Jibiki I, Kurokawa K, Matsuda H, Fukushima T, Yamaguchi N, Hisada K
Department of Neuropsychiatry, Kanazawa University, Japan.
Neuropsychobiology. 1992;26(3):120-4. doi: 10.1159/000118905.
To study the pathophysiological mechanisms of hyperventilation-induced EEG showing, i.e., the so-called 'buildup' phenomenon, changes in regional cerebral blood flow (rCBF) were investigated before and during the phenomenon in a 16-year-old woman with headache, thought to be of neurotic origin, by subtraction technique of brain images with single photon emission computed tomography using technetium-99m hexamethyl-propyleneamine oxime (99mTc-HMPAO). The tracer uptake during buildup decreased by 31-42% as compared to baseline values at rest before buildup in all of the measured regions, reflecting a widespread reduction in rCBF. Gas analyses of arterial blood collected during buildup showed a decrease in PaCO2, and increases in PaO2 and pH with a slight decrease in blood pressure and an increase in pulse rate. These results directly demonstrate a close correlation between the hyperventilation-induced EEG and rCBF changes, suggesting that the buildup phenomenon results from cerebral ischemic change, presumably due to cerebral vasoconstriction caused by the PaCO2 decrease.
为研究过度换气诱发脑电图表现（即所谓的“增强”现象）的病理生理机制，采用锝-99m六甲基丙烯胺肟（99mTc-HMPAO）单光子发射计算机断层扫描脑图像减法技术，对一名16岁、被认为是神经源性头痛的女性在该现象出现之前及期间的局部脑血流量（rCBF）变化进行了研究。与增强前静息状态下的基线值相比，所有测量区域在增强过程中的示踪剂摄取量减少了31%-42%，反映出rCBF普遍降低。在增强过程中采集的动脉血气分析显示，动脉血二氧化碳分压（PaCO2）降低，氧分压（PaO2）和pH值升高，血压略有下降，脉搏率增加。这些结果直接证明了过度换气诱发的脑电图与rCBF变化之间密切相关，提示增强现象是由脑缺血改变引起的，推测是由于PaCO2降低导致脑血管收缩所致。
