Exploding head syndrome is an interesting syndrome of unknown pathogenisis. It is documented and accepted in the International Classification of Sleep Disorders (ICSD).
An article by Casucci G, d'Onofrio F, Torelli P. discusses " trigeminal autonomic cephalalgias (TACs) and hemicrania continua, while the latter comprise classical trigeminal neuralgia, hypnic headache, primary thunderclap headache, and exploding head syndrome." This article in Neurol Sci. 2004 Oct;25 Suppl 3:S77-83 and discusses Rare primary headaches: clinical insights.
The symptoms (according to ICSD) are:
"The patient complains of a sudden loud noise or sense of explosion in the head at either the wake-sleep transition or upon waking during the night."
" The experience is not associated with significant pain complaints"
"The patient rouses immediately after the event, usually with a sense of fright"
It is considered to be a seperate entity from Idiopathic Stabbing Headache (ice pick headache) which is benign and characterized by brief stabs of pain on the side of the head.
It is also different than Thunderclap Headache which is a severe sudden-onset pain that must be considered a warning sign of a subarachnoid hemorrhage but can also be benign.
There are also cluster headaches, sleep related migraines and nocturnal paroxysmal hemicrania. It is possible that Exploding Head Syndrome is a pain free version of one of these disorders.
Severe migraines can be related to sleep apnea as well. See I HATE CPAP!! (http://www.ihatecpap.com)
PubMed abstract below:
J Neurol Neurosurg Psychiatry. 1989 Jul;52(7):907-10.
Clinical features of the exploding head syndrome.
Pearce JM.
Department of Neurology, Hull Royal Infirmary, UK.
Fifty patients suffering from the "exploding head syndrome" are described. This hitherto unreported syndrome is characterised by a sense of an explosive noise in the head usually in the twilight stage of sleep. The associated symptoms are varied, but the benign nature of the condition is emphasised and neither extensive investigation nor treatment are indicated.
PMID: 2769286 [PubMed - indexed for MEDLINE]
Neurol Sci. 2004 Oct;25 Suppl 3:S77-83.
Rare primary headaches: clinical insights.
Casucci G, d'Onofrio F, Torelli P.
U. O. di Medicina Generale, Casa di Cura San Francesco, Viale Europa 21, I-82037 Telese Terme (BN), Italy. gerardocasucci@tin.it
So-called "rare" headaches, whose prevalence rate is lower than 1% or is not known at all and have been reported in only a few dozen cases to date, constitute a very heterogeneous group. Those that are best characterised from the clinical point of view can be classified into forms with prominent autonomic features and forms with sparse or no autonomic features. Among the former are trigeminal autonomic cephalalgias (TACs) and hemicrania continua, while the latter comprise classical trigeminal neuralgia, hypnic headache, primary thunderclap headache, and exploding head syndrome. The major clinical discriminating factor for the differential diagnosis of TACs is the relationship between duration and frequency of attacks: the forms in which pain is shorter lived are those with the higher frequency of daily attacks. Other aspects to be considered are the time pattern of symptoms, intensity and timing of attacks, the patient's behaviour during the attacks, the presence of any triggering factors and of the refractory period after an induced attack, and response to therapy, especially with indomethacin. Often these are little known clinical entities, which are not easily detected in clinical practice. For some of them, e. g., thunderclap headache, it is always necessary to perform instrumental tests to exclude the presence of underlying organic diseases.
PMID: 15549575 [PubMed - indexed for MEDLINE]
