" disposed="" distal="" distance="" distinction="" distorting="" distress="" distribution="" district="" districts="" disturbance="" disturbances="" disturbed="" disturbing="" dited:="" dited="" diverse="" divided="" division="" dixon="" dj.="" do="" doctoral="" documented="" does="" dollo="" dolore="" done="" doppler="" dorpat="" dorsal="" double-blind="" double="" douloureux.="" douloureux="" draw="" drug="" drugs="" dtsch.="" du="" dubota="" ductility="" due="" duggan="" duration.="" duration="" during="" dynamic="" dynamics="" dysfunction.="" dysfunction:="" dysfunction="" dysfunctional="" e.="" e.b.="" e.g.="" e.h.="" e.m.g.="" e.t.="" e.w.="" e="" each="" earlier="" early="" ears="" easily="" easy="" eberstein="" eble="" eccles="" ecurrent="" ed.="" ed="" edema="" edentulous="" edn.="" eds.="" edu.="" edwards="" ee="" eeg="" effect="" effective="" effectively.="" effectiveness="" effector="" effects.="" effects="" efferent="" efficacy="" effort="" efforts="" ei="" eight="" either="" ekblom="" eksperimentelt="" ektronix="" elasticity="" elecktrophysiologie="" electric="" electrical="" electrically="" electro-acupuncture.="" electro-acupuncture="" electro-physiological="" electro-therapeut.="" electro-therapeutics="" electro="" electroacupuncture:="" electroacupuncture="" electroanalgesia.="" electroanalgesia="" electrode.="" electrode="" electrodes.="" electrodes="" electrodiagnosis.="" electrodiagnosis="" electromygraphy="" electromyogr.="" electromyogr="" electromyogram="" electromyograms="" electromyograph="" electromyographic="" electromyographical="" electromyographically="" electromyography.="" electromyography="" electroneural="" electronic="" electronically="" electrophysiological="" electrophysiologique="" electrostimulation:="" electrother.="" electrotherapeutic="" electrotherapy.="" electrotherapy="" elektrisk="" eletromyographic="" elettiomiografica="" elevator="" elevators.="" elevators="" elicit="" elicitable="" elicited="" elicits="" eliminate="" elimination="" elixabeth="" elizabeth="" elongation.="" elsevier="" elveback="" elzack="" em2.="" em="" ematici="" emg="" emm="" emotional="" emphasize="" employing="" emt="" en="" enberg="" end="" endogenous="" endorphin="" endorphins="" energy="" eng.="" engl.="" english.="" english="" engng="" enkephalin="" enkephalins="" enman="" enomoto="" enough="" entirely="" entry="" environmental="" episodes="" epker="" eptember="" equal="" equilibrium="" erb="" ergograph="" erickson="" ericson="" eriksson="" erschenungen.="" eruptive="" especially="" essberg="" essentially="" essette="" establish="" established.="" established="" establishment="" ester="" estimated="" et.="" et="" etiology="" etude="" eur.="" evaluate="" evaluated="" evaluates="" evaluation.="" evaluation="" evaluations="" evans="" eveille="" even="" event="" events.="" every="" evidence="" evident="" evoke="" evoked="" evoking="" ewis="" exact="" exam="" examination.="" examination="" examine="" examined="" example="" except="" exception="" excessive="" excitability="" excitable="" excitation="" excitatory="" excite="" excluded="" exercise="" exercises.="" exercising="" exerting="" exhibit="" exhibited="" exhibits="" existence="" existing="" exists.="" exists="" exp.="" exp="" expands="" expected="" expedite="" experienced="" experiment.="" experiment="" experimental="" experimentally="" experiments.="" experiments="" explained="" expressed="" expresses="" expression="" extended="" extension="" extensors="" extent="" external="" externally="" extra-oral="" extracts.="" extreme="" extremely="" extremities="" extremity="" eye="" f.="" f.m.="" f="" fabricated="" face.="" face="" facial="" facilitate="" facilitation="" fact="" factor="" factors.="" factors="" facts="" failed="" fails="" failure="" farrar="" fast="" fastened="" fatigue.="" fatigue="" fatigued="" fatigues="" fatiguing="" faulty="" favorable.="" favorable="" features="" feb.="" febiger="" fed="" feine="" feinstein="" feldman="" felt="" female="" females="" few="" fewer="" fiber="" fibers.="" fibers="" fibre="" fibres.="" fibres="" fiction="" fields="" fifteen="" fifth="" fig.4.="" fig.="" figure="" filament="" filled="" filter="" find="" finding="" findings.="" findings="" finite="" finn.="" finnish="" firing="" firmly="" first="" fitted="" fitting="" five="" fixed="" flexibility.