Clinical significance of posterior cerebral artery stenosis/occlusion in moyamoya disease

PURPOSE: The present study was aimed at clarifying the clinical significance of posterior cerebral artery (PCA) stenosis/occlusion in pediatric and adult moyamoya disease. SUBJECTS AND METHODS: This study included a total of 132 patients (52 children and 80 adults) who were diagnosed as by cerebral angiography having moyamoya disease. CT or MRI was performed to examine the location of cerebral infarction in all subjects. Cerebral blood flow and vasoreactivity to acetazolamide were measured in 80 patients before surgery, using single photon emission computed tomography (SPECT). Three-dimensional MR angiography (3D-MRA) was repeated in 32 pediatric patients after surgery in order to clarify the natural course of the PCA stenosis/occlusion. RESULTS: Of 264 sides in 132 patients, PCA stenosis/occlusion was observed in 50 sides of 40 patients (30.3%). Its incidence was significantly higher in ischemic-type patients than in hemorrhagic-type and asymptomatic patients, and was higher in patients in the advanced stage of the disease. The hemisphere ipsilateral to PCA stenosis/occlusion had higher incidence of ischemic symptoms, cerebral infarction, and impaired cerebral hemodynamics. TIA (hemianopsia) or cerebral infarction in the occipital lobe was noted in 4 (10%) of 40 patients during follow-up periods after bypass surgery for anterior circulation. Of 32 pediatric patients, none showed progression of PCA stenosis on 3D-MRA during follow-up periods. CONCLUSIONS: The present study showed that the involvement of PCA could increase the risk of TIA and/or cerebral infarction in both anterior and posterior circulation areas, suggesting that the PCA plays an important collateral role in moyamoya disease.