Hyperekplexia is a rare hereditary, neurological disorder that may affect infants as newborns (neonatal) or prior to birth (in utero). It may also affect children and adults. Individuals with this disorder have an excessive startle reaction (eye blinking or body spasms) to sudden unexpected noise, movement, or touch. Symptoms include extreme muscle tension (stiffness or hypertonia) that prevent voluntary movement and can cause the affected person to fall stiffly, like a log, without loss of consciousness. Exaggeration of reflexes (hyperreflexia), and an unstable way of walking (gait) may also occur. Hyperekplexia is usually inherited as an autosomal dominant trait, but autosomal recessive or rarely, X-linked inheritance, has also been reported.
Hyperekplexia is frequently misdiagnosed as a form of epilepsy so the process of getting an accurate diagnosis may be prolonged Treatment is relatively uncomplicated and involves the use of anti-anxiety and anti-spastic medicines Physical and cognitive therapy are supplemental treatment options.