Short-Latency Median Somatosensory Evoked Potentials on Localized Various Neurological Lesions

Keimyung Medical Journal 1987;6(2):290-299.

각종 국부적 신경병변에서의 정중신경 단잠복기체감각유발전위반응

유경무; 이상도; 박영춘

Abstract

A number of short-latency somatosensory evoked potential (SEP) studies on various localized neurological lesions has been reported recently to delineate neural generators of each SEP waves. However; their localizing value remains to be elucidated since their specific neural origins still have been debated. We studied median SEP abnormalities in 53 patients with well localized neurological lesions which were diagnosed clinically and by laboratory examinations (EMGs or brain CT scans). In 9 patients with polyneuropathy; latencies of N9; N13 and N19 were delayed; and amplitudes of N9 and N13 were decreased. Whereas amplitude of N19 and P23 and latency of P23 were normal. In 5 patients with brachial plexus injury; there were absence of N9 and subsequent SEP waves; or delayed latencies of N9 and N13 with low amplitudes. In 3 patients with cervical cord injury; there was normal N9. Whereas N13; N19 and P23 were absent or low amplitudes with normal latencies. In 3 patients with brainstem lesions (2 infarction and 1 metastatic tumor); there were normal N9 and N13 latencies; low amplitude of N13 and absent contralateral N19 and P23. In 19 patients with thalamic lesions (17 hemorrhage; 1 infarction and 1 metastatic tumor); there were normal N9 and N13; and absent N19 and P23 contralateral to the side of stimulation in cases of sensory deficit; whereas delayed or low amplitude of contralateral N19 and/or P23 in cases of mild sensory deficit. In 6 patients with putaminal hemorrhage; there were normal N9 and N13 and absent contralateral N19 and P23 in cases of sensory deficit; whereas low amplitde of N19 and P23 in cases without sensory deficit. And in 8 patient with well localized parietal infarction; there were also normal N9 and N13; and absent contralateral N19 and P23 or delayed latency of P23 in cases of sensory deficit; whereas were delayed latency of P23 or low amplitude of N19 and P23 in cases without sensory deficit. In above SEP findings in well localized neurological lesions we propose the neural generator of N9 is near brachial plexus; N13 is dorsal column of high cervical cord; N19 is in thalamus and P23 is thalamocortical radiation or parietal sensory cortex.