Intraoperative monitoring to preserve central visual fields during occipital corticectomy for epilepsy

Photic driving using a flashing strobe light was recorded via intracranial electrodes in two patients with occipital epilepsy being evaluated for surg ery. The same technique was used to monitor the visual cortex intraoperativ ely. Visual evoked potentials (VEPs) were also obtained using the intracran ial electrodes in one patient, Preoperative photic driving occurred in a se parate location from the cortical areas producing ictal epileptiform activi ty. VEPs were located in the same site as photic driving. Photic driving wa s monitored throughout the resection and remained unaffected at the end of each procedure, Postoperative visual field testing in both patients showed preservation of central vision although some reduction in peripheral fields was seen. Intraoperative monitoring of the visual cortex using photic stim ulation proved to be a reliable technique for presenting central vision dur ing occipital lobe surgery. (C) 2000 Harcourt Publishers Ltd.