[Hemispherectomy and Hemispherotomy in the Treatment of Drug-Resistant Epilepsy].

Hemispherectomy/hemispherotomy is an important surgical procedure for patients with drug-resistant epilepsy who have a unilateral large epileptogenic lesion associated with neurological deficits, such as hemiparesis. Hemispherotomy consists of corpus callosotomy and dissection of projection fibers into the internal capsule. Hemispherotomy has two major approaches: periinsular lateral hemispherotomy(PIH)and vertical parasagittal hemispherotomy(VH). The white matter is incised along the periinsular sulcus to disrupt the internal capsule before corpus callosotomy is performed within the lateral ventricle in PIH. Corpus callosotomy is performed first with an interhemispheric approach, the lateral ventricle is entered, and the internal capsule is disconnected just lateral to the thalamus in the VH. Both approaches have similar efficacy for seizure control; however, a recent study suggested the possible superiority of VH. The chance of complete seizure freedom for one or two postoperative years has been reported to be 70% or greater. The risk of postoperative hydrocephalus is as high as 20%, particularly in young children. In this article, we present and discuss the surgical anatomy of hemispherotomy techniques.