="" flexion="" flexor="" florence="" flow.="" flow="" flows="" fluctuates="" fluid="" flussi="" fold="" follow-up="" follow="" followed="" following="" follows:="" follows="" food="" for.="" for="" force="" forces="" forlossning.="" form:="" form="" formation="" former="" formula="" forssman="" forster="" fortified.="" fortunately="" forum="" forward-backward="" fothergill="" found="" foundation="" four="" fourier="" fra="" fraccari="" fraction="" fractions="" frankfort="" frankfurt="" free="" freeway="" freimann="" frequencies="" frequency:="" frequency="" fringe="" frog="" from="" frustration="" fujii="" fujita="" fukuoka="" full-wave="" full="" funakoshi="" function-facts="" function.="" function="" functional="" functionally="" functions="" fur="" further="" furthermore="" fusimotor="" fuxe="" fws.="" fws="" fx600="" g.="" g.a.="" g.d.="" g.h.="" g.k.="" g.l.="" g="" ga:="" galletti="" ganong="" gap="" gaps="" gas="" gasser="" gave="" gaw="" gefasskrampfbei="" gehrig="" gelb="" general="" generalized="" generally="" generated="" george="" german="" gernet="" gesamte="" getting="" gewisse="" gibilisco="" gingiva="" give="" given="" gives="" glossary="" glossopharyngeal="" glycogen="" gnathodynamometry="" goal="" goldberg="" goldstein="" good="" goodgold="" goodwill="" goss="" goteborg="" governed="" graber="" gradual="" gradually="" grady="" graphic="" grass="" greater.="" greater="" greatly="" greenfield="" gregg="" griffin="" grinding="" grise="" grosfeld="" grossly="" group.="" group:="" group="" groups="" grundfest="" guard="" guarded="" gueule="" guichet="" guilbaud="" guitar="" guld="" guma="" h.="" h.a.="" h.d.="" h.f.="" h.g.="" h.h.="" h.j.="" h.l.="" h.r.="" h.s.="" h.w.="" h="" habitual="" haco="" had="" haematic="" haffin="" hagfors="" hall="" halt="" halted="" hamann="" handbook="" hands-on="" hannam="" hans.="" hansson="" hapiro="" harris="" harrison="" has="" have="" haven="" having="" hawaii="" he="" head-neck-eye="" head="" headache.="" headache="" headaches="" headly="" health="" healthy="" heart="" height="" hellsing="" helped="" hence="" here="" hi="" high-energy="" high="" higher="" highest="" highly="" him="" hine="" hinge="" hinges="" hinken="" his="" histamine="" histo-chemical="" history="" hit.="" hobbled="" hodos="" hoffert="" hoffmann="" hoi="" holding="" holmdahl="" holmgren="" holmquist="" homas="" homma="" horisberger="" horizontal.="" horizontal="" horn.="" horn="" hospital="" hours.="" hours="" how="" however="" hristensen="" hua="" hugelin="" hughes="" human="" hundred="" hunter="" hymes="" hypalgesia:="" hyperactivity="" hyperaemia.="" hyperbolic="" hyperhemia.="" hypersensitivity="" hypertone="" hypomobility="" hypothalamic="" hypothalamus.="" hypotheses.="" hypothesis="" hypothesize="" hypothesized="" hypothetical="" hypoxemia="" hypoxia="" hypoxic="" hz.="" hz="" i.="" i.e.="" i.e.e.e.="" i.e.m.g.="" i:="" i="" iadr="" identification="" identified="" idi="" iemens="" iemg="" if="" ig.5c="" ig.="" igs="" igure="" ihalainen="" ii.="" ii:="" ii="" iii:="" iii="" iitasalo="" il:="" ileus="" iller="" illiamson="" illustrated="" imaginative.="" imai="" immediate="" immediately="" immermann="" immobilization="" impaired="" impedance.="" implementation="" implicated.="" importance="" important="" impossible="" impressions="" improved:="" improved="" improvement="" improving="" impulse="" impulses="" in:="" in="" inability="" inaccessible="" inaction="" inally="" inc.="" incidence="" include="" included="" includes="" including="" incorrectly="" increase.="" increase="" increased="" increases="" increasing="" incur="" indblom="" indeed="" indefinitely.="" independent.="" independent="" index="" indicate="" indicated.="" indicated="" indicates="" indicating="" indication="" indicator="" indices="" indifferent="" individual="" individuals="" indotta="" induce="" induced="" induces="" inenohrmuskulatur.="" inevitably="" inferior="" inflow="" influence="" influenced="" influences.="" influences="" influencing="" information="" informed="" ingervall="" inhibiting="" inhibition="" inhibitor.="" inhibitor="" inhibitory="" initial="" initially="" injury.="" injury="" ink-jet="" inman="" inn.