Postoperative Intelligence and Memory Performance in Temporal Lobe Epilepsy

Objective: The present study aimed to examine and compare the effect of surgery on intelligence and verbal/nonverbal memory in immediate versus delayed recall in patients with temporal lobe epilepsy.
Methods: Forty-eight patients with left (n=28) or right (n=20) Temporal Lobectomy (n=22) or Amygdalohippocampectomy (n=26), which were medically interactable to epilepsy participated in the study. They were grouped according the side of surgery (Left; Right) and type of surgery (Temporal Lobectomy (TL) or Amygdalohippocampectomy (AH)). There were eleven healthy controls. Intelligence and memory were examined in all groups according to Wecshler Adult Intelligence Scaled-Revised tests for Verbal, Performance and Full Scale IQs; and Wecshler Adult Memory Scale, Form II, for verbal and nonverbal memory. Three memory subtests were selected to provide measures of both immediate and delayed recall: Logical memory, Visual reproduction and Paired associate learning of words. T-test, On-way ANOVA and Two-way ANOVA were used for analysis the tests data in SPSS.
Results: Left Temporal lobe epilepsy groups (LT and LAH) demonstrated a significantly decline in verbal memory after left temporal lobe resection; whereas in right sided surgical groups (RT and RAH) a significant decrease in nonverbal memory was observed. For the difference between intelligence and memory, our results showed that the deficit is selective to memory and not extending to verbal or nonverbal functions in general in the two left sided surgucal groups. Working memory has a decline in RAH goups.
Conclusion: Postoperative memory performance has significantly decreased for verbal memory in temporal epilepsy group with left temporal lobe resection; on the other hand, nonverbal memory after operation had significant decline in patinets whith right side resection of temporal lobe. The other aspects of intelligence and verbal and nonverbal functions were intact after surgery so it is confirmed that they are not dependent on medial temporal lobe areas. Working memory has a meaningful decrease in RAH goups after operation with lowest scores in FS IQ and VIQ. There was a classic double dissociation for verbal and nonverabl paired associate learning and delayed recall in left and right temporal lobes.