皮質動脈圧，局所脳血流測定によるモヤモヤ病の血行動態の検討

PATHOPHYSIOLOGICAL STUDIES IN MOYAMOYA DISEASE BY RCBF AND CORTICAL ARTERY PRESSURE MEASUREMENTS IN COMPARISON TO THOSE IN ICA OR MCA OCCLUSION

　抄録　モヤモヤ病，内頸動脈閉塞，中大脳動脈閉塞の局所脳血流（rCBF）とこれらの疾患に対するSTA-MCA吻合術術中に測定した皮質動脈圧により，モヤモヤ病の循環動態を検討した。モヤモヤ病13例，内頸動脈閉塞22例，中大脳動脈閉塞8例を対象とした。rCBFは，single photon emission CTを用い，OMラインより5cm上のスライスで血流マップを求め，中大脳動脈領域の血流を算出した。モヤモヤ病群の体動脈圧と皮質動脈圧は，各々平均103,28mmHg，内頸動脈閉塞群は98,45mmHg，中大脳動脈閉塞群は89,36mmHgであった。モヤモヤ病，内頸動脈閉塞，中大脳動脈閉塞群のrCBFは，各々平均39,37，32ml／100g／minであった。このrCBFと皮質動脈圧より近位側脳血管抵抗（Rp）＝（平均体動脈圧-平均皮質動脈圧）／rCBFと，遠位側脳血管抵抗（Rd）＝（平均皮質動脈圧）／rCBFを求めた。モヤモヤ病，内頸動脈閉塞，中大脳動脈閉塞群のRpは，各々平均2.01,1.21,1.70,Rdは0.79,1.37,1.22であった。以上よりモヤモヤ病の脳底部異常血管網を介する側副血行路は極めて高い血管抵抗を有することが示唆された。

The authors measured preoperative rCBF and intraoperative cortical artery pressure (CAP) dur-ing STA-MCA anastomosis to investigate cerebral hemodynamics in moyamoya disease. Six of 13 patients including 3 children showed ischemic at-tack and the remaining presented hemorrhagic attack. rCBF was measured by single photon ECT with Xe-133 inhalation technique. CAP's and rCBF's in moyamoya disease were compared to those in the 22 internal carotid artery (ICA) and 8 middle cerebral artery (MCA) occlusion. Sys-temic arterial blood pressure (SABP) was obtained at the radial artery. Mean rCBF in the MCA ter-ritory in moyamoya disease, ICA occlusion, and MCA occlusion were 39, 37, and 33 ml/100g/min respectively. Mean SABP and CAP in moyamoya disease were 103 and 28 mmHg, respectively. In ICA occlusion, mean SABP and CAP were 98 and 45 mmHg, respectively. In MCA occlusion, mean SABP and CAP were 89 and 36 mmHg, respec-tively. To clarify the hemodynamics, vascular resis-tance was obtained from the following equations : The proximal vascular resistance (Rp), which was produced from the cervical ICA to cortical artery, was obtained by (mean SABP - mean CAP)/(rCBF). And distal vascular resistance (Rd) which was produced from the cortical artery to jugular vein, was obtained by (mean CAP)/ (rCBF). Mean Rp in moyamoya disease ICA oc-clusion and MCA occlusion were 2.01, 1.21 and 1.70, respectively. Rd in moyamoya disease, ICA occlusion and MCA occlusion were 0.79, 1.37 and 1.22, respectively. There were significant diffe-rences in Rp and Rd between moyamoya disease and ICA or MCA occlusion. In ischemic group in moyamoya disease, rCBF, SABP, CAP, Rp and Rd were 41 ml/100 g/min, 111 mmHg, 28 mmHg, 1.92 and 0.70, respectively. In hemorrhagic group, mean rCBF, SABP, CAP, Rp and Rd were 37 m// 100 g/min, 97 mmHg, 29 mmHg, 2.07 and 0.87, respectively. There were no significant differ-ences in these parameters between ischemic and hemorrhagic group.

This study clarified a prominent low CAP, 20-30 mmHg, in moyamoya disease, which must be a critical level of cerebral circulation. And the col-lateral circulation in moyamoya disease would have much more vascular resistance than that in ICA or MCA occlusion.