="" innep="" innervated="" innervating="" innervation="" inoperative="" inorganic="" input="" inserted="" insertion="" insight="" inspection="" instance="" instructed="" instruction="" instrument="" instrumentation:="" instrumentation="" insufficient="" integrated="" intense="" intensity-="" intensity-duration="" intensity="" interacting="" intercuspal="" intercuspation="" interest.="" interesting="" interference="" interferences="" intermediate="" intermittens="" intermittent="" intermittierendem="" intermuscular="" internal="" international="" interneurones.="" interneurons="" interocclusal="" interpretation="" interpreted="" interrupted="" interruption="" interstitial="" interval="" intervals.="" intervals="" into="" intractable="" intramuscular="" intraneuronal="" intraoral="" intrasegmental="" intrinsic="" introduced="" introduction="" intrusive="" intubated="" intubation="" inverse="" inversely="" invest.="" investigate="" investigated="" investigation.="" investigation="" investigations="" investigators="" involuntarily="" involuntary="" involved.="" involved="" involvement="" involving="" io="rheobase" iper="" ipsilateral="" is="" ischaemic="" ischemia.="" ischemia="" ischemic="" isichemia="" isolated="" isometric="" isotonic="" issin="" iswonger="" it.="" it="" ital.="" itch="" its="" itself.="" itself="" itti="" iv.="" iv="" ixon="" j-4="" j.="" j.a.="" j.b.="" j.c.="" j.d.="" j.g.="" j.j.="" j.l.="" j.m.="" j.p.="" j.prothat.="" j.r.="" j.s.="" j.t.="" j.v.="" j.w.="" j="" jach="" jama="" jankelson="" jannetta="" jap.="" japan="" japanese="" jaw-="" jaw-closing="" jaw-jerk.="" jaw-jerk="" jaw="" jaws.="" jaws="" jelly="" jerge="" jerk="" jig="" johansson="" johnson="" joint.="" joint="" jolund="" jonas="" jones="" journal="" jr.="" julius="" junction.="" junction="" june="" juzen="" k.="" k.a.="" k.b.="" k.d.="" k.e.="" k.s.="" k5r="" k="characteristic" kaada="" kaebernes="" kako="" kaliana="" kaneko="" kanmuskein="" kapillomotorische="" kappert="" karger="" katt.="" katz="" kawamura="" keep="" keith="" kept="" kindenzu="" kinds="" kinesiografica="" kinesiograph.="" kinesiograph:="" kinesiograph="" kinesiographic="" kinesiographs="" kinesiography="" kinesiologic="" kinesiometric="" kissin="" kitahata="" knorring="" knowledge="" known.="" known="" komi="" konchak="" koria="" kosaka="" kosterlitz="" kovacs="" krebs="" kugelberg="" kwatny="" kymograph="" l.="" l.a.="" l.c.="" l.e.="" l.j.="" l.m.="" l.r.="" l.v.="" l.w.="" l33xenon="" l="" la.="" la="" lack="" lactic="" laegeforen.="" lagfrekvent="" lakartidningen="" lamarre="" lamina="" lamp="" lancet="" lanigan="" large="" largely="" larger="" lasagna="" laser="" laskin="" last="" lasted="" lasting="" lasts="" late="" latencies="" latency.="" latency="" lateral="" latter="" le="" lea="" lead="" leading="" leads="" least-squares="" least="" leave="" lebars="" lefkowitz="" left="" lend="" length="" lengthening="" lengths.="" lenman="" leroy="" leseth="" less="" lett.="" level="" levels.="" levels="" levy="" lewis="" libre="" licht.="" licht="" liebeskind="" liebman="" life="" ligament="" ligand="" light="" like="" likelihood.="" likely="" limb="" limbs.="" limit="" limited="" lindblom="" lindegard="" lindquist="" lindsstrom="" lindstrom="" line="" linearly="" lip="" lippincott="" lippold="" lips="" lipton="" literature.="" literature="" little="" load="" loading.="" loads.="" local="" located="" location="" loeser="" london="" long-lasting="" long-term="" long="" longer="" look="" louis.="" louis="" lous="" low-grade="" low-pass="" low.="" low="" lower="" lowered="" ltra="" lucia="" luminograph="" lund="" lundberg="" lundeen="" lupton="" lymph="" lymplantopratessi="" lzak="" m-c.="" m.="" m.b.e.="" m.c.="" m.e.="" m.h.="" m.h.son.="" m.k.="" m.k.g.="" m.m.="" m.p.d.="" m="" macmillan="" made="" magladert="" magnetic="" magnusson="" magora="" mahan="" mainly="" maintain="" maintained="" make="" making="" male="" males="" malocclusion="" malocclusions.="" malocclusions:="" malrelation="" malrelations.="" malrelations="" mammalian="" man.="" man="" management="" mandible.="" mandible="" mandibular="" mann="" manner.="" manner="" manual.="" manual="" manuale="" manuscript="" many="" march="" mark="" marked="" markedly="" marshall="" martin="" maruzen="" masseter="" masseteric="" mastication.="" mastication:="" mastication="" masticatori="" masticatory="" match="" material="" materials="" mathematical="" mathematically.