Spontaneous occlusion of the circle of Willis in children: pediatric moyamoya summary with proposed evidence-based practice guidelines

A review

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Moyamoya is a progressive arteriopathy of unknown origin affecting the branches of the internal carotid artery (ICA). The arteriopathy can present as an isolated medical condition, affecting both sides of the brain (“moyamoya disease”) or can be unilateral or found in association with systemic disorders (“moyamoya syndrome”). The ischemia resulting from luminal narrowing predisposes children to transient ischemic attacks and stroke—the primary presentations of affected patients. Although it is rare—affecting 1 in 1 million children in the US—moyamoya is implicated in 6% of all childhood strokes. Diagnosis is defined by characteristic findings on arteriograms, including stenosis of the branches of the ICA and a pathognomonic spray of small collateral vessels in this region, descriptively likened to a “puff of smoke” (“moyamoya” in Japanese). Treatment is predicated on restoration of cerebral blood flow by surgical revascularization. The rarity of this disorder has limited research and the development of evidence-based clinical management. While acknowledging these limitations, in this article the authors aim to summarize current studies of pediatric moyamoya, with the objective of providing a framework for construction of evidence-based guidelines for treatment. The compilation of current data in these guidelines should serve as a resource to aid pediatric neurosurgeons in their role as advocates for providing appropriate care to affected children.

Abbreviations used in this paper:ACA = anterior cerebral artery; AHA = American Heart Association; CCA = common carotid artery; CTA = CT angiography; ECA = external carotid artery; ICA = internal carotid artery; MCA = middle cerebral artery; MRA = MR angiography; STA = superficial temporal artery; TCD = transcranial Doppler; VA = vertebral artery.

Article Information

Address correspondence to: Edward R. Smith, M.D., Department of Neurosurgery, Children's Hospital Boston, Hunnewell 2, 300 Longwood Avenue, Boston, Massachusetts 02115. email: edward.smith@childrens.harvard.edu.

Please include this information when citing this paper: DOI: 10.3171/2011.12.PEDS1172.

© AANS, except where prohibited by US copyright law.



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    Representative anteroposterior projection angiograms with injections of the ICA illustrating the progressive stages of moyamoya. A: Suzuki Stage I–II, with ICA narrowing (arrow), but prior to development of extensive collateral vessels. B: Suzuki Stage III–IV, with significant ICA narrowing and characteristic “puff-of-smoke” (arrow) appearance. C: Suzuki Stage V–VI, with obliteration of ICA flow (arrow) (note: CCA injection). This occlusion of the ICA results in concomitant disappearance of the puff-of-smoke collateral vessels, because they are supplied by the ICA.



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