Route learning performance: is it a hippocampus function?

Introduction: In temporal lobe epilepsy (TLE), about 30% of the patients do not achieve adequate pharmacologic control of refractory crises, and surgery becomes an alternative. In ablative interventions, neuropsychologic testing of memory is a crucial step. However, evaluations of the right hippocampal functions have not been consistent. Aim: To assess the hippocampal function in remote orientation and visuospatial memory in patients with refractory temporal epilepsy. Methods: A controlled study of patients with left (LTLE) or right (RTLE) TLE. The subjects were submitted to a neuropsychologic evaluation through the Route Learning Test and the Childhood Home Test in the preoperative period. The statistical analysis was performed using the Kruskal-Wallis, analysis of variance, chi(2), and Mann-Whitney U tests. Results: There was no significant difference in performance in the remote visuospatial memory (as measured by the Childhood Home Test) across the groups (LTLE, RTLE, and control). Concerning the spatial orientation memory, however, there was a significant difference between the LTLE and controls as compared with the RTLE group (P < 0.001), the latter showing a poorer performance. Conclusions: The study suggests that spatial orientation memory relies on the integrity of the right hippocampus. Nevertheless, further studies are necessary to confirm this hypothesis.