Epilepsy and perisylvian lipoma/cortical dysplasia complex.

Intracranial lipomas are congenital malformations composed of mature adipocytes. They are usually located in the midline, particularly in the pericallosal region, a hemispheric location accounting for only 3 to 7% of cases. Review of the literature found 21 previous cases of hemispheric lipoma. Although hemispheric cerebral lipomas are rare, association with epilepsy appears to be frequent. We have recently studied two patients in whom epilepsy was the first clinical manifestation of hemispheric cerebral lipoma in the sylvian region. The patients presented with simple motor partial seizures as the first manifestation of the lesion. Neurological examination was normal. MRI disclosed in both cases a lesion involving the sylvian fissure with characteristics of the lipid signal. MRI also demonstrated abnormalities involving the cerebral cortex in the vicinity of the lesion (pachygyria-like aspect). Partial excision of the lesion was achieved in one patient but was followed by a worsening of seizures and neurological condition (hemiparesis). According to the literature, the prognosis for epilepsy in patients with hemispheric lipoma appears good. Several other arguments support non-surgical management: the lesion is benign and can be identified with a high degree of certainty by imaging; surgery is technically difficult due to adherence to adjacent vascular and cerebral structures and hypervascularity; location near functional brain tissue increases the risk of postoperative sequelae. In addition, mechanisms of epilepsy probably involve vascular and cortical dysplasic abnormalities. In consideration of the complexity of the lesion, hemispheric lipomas are more appropriately classified with localized cortical malformations rather than as simple extracerebral malformations.