Somatosensory, motor, and reaching/grasping responses to direct electrical stimulation of the human cingulate motor areas.
OBJECTIVE
Surgery for frontal lobe drug-resistant epilepsies is often limited by the apparent widespread distribution of the epileptogenic zone. Recent advances in the parcellation of the medial premotor cortex give the opportunity to reconsider "seizures of the supplementary motor area" (SMA), and to assess the contribution of cingulate motor areas (CMAs), SMA proper (SMAp), and pre-SMA to the symptomatology of premotor seizures.


METHODS
The authors reviewed the results of extraoperative electrical stimulation (ES) applied in 52 candidates for epilepsy surgery who underwent stereotactic intracerebral electroencephalographic recordings, focusing on ES of the different medial premotor fields; that is, the anterior and posterior CMA, the SMAp, and the pre-SMA. The ES sites were localized by superposition of the postoperative lateral skull x-ray and the preoperative sagittal MR imaging studies.


RESULTS
Among 94 electrodes reaching the medial premotor wall, 57 responses were obtained from the anterior CMA (13 cases), the posterior CMA (11), the pre-SMA (18), and the SMAp (15). The ES of the pre-SMA and SMAp gave rise most often to a combination of motor (31 cases), speech-related (22), or somatosensory (3) elementary symptoms. The ES of the CMA yielded simple (17 of 24) more often than complex responses (7 of 24), among which sensory symptoms (7) were overrepresented. Irrepressible exploratory reaching/grasping movements were elicited at the vicinity of the cingulate sulcus, from the anterior CMA (3 cases) or the pre-SMA (1). Clinical responses to ES were not predictive of the postoperative neurological outcome.


CONCLUSIONS
These findings might be helpful in epilepsy surgery candidates, to better target investigation of the CMA, pre-SMA, and SMAp, and therefore to provide a better understanding of premotor seizures.
Chassagnon
Serge
S
Department of Neurology, University Hospital of Strasbourg, France. serge.chassagnon@chru-strasbourg.fr
Minotti
Lorella
L
Kremer
Stéphane
S
Hoffmann
Dominique
D
Kahane
Philippe
P
D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D002648:Child; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D017034:Epilepsy, Frontal Lobe / Q000503:physiopathology* / Q000601:surgery; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D006179:Gyrus Cinguli / Q000033:anatomy & histology* / Q000502:physiology*; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D009044:Motor Cortex / Q000033:anatomy & histology / Q000502:physiology; D013003:Somatosensory Cortex / Q000033:anatomy & histology / Q000502:physiology; D016896:Treatment Outcome