Hayashi T, Suzuki A, Hatazawa J, Kanno I, Shirane R, Yoshimoto T, Yasui N
Department of Surgical Neurology, Research Institute for Brain and Blood Vessels, Akita, Japan.
J Neurosurg. 2000 Dec;93(6):1014-8. doi: 10.3171/jns.2000.93.6.1014.
The mechanism of reduction of cerebral circulation and metabolism in patients in the acute stage of aneurysmal subarachnoid hemorrhage (SAH) has not yet been fully clarified. The goal of this study was to elucidate this mechanism further.
The authors estimated cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO2), O2 extraction fraction (OEF), and cerebral blood volume (CBV) preoperatively in eight patients with aneurysmal SAH (one man and seven women, mean age 63.5 years) within 40 hours of onset by using positron emission tomography (PET). The patients' CBF, CMRO2, and CBF/CBV were significantly lower than those in normal control volunteers. However, OEF and CBV did not differ significantly from those in control volunteers. The significant decrease in CBF/CBV, which indicates reduced cerebral perfusion pressure, was believed to be caused by impaired cerebral circulation due to elevated intracranial pressure (ICP) after rupture of the aneurysm. In two of the eight patients, uncoupling between CBF and CMRO2 was shown, strongly suggesting the presence of cerebral ischemia.
The initial reduction in CBF due to elevated ICP, followed by reduction in CMRO, at the time of aneurysm rupture may play a role in the disturbance of CBF and cerebral metabolism in the acute stage of aneurysmal SAH.
动脉瘤性蛛网膜下腔出血（SAH）急性期患者脑循环和代谢降低的机制尚未完全阐明。本研究的目的是进一步阐明这一机制。
作者采用正电子发射断层扫描（PET）对8例动脉瘤性SAH患者（1例男性和7例女性，平均年龄63.5岁）在发病40小时内进行术前脑血流量（CBF）、脑氧代谢率（CMRO2）、氧摄取分数（OEF）和脑血容量（CBV）的评估。患者的CBF、CMRO2和CBF/CBV显著低于正常对照志愿者。然而，OEF和CBV与对照志愿者相比无显著差异。CBF/CBV显著降低表明脑灌注压降低，据信这是由于动脉瘤破裂后颅内压（ICP）升高导致脑循环受损所致。在8例患者中的2例中，显示出CBF和CMRO2之间的解偶联，强烈提示存在脑缺血。
动脉瘤破裂时由于ICP升高导致的CBF最初降低，随后CMRO降低，可能在动脉瘤性SAH急性期的CBF和脑代谢紊乱中起作用。
