Transient epileptic foci associated with intracranial hemorrhage in patients with subdural and epidural electrode placement

We report two cases of transient epileptic foci in humans associated with p lacement of intracranial electrodes. The abnormalities consisted of restric ted areas of active, almost continuous, rhythmic spiking, intermittently ev olving into electrographic seizure activity, which resolved spontaneously w ithin 3-4 days. The first occurred after placement of a subdural electrode grid and the second following insertion of epidural peg electrodes. Neuroim aging demonstrated a small subdural hematoma overlying the grid and a focal intraparenchymal hemorrhage underlying the affected epidural electrodes. T he insertion of intracranial electrodes may be complicated by the induction of transient epileptic foci unrelated to a patient's typical epileptic gen erator. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.