Focal pathological startle following pontine infarction.
A 36-year-old male developed an acute right-sided weakness due to left-sided pontine infarction. Two months later, he first noticed sudden right elbow flexion in response to a loud unexpected noise. Detailed electrophysiological assessment was performed. A large, short-latency (median 39 msec), synchronous electromyographic discharge occurred in the right biceps brachii electrodes following a 50-msec, 120-dB 1-kHz tone burst, with habituation only with very short (30-second) interstimulus intervals. Less synchronous activity at longer latencies was present both in a number of right-sided arm muscles at rest and on the clinically unaffected side during a tonic voluntary contraction. We discuss possible underlying mechanisms and our reasons for considering this a focally enhanced startle response. Our report broadens the range of expression of acquired startle disorders.
Watson
Shaun R D
SR
Institute of Neurological Sciences, Department of Neurology and Clinical School, Prince of Wales Hospital, Randwick, Sydney 2031, Australia.
Colebatch
James G
JG
D000328:Adult; D002544:Cerebral Infarction / Q000150:complications* / Q000473:pathology; D016057:Evoked Potentials, Auditory, Brain Stem; D005073:Evoked Potentials, Somatosensory; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D018908:Muscle Weakness / Q000175:diagnosis / Q000209:etiology*; D011149:Pons / Q000098:blood supply* / Q000473:pathology; D013216:Reflex, Startle / Q000502:physiology; D014743:Videotape Recording