Abstracts

RATIONALE: MR Spectroscopy is a non-invasive technique that provides sensitive lateralization of the temporal seizure focus. Evaluating the patterns of biochemical disturbances among the different temporal lobe regions may provide a promising tool for mapping the seizure focus. METHODS: Eleven patients who underwent presurgical evaluation for intractable temporal lobe epilepsy, were evaluated by Proton MR Spectroscopy. We used the PROBE-P Technique to measure the spectra of N-Acetyl Aspartate (NAA), choline, creatine, myoinositol and lactate from three bilateral 15X12X12 mm single voxels applied to three temporal lobe regions sampling the amygdala/head of the hippocampus, the body and tail/parahippocampus and the lateral temporal neocortex. Decreased NAA peak and NAA/choline or creatine ratio were mainly considered in the lateralization and localization of the seizure focus and prediction of neuronal loss. RESULTS: NAA depletion and choline and myoinositol elevation were observed in the anterior and posterior medial temporal regions ipsilateral to the seizure focus in all patients and in the ipsilateral temporal neocortex in most patients. More profound changes were encountered in the amygdala/head of the hippocampus compared to those observed in the posterior hippocampus/parahippocampal region. Less, but significant changes occurred in the lateral temporal neocortex. Less significant changes were encountered contralaterally in most patients. Resected temporal lobes demonstrated neuronal loss and gliotic reaction in the hippocampal and neocortical regions in eight patients who underwent surgery. CONCLUSIONS: The differences in the biochemical disturbances between the anterior and posterior hippocampal/medial temporal regions and between the medial and lateral temporal areas may be related to a variable degree of associated histological and/or functional changes involving these temporal regions. MR Spectroscopy may allow mapping of these changes in the different temporal lobe regions and may add further benefit in the non-invasive presurgical evaluation.