The Moyamoya disease [MMD] is a cereberovascular disorder characterized by progressive stenosis of intracranial internal carotid arteries and compensatory collateral formation at the base of the brain, mainly around the circle of Willis. When no particular associated risk factors can be identified, it is termed as Moyamoya disease. However, it may be associated with other neurological and extra- neurological disorders where it is termed as Moyamoya syndrome [MMS]. The condition is predominantly seen in East Asia and has bimodal age of distribution. The clinical manifestations are also age dependant with ischemia predominating in childhood and hemorrhagic manifestations being more common in adults. The pathogenesis is not entirely known, but genetic susceptibility is believed to be an important predisposing factor. The Suzuki staging system is most widely used for evaluation and staging of Moyamoya disease. The gold standard diagnostic modality is cerebral angiography but magnetic resonance imaging [MRA] has also been employed for diagnosis. Treatment is primarily surgical revascularization which is of 3 types: direct, indirect or combined revascularization. Although the role of revascularization surgery has been well established for ischemic MMD, the ideal surgical approach and the role of surgery in hemorrhagic MMD remains controversial.
Part of the book: Moyamoya Disease