Abstracts

RATIONALE:_The objective of this study was to assess whether magnetic resonance spectroscopy of the mesial temporal lobe structures can reflect specific memory deficits, and whether this results may attribute to postoperative prognosis of neuropsychological and seizure outcome. METHODS:_55 TLE patients scheduled for epilepsy surgery were preoperatively investigated by high spatial resolution chemical shift imaging spectroscopy (CSI) and neuropsychological assessment including intracarotid sodium amytal test (IAT). Postoperative outcome of seizures and memory was examined one year after surgical treatment. Verbal memory and figural memory were measured and the laterality ratio was computed for the CSI as well as for memory functions. RESULTS:_CSI spectroscopy values for the dominant hippocampal formation has been proven to be significantly correlated to verbal memory scores. Pathological NAA/Cho ratios for the dominant hemisphere were associated with low verbal memory performance and with left hemispheric memory deficits identified by the IAT procedure. The correlation between the laterality ratios for CSI and memory was found to be statistically significant. For those patients who became seizure free postoperative, memory deficits were accompanied by pathological increased CSI values for the ipsilateral hippocampal structures. In these patients, preoperative contralateral pathological values returned postoperative to values within the normal range. In those patients who did not become seizure free postoperatively, ipsilateral and bilateral memory deficits were related to bilateral enhanced CSI values. CONCLUSIONS:_Our results demonstrate that CSI spectroscopy findings of hippocampal pathology are related to lateralized memory deficits in patients with mesial temporal lobe epilepsy. In patients undergoing preoperative evaluation, CSI investigation may provide a promising tool for prediction of memory function and postoperative outcome