Abstracts

Rationale: Major post-operative decline in verbal memory is a feared complication of temporal lobe surgery for pharmaco-resistant epilepsy. However, up to now, no reliable measurement exists to predict the degree of verbal memory deficit in individual patients. In the present study we were interested in determining the contribution of post-ictal memory testing for individual prediction of post-operative verbal memory decline. Methods: 45 patients suffering from pharmaco-resistant right- or left-sided temporal lobe epilepsy (R-TLE, L-TLE) underwent interictal, post-ictal and post-operative (3-6 months after surgery) verbal memory evaluation. Acquisition Rate (AR) and Delayed Recall (DR) were tested using Rey’s 15-word lists, repeated 5 times, and recall after >30 min. Post-ictal testing used a shorter version of 10 words. Results: Post-ictal and post-operative DR were significantly different in L-TLE and R-TLE. In contrast, interictal memory could not lateralize between R-TLE and L-TLE. Moreover, post-ictal DR scores were significantly correlated with post-operative DR (p=0.009). In the subgroup of L-TLE with hippocampal sclerosis, regression model using post-ictal DR results with age of epilepsy onset explained 80% of post-operative variance of verbal memory. AR showed similar pattern of post-ictal and post-operative decline, however, the predictive value for the post-operative decline was less good. Conclusions: Post-ictal memory performance is highly predictive of post-operative verbal memory outcome in L-TLE patients, particularly when results are considered together with age at epilepsy onset in patients with hippocampal sclerosis. Post-ictal memory tests appear to be a very useful non-invasive tool to predict verbal memory outcome after surgery for pharmaco-resistant TLE.