[Surgery for intractable epilepsy--selection and presurgical evaluation]

Abstract

Success in epilepsy surgery depends upon the exact localization of epileptogenic lesion identified by recordings of scalp and/or intracranial EEG and observation of clinical seizures in addition to the neuroimaging techniques such as CT, MRI, SPECT, PET. Thinking of the postoperative outcome in the literatures regarding epileptic seizures according to surgical procedure, main candidates for surgery are patients with intractable symptomatic localization-related epilepsies. Walker's criteria (1974) are generally agreed as selection criteria of candidate for epilepsy surgery. In our hospital, candidates for temporal lobe resection are selected according to the following criteria: 1) presence of an epileptogenic region presumably within the temporal lobe, 2) appropriate drug treatment for at least 5 years, 3) complex partial seizures more frequently than once a week, 4) adolescent or adult patients over 15 years of age with no persistent psychiatric symptoms, and 5) patients capable of social rehabilitation if recurrent seizures subside. Presurgical evaluation consists of noninvasive and invasive evaluation. Noninvasive evaluation includes neuro-psychological tests including Wada test, neuroimagings, interictal and ictal long-term intensive EEG/CCTV monitoring by the scalp EEG using 10/20 electrode placement as well as sphenoidal electrode to catch at least 3 spontaneous seizures. Invasive evaluation is interictal and ictal long-term intensive EEG/CCTV monitoring by intracranial electrodes for two weeks. The presurgical evaluation is performed by the team composed of neurosurgeon, neurologist, neuropsychiatrist, and neuropediatrician to decide the localization of epileptogenic lesions for resection. Outcome concerning seizure, neuropsychological aspects, and QOL is followed for more than 3 years after operation. Surgery for epilepsy should not be done without strict presurgical evaluation.