Abstract

Startle Syndrome/Hyperekplexia is a rare, neurological disorder that may affect newborns, children and adults. The disease is caused by multiple genetic mutations. The early manifestations include abnormal responses to unexpected auditory, visual, and so esthetic stimuli such as sustained tonic spasm, exaggerated startle response and fetal posture with flexion of forearm and legs, clenched fists, and anxious stare. Spasms may be severe enough to cause apnea, bradycardia and death. These movements must be distinguished from startle epilepsy. Diagnosis is based on the clinical signs, molecular genetic testing and electrophysiology. Prognosis is variable. Diazepam and clonazepam are considered the drugs of choice. Forced flexion of the head and legs towards the trunk (Vigevano maneuver) can be life saving when prolonged stiffness impedes respiration. A timely diagnosis in cases of hyperekplexia is crucial because affected neonates are at risk of sudden death from apnea. A neonatal case is presented below.

Keywords

Startle syndrome, Hyperekplexia, Clonazepam, Vigevano maneuver, Genetic counseling, Chloride channel, Epilepsy