Role of magnetic resonance spectroscopy (MRS) in nonlesional temporal lobe epilepsy

Abstract

ObjectiveThe purpose of this study was to evaluate the role of magnetic resonance spectroscopy (MRS) in nonlesional temporal lobe epilepsy. Subjective and methodsBetween April 2011 and December 2013, a total of 30 patients having partial seizures with or without secondary generalization were selected from the Neurology Department, Sayed Galal Hospital, Al Azhar University and were studied in this work. All patients included in the study had clinical history, seizure symptoms, inter-ictal electroencephalography and neuroimaging findings that were consistent with “non-lesional epilepsy of temporal lobe origin”. We mean by non-lesional epilepsy that those cases are not secondary to other pathological lesions e.g. tumor, vascular insult or post inflammatory. Mesial temporal sclerosis was considered as nonlesional temporal lobe epilepsy. Each patient was thoroughly asked about the detailed clinical history after reviewing the referring imaging request and laboratory findings. The MRI and MRS examinations were performed in all the patients in one session. They were performed at 1.5T super conducting system. ResultsMRS was performed in a total of 30 patients. Sixteen patients were males and 14 were females. The average age of the patients was 32years (range: 17–47years). Seventeen patients (56.7% of total patient number) were found to have clinical and EEG criteria of epileptic activity related to temporal lobe origin on the right side, while 11 patients (36.7% of total patient number) were found to have these findings on the left side. Two patients (6.6% of total patients’ number) were having bilateral temporal lobe epileptic activity. Twenty six patients (about 87% of total patient number) were able to be lateralized with MRS using asymmetry index, 16 cases lateralized to the right side (about 53% of total patient number) and 10 cases lateralized to the left side (about 34% of total patient number). The remaining 4 patients (about 13% of total patient number) failed to be lateralized in our study. The sensitivity and specificity of the Conventional MRI and MR spectroscopy for detection of mesial temporal lobe epilepsy were 60% & 65% and 86% & 83% respectively. ConclusionMR spectroscopy is a very sensitive guiding tool in predicting the temporal lobe epilepsy (TLE) and the side of involvement in patients with TLE even in patients with MR negative studies. It helps in detecting abnormal spectra of various brain metabolites. MR spectroscopy has demonstrated consistent metabolic abnormalities in partial seizures. MRS can also detect bilateral affection with the ipsilateral side more affected.