REESTABLISHMENT OF CEREBRAL METABOLISM AFTER CAROTID ENDARTERECTOMY

Objectives: The purpose of this study was to evaluate the metabolic ch anges that occur in the human brain in patients with a symptomatic car otid artery stenosis. Materials and Methods: N-acetyl-aspartate (NAA), choline, creatine and lactate were measured both before, and 4 days a fter, carotid endarterectomy, by magnetic resonance spectroscopic imag ing (MRSI). Eight controls and 16 patients were examined. MRT and MRSI studies were performed on a Philips Gyroscan S15 whole body system op erating at 1.5 Tesla. H-1 spectra were selected from regions in the ce ntrum semi-ovale outside areas showing white matter hyper intensities on MRI. Results: All patients showed a decrease of the NAA/choline and NAA/creatine ratio in the symptomatic hemisphere compared to the cont ralateral hemisphere and also compared to the controls. Lactate was pr esent in some patients (5/16). After endarterectomy, the NAA/choline a nd NAA/creatine ratios increased significantly compared to the ratios preoperative. Lactate was absent or more than 50% reduced after the op eration. MRSI showed metabolic changes in areas of the brain that did nor show any abnormalities on MRI. Conclusions: There are marked chang es in brain metabolism in the symptomatic hemisphere of patients with a severe carotid artery stenosis. These metabolic changes normalise fo ur days after endarterectomy.