Presurgical evaluation of epileptic patients with subdural recording and functional mapping

The indications and applications of brain functional mapping with subdurally implanted electrodes are reviewed briefly. The mapping can be performed outside the operating room and is useful for presurgical study of patients who have a complex distribution of epileptiform discharges and for minimizing functional deficits postoperatively. The major disadvantages of the procedure are the inflexibility of the electrode positions and the necessity of a craniotomy to insert and remove the subdural electrodes.