Wednesday, May 6, was World Moyamoya Day, helping to raise awareness of the rare cerebro-vascular disorder that affects the internal carotid arteries at the base of the brain. It is characterized by the narrowing (stenosis) or closing (occlusion) of the internal carotid arteries, the major arteries that deliver blood to the brain. The walls of the arteries become thickened, which narrows the inside diameter of the vessel.
To compensate for the narrowing of the arteries, tiny blood vessels at the base of the brain open up in an apparent attempt to deliver blood to the deprived areas of the brain. Since these vessels are more fragile than normal blood vessels, they can break and bleed into the brain, causing hemorrhages. The name “Moyamoya” is the Japanese term for “puff of smoke.” It describes the appearance of the tiny vessels that form to compensate for the blockage.
Symptoms are most likely to appear with an ischemic stroke, hemorrhagic stroke or transient ischemic attack (TIA or mini-stroke). Other symptoms that may result include headaches, visual disturbances, developmental delay and seizures. Patients in whom the artery changes occur in association with another process such as sickle cell disease or Down syndrome are said to have Moyamoya.
The exact cause of Moyamoya is not known. It is believed to be hereditary. It is most commonly seen in children and young adults and is typically diagnosed in children 10 years of age and younger, as well as in adults (more commonly women) in their 30s and 40s.
People with Moyamoya disease have been found to have a higher incidence of elevated thyroid antibodies. While this is an association in some individuals, the significance is not clear. However, it suggests that immune abnormalities may play some role in Moyamoya disease.
The diagnosis, treatment and management of Moyamoya requires a collaborative team approach between numerous specialists including neurosurgery, neuroradiology, genetics, neuropsychologists, physical, occupational and speech therapists.
Treatment strategies are aimed at preventing recurrent symptoms, including stroke and non-stroke symptoms such as progressive cognitive or learning impairment. General treatment strategies aimed at preventing the clotting of blood in the narrowed blood vessels include the use of anti-platelet therapies (such as aspirin) or specific re-vascularization procedures.