Abstracts

RATIONALE: The intracarotid amobarbital procedure (IAP) is widely used in the evaluation of candidates for epilepsy surgery to assess memory function. Epilepsy in these patients frequently results from diffuse neurologic insults (such as febrile seizures or meningitis) that can cause bilateral cerebral injury. Further, frequent seizures may produce progressive bilateral neurologic dysfunction. We used a recently developed 16 item, 7 foil IAP test to assess the frequency of bilateral memory deficits in patients undergoing evaluation for resective surgery. METHODS: The records of 93 consecutive patients who underwent IAP testing over a 36 month period were reviewed. The IAP test consisted of 8 words and 8 figures (or a recently modified version consisting of 9 words and 9 figures) presented over a three minute period after the injection of 100 - 120 mg amobarbital into the carotid artery. After recovery, patients were asked to select previously shown objects from a group of eight similar objects. In each case the suspected epileptogenic hemisphere was injected first, followed by the contralateral hemisphere 30 minutes later. Bilateral memory dysfunction was defined as <50% recall on both hemispheres. Data was analyzed by Fisher's Exact Test, using the Instat Program (Graphpad Software). RESULTS: 27/93 (29%) of patients had evidence of bilateral memory dysfunction on IAP testing. Bilateral memory dysfunction was not related to duration or age of onset of epilepsy. Patients with bilateral memory dysfunction were more likely to have epilepsy resulting from traumatic brain injury (35% vs. 16%, O.R. 2.7, p=0.057), and less likely to have seizures of focal neocortical onset (7% vs. 30%, O.R. 0.222, p=0.035). CONCLUSIONS: Bilateral memory dysfunction is common in patients with intractable partial epilepsy. While it does not appear to be related to duration or age of onset of seizures, it may be related to the nature of the initial insult. Whether memory dysfunction detected by IAP testing as performed at our center predicts functionally limiting amnesia post-operatively remains to be determined.