[Epileptogenicity and evaluation of epileptic risk]

Epilepsy is the more frequent clinical manifestation of hemispheric cavernomas in 50 to 75% of symptomatic cases; the annual risk of a first seizure is evaluated from 1.5 to 2.5%. As for all epileptogenic lesions, many questions arise: Is the pathologic tissue or the perilesional cortex responsible for the epileptic symptoms? Is the risk related with the topography of the lesion? Is the prognosis of the epilepsy related with the number of seizures? Can the epilepsy become drug-resistant? Can surgical treatment cure the epilepsy? When surgery is indicated, should lesionectomy alone or lesionectomy plus perilesional tissue resection be performed? The iron and the hemosiderin deposits induce metabolic perturbations and tissue reorganization (gliosis and sclerosis) around the cavernoma. These cortical modifications seem to be responsible for the epileptic discharges but this is difficult to demonstrate. Epileptic discharges have been recorded in the perilesional tissue in only one study of the literature. Drug therapy can usually control the seizures, but it appears that surgery is more effective when the epilepsy is recent and the seizures are not too frequent. For these reasons it would appear licit to propose the resection of the lesion when the surgical risk is not too great. In case of drug-resistant epilepsy, the same function-targeted surgical strategy may be used as for the management of any severe epilepsy.