Individuals with exploding head syndrome hear or experience loud imagined noises as they are falling asleep or waking up, have a strong, often frightened emotional reaction to the sound, and do not report significant pain; around 10% of people also experience visual disturbances like perceiving visual static, lightning, or flashes of light. Some people may also experience heat, strange feelings in their torso, or a feeling of electrical tingling that ascends to the head before the auditory hallucinations occur.[2] With the heightened arousal, people experience distress, confusion, myoclonic jerks, tachycardia, sweating, and the feeling that they have stopped breathing and need to make a conscious effort to breathe again.[4][6][7][8]
The pattern of the auditory hallucinations is variable. Some people report having a total of two or four attacks followed by a prolonged or total remission, having attacks over the course of a few weeks or months before the attacks spontaneously disappear, or the attacks may even recur irregularly every few days, weeks, or months for much of a lifetime.[2]
The cause of EHS is unknown.[3] A number of hypotheses have been put forth with the most common being dysfunction of the reticular formation in the brainstem responsible for transition between waking and sleeping.[2]
Other theories into causes of EHS include:
Exploding head syndrome was first described in the 19th century,[2] and may have first been mentioned in the 17th century.[9]
Exploding head syndrome is classified under other parasomnias by the 2014 International Classification of Sleep Disorders (ICSD, 3rd.Ed.) and is an unusual type of auditory hallucination in that it occurs in people who are not fully awake.[10][11]
According to ICD-10 and DSM-5 EHS is classified as either other specified sleep-wake disorder (codes:780.59 or G47.8) or unspecified sleep-wake disorder (codes: 780.59 or G47.9).[12][13]
As of 2018[update], no clinical trials had been conducted to determine what treatments are safe and effective; a few case reports had been published describing treatment of small numbers of people (two to twelve per report) with clomipramine, flunarizine, nifedipine, topiramate, carbamazepine.[2] Studies suggest that education and reassurance can reduce the frequency of EHS episodes.[4] There is some evidence that individuals with EHS rarely report episodes to medical professionals.[8]
There have not been sufficient studies to make conclusive statements about how common or who is most often affected.[2] One study found that 14% of a sample of undergrads reported at least one episode over the course of their lives, with higher rates in those who also have sleep paralysis.[14]
Case reports of EHS have been published since at least 1876, which Silas Weir Mitchell described as "sensory discharges" in a patient.[14] However, it has been suggested that the earliest written account of EHS was described in the biography of the French philosopher René Descartes in 1691.[9] The phrase "snapping of the brain" was coined in 1920 by the British physician and psychiatrist Robert Armstrong-Jones.[14] A detailed description of the syndrome and the name "exploding head syndrome" was given by British neurologist John M. S. Pearce in 1989.[15] More recently, Peter Goadsby and Brian Sharpless have proposed renaming EHS "episodic cranial sensory shock"[1] as it describes the symptoms more accurately and better attributes to Mitchell.
International Classification of Sleep Disorders. Darien, IL: American Academy of Sleep Medicine. 2014.
World Health Organization. International Statistical Classification of Diseases and Related Health Problems. 10th ed. Geneva, Switzerland: World Health Organization; 2008.
American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders: DSM-5. 5th ed. Arlington, VA: American Psychiatric Association; 2013.