Purpose: To evaluate the ability of proton MR spectroscopy to detect metabolic abnormalities in the seizure focus of humans with epilepsy.
Methods: Single-voxel MR spectroscopy and MR imaging was performed in a group of 13 patients with a variety of seizure disorders and in the temporal lobes of 14 healthy volunteers. Signals from choline, creatine, N-acetyl-L-aspartate, and lactate were quantitated in both the epileptogenic focus and the contralateral brain region.
Results: In normal temporal lobe, concentrations of choline, creatine, and N-acetyl-L-aspartate were 2.0 +/- 0.7, 7.8 +/- 1.9, and 11.0 +/- 2.1 mumol/g wet weight, respectively, with no detectable lactate. In all patients, a reduction in the N-acetyl-L-aspartate signal was observed in the electrically defined (scalp electroencephalogram) seizure focus compared with the mirror-image contralateral side. Lactate was elevated only in patients who had seizures during or immediately before the MR examination. Seven of 13 patients studied had normal MR examinations.
Conclusions: Proton spectroscopy demonstrates alterations in N-acetyl-L-aspartate and lactate levels that can be used to locate the epileptogenic focus and may be a useful adjunctive diagnostic technique for the evaluation of patients with seizures who are eligible for resective surgery.