Proton MR spectroscopy in patients with seizure disorders.

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.