Long-term effects of temporal lobectomy on intelligence.

Abstract

To characterize the long-term effects of anterior temporal resection on intelligence. Twenty-eight left temporal lobectomy (LTL) and 43 right temporal lobectomy (RTL) patients were followed at standard time points for at least 6 years after surgery. The average gain 6 years after operation was 3.6 Verbal IQ (VIQ) points and 10.3 Performance IQ (PIQ) points in LTL patients and 2.9 VIQ points and 7.7 PIQ points in RTL patients. A seizure-free outcome did not influence the increase in IQ, nor was the extent of resection related to IQ scores at the 6-year follow-up. Patients with exclusively mesial temporal sclerosis did not perform as well as patients with other pathologies, both before and after surgery. Major predictors of improved performance at 6 years were initial higher level of performance and lower age at surgery. Much of the observed improvement may be related to retest effects. The effects of epilepsy surgery on intelligence in the long term are limited. The largest gain in VIQ is seen from 2 to 6 years after surgery.