Delayed posterior circulation insufficiency in pediatric moyamoya disease

Approximately 30 % of patients with moyamoya disease (MMD) have presented with involvement of the posterior circulation, mainly the posterior cerebral artery (PCA). Diagnosis of delayed progression of PCA stenosis in MMD may be difficult due to the diversity in clinical features. The goal of this study was to evaluate pediatric MMD patients with delayed PCA involvement after completion of revascularization of the anterior circulation. Forty-one pediatric MMD patients who underwent revascularization of the PCA territory due to delayed posterior circulation insufficiency MMD from 2006 to 2011 were retrospectively reviewed. The average interval between the initial operation and the occipital artery (OA) procedure was 5.0 years. Common symptoms were headaches and transient visual symptoms. The decision to operate was made based on a combination of diagnostic tools. The results obtained with perfusion MRI, SPECT, MR angiography, and EEG supported posterior circulation insufficiency in 78, 41, 73, and 71 % of patients, respectively. Encephaloduroarteriosynangiosis (EDAS) using the OA was performed in 15 patients, and 26 patients received multiple burr hole trephination of the occipital area. All patients showed clinical improvement. Clinicians should be aware of the possibility of delayed involvement of the PCA in pediatric MMD patients. The clinical decision regarding treatment should be based on a combination of symptomatology and the results obtained with various tools to assess whether the blood flow in the PCA territory is insufficient. Surgical treatment using indirect revascularization appears to be effective for patients with delayed PCA involvement.