Abstracts

Rationale: The aim of the study was to assess the value of a verbal memory test, a semantic fluency test, and measures of anxiety and depression in lateralizing temporal lobe dysfunction preoperatively in a series of patients with unilateral mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS). Methods: Twenty-three right MTLE-HS (65% women, 100% right handed, age=4011.8, education age=8.13.4, age at seizure onset=16.611.4 years, disease duration=23.4 years14.5, AED=2.71.0) and 26 left MTLE-HS (58% women, 85% right handed, age=43.49.7, education=8.95.1, age at seizure onset=12.39.4, disease duration=31.2 years13.2, AED=2.71.0) performed the Portuguese version of the Rey Auditory Verbal Learning Test (AVLT) and the Semantic Fluency test (animals) and answered the Hospital Anxiety and Depression Scale (HADS) and the modified Geschwind-Oldfield Handedness Questionnaire. None of the participants had epilepsy surgery prior to the assessment. Two neurorradiologists, blinded to the neuropsychological test results, identified by consensus the side of sclerosis based on 1.5 or 3.0 Tesla MRI scans. Chi-square test and t-test for independent samples were used for group comparisons. ROC curves were calculated to identify the best cut-off scores to discriminate left from right MTLE-HS. Results: The groups had similar demographic and clinical characteristics (p>0.05). Among AVLT measures, the Delayed Recall (mean scores: right MTLE-HS=8.12, left MTLE-HS=5.53) had an AUC=0.799 (95%CI: 0.667-0.932; p < 0.001) and the Long-Term Percent Retention index (LTPR; mean scores: right MTLE-HS=81.517.8, left MTLE-HS=58.230.1) had an AUC=0.787 (95%CI: 0.654-0.919; p=0.001). A Delayed Recall < 7 and a LTPR < 72 were found respectively in 73% and 77% of left MTLE-HS patients, whereas 78% of right MTLE-HS patients scored 7 or above on the Delayed Recall and 74% scored 72 or above on the LTPR index. However, none of the AVLT Immediate Recall trials (including the derived indexes: Total Learning and Learning Over Trials) or the Delayed Recognition trial discriminated right from left MTLE-HS (p>0.05). Also, neither the Semantic Fluency test nor the HADS scores were significantly associated with side of MTLE-HS (p>0.05). Conclusions: Structural asymmetry of the hippocampus was strongly associated with a verbal memory test, but not with a language test nor with measures of anxiety and depression. Impaired delayed recall of verbal information has high concordance with unilateral left MTLE-HS. This cognitive indicator can be useful in determining the lateralization of MTLE-HS before surgery. The study findings are consistent with recent clinical-pathological studies performed in resected hippocampal specimens of MTLE-HS patients. Funding: N/A