Introduction: Hyperekplexia is a disease characterized by an exaggerated startle reflex in front of minimal tactile and/or acoustic stimuli, that usually goes with high muscular tone, except when the patient is sleep. When the patient grows, high muscular tone decreases and then appear sudden hypertonic episodes that make fall the patient. Presence of inguinal and/or umbilical hernia is common, as well as sudden infant death. Neurophysiological findings can give guidance to diagnosis. It's an autosomal dominant transmission disease, but sporadic cases can appear. Clonazepam is the drug of choice, obtaining a marked improvement in a lot of patients.
Clinical case and conclusions: Although rare, hyperekplexia is a diagnosis we must think about when we see an hypertonic newborn, and this is the reason why we report this case recently diagnosed in our hospital.