Regression of moyamoya vessels and hemodynamic changes after successful revascularization in childhood moyamoya disease

Successful revascularization improves ischemic symptoms in the pediatric patients with moyamoya disease. However, it is not clear whether the revascularization prevents future intracranial hemorrhage from the residual moyamoya vessels. The purpose of this study is to investigate perioperative morphological and hemodynamic changes in the moyamoya vessels. Four pediatric patients (age <15 years old) with bilateral moyamoya disease were selected for this study. To quantify the number of moyamoya vessels, T1-weighted transverse images at the level of the basal ganglia and the thalamus were selected and characteristic flow voids in the lentiform nucleus were counted. Resting CBF and cerebrovascular reserve capacity (CRC) were measured pre- and 1 year after surgery using Xenon-CT CBF method with acetazolamide test. The ratio of deep CBF/cortical CBF was calculated as an index of hemodynamic stress distribution. The one-year follow-up studies showed that 1) the number of moyamoya vessels decreased on the operative side, but did not change on the nonoperative sides in all cases 2) the ratio of deep CBF/cortical CBF decreased on the operative sides, but did not change in the non-operative sides; and 3) the CRC increased on both sides. This observation suggests the possibility that revascularization surgery may be effective for preventing the future risk of intracranial hemorrhage.