The predictive localizing value of tonic limb posturing in supplementary sensorimotor seizures

Objective: To determine whether early tonic limb posturing is reliable in lateralizing or localizing of the seizure generator in 14 patients with pharmacoresistent supplementary sensorimotor area (SSMA) seizures. Methods: All patients underwent high-quality MRI scans and stereo-EEG recordings. Results: The SSMA seizure semiology predicted focal or regional ictal onset in the SSMA in six (43%) patients: Three had a focal SSMA seizure onset, and three had a regional seizure onset with involvement of one SSMA plus adjacent neocortex. The eight remaining patients had diffuse uni- or bilateral seizure onset. Eight of 14 patients underwent a frontal or central cortical resection, but a good outcome was seen in only 3: 2 with no SSMA resection and 1 with an extensive central removal. Conclusions: SSMA semiology is suggestive of early involvement of this region but is by no means a reliable indicator that the primary SSMA contains the seizure focus.