="" mathews="" maurer="" maxilla="" maxillary="" maxillofacial="" maxillomandibular="" maximal="" maximally="" maximum="" may="" mayer="" mcardle="" mcburney="" mccall="" mccarty="" mcgrath="" mcintyre="" mckenna="" mcnamara="" md="" mean="" means="" measurable="" measure="" measured="" measurement="" measurements="" meatus="" mechanical="" mechanism.="" mechanism="" mechanisms.="" mechanisms:="" mechanisms="" med.="" med="" medial="" median="" mediated.="" mediated="" mediation="" medical="" medications="" medicine.="" medicine="" medium="" meizack="" melinkoff="" membrane="" men="" menetrey="" menschen.="" menschen="" menschlicher="" mentioned="" merton="" mesencephalic="" mesencephalon.="" metabolic="" metabolism="" metabolite="" metabolites.="" metabolites="" meters="" method.="" method="" methodology="" methods="" microvascular="" midbrain="" might="" mikhail="" miki="" milan="" mild="" miledi="" miles="" miller="" milliampere="" millisecond="" milner-brown="" mingograph="" miniature="" miniclinic="" minimal="" minimally="" minimum="" mins="" minute.="" minute="" minutes="" mishimagi="" missed="" mitani="" mixture="" mixtures="" miyoshi="" mkg="" mm.="" mm="" mn="" mobility.="" modalities.="" modalities="" model="" moderate="" modern="" modifications="" modificazione="" modified="" modulation="" moebius.="" molars="" moller="" moment="" monamine="" monitor="" monitored="" monitoring.="" monitoring="" monoaminergic="" monosynaptic="" monosynaptically.="" monosynaptically="" monosynaptique="" months="" more="" moreover="" morgan="" morphine-like="" morphine="" morphines.="" morphologica="" morphology.="" morphology="" morphometric="" morris="" mortimer="" mosby="" moss="" most="" mostly="" motion.="" motion="" motoneuron="" motoneurones="" motoneurons.="" motoneurons="" motor="" mounted="" mouse.="" mouth-closing="" mouth="" mouvements.="" move="" movement.="" movement="" movements="" moves="" moyers="" mpd="" mpf="" ms.="" ms="" mschr.="" msec.="" msec="" mt.="" mt="" much="" mumford="" munksgaard="" munro="" muscle.="" muscle="" muscles.="" muscles:="" muscles="" muscoli="" muscolocutanei="" muscular="" muscularly="" musculature.="" musculature="" musculo-cutaneous="" musculocutaneous="" musculoskeletal="" muskein="" muskeispindein="" muskelspindein="" must="" myhaug="" myo-centric="" myo-facial="" myo-monitor.="" myo-monitor:="" myo-monitor="" myo-neural="" myo-print="" myo-tronic="" myo-tronics="" myo="" myocentric="" myoelectric="" myofacial-pain="" myofacial="" myofascial="" myogram="" myograph="" myographic="" myography="" myomonitor.="" myomonitor="" myopathy="" myopulse="" myospasms="" myostatic="" myotatic="" myotatique.="" myotronics="" myriad="" n.="" n.o.="" n.p.="" n.r.="" n="" nachweis="" nakamura="" naloxone="" nanzando="" narc.="" nasal="" natural="" nature="" nbsp="" ndersson="" near="" nearly="" necessarily="" necessary="" neck.="" neck="" needleing="" neerlando="" negating="" negative="" neilson="" neilzen="" neironi="" neither="" nella="" nelson="" nerve.="" nerve="" nerves.="" nerves="" nervous="" neural="" neurale="" neuralgia.="" neuralgia:="" neurally.="" neurally="" neuro-muscular="" neuroanatomical="" neurodiagnostic="" neurol.="" neurologic="" neurological="" neurology="" neurolysis="" neuromuscular-induced="" neuromuscular="" neuron="" neuronal="" neurones.="" neurons="" neurophysiol.="" neurophysiol="" neurophysiologic="" neurophysiologie="" neurophysiology="" neurosci.="" neurosurg.="" neurosurgery.="" neurosurgery="" neurovascular="" neutral="" nevertheless="" new="" newrological="" nielzen="" nitrous="" nman="" no.="" no="" nociception="" noel="" noise="" noises="" non-="" non-relaxed="" non-t.m.j.="" none="" noninvasive="" nonparametric="" nor="" nordstrom="" normal.="" normal="" normalize="" norske="" north-holland="" north="" northwest="" not="" notch.="" notch="" note="" noted="" noticeable="" noxious="" nuclear="" nuclei.="" nuclei="" nucleus.="" nucleus="" number="" numerical="" nutritional="" nyamom="" nygaard-ostby="" o.="" o.c.="" o.c.j.="" o.s.="" o="" obicularis="" objective="" objectively="" objectivity="" objektiver="" observation="" observations="" observed="" observes="" obstruction="" obtain="" obtained="" obvious="" obviously="" occasional="" occlusal="" occlusale.="" occlusion.="" occlusion="" occlusional="" occup="" occur.="" occur="" occurred.="" occurrence="" occurring="" occurs="" oct.="" october="" odbard="" odel="" odont.