The Baby Who ‘Startles Easily’: A Challenging Case of Hereditary Hyperekplexia

Background: Hereditary hyperekplexia is a rare neurological disorder characterised by an exaggerated startle response to unexpected stomato-sensory or auditory stimuli. In infants, they can present with generalised hypertonia, nocturnal myoclonus and recurrent apneic episodes which may be fatal. Hyperekplexia may be linked to sudden infant death syndrome.

Observation: We describe a case of a young infant who presented with recurrent episodes of apnea, bradycardia and desaturations. He is the first-born of consanguineous parents. There is no known family history of hyperekplexia. The patient was born full term via normal vaginal delivery and did not require resuscitation at birth. In his first of life, he developed recurrent episodes of tonic spasms with apnea and required intubation. Of note, these episodes are often triggered by tactile or painful stimuli. These episodes were initially thought to be seizures, but electroencephalography done during these episodes did not reveal seizure activity. Following extensive investigations, he was diagnosed with hyperekplexia at two months old. Treatment with clonazepam in this case was effective in reducing these episodes of exaggerated startle and apneic episodes.

Key message: This case highlights the diagnostic challenges of hyperekplexia. Early recognition and treatment of this rare neurological disorder in the neonatal period has life-saving implications.