[Localized glioma in the occipital lobe manifesting as scintillating scotoma: case report].

An 11-year-old female presented with headache in May 1993. Magnetic resonance (MR) imaging disclosed a small lesion (9 mm in diameter) in the left occipital lobe. No treatment was performed because the lesion was small. She subsequently developed frequent episodes of scintillating scotoma in the right visual field eleven months later. MR imaging eleven months after the first MR imaging showed the lesion had enlarged to 14 mm in diameter. Preoperative surface electroencephalography (EEG) detected no spike waves. The diagnosis was localized glioma. The mass was totally removed by gyrectomy in December 1994. Intraoperative cortical EEG demonstrated spike waves which disappeared after tumor removal. The histological diagnosis was pleomorphic xanthoastrocytoma. No postoperative neurological deficit was recognized, and scintillating scotoma and headache disappeared. Postoperative stereotactic radiosurgery was performed. The scintillating scotoma was caused by the tumor, because the spike wave and phase reversal were detected by the intraoperative cortical EEG. Intraoperative EEG is useful for the diagnosis of epilepsy caused by tumor. Sulcotomy and gyrectomy are the optimal surgical treatments for epilepsy caused by a localized glioma.