Introduction
Proton magnetic resonance spectroscopy (1H-MRS) is a useful method to evaluate cerebral metabolism directly and non-invasively. We examined 1H-MRS in the patients with major cerebral artery occlusive diseases and hemodynamic cerebral ischemia to study whether cerebral metabolism can improve after STA-MCA bypass.
Methods
The subjects were 11 patients. The age of the patients varies between 47–74 years. Six patients had internal carotid artery occlusion. Two patients had middle cerebral artery occlusion. Three patients had internal carotid artery severe stenosis. We examined Xenon-CT including acetazolamide challenge to evaluate the regional cerebral blood flow (CBF) and examined multi-voxel 1H-MRS using SE-2D-CSI method placed axially above the lateral ventricle before and at 6 months after STA-MCA bypass.
Results
The patency of STA-MCA bypass was good in 10 patients. In 8 of the 10 patients, percentile changes of regional CBF after acetazolamide challenge in the affected cortex were less than +10%. In 5 of the 8 patients, the regional CBF was normalized (more than +10%) after STA-MCA bypass. In 3 of the 8 patients, N-acetyl aspartate/creatine (NAA/Cr) ratios in the affected cortex were normal. In 5 of the 8 patients, NAA/Cr ratios were less than the lower limit (mean-2×standard deviation). In all 8 patients at the range of less than +10% in percentile change of regional CBF after acetazolamide challenge in the affected cortex, NAA/Cr ratios increased after STA-MCA bypass.
Conclusion
Cerebral metabolism improved after STA-MCA bypass in the patients with the impaired cerebrovascular reserve capacity in the affected cortex.