Moyamoya disease or syndrome is a condition that narrows and ultimately closes the internal carotid arteries of the brain. The condition was first observed in Japan, where it gets the name Moyamoya, meaning “puff of smoke.” This description refers to the appearance of new blood vessels that are created to bypass the blockage.
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What Is Moyamoya Disease?
Moyamoya disease is a chronic condition that is characterized by a progressive narrowing of the internal carotid artery of the brain. The cause of Moyamoya disease is still unknown, although genetics is likely a factor. The carotid arteries of the brain are the two largest arteries; if they are blocked, the body will grow new, smaller blood vessels to bypass the blockage.
These new blood vessels appear almost like a cluster of vessels or something hazy like a puff of smoke drifting in the air.
What are the types of moyamoya disease?
Moyamoya can be considered both a disease and a syndrome. This difference depends on whether the condition is the main issue or an issue resulting from another condition.
How common is moyamoya disease?
Moyamoya disease was initially recognized in Japan and remains a more common condition for people of East Asian descent than any other ethnicity. There are two windows in which Moyamoya is most commonly discovered, ranging from the ages of 5 to 10 and 25 to 49. It was originally more prevalent in women, but has begun to become more common in men, most likely a result of more accurate testing.
What causes moyamoya disease?
The direct cause of Moyamoya disease is still unknown, but genetics are thought to be a significant factor, as this condition is much more common in people of east Asian descent.
Moyamoya disease risk factors
The direct cause of Moyamoya disease is not yet known, but the fact that it occurs within a specific ethnicity shows that this condition is largely an inherited disease. This means the risk factors are mostly a family history of the condition.
Complications of moyamoya disease
Moyamoya disease or syndrome can lead to serious deterioration of the brain. The new blood vessels formed can create higher blood pressure, which can lead to seizures, rupture, and internal bleeding of the brain.
If left untreated, Moyamoya can cause serious damage to the brain and even death. The increased pressure of the blood vessels can lead to undue pressure on other parts of the brain, impacting motor function or inducing a stroke.
What Are the Signs and Symptoms of Moyamoya Disease?
Because Moyamoya disease may be an inherited genetic abnormality, a doctor will review your family history.
Signs and symptoms of Moyamoya disease may include:
- Aphasia (loss of ability to use or comprehend words).
- Blurred vision.
- Cognitive (reasoning or remembering) impairment.
- Convulsions.
- Involuntary movements.
- Numbness in arms and legs.
- Seizures.
- Severe headaches.
Adults with moyamoya disease also often experience hemorrhagic stroke (a burst blood vessel inside the brain).
When should I see a doctor about my moyamoya disease symptoms?
Moyamoya disease shows as a cluster of newly formed blood vessels in the brain. It rarely has symptoms that would immediately be connected to the condition. If you are experiencing any of the above symptoms, you should see your doctor and mention moyamoya, especially if you have a family history of the condition.
How Do You Diagnose Moyamoya Disease?
Because moyamoya disease affects the blood flow to the brain, your doctor will need to use imaging technology that allows them to view the brain. Once your brain has been imaged, your doctor will determine if your condition is associated with moyamoya.
Tests to diagnose Moyamoya disease
- Cerebral angiography – If your imaging scans show the potential of moyamoya, your doctor will use a cerebral angiogram that creates images of the blood flow through the brain.
- CT and MRI scans – These imaging scans can help doctors see the initial indications of moyamoya.
UPMC is one of the few centers in the nation to have all major methods of measuring brain blood flow.
How Do You Treat Moyamoya Disease?
Moyamoya disease can be treated by either administering drugs to limit or control the effects of the condition or correcting the condition through a surgical procedure.
Revascularization procedures performed at UPMC include:
- External carotid to internal carotid (EC-IC) bypass — The doctor attaches the superficial temporal artery in the scalp to the middle cerebral artery, one of the major arteries in the brain.
- EDAS (encephaloduroarteriosynangiosis) — The doctor frees up, without severing, a scalp artery for several inches and then makes a small temporary opening in the skull directly beneath the artery. The artery is then sutured to the surface of the brain, and the bone replaced.
- EMS (encephalomyosynangiosis) — A muscle in the temple region of the forehead is dissected and placed onto the surface of the brain through an opening in the skull. Multiple burr holes are drilled into the skull to allow new blood vessels to grow.
- Superficial temporal artery-middle cerebral artery (STA-MCA) bypass — A scalp artery is directly sutured to a brain surface artery to bring blood directly to where the brain needs it most.
In rare circumstances, our endovascular team will evaluate the person for minimally invasive alternatives such as:
- Angioplasty.
- Stenting to widen the narrowed artery.
Without surgery, the majority of people with moyamoya disease will experience mental decline and multiple strokes because of the progressive narrowing of the arteries. If untreated, moyamoya disease can be fatal.
How effective is treatment?
Treatment is largely effective for moyamoya disease. More frequent diagnosis of this condition is a result of more accurate screenings finding more cases.
