1H MR spectroscopy in histopathological subgroups of mesial temporal lobe epilepsy

The aim of the study was to analyze the lateralizing value of proton magnetic resonance spectroscopy (H-1 MRS) in histopathologically different subgroups of mesial temporal lobe epilepsies (MTLE) and to correlate results with clinical, MRI and seizure outcome data. A group of 35 patients who underwent resective epilepsy surgery was retrospectively studied. Hippocampal H-1 MR spectra were evaluated. Metabolite concentrations were obtained using LCModel and NAA/Cr, NAA/Cho, NAA/(Cr+Cho), Cho/Cr ratios and coefficients of asymmetry were calculated. MRI correctly lateralized 89% of subjects and H-1 MRS 83%. MRI together with H-1 MRS correctly lateralized 100% of patients. Nineteen subjects had "classical" hippocampal sclerosis (HS), whereas the remaining 16 patients had "mild" HS. Nineteen patients had histopathologically proven malformation of cortical development (MCD) in the temporal pole; 16 subjects had only HS. No difference in H-1 MRS findings was found between patients in different histopathological subgroups of MTLE. Our results support the hypothesis that H-1 MRS abnormalities do not directly reflect histopathological changes in MTLE patients. Subjects with non-lateralized H-1 MRS abnormalities did not have a worse postoperative seizure outcome. We found no significant impact of contralateral H-1 MRS abnormality on post-surgical seizure outcome.