Tectal glioma is an indolent and benign tumor that occurs predominantly in the pediatric population. It arises in the tectum of the midbrain and, due to its location, contributes to the development of obstructive hydrocephalus, typically presenting with increased intracranial pressure (IICP) symptoms or signs. Here we report a rare case of tectal glioma that presented as adult-onset epileptic seizures without IICP symptoms and was treated with endoscopic third ventriculostomy and antiepileptic drugs.

We present a recordings of 37-year-old woman with simultaneous ictal scalp and subdural electrodes. The ictal rhythmon subdural electrocorticography (ECoG) started earlier (median 24.5 sec) and ended later (median 2.0 sec) compared toictal rhythm on scalp EEG. Eight ictal ECoG recordings were well localized to left temporal area, whereas ictal scalp EEGrecordings were not. Our case shows the obvious timing relations between two recordings, and different electrophysiologicinformation about localization of ictal onset zone.