PREDICTORS OF OUTCOME AFTER ANTERIOR TEMPORAL LOBECTOMY - THE INTRACAROTID AMOBARBITAL TEST

The intracarotid amobarbital test (VIT) examines hemispheric memory an d language. We set out to determine whether memory performance on the IAT correlated with seizure relief after anterior temporal lobectomy i n 117 patients with refractory epilepsy. The IAT assessed recognition memory performance for nine items with correction for false-positive r ecognitions. We then compared performance of one hemisphere with that of the other, defining a correctly lateralized memory deficit as worse performance when using the hemisphere containing the operated tempora l lobe than when using the other hemisphere. The analysis included con current factors that might also affect outcome, such as age at first r isk for epilepsy, presence or absence of tumor, and Full Scale IQ. A d iscriminant function analysis demonstrated that patients with a correc tly lateralized memory deficit on the IAT had an increased probability of being seizure-free following surgery after controlling for other p redictors. The performance of the nonoperated temporal lobe related to outcome, although less strongly. The magnitude of the difference in p erformance between the two hemispheres and the performance of the oper ated hemisphere did not relate to outcome. Patients who became seizure -free had an earlier age at first risk than did those with persistent seizures, and tumor presence weakly correlated with postoperative outc ome. IQ did not correlate with outcome. We conclude that the IAT predi cts seizure relief after anterior temporal lobectomy independent of ot her known risk factors we examined.