A fatal infantile case with suspected hyperekplexia

Hyperekplexia is a hereditary disorder characterized by generalized muscle hypertonia and an excessive startle reflexes.It is associated with serious injuries from startle-induced falls ; and risk of sudden death exists due to respiratory arrest induced by muscular stiffness.Hyperekplexia is treatable with clonazepam.However, due to low public awareness of this disease, many cases may remain undiagnosed and untreated.We report the case of a one-day-old male neonate with muscle hypertonia admitted to our hospital.Blood test results and electroencephalography and brain magnetic resonance imaging findings were normal.Hyperekplexia was strongly suspected based on clinical symptoms, family history, and the positive nose-tapping test.Oral clonazepam was administered ; however, the dose could not be increased to a sufficient level due to lack of parental consent ; he was discharged on day 37.After self-interruption of clonazepam, he was transported to our hospital in a state of cardiopulmonary arrest and later died at 2 months of age.Although hyperekplexia is often associated with good prognosis, we encountered a fatal case, highlighting the need for promoting disease awareness and educate patient guardians.