Essential startle disease may not be a uniform entity

A 25-year-old man with essential startle disease has been reported. He had a history of sudden jerks and falls in response to unexpected stimuli. Abno rmal falling developed when he learned to walk. No similar cases are known in his family. Physical examination revealed hyperreflexia. Pathologic star tle reflex was elicited by light touching on the patient's nose, clapping o r making other noises. EEG response to startle stimuli consisted of spikes recorded from both centroparietooccipital regions immediately preceding dif fuse muscle and movement artifacts. The motor responses to auditory stimuli , which are startle reflex on the orbicularis oculi, sternocleidomastoid, b iceps and quadriceps femoris muscles, habituated within 2-4 trials. Electri cal stimulation of the median nerve at the wrist elicited a consistent C re flex (cortical long loop reflex) but not any giant cortical somatosensory e voked potentials. Our patient showed early disease onset and habituation of motor response, w hich are not seen in other essential hyperekplexia cases, and clinically di ffers from the patients with hereditary hyperekplexia in which neonatal rig idity, epilepsy, apneic attacks, low intelligence, congenital dislocated hi ps and inguinal hernia can be seen in differing frequency.