PROTON MAGNETIC-RESONANCE SPECTROSCOPIC IMAGING IN PATIENTS WITH EXTRATEMPORAL EPILEPSY

Purpose: Reduced levels of N-acetylaspartate (NAA) in temporal lobes r esponsible for temporal lobe epilepsy have been observed consistently in proton magnetic resonance spectroscopy (MRS) studies. Methods: We i nvestigated the potential of proton MRS to detect low NAA outside of t he temporal lobes in patients with non-lesional partial extratemporal epilepsy. Proton MR spectroscopic imaging (MRSI) data of both frontal lobes and central/postcentral regions were obtained in 20 such patient s and 16 normal control subjects. The epileptogenic region was determi ned by an extensive clinical-EEG investigation, including the recordin g of habitual seizures in each patient, and intracranial EEG recording s in 10 patients. Results: The relative NAA resonance intensities (i.e ., NAA/ phosphocreatine plus creatine (CRt), NAA/choline-containing me tabolites (Cho(t)) and NAA/Cr-t + Cho(t)), were all significantly redu ced throughout the spectroscopic image as compared with that of the co ntrols. Furthermore, reduction of the NAA ratios was greater in the ep ileptogenic region as compared with the nonepileptogenic regions, on E EG investigation. Conclusions: In vivo proton MRSI of patients with no nlesional partial extratemporal epilepsy detected evidence of widespre ad neuronal damage or dysfunction that was greatest in the region of s eizure focus.