Lipomas of the corpus callosum and epilepsy.

An analysis of four cases of lipomas of the corpus callosum with epilepsy, and a review of the literature, have led to the following conclusions: (1) Epilepsy as an almost constant feature is often severe, nearly always partial, and begins before the age of 15. (2) Pathophysiology of the seizures appears to be essentially an interhemispheric disconnection (rather than the classic theory that seizures depend upon an infiltration of the cingulate gyri by fibrous tissue growing out from the capsule of the lipoma). This disconnection is responsible for a facilitatory and disinhibitory action that favors the appearance of seizures caused by an epileptogenic lesion (the effects of which remain subthreshold in the presence of an intact corpus callosum playing its normal inhibitory role). This hypothesis is clearly applicable in explaining the epilepsies--in every way comparable--that are observed in agenesis of the corpus callosum and in Marchiafava-Bignami disease.