="" odontol.="" odotostomatologia="" oester="" of="" off="" offers="" often="" ohl="" oliveras="" oller="" olotolatrico="" omme="" omura="" on.="" on="" once="" onchak="" ond.="" ond="" onde-petersen="" one-directional="" one-year="" one.="" one="" ongoing="" only="" onnor="" onset="" opened.="" opening.="" opening="" opens="" opiate="" opiates="" oploid="" opposed="" or="" oral.="" oral="" orbicularis="" orbital="" order="" organic="" organization="" orientation="" oriented="" origin.="" originate="" originates="" oris="" orisberger="" orland="" orleans="" oro-facial="" orofac="" orofacial="" orpat="" orthgnathic="" orthod.="" orthodontic="" orthodontics="" orthodontist="" orthodontists="" orthodromic="" orthognathic="" orthop.="" orthopantomograph="" orthopedic="" orthopedics.="" orthopedics="" ortimer="" ortodontico="" ortop.="" osaka="" oscarsson="" oscilloscope="" oss="" osteoarthritic="" ota="" other="" others="" otolaryngology="" ott="" ottoson="" oud.="" our="" ous="" out="" outlined="" output="" ouverture="" over="" overall="" overflow="" overly="" overlying="" ow="" own="" oxford="" oxide="" oxygen="" oyers="" p-cpa="" p.="" p.a.="" p.d.="" p.e.="" p.f.="" p.h.="" p.j.="" p.m.="" p.t.="" p.v.="" p="" pa="" page="" pagnacco="" paillard="" pain-="" pain-dysfunction="" pain.="" pain:="" pain="" painful="" pains="" pair="" pairs="" palate.="" palla="" palpation.="" palpation="" palsy.="" pancherz="" panel="" pantaleo="" paolini="" paper="" par="" parafunktionen="" paralyzer.="" parameter="" parameters.="" parameters="" paris="" park="" parodontologie="" part="" partially="" participation="" particular="" particularly="" passing="" passive="" pathogenesis="" pathologic="" pathological="" pathology.="" pathology="" pathophysiology="" paths="" pathway="" pathways.="" pathways="" patient.="" patient="" patients.="" patients="" patologia="" pattern="" patterns="" patton="" paul="" pause="" peak="" peaked="" peking="" pentapeptides="" people="" peptides="" per="" percent="" percentage="" perception="" percutaneous="" percutaneously.="" percutaneously="" perfectly="" performance="" performed.="" performed="" perfusion.="" periaqueducale="" period.="" period="" periodontal="" periodontium.="" periodontium="" periods="" peripheral="" perkki="" permanent="" permanently="" permit="" persistent="" personal="" persons="" pert="" petersen="" peterson="" pfluegers="" ph="" pharmaca="" pharmacol.="" pharmacol="" pharmacologic:="" pharmacologic="" pharmacological="" phase.="" phase="" phases="" phenomena="" phenomenon="" phenoperidine="" philadelphia="" phosphate="" phosphates="" phosphocreatine="" phosphorus="" phosphorylase="" phosphorylation="" photographs="" phsiol="" phys.="" physial.="" physical="" physio.="" physiol.="" physiol="" physiologic.="" physiologic:="" physiologic="" physiologica="" physiological="" physiology.="" physiology="" physiopatholgy="" physiopathology="" physiotherapy="" picaza="" picked="" pickering="" pilot="" pin-pointed="" pin="" pini-prato="" pini="" pinna="" piper="" pitched="" pl="" placebo="" placed="" placement.="" placement="" places="" placing="" plagued="" plan="" plane="" planning="" plate="" plateau="" plateaux.="" plentiful="" plotted="" pneumatic="" point.="" point="" points.="" points="" pomeranz="" pool="" poor="" popular="" population.="" population="" portion="" portions="" position.="" position="" positioning="" positions.="" positions="" positive="" possessed="" possibilities="" possible.="" possible="" post-exercise="" post-stimulation="" post-tens="" post-therapeutic="" post-traumatic="" post-treatment="" post="" posterior="" postnormal="" postoperative="" posttraumatic="" postulated="" postulates="" postural="" posture="" potassium="" potent="" potential="" potentials="" power="" pp.="" pp="" pps="" practical="" practices.="" pragay="" pratico="" prato="" prayer-="" prayer-galletti="" pre-="" pre-treatment="" pre="" preauricular="" preceded="" precise="" precisely="" precision="" prefabricated="" preliminar="" preliminary="" preparation="" prepulsed="" prescribed="" presence="" present.="" present="" presentation="" presented="" presenting="" presently="" preserpine="" press.="" press="" pressure="" prevention="" previous="" previously="" price="" pril="" primarily="" primary="" principato="" principles="" printer="" printy="" prior="" probable.