Contribution of neuropsychology to epilepsy surgery.

Surgical treatment is being used with increasing frequency for patients with intractable epilepsy. Operative success depends to a large degree on the results of a comprehensive pre-operative patient evaluation the main purpose of which is to delineate the epileptogenic lesion. The pre-operative assessment includes video EEG monitoring, structural and functional (fMRI) neuroimaging and neuropsychological evaluation. The likelihood of the success of surgery is increased when all test results point to a single epileptogenic focus. The unique contribution of neuropsychology, which includes standard neuropsychological assessment and intracarotid sodium amytal (Wada) testing, is its capability to predict lateralization and often localization of a brain lesion based on cognitive function and dysfunction, which can be demonstrated also in the absence of a structural lesion. The Wada test is used to determine the cerebral speech dominance, to predict postsurgical amnesia and is found to be useful in predicting laterality of seizure focus in candidates for temporal lobectomy.