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Focal capsular vascular lesions can selectively deafferent the prerolandic or the parietal cortex: Somatosensory evoked potentials evidence
Author(s) -
Mauguière François,
Desmedt John E.
Publication year - 1991
Publication title -
annals of neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.764
H-Index - 296
eISSN - 1531-8249
pISSN - 0364-5134
DOI - 10.1002/ana.410300113
Subject(s) - somatosensory evoked potential , internal capsule , somatosensory system , posterior parietal cortex , motor cortex , lesion , cortex (anatomy) , neuroscience , thalamus , medicine , sensory system , anatomy , hemiparesis , median nerve , stimulation , psychology , magnetic resonance imaging , pathology , radiology , white matter
Four patients with a unilateral focal vascular accident involving the internal capsule (but not the cortex) were studied electrophysiologically. Averaged somatosensory evoked potentials (SEPs) to electrical stimulation of the median nerve on the left or the right side were analyzed. In the 3 patients with hemiparesis and normal somatic sensation, the precentral P22 and N30 SEP components were lost, whereas the parietal components were preserved. In another patient with clinical somatosensory loss unaccompanied by any central motor impairment, the precentral SEP components were preserved, whereas the parietal SEP components were lost. Thus, a small capsular lesion can eliminate distinct cortical SEP components by selectively involving either the axons of the thalamic VPLc nucleus going to parietal receiving cortex or the axons of thalamic VPLo going to motor area 4. These findings extend to subcortical lesions the diagnostic value of SEPS in patients with dissociated clinical motor and sensory signs.