="" probably="" probe="" problem="" problems="" proc.="" proc="" procedure="" procedures.="" procedures="" proceedings="" process="" processor="" produce="" produced="" produces="" producing="" product="" production="" professed="" prog.="" prognosis.="" program="" progresses="" progressive="" project="" prolonged="" promote="" promotes="" propagation="" proper="" properties="" proportional="" proportions.="" proprioceptive="" pros.="" prosth.="" prosth="" prosthet.="" prosthetic="" prosthetists.="" prosthetists="" prosthodontic="" protect="" protocol="" protracted="" prove="" proved="" provide="" provided="" providers="" provides="" providing="" provocate="" provokerede="" provokes="" proximal="" prpm="" psychiatric="" psychiatry="" psychic="" psychogenic="" psychol.="" psychologic="" psychological="" psychosis.="" psychotherapy="" pterygoid="" pub.="" publication="" publishers="" publishing="" pulpe="" pulsation="" pulse.="" pulse="" pulsing.="" pulsing="" purpose="" put="" pyrithioxin="" qualities="" quantified="" quantify="" quantitative="" quantity.="" quantity="" queen="" question.="" question="" quickly="" quinlivan="" quinn="" quintessence="" quite="" quo="" quoted="" r.="" r.a.="" r.b.="" r.d.="" r.e.="" r.f.="" r.g.="" r.h.="" r.i.="" r.r.="" r.w.="" r=".72)," raab="" radio-graphic="" radio="" radiograph="" radiographic="" radiographs:="" radiographs="" radiography="" radke="" rafii="" ralph="" ralston="" ramfjord="" range="" ranged="" ranging="" ranson="" rapid="" rapport.="" rasmussen="" rass="" rat.="" rate.="" rate="" rather="" ratio="" ration="" ratzlavsky="" rau="" raven="" rb="" reach="" reaches="" reactions="" reactive="" ready="" rec.="" rec="" recalls="" receive="" received="" recent="" recently="" receptor.="" receptor="" receptors.="" receptors="" rech.="" reciprocal="" recognition="" recognized="" recommendations="" reconstruction="" record="" recorded="" recorder="" recording.="" recording="" recordings.="" recordings="" records="" recover="" recovery="" rectified="" reduce="" reduced="" reduces="" reduction="" reestablishes="" reevaluation="" reference="" references="" referral.="" refinement="" reflect="" reflects="" reflex.="" reflex:="" reflex="" reflexe="" reflexes.="" reflexes="" regarding="" regimen="" region.="" region="" regions="" registered="" registration="" registrations="" regulated="" rehab.="" rehabil.="" rehabilitation.="" reichliches="" related="" relation="" relations="" relationsbetimmung.="" relationship.="" relationship="" relationships.="" relationships="" relative="" relatively="" relax.="" relax="" relaxation.="" relaxation="" relaxed="" relaxing="" relearning.="" release="" released="" reliable:="" reliable="" reliably="" relief="" relieve="" relieved="" remaining="" remains="" remarkable="" remarkably="" remission="" remote="" removed="" removing="" renberg="" rendered="" rep.="" repeated="" repeatedly="" repetitive="" replaced="" report.="" report:="" report="" reported="" reports="" repositioning="" represent="" represented="" represents="" republic="" require="" required="" requires="" res.="" res="" research.="" research="" researchers="" resin.="" resistant="" resolution="" resolve="" resolved="" resolving="" respect="" respective.="" respectively.="" respectively="" response.="" response="" responses.="" responses="" responsible="" rest.="" rest="" rested="" resting="" restore="" restored="" restores="" restoring="" result="" resultant="" resulted="" resulting="" results.="" results="" resumption="" reticular="" reticulo="" reticulospinal="" retruded="" return="" rev.="" reveal="" revealed="" reveals="" reversed="" reversing="" review="" reviewed="" reviewing="" rheobase="" rheumatoid="" rhyihmic="" rhythmic="" ricerche="" right="" rigid="" rill="" rise="" rising="" ritchie="" rivista="" rn="" robinson="" rodbard="" roos="" root="" roots="" rosen="" rosenbert="" rosenfalck="" roth="" rothchild="" rott="" roupe="" routine="" royal="" rudy="" rule="" ruled="" rushton="" ruth="" ryall="" s-n="" s.="" s.a.="" s.e.="" s.g.="" s.p.="" s.r.="" s.w.="" s="" safe="" safely="" safety="" said="" same="" sample="" sapphire="" sarnat="" saskatchewan="" sassouni="" satisfactorily="" satisfactory="" satisfied="" saunders="" sc.="" scan.="" scand.="" scandinavica.="" schireson="" school="" schubeler="" schwartz="" schweiz="" schweizer="" sci.