Abstracts

Rationale: Mesial temporal lobe epilepsy (MTLE) consists of a syndrome that is often refractory to clinical treatment, with up to 50-60% of patients not achieving optimal seizure control despite adequate antiepileptic drugs (AEDs) according to hospital series. However, recently it has been described a subgroup of MTLE patients with excellent response to AEDs, referred to as "benign MTLE". It is well established that MTLE patients have memory deficits due to hippocampal system damage, however, little is known about the impact of seizure frequency on memory in these patients. Therefore, the main purpose of this study was to compare memory performance between patients with refractory MTLE and patients with benign MTLE and to investigate the association between memory deficits, hippocampal volumes (HV) and the clinical response to AEDs. Methods: MRIs were acquired in a 3-T scanner (Philips Medical Systems) from 25 patients with refractory MTLE (mean age 47.76 ± 9.68 years, 14 women), 21 patients with benign MTLE (mean age 44.00 ± 13.31 years, 14 women) and 30 healthy subjects (mean age 40.03 ± 13.19 years, 15 women) for comparison of volumetric data. Hippocampus manual segmentation was performed by a single observer using the Display software (http://www.bic.mni.mcgill.ca/ServicesSoftware/MINC) without prior knowledge of disease history and participant's identification. The neuropsychological assessment included: the Edinburgh Handedness Inventory; subtests of the Wechsler Memory Scale-Revised (WMS-R); Rey Auditory Verbal Learning Test (RAVLT) and subtests of the Wechsler Adult Intelligence Scale-III. Statistical analysis was performed using Systat 9 software. Results: The groups were homogeneous regarding demographic and clinical features as shown in Table 1. However, there was a difference between the HA laterality which was most frequently on the right side in the refractory group (72% versus 38.1% in the benign group). We observed a reduction of ipsilateral and contralateral HV in patients when compared to the controls (p<0.001), as shown in Figure 1. Both patients' groups showed memory impairment, without significant differences between groups. We also observed a correlation between duration of epilepsy and estimated IQ (r= -0.28, p<0.05) and with performance on the WMS-R delayed recall (r= -0.3, p=0.04), between seizure frequency and ipsilateral HV (r=0.33, p<0.05) and with contralateral HV (r=0.32, p<0.05), as well as between the right HV and RAVLT recognition (r=0.3, p=0.04) and between the left HV and RAVLT A6 (r=0.28, p<0.05). Conclusions: We conclude that patients with MTLE exhibit memory deficits related to the presence of HA and duration of epilepsy, but independent of seizure frequency.