Pre- and postoperative intracarotid amytal procedure: an assessment of validity

The intracarotid amytal procedure (IAP) was used twice to assess the suitability of three male patients for two successive neurosurgical procedures to relieve intractable temporal lobe epilepsy. First an amygdalohippocampectomy was performed, then further tissue was removed in a temporal lobe resection because their seizures had failed to remit. Repetition of the IAP following amygdalohippocampectomy when there was a known excision allowed inferences to be made regarding its validity in assessing lateralization of language functioning, memory functioning, and lateralization of seizure focus. The procedure was found to be reliable in assessing both language dominance and adequacy of memory functioning of the hemisphere contralateral to the lesion site. The procedure's third function of lesion lateralization was valid for identifying the known neurosurgical lesion. However, it was less successful in corroborating the lateralization of seizure focus before amygdalohippocampectomy. Differences in cognitive outcome between the two neurosurgical procedures are discussed.