="" sci="" science="" sciences="" scientia="" scientific="" scientifiche="" sclerosing="" scope="" scott="" search="" seated="" seats="" seattle="" sec.="" sec="" second="" secondary="" secondly="" seconds.="" seconds="" section="" see="" seem="" seemed="" seems="" seen.="" seen="" sees="" segmental="" seldom="" selected="" selection="" selective="" sellanasion="" semipermanent="" sensation.="" sensation="" sensations="" senses="" sensitive="" sensory="" seoul="" sep="" separate="" separated="" sept.="" sept="" september="" sequence.="" sequence="" sequentially="" series="" serious="" serotonin="" serv-control.="" served="" ses="" sessions.="" sessions="" set="" setekleiv="" seven="" seventeen="" seventh="" several="" severe="" severely="" severity="" shafer="" shahani="" shan="" shanghai.="" shanghai="" shape="" shapiro="" sharp="" sharper="" shaw="" shealy="" sheikoleslam="" sherrington="" shift="" shifted="" shifting="" shifts="" shock="" short-term="" short="" shortening.="" shorter="" shortest="" should="" show="" showed="" showing="" shown="" shows="" sian="" side.="" side="" sigmoid="" signal="" signals="" significance="" significancy="" significant="" significantly="" signs="" silent="" similar.="" similar="" simons="" simple="" simplest="" simply="" simultaneous="" simultaneously="" since="" sindrome="" single="" sinica.="" sins.="" site="" sites="" sitting="" situ.="" situated="" situation="" situations="" six="" sixty-two="" size="" sjoberg="" sjolund="" skeletal="" skin.="" skin="" slide="" sliding="" slightly="" slowing="" slowly="" small="" smartlindring="" smith="" sn="" so="" soc.="" soc="" society="" soft="" solid="" somatic="" some="" sometimes="" sons="" sony="" soreness="" sort="" sought="" sound="" source.="" source="" south="" space.="" space="" spaces.="" span="" spark="" sparks="" spasm.="" spasm="" spasms="" spatial="" special="" specific="" spectral="" spectrum.="" spectrum="" speed="" sphygmomanometer.="" spike="" spinal="" spindle="" spindles="" splint.="" splint="" splints:="" splints="" spread="" sprinfield="" springer="" st.="" stability="" stable="" stage="" stalberg="" standard="" staple="" start="" starting="" state.="" state="" states-="" states="" static="" statistically="" status="" stein="" steno="" stephens="" still="" stillwell="" stimulate="" stimulated="" stimulates="" stimulating="" stimulation-produced="" stimulation.="" stimulation:="" stimulation="" stimulator="" stimulators="" stimulazioue="" stimulering="" stimuli.="" stimuli="" stimulus.="" stimulus:="" stimulus="" stom.="" stomalogia="" stomat.="" stomatognathic="" stonnington="" stovner="" straight="" straightforward="" strain="" stream.="" strength="" strengths="" stress.="" stress="" stretch.="" stretch="" stretched="" stretching="" striated="" strict="" strips="" strong="" strongly="" structure="" studied.="" studied="" studies="" study.="" study="" subject="" subjected="" subjective="" subjects.="" subjects:="" subjects="" subliminal="" submitted="" subsequent="" subsequently="" subside.="" substance="" substances.="" substances="" substantiagelatinosa.="" succeeded="" success="" successful="" succinyicholine="" such="" sudden="" sufficient="" suggest="" suggested="" suggesting="" suggestion="" suggestive="" suggests="" sulfate.="" summary="" superficial="" superimposable="" superior="" supp.="" suppi="" suppl.="" supply="" support="" supported="" supporting="" supportive="" supports="" supposing="" suppression="" supra-orbital="" supramaximal="" supraspinal="" sur="" surface="" surg.="" surg="" surgeons="" surgery.="" surgery="" surgical-orthodontic="" surgical="" surv.="" survey="" suspended="" sustained="" sutcher="" swain="" sweden="" swedish="" sweet="" symptom="" symptomatology="" symptomology.="" symptoms.="" symptoms="" synapse.="" synaptic="" syndrome.="" syndrome="" syndromes.="" synthesis="" system.="" system:="" system="" systemic="" systems.="" szentagothai="" szentagothhai="" t.="" t.a.="" t.c.="" t.e.n.s.="" t.e.n.s="" t.e.n="" t.f.="" t.l.="" t.l="" t.m.="" t.m.j.="" t.t.t.="" t.w.="" t="" table="" tables="" takata="" takehana="" taken.="" taken="" takes="" taking="" tandlaegebladet="" tannenbaum="" tape="" taperecorder="" taub="" taught="" taylor="" teach="" teaching="" technique.="" technique="" technology.="" technology="" teeth.