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/kortical 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 CBFkortical 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.

The purpose of this study was to evaluate hemodynamic compromise in terms of baseline CBF and CRC in patients with chronic cerebral occlusive lesions and its modulation by a superficial temporal artery to middle cerebral artery (STA‐MCA) anastomosis. The study subjects were 10 healthy volunteers and 49 chronic ischemic patients with stenosis or occlusion of the internal carotid artery (ICA) or middle cerebral artery (MCA) The hemodynamics were measured using stable xenon enhanced computed tomographic CBF measurement with the acetazolamide challenge. The compromised hemodynamics in patients with chronic steno‐occlusive lesions did not improve during their natural course after two months. STAMCA bypass modulated hemodynamic compromise in the ischemic patients. We recommend STAMCA bypass for patients with reduced CRC, regardless of whether baseline CBF is reduced or normal. Hemodynamic classification using a combination of baseline CBF values and CRC values is useful for evaluating cerebral hemodynamics and for choosing the best treatment for cerebral ischemia with occlusive lesions.