Functional Mapping of Human Supplementary Motor Area Studied by Electrical Stimulation
Abstract number :
3.109
Submission category :
Year :
2000
Submission ID :
1725
Source :
www.aesnet.org
Presentation date :
12/2/2000 12:00:00 AM
Published date :
Dec 1, 2000, 06:00 AM
Authors :
Serge Chassagnon, Dominique Hoffmann, Lorella Minotti, Alim L Benabid, Philippe Kahane, Epilepsy unit, Strasbourg, France; Neurosurgery unit, Grenoble, France; Epilepsy unit, Grenoble, France.
RATIONALE: Recent neurophysiological data ara consistent with complex parcellation and cooperativity between higher order and executive motor areas. A few previous studies using grid electrodes and electrical stimulations (ES) have investigated the somatotopic organization of the human supplementary motor area (SMA). METHODS: ES have been reviewed from 53 medically intractable epileptic patients with at least one depth electrode reaching the SMA and/or anterior cingulate motor cortex (ACM), during evaluation for surgery. Only responses obtained at minimal intensity (0,4 - 3 mA) and without afterdischarge were taken into account. Anatomical correlates were investigated by standardization in stereotactic coordinates in Talairach's atlas and by individual radiological analysis. RESULTS: 95 elicited responses in 42 patients were available. 1 Hz ES induced about 27 responses, most often as negative motor responses (NMR) like transient limb postural disruption or weakness, speech disturbance. 50 Hz ES have elicited positive motor responses more often than NMR or numbness. SMA-proper and pre-SMA ES provided a broad spectrum of simple or complex symptoms, involving separately or associated contralateral upper limb,speech, leg, oculo-cephalic (OC)deviation, with a somatotopic organization : speech disturbance and complex symptoms (ARM?speech?OC) never located behind VCA plane, leg movements between VCA and VCP, upper limb movements broadly distributed on both sides of VCA plane. Subjective sensitive responses were rather rare above cingulate sulcus. Sensory or motor cingulate responses seemed to be mainly located in the so-called intermediate rostral and caudal ACM; anterior rostral ACM was never investigated but once, leading to a complex compulsive behaviour. CONCLUSIONS: Low intensity ES of the medial frontal cortex provided motor responses mainly related to the pre-SMA, defined as SMA part statisticaly located anterior to VCA plane. Results are discussed taking into account individual sulcal anatomy of the medial wall.