Cognitive outcome 10 years after temporal lobe epilepsy surgery: a prospective controlled study.

OBJECTIVE

To explore late effects of temporal lobe resection (TLR) for epilepsy on general cognitive level and memory.

METHODS

Fifty-one patients who had undergone TLR (23 in the speech-dominant temporal lobe [DTL] and 28 in the nondominant temporal lobe [NDTL]) were assessed preoperatively and 2 and 10 years postoperatively. Twenty-three healthy controls were assessed at baseline and at corresponding intervals. A battery of standardized tests for assessment of general cognitive level and memory was analyzed using a linear mixed model of between-subjects treatment effect and within-subject time effect.

RESULTS

The main result was cognitive stability from 2 to 10 years after TLR. The DTL group had declined in verbal memory at the 10-year follow-up compared to the NDTL group and to the controls. However, this decline was detected already 2 years postoperatively, with no further decline from 2 to 10 years. The memory decline was not related to seizure outcome or AED treatment. The NDTL group showed less improvement in performance IQ (PIQ) at the 10-year follow-up compared to the controls. The most important correlate to inferior PIQ scores was continuing seizures, which was more frequent in the NDTL group.

CONCLUSIONS

In this study, the main finding was cognitive stability from 2 to 10 years after temporal lobe resection. There was no further decline in verbal memory from 2 to 10 years after surgery, lending no support to the notion of an ongoing progressive decline in verbal memory after temporal lobe resection. The verbal memory course was not dependent on seizure outcome or antiepileptic drug treatment.