Immediate cortical reorganization after local anesthetic block of the thumb: source localization of somatosensory evoked potentials in human subjects.
Psychophysical observations after anesthesia of the thumb raise the question whether the functional border between the thumb and the index is functionally distinct. We present a source localization study using equivalent current dipole modeling of somatosensory evoked potentials (SEPs) following mechanical air-puff stimulation of the first, second and third digits before and during anesthesia of the thumb. Source reconstruction was based on 96-channel SEP recordings. During anesthesia of the thumb the distance between the cortical representation of the thumb and the second and third digits immediately decreased. This indicates a shift of the cortical representation of the second and third digits towards the deafferented area of the anesthetized thumb. Thus, the present results did not confirm the hypothesis of a functional border of the cortical representation between thumb and index finger in this particular task.
Waberski
T D
TD
Department of Neurology, University Hospital Aachen, Pauwelsstrasse 30, D-52057, Aachen, Germany. till.waberski@post.rwth-aachen.de
Gobbelé
R
R
Kawohl
W
W
Cordes
C
C
Buchner
H
H
D000328:Adult; D000344:Afferent Pathways; D000779:Anesthetics, Local; D002540:Cerebral Cortex / Q000502:physiology*; D005073:Evoked Potentials, Somatosensory / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D008619:Mepivacaine; D010812:Physical Stimulation; D013933:Thumb / Q000294:innervation*
D000779:Anesthetics, Local; D008619:Mepivacaine