[Stiff baby syndrome is a rare cause of neonatal hypertonicity].

Stiff baby syndrome (hyperekplexia) is a rare genetic disorder. The condition can easily be misdiagnosed as epilepsy or severe sepsis because of hypertonicity and seizure-like episodes and has an increased risk of severe apnoea and sudden infant death. Tapping of the nasal bridge inducing a startle response is the clinical hallmark. We report cases of two sisters born with stiff baby syndrome with hypertonicity, exaggerated startle reaction and cyanosis. The syndrome has a good prognosis if treated with clonazepam and both cases were developmental normal after one year.