A Report of a Patient with Hyperekplexia

Introduction: Hyperekplexia, or startle disease, is a rare neurological disorder characterized by excessive startle responses to noise or touch stimulation that can cause serious injury from frequent falls. The disease is characterized by a triad of generalized stiffness while the patient is awake, nocturnal myoclonus, and an exaggerated startle reflex. Hereby, an interesting case of hyperekplexia with comorbidities is reported that was misdiagnosed as epilepsy for some years. Methods: Our patient was a 16yearold right handed boy with frequent falls, without loss of consciousness that caused serious head trauma. He had exaggerated myoclonic jerks with tactile and auditory stimuli. Also, he had nocturnal attacks including a startle myoclonic jerk followed by sudden stiffening of the limbs and trunk with vocalization that lasted about 3 seconds without loss of awareness. There was a positive family history of jerky movements in his mother only when she was sleeping. He had a posttraumatic encephalomalacia in the right frontotemproparietal region due to one of his falls 10 years ago. He was diagnosed with epilepsy and was treated with valproate with no success. After total antiepileptic discontinuation and 10 days of videoEEG monitoring, no interictal epileptifrom finding was recorded. The attacks were not accompanied with ictal activity on EEG. Hyperekplexia may be misdiagnosed with startle epilepsy. The preservation of consciousness and absence of epileptiform discharges on EEG can be helpful for differentiating hyperekplexia from startle epilepsy. Startle epilepsy is often resistant to treatment; however, hyperekplexia usually responds well to clonazepam.