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Moyamoya Disease

Moyamoya Disease is a rare condition in which the walls of the carotid arteries thicken and narrow, restricting or blocking the blood flow to the brain. It is a progressive disease meaning the vessels will continue to narrow over time. This disease is most commonly diagnosed in childhood or adolescence.

What causes Moyamoya Disease?

The exact cause of Moyamoya Disease is unknown although genetics is thought to be a factor. The body tries to compensate for  the blockage of the vessels by creating new, smaller pathways or collateral vessels. The term “Moyamoya” translates as “puff of smoke” in Japanese and refers to the appearance of these networks of new blood vessels on a cerebral angiogram (a test that shows the blood flow in the brain).

What are the symptoms of Moyamoya Disease?

The symptoms of Moyamoya disease are related to the part of the brain that is affected by the blockage of the vessels. Some children will present with weakness or paralysis to one side of the bodies, severe headaches, speech problems, seizures, poor balance, and involuntary movements.

How is Moyamoya Disease diagnosed?

Early detection is critical to optimize a favorable outcome. Computed Tomography (CT) and magnetic resonance imaging (MRI) scans will likely be done initially. If Moyamoya disease is suspected, a cerebral angiogram where the blood flow pathways in the brain are highlighted will be performed to confirm the diagnosis. In a child with Moyamoya Disease, the angiogram will show blockage of the internal carotid artery, an abnormal network of blood vessels (the “puff of smoke). Sometimes a Magnetic resonance angiography (MRA), another imaging study that shows the blood vessels in the brain, also may be used.

In addition, single photon emission computerized tomography (SPECT) scans may be used to identify the regions of the brain that are not receiving sufficient oxygen.

Treatment of Moyamoya Disease:

Moyamoya Disease is progressive disease and medications do not seem to offer any slowing of the disease. Unfortunately, some children may experience significant neurological impairment before diagnosis and treatment is done. Neurosurgeons may perform a revascularization procedure where blood flow from other regions in the brain to feed the oxygen deprived areas of the brain. In Edmonton, we have a particular interest and experience in pial synangiosis for the treatment of Moyamoya Disease and Moyamoya Syndrome (secondary to NF-1, cranial irradiation, sickle-cell anemia and PHACES syndrome).

Other treatments for Moyamoya Disease address only its symptoms or effects. For example, children at risk of stroke may be treated with blood thinners and those at risk of hemorrhage may be treated with high blood pressure drugs.