ObjectiveTo determine the value of 1HMR spectroscopy in lateralization of patients with temporal lobe epilepsy (TLE).MethodsFiftyseven patients with nonlesional TLE and 20 controls were investigated by high resolution MRI and 1HMRS.Hippocampal volume and the ratios of NAA/Cr+Cho were measured and compared between two groups.Lateralization of the patients was classified by the predominance of interictal epileptiform discharges (IED).The lateralization rate was compared between diffirent methods.ResultsFourtyone patients(71.9%) were lateralized to one temporal lobe according to characteristic of the interictal EEG, with 24 patients diagnosed as left temporal lobe epilepsy (LTLE) and 17 as right temporal lobe epilepsy (RTLE).The other 16 patients were diagnosed as bilateral temporal lobe epilepsy (BTLE).(1)NAA/(Cho+Cr) ratios decreased in bilateral hippocampus in 56 TLE patients(98.2%) compared with controls.NAA/(Cho+Cr) ratios were significantly lower in the ipsilateral (affected) compared with contralateral (nonaffected) hippocampus in both LTLE group (P<0.001) and RTLE group(P<0.001).(2)Hippocampus atrophy was found in 28 TLE patients (49.1%) and 4 of them were bilateral.(3)28 patients (49.1%) were lateralized by hippocampal volume and 15 of them were accordant with IEDs (coincidence rate 53.6％), while 41 patients (71.9%) were lateralized by 1HMRS abnormalities and 32 of them were accordant with IEDs (coincidence rate 78.0％).ConclusionsTemporal lobe epilepsy is associated with widespread metabolic abnormalities in bilateral hippocampus.The degree of NAA/(Cho+Cr) ratios reduction is more sensitive than hippocampal volume in evaluating hippocampal dysfunction.1HMRS can be used in hemispheric lateralization of nonleisional TLE.