="" teeth="" tei="" temperature="" temporal="" temporalis="" temporary="" temporomandibular="" ten="" tend="" tendency="" tenderness="" tends="" tenotomy="" tens.="" tens="" tense="" tension-fatigue="" tension="" tensions="" terenius="" term="" termed="" terminal="" terminations.="" terminations="" terms.="" terms="" tes.="" tes:="" tes="" test="" tested="" testing.="" testing="" tetanus="" textbook="" than="" that:="" that="" the="" their="" them="" themselves="" then="" theoretical="" theory.="" theory="" ther.="" therap.="" therapeutic="" therapies.="" therapy.="" therapy:="" therapy="" there="" thereby="" therefore="" these="" thesis="" they="" thilander="" third="" thirty="" this="" thomas="" thompsan="" thomson="" thoracic="" thorough="" thorsteinsson="" those="" though="" thought="" three="" threshold.="" threshold="" through="" throughout="" thus="" thyroidectomy.="" tiber="" tic="" tief="" tiere.="" tighten="" tightness="" time.="" time="" times:="" times="" tiny="" tissue.="" tissue="" tissues="" tm="" tmd.="" tmj.="" tmj="" tns="" to:="" to="" together="" tokizane="" tokyo.="" tokyo="" tolerated.="" tomogram="" tomography="" tone.="" tone="" tongue="" tonic="" too="" tool="" tooth="" toronto="" total="" touching="" toward="" towe="" toxin.="" toxin="" tr.="" trace="" tracings="" tract="" tracts="" traditionally="" training="" trajectories="" trajectory.="" trajectory="" trans="" transcutanea="" transcutaneous="" transformation="" transformer="" transkutan="" transmission="" transmitted="" transverse="" trapezius="" trauma.="" trauma="" travell="" treated.="" treated="" treating="" treatment.="" treatment:="" treatment="" treatments="" trends="" trial="" trigeminal="" trigger="" tronics="" trott="" truder="" true="" trunk="" trunks="" tryde="" turker="" turn="" turned="" twenty-one="" twenty="" twice="" two="" type="" types="" typical="" tyreman="" u="" uber="" ubmitted="" uchthal="" ugelberg="" ugelin="" ujii="" ulf-tens="" ulf="" ultimate="" uly="" un="" unable="" unakoshi="" unchallenged="" unchanged.="" und="" under="" undergoing="" underlying="" understood.="" understood="" undertaken="" underway="" underwent="" unenviable="" unequaled="" unequivocally="" uniform.="" unilaterally="" unit="" units.="" units="" univ.="" university="" unless="" unlike="" unpublished.="" unpublished="" unstrained="" unsuccessful="" untersuchung="" until="" up.="" up="" upon="" upper="" uppermost="" upright="" us="" use.="" use="" used="" useful="" using="" usual="" usually="" utilising="" utilizing="" uv="" uxley="" v.t.="" v="" vagal="" value="" values.="" values="" van="" variability="" variables="" variance="" variation="" variations="" varied="" various="" varying="" vascular="" vaso-motorial="" ved="" velocimeter.="" velocities="" velocity.="" velocity="" venter="" ventral="" verlag="" vertical="" very="" vesanen="" vessels="" via="" vibratory="" vibrissae="" vicious="" vid="" vie="" view.="" view="" viewed="" viitasalo="" viitasalso="" viith="" virtually="" vitti="" vivo="" vol.="" vol="" voltage="" volts="" voluntarily="" voluntary="" volunteers="" von="" vorkommen="" voss="" vrendenbregt="" vs.="" vth="" w.="" w.b.="" w.d.="" w.e.="" w.f.="" w.g.="" w.h.="" w.j.="" w.l.="" w.r.="" wa="" wahlstrom="" walking="" wall="" warranted="" was="" washburn="" washington.="" washington="" watkins="" wave.="" wave="" waves="" way.="" way="" we="" wearing="" weiss="" well="" were="" wesley="" wessberg="" west="" what="" when="" where:="" where="" whereas="" whereby="" whether="" which="" while="" whiplash="" who="" whom="" whose="" widely="" widerlof="" widest="" width.="" wien.="" wilkin="" wilkins="" will="" william="" williams="" williamson="" wilson="" window="" wininger="" winkimair="" wire="" with="" within="" without="" woda="" wolfle="" wolford="" women.="" women="" wood="" woodbury="" words="" work="" works="" world="" worst="" worthy="" would="" wright="" wrong="" wyon-maillard="" xenon-133-wash-out="" y.="" y.t.="" y="" yaksh="" yang="" yavelow="" year.="" year="" years.="" years="" yemm="" ygomatic="" yield="" yielded="" yields="" yo-monitor="" yo-tronics="" yonehiro="" york:="" york="" yotronics="" young="" z.="" zahi="" zahnarztl.="" zahnarztliche="" zahnheilk="" zak="" zeitschrift="" zero.="" zieglgansberger="" zimmerman="" zimmermann="" zotterman="" zur="" zygomatic="">