Source: Scott RM, Smith JL, Robertson RL, et al. Long-term outcome in children with moyamoya syndrome after cranial revascularization by pial synangiosis. J Neurosurg: Pediatrics. 2004;100:142–149.Moyamoya syndrome is defined by progressive occlusion of the internal carotid artery just beyond its point of entry into the cranial cavity. The insidious development of brain ischemia elicits the development of tiny collateral arterial vessels deriving from the external carotid distribution and the vertebrobasilar system. The cloud-like, indistinct appearance of these collateral vessels on cerebral arteriography gives rise to the esoteric name for this condition, a Japanese term meaning a puff of smoke.1 In children, the syndrome usually presents as cerebral ischemia, while in adults hemorrhage from fragile collateral vessels dominates the clinical picture. Moyamoya syndrome may be idiopathic, but most often arises in the setting of cerebral or systemic disease, such as neurofibromatosis type 1,2 trisomy 21,3,4 sickle cell disease,5 or neoplastic conditions that have been treated with parasellar radiotherapy.6,7Reported here, by investigators from Children’s Hospital, Boston, Mass, and Indiana University, Indianapolis, is the largest North American experience with the surgical management of moyamoya syndrome in childhood. Over a 17-year period, 271 craniotomies for cerebral revascularization were performed in 143 patients. The technique of the principal surgical procedure remained stable during this epoch; 1 of the major branches of the superficial temporal artery is dissected from the scalp with preservation of the origin of the artery and its distal branches to avoid interruption of arterial flow and thrombosis. A long elliptical craniotomy is performed corresponding in orientation to the original course of the artery, and the dura is opened. Under the magnification of the operating microscope, the arachnoid membrane surrounding the superficial cerebral vessels is opened as well, and the arterial graft is laid on the surface of the brain and sutured to the pial surface. Angiogenic factors secreted by the ischemic brain eventually call forth new vessels from the graft, which lies in direct contact with brain tissue through the opened arachnoid. This procedure has been called pial synangiosis.The success of this treatment may be judged by arteriographic evidence of collateralization of the brain from the graft and, more importantly, by interruption of the relentlessly progressive natural history of the condition. Among 195 cerebral hemispheres for which follow-up arteriography was available, 65% exhibited filling more than 2/3 of the middle cerebral artery distribution by perfusion from the graft. Only 10% exhibited filling 1/3 or less. Among 126 children with more than 1-year follow-up, 90 had no disability, and an additional 13 had some disability but were still independent. The long-term functional outcome was determined predominantly by preoperative functional status. Among 46 patients who had presented with cerebral infarction and who had been followed postoperatively at least 5 years, there were 21 strokes per 100 patient-years before surgery and 2 strokes per 100 patient-years after surgery. There were 11 strokes, 3 severe transient ischemic attacks, and no deaths within 30 days of surgery.Moyamoya syndrome is not common, but it arises in the setting of a number of common childhood diseases, such as sickle cell disease. Programs devoted to the management of predisposing diseases will enrich the parent institution’s experience with moyamoya, so pediatricians working in and around such programs must become familiar with it. It should always be considered in the differential diagnosis of cerebral infarction in childhood, particularly because it is so readily treatable. Happily, pial synangiosis is not technically challenging to perform, so satisfactory clinical results may be achievable even by surgeons without the enormous personal experience of the first author of this report.