Moyamoya disease is a disease in which certain arteries in the brain are constricted. Blood flow is blocked by constriction and blood clots (thrombosis). A collateral circulation develops around the blocked vessels to compensate for the blockage, but the collateral vessels are small, weak, and prone to bleeding, aneurysm and thrombosis. On conventional angiography, these collateral vessels have the appearance of a "puff of smoke" (described as "もやもや (moyamoya)" in Japanese).When moyamoya is diagnosed by itself, with no underlying correlational conditions, it is diagnosed as moyamoya disease. This is also the case when the arterial constriction and collateral circulation are bilateral. Moyamoya syndrome is unilateral arterial constriction, or occurs when one of the several specified conditions is also present. This may also be considered as moyamoya being secondary to the primary condition. Mainly, occlusion of the distal internal carotid artery occurs. On angiography, a "puff of smoke" appearance is seen, and the treatment of choice is surgical bypass. Presentation
Patients usually present with TIA, ischemic/hemorrhagic stroke, or seizure. The age distribution is bimodal being either young adolescence or mid-forties. Cause
About 10% of cases of moyamoya disease are familial, and some cases result from specific genetic mutations. Susceptibility to moyamoya disease-2 (MYMY2; 607151) is caused by variation in the RNF213 gene (613768) on the long arm of chromosome 17 (17q25).
In this case a 44-year-old man presented with headache, tinnitus, and an intraventricular hemorrhage, as seen on computed tomographic scans. Cerebral angiography showed a right moyamoya pattern and an ipsilateral dural AVF fed by branches of the external carotid artery and draining into the transverse sinus. This extremely rare coincidental presentation may have deeper pathogenic implications.The research into the pathogenesis of moyamoya disease has found a breakthrough with the proposal of a "Mechano-biological theory" of pathogenesis of this disease. A research group in southern India have proposed this unifying theory based on computational fluid dynamics studies and longitudinal data. This proposal unifies the pathogenesis of moyamoya disease and moyamoya syndromes described in literature under a single mechanism. References
External links
moyamoya.eu—International website for information about diagnostics and treatment of moyamoya patients
Orphanets disease page on moyamoya disease
Moyamoya Disease Portal—Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum (SCTIMST)