Surgery of Intractable Epilepsy with Calcified Mass Lesions in the Temporal Lobe

ABSTRACT

We present 10 patients who underwent temporal lobe surgery for seizure control on our institution between December, 1992 and October, 1994. Preoperative neuroimaging studies of all 10 patients showed calcified mass lesions within the temporal lobe. Among them, 5 cases had mesial temporal calcified mass close to the hippocampus, 3 diffuse mass in the temporal lobe or multilobes and 2 in the temporal tip. All patients presented with complex partial seizure and seven had secondary generalization from their seizures. The duration of epileptic seizure varied between 4 and 23 years(mean 13 year). The patients were refractory to therapeutic levels of anticonvulsant medication. Presurgical evaluations of epilepsy included a detailed clinical history, multiple scalp/shenoidal EEG, prolonged Video-EEG monitoring, neuroimaging, neuropsychological test, WADA test and invasive study with subdural strip electrodes. Anterior temporal lobectomy with lesionectomy were performed in six cases and anterior temporal lobectomy in four cases using intraoperative electrocorticography(EcoG) and/or functional mapping under local or general anesthesia. The extent of resection of amygdala and hippocampus were determined according to electrocorticographic findings. The verified histopathology of the calcified lesions revealed 1 oligodendroglioma, 1 mixed glioma, 1 arterioveous malformation, 1 paragonimiasis, 2 neurocysticercosis, 1 other parasitic granuloma and 3 calcified fibrous nodule. In four patients, severe hippocampal sclerosis with neuronal cell loss and gliosis were observed. After a mean postoperative follow-up of 9 months, 9 patients showed a seizure-free outcome and one patient a significant reduction in seizure activity. We conclude from our studies that temporal lobe surgery for patients refractory to therapeutic levels of long-term anticonvulsant medication can result in excellent postoperative seizure-free outcome in the majority of the patients, and that brain tumors, vascular malformations, and parasitic infections may be considered as etiologic factors of calcified mass lesions in the temporal lobe of such patients.