title: Characteristics and clinical impact of stimulation-evoked seizures during extraoperative cortical mapping.
abstract: Extraoperative electrocortical stimulation mapping (ESM) is used to identify functional cortex prior to epilepsy surgery, with the goal of preserving function postoperatively. Although attempts are made to avoid stimulation-evoked seizure activity, the clinical impact of these events with regard to safety, clinical utility, functional outcome, and even disruption to the procedure itself is unknown. We conducted a retrospective review of 57 patients with pharmacoresistant focal epilepsy who underwent intracranial electrode implantation and ESM. Stimulation-evoked seizures (afterdischarges associated with clinical signs or symptoms) occurred in 19 patients (33%). Mapping sessions were disrupted for 11 of these patients (i.e., 19% of the full sample and 58% of the subgroup of patients with stimulation-evoked seizures). Patients who had ESM disruption were no less likely than patients without ESM disruption to be seizure-free at one year (p=0.63) and two years (p=0.57) postoperatively. Among 23 patients who underwent language assessment pre- and postoperatively, 4 (17%) had evoked seizures that disrupted language mapping; these patients were no more likely to show postoperative language declines relative to those who had no ESM disruption (p=0.26). Results suggest that evoked seizures occur frequently during ESM and can disrupt the procedure; however, these events do not appear to adversely affect postoperative outcomes. Nevertheless, attempts should be made to limit stimulation-evoked seizures in order to reduce patient discomfort, increase efficiency, and maximize the utility of ESM.
authors.affiliation: Department of Neurology, Columbia University Medical Center, 710 W. 168th Street, 7th Floor, New York, NY 10032, USA. Electronic address: abank@partners.org.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Bank
authors.affiliation: Department of Neurology, Columbia University Medical Center, 710 W. 168th Street, 7th Floor, New York, NY 10032, USA. Electronic address: cas2044@columbia.edu.
authors.forename: Catherine A
authors.initials: CA
authors.lastname: Schevon
authors.affiliation: Department of Neurology, Columbia University Medical Center, 710 W. 168th Street, 7th Floor, New York, NY 10032, USA. Electronic address: mh61@columbia.edu.
authors.forename: Marla J
authors.initials: MJ
authors.lastname: Hamberger
mesh_terms: D000293:Adolescent; D000328:Adult; D001931:Brain Mapping / Q000379:methods*; D002540:Cerebral Cortex / Q000503:physiopathology* / Q000601:surgery; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D007802:Language; D007807:Language Tests; D008297:Male; D008875:Middle Aged; D057234:Preoperative Period; D012189:Retrospective Studies; D012640:Seizures / Q000503:physiopathology* / Q000601:surgery; D055815:Young Adult
keywords: Cortical stimulation; Epilepsy; Epilepsy surgery; Functional brain mapping; Language; Neuropsychology