Exploding Head Syndrome

Exploding head syndrome (EHS) is a benign parasomnia characterized by the perception of a loud sound while asleep, which leads to abrupt awakening. These events occur during the wake-sleep/sleep-wake transition period and generally last less than a second. Events are often accompanied by flashes of light and patient distress, but there is no significant associated pain. The sounds have most commonly been described as explosions, gunshots, or thunder but can be almost any loud noise. The events occur with variable frequency, and there may be prolonged remission between episodes.EHS was first described in medical literature in 1876 by American neurologist Silas Weir Mitchell. He reported a case study of two patients, who experienced the nocturnal sensation of loud sounds he described as “sensory shocks.” Despite earlier descriptions and case reports of EHS, it was not classified as a sleep disorder until 2005, when it gained inclusion in the 2nd edition of International Classification of Sleep Disorders (ICSD-2). More recently, the term episodic cranial shock has been proposed to describe this phenomenon. The phenomenon is often frightening to those who are unaware of its benign nature. Patients may initially fear a more ominous cause is responsible for the sounds, such as a stroke, brain tumor, or brain hemorrhage. These concerns are the reasons many seek medical evaluations. It is an underdiagnosed and under-reported syndrome because patients may feel embarrassed about their symptoms, and healthcare providers may not be familiar with the diagnosis.