Abstracts

In mesial temporal lobe epilepsy associated with hippocampal sclerosis (MTLE-HS), neuropsychological testing might show memory deficits contralateral to the side of mesial temporal sclerosis. When such unexpected findings occur, little is known about the effects of temporal lobectomy on post-surgical cognitive function and seizure control. This study assesses possible memory dysfunction and seizure outcome after temporal lobectomy in these patients., Retrospective analysis of a cohort of 462 MTLE-HS patients refractory to antiepileptic drugs and submitted to surgical treatment at CIREP (Center for Epilepsy Surgery), from 1994 to 2005. Seizure outcome was assessed according to Engel classification: a) satisfactory seizure control: Engel I; b) non-satisfactory seizure control: Engel II-IV. From these patients we selected all right-handed patients with discordant neuropsychological (NPS) results on presurgical evaluation (Group I = 17 patients) AND compared their pre- and post-surgical NP results with a matched control group of patients with concordant NPS results (Group II = 60 patients). We compared Logical Memory (Verbal Memory) for evaluating cognitive function of the left temporal lobe and Visual Reproduction (Non-Verbal Memory) for evaluating the function of the right temporal lobe. The results were analyzed by Paired Samples t-Test, comparing pre- and post- operative scores., There were 17 (3.68%) right-handed patients with discordant NPS findings. Post-surgical seizure control did not differ between groups I (81.6%) and II (82.3%) ([italic]p[/italic]=1.00). There were no significant differences for immediate memory recall scores between groups. Regarding memory consolidation, group II patients did not show impairments after surgery. However, group I patients (discordant NPS group) showed memory consolidation impairment after surgery, when compared to themselves during pre-operative tests [mean pre-surgical memory retention score = 54.87 (26.94); mean pos-surgical retention score = 42.95 (23.97) [italic]p[/italic]=0.002)., Discordant neuropsychological findings do not affect post-surgical seizure outcome. Interesting, discordant group showed greater memory consolidation impairment after surgery. Because some patients still present pre-surgical good memory performance in the side of the mesial temporal sclerosis, our observation might suggest that in spite of sharing some possible common mechanisms, there seems to be important dissociation between memory consolidation and epilepsy mechanisms in mesial temporal lobe epilepsy., (Supported by FAPESP.)