Focal cortical dysplasia type IIa underlying epileptogenesis in patients with epilepsy associated with Sturge-Weber syndrome.

In patients with epilepsy associated with Sturge-Weber syndrome (SWS), epileptogenesis has been suggested to be caused by chronic ischemia in cortical areas affected by leptomeningeal angiomatosis or by ischemia-related cortical malformations. However, this has not been fully verified electrophysiologically. We herein present two cases of SWS with medically intractable epilepsy in which the epileptogenic area involved focal cortical dysplasia (FCD) type IIa near the region of leptomeningeal angiomatosis. In both cases, the ictal-onset zones were identified by chronic subdural electrodes, and the presence of FCD type IIa was shown histopathologically. In SWS, especially in association with focal leptomeningeal angiomatosis, FCD may thus play a major role in epileptogenesis. FCD should therefore be demonstrated by the collective findings of perioperative neurophysiologic examination, anatomic and functional neuroimaging, and histopathologic examination.