Abstracts

Familial mesial temporal lobe epilepsy (FMTLE) is highly associated with hippocampal atrophy (HA), which can be found not only in patients with refractory seizures, but also in family members with good outcome and even asymptomatics. Our objective was to investigate metabolic changes in patients with FMTLE, using ¹H magnetic resonance spectroscopy (MRS), and correlate these findings with seizure control and hippocampal volumetry. MRI and ¹H MRS were acquired in an Elscint 2T scanner (Prestige, Haifa, Israel), after signed informed consent. Anatomical MRI included coronal T2 and T1-IR 3mm slices, perpendicular to hippocampal long axis and T1-3D volumetric acquisition. HA was determined by visual and quantitative studies, using a standard protocol: volumes were corrected by the variation in total intracranial volumes and an asymmetry index (AI) was defined as the ratio smaller/larger hippocampus for each subject. Volumes or AI below two standard deviations from the mean of the control group were considered abnormal. We used PRESS sequence for single voxel ¹H MRS (TR= 1500 ms, TE=135ms, NEX=200), over the head of hippocampal formation bilaterally. The spectra were post-processed using software supplied by the MRI machine manufacturer. After zero-filling and baseline correction we determined peak areas by integration of the corresponding signals from from [italic]N[/italic]-acetyl compounds, mainly the neuronal marker N-acetylaspartate (NAA) at 2.01 ppm, choline-based compounds (Cho) at 3.2 ppm and creatine and phosphocreatine contained compounds (Cr) at 3.0 ppm and determined NAA/Cr ratios. Spectra with broad peaks and poor separation of individual peaks were excluded from analysis. Values below two standard deviations from controls were considered abnormal. We studied 30 FMTLE individuals: ten with good seizure control, five with refractory seizures, and 13 asymptomatics. HA determined by volumetry was found in 23 individuals: 11 bilateral, five right and seven left. Abnormal NAA/Cr ratios were found only in three asymptomatic individuals: one had bilateral HA and left NAA/Cr reduction, one had left HA and NAA/Cr reduction on the left and the third had normal hippocampal volumes and bilateral NAA/Cr reduction. This preliminary study in patients with FMTLE showed that relative NAA reduction was less frequent than the reported figures in series of patients with refractory TLE. Whether this is related to better seizure control in this group of FMTLE or to other differences between FMTLE and sporadic refractory TLE remains to be determined. (Supported by Funda[ccedil][atilde]o de Amparo [agrave] Pesquisa do Estado de S[atilde]o Paulo (FAPESP), S[atilde]o Paulo, Brazil (grants number 95/9659-5, 97/07584-3 and 99/10702-3).)