World Moyamoya Day Date in the current year: May 6, 2025

Moyamoya disease usually affects the internal carotid artery and nearby sections of the adjacent arteries. It was discovered in Japan in the 1960s; its name means “puff of smoke” in Japanese. The disease is so named because small collateral blood vessels develop in the brain to compensate for the narrowed arteries, which look like a puff of smoke on conventional angiography. Since its discovery, moyamoya disease has been diagnosed in people in Asia, North America, Europe, Africa and Australia.

Moyamoya disease can be congenital or acquired. The exact cause of congenital moyamoya disease is unknown, but it is believed to be genetic. Acquired moyamoya disease can be secondary to a number of primary conditions, including activated protein C resistance, congenital heart disease, Down syndrome, fibromuscular dysplasia, head injury, neurofibromatosis type I, or sickle cell disease. Secondary moyamoya disease may be called moyamoya syndrome.

Moyamoya disease can affect both children and adults; women are more often affected than men. In children, the first symptom is often transient ischemic attacks (TIA) or stroke, often accompanied by seizures or muscle weakness or paralysis on one side of the body. Adults most often have a hemorrhagic stroke. Other symptoms caused by blocked blood flow in the brain include aphasia and other speech problems, cognitive and sensory impairments, vision problems, involuntary movements, and altered consciousness.

Moyamoya disease is progressive, meaning that the narrowing of the arteries gets worse over time. Antiplatelet medications can be used to prevent blood clots, but they do not slow the progression of the disease. The only reliable way to restore blood flow to the brain is to have surgery to bypass the blocked arteries with other arteries in the brain. There are different types of surgery; some increase blood flow immediately, while others take several months after the surgery to see significant improvement, although there is some improvement immediately after the procedure.

Without surgery, patients with moyamoya disease will experience mental decline and multiple strokes. Once a patient has suffered a major stroke or hemorrhage, they may never fully recover, so it is very important to diagnose and treat the condition promptly to prevent serious complications and permanent loss of function.

World Moyamoya Day was established in 2013 and is celebrated annually on May 6. Its main goal is to raise awareness of this rare disease, support patients and their families, and advocate for better research and care. You can get involved by learning more about moyamoya disease and sharing what you’ve learned with others, donating to an organization that helps patients or funds research, and spreading the word on social media with the hashtags #WorldMoyamoyaDay and #MoyamoyaDay.