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

Abstract

<jats:p>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.</jats:p>

Quantitative Cerebral Perfusion Imaging in Children and Young Adults with Moyamoya Disease: Comparison of Arterial Spin-Labeling-MRI and H2[15O]-PET

“…21 However, to the best of our knowledge, there has been no study comparing cerebral perfusion imaging with ASL and the current reference standard of H 2 Because this difference is substantially larger than that between ASL and PET in our study, the underestimation that we found could be considered negligible. This is supported by the lack of a significant difference in CBF or rCBF in territories with qualitatively normal perfusion.…”

“…The condition is rare; however, it is implicated in approximately 6% of childhood strokes. 2 The main goal of treatment of children with Moyamoya is the prevention of future strokes by means of surgical revascularization. To determine the optimal targets for revascularization procedures as well as for postoperative follow-up, CBF studies with the use of Xe-CT, SPECT, or PET have been shown to be of high clinical value.…”

Bilateral pial synangiosis in a child with PHACE syndrome

“…Guidelines regarding treatment via revascularization surgery have been published for MMD; patients for whom revascularization surgery is recommended include those with ongoing ischemic events and/or cerebral blood flow and perfusion reserve. 29 In contrast to the situation with respect to MMD, a relative lack of literature documenting the natural history of arteriopathy in PHACE patients results in difficulty developing such guidelines for the care of asymptomatic patients.…”

“…MMD guidelines regarding timing of surgical intervention suggest minimizing the time between diagnosis and treatment, although delays to increase the safety of the procedure are warranted, and unstable disease has been shown to increase perioperative morbidity. 10,29 Furthermore, revascularization surgery may prove futile if the extracranial vasculature undergoes the same progressive stenosis and occlusion. Moreover, there is little evidence documenting concrete risk factors for neurological complications related to abnormal cerebrovasculature in PHACE patients.…”

Editorial: Pediatric moyamoya

“…Smith and Scott, 1 who are world-leading scholars in the field, are a wellsummarized reference for doctors managing the treatment of patients with MMD, especially in areas in which MMD is not prevalent. These investigators have created a framework that can be modified as knowledge and experience are accumulated in the field of basic research as well as clinical practice.…”