Introduction: It is reported that moyamoya disease (MMD) associated with posterior cerebral artery (PCA) stenoses or occlusions (PCS/PCO) progresses aggressively in clinical course and results in poor prognosis. In these cases, the thalamic perforating branches from PCA and the posterior choroidal arteries develop and present as moyamoya vessels. But it still remains unclear that the correlation between collateral circulations, cerebral metabolisms and PCS/PCO.
Hypothesis: In the current study, we assessed hypothesis that PCS/PCO leads to misery perfusion in the anterior circulation and results in unstable MMD.
Methods: A total of 79 patients, 158 hemispheres were included in this study. The average age was 42.5±15.6 years and 53 patients were women. We divided them into 2 groups (PCS/PCO positive or negative group) and cerebral blood flow (CBF), cerebral blood volume (CBV), oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO2) were examined by 15O-gas PET in following regions: anterior cerebral artery (rACA), anterior and posterior part of middle cerebral artery (rMCAa and rMCAp), and posterior cerebral artery (rPCA). Angiogram helped us to evaluate the development of the collateral vessels.
Results: In PCS/PCO positive group, CBF and CMRO2 were reduced whereas CBV and OEF were elevated in rMCAp compared to negative group. These parameters were all statistically significant (p<0.05). In addition, collateral circulations including anterior meningeal artery (AMA), middle meningeal artery (MMA) and posterior choroidal artery (PchoA) sufficiently developed in PCO/PCS positive group (P<0.05).
Conclusions: MMD associated with PCS/PCO has well developed AMA, MMA and PchoA because the stenotic or obliterative changes in the terminal portions of internal carotid artery have already progressed. In these patients, decreased CBF, increased CBV and OEF lead to misery perfusion in rMCAp despite the growth of the collateral flow. Early revascularization is recommended because PCS/PCO causes repeated stroke and unstable MMD.