Abstracts

Rationale: Mesial temporal lobe epilepsy (MTLE) is the most common type of focal epilepsy and 30% to 40% of these patients are refractory to antiepileptic drugs (AEDs). The surgical removal of the epileptogenic focus is indicated for this subgroup of MTLE patients. Nevertheless, it is still unclear how different surgical approaches influence on postoperative cognition and seizure control in MTLE. Our aim was to compare selective amygdalohipocampectomy (SelAH) and anterior temporal lobe resection (ATL) in memory performance and seizure control in MTLE patients with long term follow up. Methods: We evaluated 25 patients with MTLE and MRI evidence of hippocampal sclerosis (HS) who underwent SelAH and 22 who had ATL surgery. All patients underwent a comprehensive clinical-EEG evaluations and the same protocol for MRI acquisition (2 Tesla; 3D- T1-weighted images) and neuropsychological assessment (NPs). The volumetry of the surgical lacune (VSL) was performed with the Display software (David McDonald, www.bic.mni.mcgill.ca/software) and NPs used the Wechsler memory scale- R subtests: logical memory I and II, verbal and visual paired associated I and II, figural memory and visual reproduction I and II; Rey auditory verbal learning test (RAVLT); Wechsler adult intelligence scale- III subtests: vocabulary and block design to estimate the intelligence quotient (IQ- estimated). This evaluation was performed within a mean interval of 8.5 years after surgery. We performed Mann-Whitney test to compare the cognitive performance between groups. The correlation between VSL and NPs was performed using Spearman test. Seizure outcomes were evaluated using Engel classification and we conducted a two-sided Fischer exact test to evaluate the differences between the proportions of patients classified as Engel IA (seizure-free) and other outcomes according to the type of surgical approach. We considered only p<0.05 corrected for multiple comparisons. Results: There was no significant differences between SelAH and ATL groups related to cognitive performance in all NPs tests (p>0.05). In addition, the proportions of patients classified as Engel IA and other outcomes was not different in the SelAH and ATL groups (p=0.076). We found a positive correlation between QI- estimated and VSL for ATL group (r=0.479). Conclusions: These findings indicate that the postoperative outcome of memory performance and seizure control is similar for both SelAH and ATL in patients with MTLE and HS. The relationship between more extensive resections (VSL) and better estimated IQ needs further investigations and may be related to better seizure control in those with more extensive surgical resections.