| Research Abstract |
To study how neuronal tissues are affected by impairment of cerebral circulation during development of chronic cerebral vasospasm after subarachnoid hemorrhage (SAH), the changes in cerebral energy metabolism and neuronal metabolites during chronic cerebral vasospasm were evaluated by means of phosphorus and proton magnetic resonance spectrosopy (MRS), in a primate vasospasm model. The SAH was produced by introduction of blood clot around the right middle cerebral aretry (MCA). Angiography revealed severe vasospasm in the right middle cerebral artery on Day 7 after SAH induction. Phosphorus MRS revealed that drug-induced systemic hypotension (mean 60 mmHg) caused a significant decrease in the tissue ATP level in the spasm side parietal lobe on Day 7. Proton MRS was performed before SAH,on Day 7 and Day 14. The peak areas for choline-containing compounds (Cho), creatine and phosphocreatine (Cr) and N-acetyl-aspartate (NAA), and the ratios of Cho/Cr and NAA/Cr were evaluated in the bilateral parietal lobe. The proton MRS study revealed a significant reduction in NAA/Cr ratio on both Day 7 and Day 14, and a ignificant increase in Cho/Cr ratio, in the spasm side right parietal region. The histopathological study demonstrated the ischemic neuronal change in some (less than 10 %) of the cortical neurons in the territory of the spastic artery. The results suggest that the development of cerebral vasospasm caused impairment of cerebral circulation and energy metabolism in the territory of the vasospastic artery resulting in ischemic damage in some of the cortical neurons. The proton and/or phorphorus MRS may be useful to evaluate the effect of ischemic insult on neuronal cells during cerebral vasospasm.
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