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Moyamoya
What is moyamoya?
Moyamoya is a rare children's and young adults' cerebrovascular disorder characterised by the progressive occlusion of major intracranial arteries. The cause of this progressive and difficultly treatable disease is as yet unknown.
At the beginning of the disease, the flow of blood in the vessels leading into the brain gradually weakens and passing symptoms develop, due to depletion of blood: one-sided sensory disorders and clumsiness. As the disease progresses, cerebral infarctions occur and consequently permanent functional disorders develop.
As a consequence of ischemia a cloud-like network of new vessels develops; whence the name for the disease. The Japanese were of the opinion that the phenomenon on an x-ray looked like a puff of smoke, hence the Japanese name moyamoya. This network does not, however, enhance the patient’s blood flow as the problem lies between the vascular network and the heart.
How is moyamoya treated?
As the disease affects almost exclusively the intracranial blood vessels, we try to utilise the extra cranial circulation. During neurosurgery blood vessels, muscle or periosteum is transplanted from outside to the inside of the skull. As tissue depleted of blood secretes substances to promote neovascularisation, blood vessels develop joining the transplanted tissue and the vascular bed distal to the occluded vessels. This neovascular network transports essential blood to the brain, i.e., blood bypasses the occluded blood vessels.
The disease nearly always presents on both sides of the brain for which reason surgery is carried out on both sides at half year intervals.
The development of new blood vessels usually takes months, so symptoms may continue to appear for some time after the operation. In the case of children, the prognosis is poor if the disease is left untreated, but when treated the prognosis is good and life may continue normally. In the case of adults, the disease may cease even if left untreated.
At HUCH Department of Neurosurgery, 1-2 moyamoya cases are operated, annually.