Hemispherotomy is an effective epilepsy surgery in medically refractory epilepsy secondary to large unilateral hemispheric epileptogenic lesions, with reported long-term seizure freedom rates around 75%. The patients selected for hemispherectomy typically have a preexisting hemiparesis, and their affected hemisphere is nondominant for language, so hemispherotomy in this setting rarely leads to new unacceptable deficits.