Purpose: Carotid endarterectomy (CEA) has proven to be effective in the prevention of stroke in patients with significant internal carotid artery (ICA) stenosis. However, whether increased cerebral blood flow after CEA improves the cerebral metabolism in patients with asymptomatic ICA flow lesions is unknown. Localized in vivo proton magnetic resonance spectroscopy ((1)H-MRS) has been used to measure the metabolic status of the human brain in a totally noninvasive manner. The aim of this study was to investigate the cerebral metabolism after CEA in patients with asymptomatic ICA flow lesions and no visible infarction on magnetic resonance imaging (MRI).
Materials and methods: We designed a prospective study to investigate the metabolic changes in the middle cerebral artery (MCA) territory with (1)H-MRS for 18 consecutive patients with asymptomatic severe stenosis of the ICA (>70% reduction in diameter) and for 16 healthy control subjects. The 18 patients with ICA flow lesion and no visible infarction on MRI who underwent CEA were evaluated before and 7 days after surgery (CEA group). The 16 control subjects had never had a cerebral event, and brain MRI and carotid duplex scan study results were normal in all (control group).
Results: Preoperative ICA volume flow was severely decreased to less than 150 mL/min in all 18 patients, in comparison with our laboratory normal value of matched age group of 250 to 300 mL/min. After CEA, ICA volume flow was increased to greater than 300 mL/min in all patients (P =.00). For patients in the CEA group, preoperative N-acetylaspartate/creatine and choline/creatine ratios in the MCA territory were slightly decreased compared with the healthy subjects in the control group but were within normal limits. However, the postoperative values of N-acetylaspartate/creatine and choline/creatine ratios in the ipsilateral MCA territory were significantly increased as compared with the preoperative values (P <.05). In the contralateral side, the postoperative increase of choline/creatine ratio and the decrease of myo-inositol/creatine ratio were statistically significant as compared with the preoperative values (P <.05).
Conclusion: CEA seems to improve the cerebral metabolic status in patients with asymptomatic ICA flow lesions and no visible infarction on MRI.