INTRACAROTID AMOBARBITAL PROCEDURE AS A PREDICTOR OF MATERIAL-SPECIFIC MEMORY CHANGE AFTER ANTERIOR TEMPORAL LOBECTOMY

Memory testing during the intracarotid amobarbital procedure (IAP) is used extensively to identify temporal lobe surgery candidates ''at ris k'' for developing severe postoperative anterograde amnesia. However, the utility of the IAP in predicting commonly observed material-specif ic memory deficits has not been thoroughly investigated. We examined t he utility of contralateral IAP memory testing, as an index of the fun ctional capacity of the surgical temporal lobe, to predict postoperati ve material-specific memory changes on the Wechsler Memory Scale-Revis ed (WMS-R) in patients with left hemisphere speech dominance undergoin g left (n = 32) and right (n = 31) temporal lobectomy (TL). Left TL pa tients who ''passed'' contralateral IAP memory testing (greater than o r equal to 68% recognition of memory items) had significantly greater verbal memory decrements than those who ''failed'' the IAP, presumably as a result of removal of functional tissue. A similar relationship b etween contralateral IAP performance and visual memory performance was not observed among right TL patients. Thus, the functional adequacy o f the tissue to be resected appears to be inversely related to postope rative verbal memory decrement, at least among left TL patients. This relationship is consistent with results of recent studies demonstratin g an inverse relationship between verbal memory decrements after left TL and preoperative neuropsychological verbal memory performance, magn etic resonance imaging (MRI) hippocampal volumes, and degree of mesiot emporal sclerosis (MTS).