Somatosensory-evoked potentials elecited by bilateral stimulation of the median nerve and its clinical application
Yamada, T.; Kimura, J.; Young, S.; Powers, M.
Neurology 28(3): 218-223
1978
ISSN/ISBN: 0028-3878 PMID: 203875 Document Number: 125923
Somatosensory evoked potentials (SEP) elicited by bilaterally simultaneous median nerve stimulation (BS) were studied in 28 normal subjects and in 20 patients with various cerebral lesions. In normals, SEP evoked by BS were symmetric between the homologous areas of the 2 hemispheres and resembled the response contralateral to unilateral stimulation (US). In patients with a cerebral lesion, BS responses were not only asymmetric, but often differed in wave form from the response of the affected hemisphere to contralateral US. These alterations were attributed to the cumulative interactions of the anomalous contralateral and ipsilateral components. The additional use of BS made it possible to demonstrate SEP abnormalities that might have been regarded as normal or equivocal if only the US method had been used. The neurophysiologic mechanisms of the origin of SEP were discussed.