Hematoma-related seizures detected during subdural electrode monitoring.

A 28-year-old woman with epilepsy developed the new onset of paroxysmal tongue tingling during subdural electrode monitoring. Her symptoms coincided with electrographic seizure activity arising from an area of the perisylvian region that had not previously been involved in her habitual seizures. At electrode removal, a focal 2 x 2 cm hematoma was detected and evacuated from beneath these electrode contacts. Unexpected episodic events may represent nonhabitual seizure activity related to the surgical procedure.