Moyamoya: past, present, future

This special issue of the Journal of Pediatric Neuroradiology is devoted to moyamoya disease and syndrome. Extensively researched, yet poorly understood, moyamoya literally means, “feeling confused, curious, foggy”. Although the classic notion of “puff of smoke” is well accepted in the scientific community, the term moyamoya has a different connotation to a Japanese medical student: “When I am talking to someone and I don't really fully understand, I would say that I am moyamoya.” In this sense, moyamoya perfectly describes this ill-defined progressive cerebral vasculopathy, which can be unilateral or bilateral, and involve the anterior or posterior circulations. Nearly 60 years after its initial description, our understanding of the etiology and underlying mechanisms leading to moyamoya remains elusive. For example, the fundamental risk factors and predictors for disease development and progression or the optimal timing of surgical intervention are still unclear. The purpose of this special issue was to engage physicians and scientists from various disciplines to share their current understanding and management approach for children with moyamoya, and discuss future neurosurgical and endovascular therapies whose efficacies can be assessed objectively by neuronal biomarkers and advanced imaging techniques. This multidisciplinary effort involves specialists from pediatric neuroradiology, neurology, hematology, neurosurgery, and interventional neuroradiology. Bosemani et al. review the imaging findings and differential diagnosis in moyamoya disease and syndrome, highlighting the critical role of neuroimaging in moyamoya management. Advanced imaging techniques are described by Choudri et al, who present a multimodality approach for the assessment of anatomic and perfusion variables in moyamoya, and explain how this information aids in treatment planning and patient monitoring. The authors also discuss the diagnostic and management challenges presented by asymptomatic patients and emphasize the importance of interpreting the results of physiologic imaging studies in a multidisciplinary forum including neurologists and vascular neurosurgeons. Carpenter et al, review the etiology and clinical manifestations of moyamoya and provide an insight into a specific subset of patients at high risk for the development of moyamoya, i.e., children with sickle cell disease. Medical therapies, including steroids, vasodilators, anticoagulants, calcium channel blockers, and aspirin, have been tried with variable success, yet the only currently effective therapy involves surgical revascularization. The surgical options for moyamoya are reviewed by Rhee et al, who discuss the relative advantages and disadvantages of direct versus indirect bypass procedures, and underscore the importance of maintaining specific physiologic parameters to prevent peri-operative ischemia. Although surgical revascularization has been shown to be beneficial, the timing of intervention in asymptomatic patients and in those with borderline imaging features requires further investigation. *Address for correspondence: Monica S. Pearl, Division of Interventional Neuroradiology, The Johns Hopkins Hospital, 1800 Orleans Street, Bloomberg Building, 7218, Baltimore, MD 21287 USA. Tel.: +1 410 955 8525; Fax: +1 410 614 8238; E-mail: msmit135@jhmi.edu. Journal of Pediatric Neuroradiology 3 (2014) 1–2 DOI 10.3233/PNR-14080 IOS Press 1