title: Topography of somatosensory evoked potentials to median nerve stimulation in patients with cerebral lesions.
abstract: Scalp distributions and topographies of early cortical somatosensory evoked potentials (SEPs) to median nerve stimulation were studied in 22 patients with 5 different types of cerebral lesion due to cerebrovascular disease or tumor (thalamic, postcentral subcortical, precentral subcortical, diffuse subcortical and parieto-occipital lesions) in order to investigate the origins of frontal (P20, N24) and central-parietal SEPs (N20, P22, P23). In 2 patients with thalamic syndrome, N16 was delayed in latency and N20/P20 were not recorded. No early SEP except for N16 was recorded in 2 patients with pure hemisensory loss due to postcentral subcortical lesion. In all 11 patients with pure hemiparesis or hemiplegia due to precentral subcortical lesion N20/P20 and P22, P23/N24 components were of normal peak latencies. The amplitude of N24 was significantly decreased in all 3 patients with complete hemiplegia. These findings support the hypothesis that N20/P20 are generated as a horizontal dipole in the central sulcus (3b), whereas P23/N24 are a reflection of multiple generators in pre- and post-rolandic fissures. P22 was very localized in the central area contralateral to the stimulation.
authors: Department of Neurology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu City, Japan.
authors: S
authors: S
authors: Tsuji
authors: Y
authors: Y
authors: Murai
authors: C
authors: C
authors: Kadoya
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001927:Brain Diseases / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002648:Child; D004558:Electric Stimulation; D005073:Evoked Potentials, Somatosensory; D005260:Female; D006429:Hemiplegia / Q000503:physiopathology; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000503:physiopathology*; D008875:Middle Aged; D009068:Movement; D009422:Nervous System Diseases / Q000503:physiopathology; D012535:Scalp / Q000503:physiopathology; D012677:Sensation; D013577:Syndrome; D013786:Thalamic Diseases / Q000503:physiopathology; D014057:Tomography, X-Ray Computed