1H-MRS profile in MRI positive- versus MRI negative patients with temporal lobe epilepsy

Introduction: The objective of this study was to quantitate and compare ipsilateral total N-acetyl aspartate (tNAA), creatine (Cr), choline (Cho), myo-inositol (m-Ins) and glutamate plus glutamine (Glx) levels in the hippocampi of patients with temporal lobe epilepsy (TLE) with and without magnetic resonance imaging (MRI) evidence for mesial temporal sclerosis (MRI positive/negative). Patients and methods: Twenty-three age matched healthy controls and 26 consecutive patients with unilateral TLE, based on intensive 24 h video-EEG, were investigated with proton magnetic resonance spectroscopy ((1)H-MRS) (17 with unilateral hippocampal sclerosis (HS) in MRI-MRI positive; 9 MRI negative). For statistical analysis one-way analysis of variance (ANOVA) with post hoc multiple comparisons and Bonferroni correction was applied. The significance level was based on p < 0.05. Results: The mean tNAA level ipsilateral to the seizure focus was significantly decreased in MRI negative, respectively MRI positive patients in comparison to healthy controls (p < 0.001). The lowest tNAA level was noticed in the MRI positive group (p < 0.001). Statistical analysis highlighted a clear tNAA cut-off (95% confidence interval) between MRI positive- and MRI negative patients and healthy controls. Mean level of Glx and m-Ins was not significantly elevated or reduced. However, in individual cases a significant elevation was noticed for Glx in MRI negative patients, respectively for m-Ins in MRI positive patients. Conclusion: MRI negative TLE patients have a different MRS profile than MRI positive patients (HS) with marginal but significant decrease of tNAA. Our results reveal a clear tNAA cut-off between the groups. The value of m-Ins and Glx in focus detection in TLE patients remains controversy. (C) 2008 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.