SENSITIVITY AND SPECIFICITY OF ASYMMETRIC RECALL ON WADA TEST TO PREDICT OUTCOME AFTER TEMPORAL LOBECTOMY

Some reports suggest that the intracarotid amobarbital test (IAT) is u seful for predicting good seizure outcome after temporal lobectomy. Th e sensitivity, specificity, and predictive value of the IAT in this co ndition has not been previously studied. We designed this study to est ablish the value of memory recall asymmetry on the IAT as a predictor of outcome after temporal lobectomy. We studied memory recall on the I AT in 108 consecutive patients with intractable epilepsy who underwent presurgical evaluation for temporal lobectomy and had at least 1 year follow up after surgery. At a level of 30% asymmetry of recall, speci ficity for favorable outcome (Engel Class I and II) was 100% (95% conf idence interval [CI], 85 to 100), sensitivity 51% (95% CI, 40 to 62), positive predictive value 100% (95% CI, 92 to 100), and negative predi ctive value 34% (95% CI, 23 to 47). At the same level of asymmetry, sp ecificity for seizure-free outcome (Engel Class I) was 88% (95% CI, 68 -95), sensitivity 37% (95% CI, 40 to 64), positive predictive value 87 % (95% CI, 71 to 96), and negative predictive value 38% (95% CI, 27 to 50). Asymmetric recall on the IAT is highly specific but not very sen sitive in predicting outcome after temporal lobectomy.