Moyamoya disease is a rare blood vessel (vascular) disorder in which the carotid artery in the skull becomes blocked or narrowed, reducing blood flow to your brain. Tiny blood vessels then develop at the base of the brain in an attempt to supply the brain with blood.
The condition may cause a ministroke (transient ischemic attack), stroke or bleeding in the brain. It can also affect how well your brain functions and cause cognitive and developmental delays or disability.
Moyamoya disease most commonly affects children, but adults may have the condition. Moyamoya disease is found all over the world, but it's more common in East Asian countries, especially Korea, Japan and China. This may possibly be due to certain genetic factors in those populations.
Moyamoya disease may occur at any age, though symptoms most commonly occur between 5 and 10 years of age in children and between 30 and 50 years of age in adults.
Moyamoya disease causes different symptoms in adults and children. In children, the first symptom is usually a stroke or recurrent transient ischemic attack (TIA), especially in children. Adults also may experience these symptoms but also experience bleeding in the brain (hemorrhagic stroke) from abnormal brain vessels. Spotting symptoms early is very important to prevent serious complications such as a stroke.
Accompanying signs and symptoms of moyamoya disease related to reduced blood flow to the brain include:
These symptoms can be triggered by exercise, crying, coughing, straining or a fever.
Seek immediate medical attention if you notice any signs or symptoms of a stroke or TIA, even if they seem to fluctuate or disappear.
Think "FAST" and do the following:
Call 911 or your local emergency number right away. Don't wait to see if symptoms go away. Every minute counts. The longer a stroke goes untreated, the greater the potential for brain damage and disability.
If you're with someone you suspect is having a stroke, watch the person carefully while waiting for emergency assistance.
See your doctor if you have any of the signs or symptoms of moyamoya disease, as early detection and treatment can help prevent a stroke and serious complications.
The exact cause of moyamoya disease is unknown. Moyamoya disease is most commonly seen in Japan, Korea and China, but it also occurs in other parts of the world. Researchers believe the greater prevalence in these Asian countries strongly suggests a genetic factor in some populations.
Sometimes, vascular changes can occur that mimic moyamoya disease but may have different causes and symptoms. This is known as moyamoya syndrome.
Moyamoya syndrome is also associated with certain conditions, such as Down syndrome, sickle cell anemia, neurofibromatosis type 1 and hyperthyroidism.
Though the cause of moyamoya disease is unknown, certain factors may increase your risk of having the condition, including:
Most complications from moyamoya disease are associated with the effects of strokes, including seizures, paralysis, and vision problems. Other complications include speech problems, movement disorders and developmental delays. Moyamoya disease can cause serious and permanent damage to the brain.
Moyamoya disease is usually diagnosed by a neurologist who specializes in the condition. The specialist will review your symptoms and your family and medical history, and perform a physical examination. Several tests are generally needed to diagnose moyamoya disease and any underlying conditions.
Tests may include:
If necessary, your doctor may order other tests to rule out other conditions.
Doctors will evaluate your condition and determine the most appropriate treatment for your condition. Treatment doesn't cure moyamoya disease but can be very effective in preventing strokes. The goal of treatment is to reduce your symptoms, improve brain blood flow, and lower your risk of serious complications such as an ischemic stroke caused by a lack of blood flow, bleeding in your brain (intracerebral hemorrhage) or death. The prognosis for moyamoya disease depends on several factors, including:
Your treatment may include:
Medications may be prescribed to manage symptoms, to reduce the risk of a stroke or to aid in seizure control, including:
Early surgical treatment can help slow progression of moyamoya disease. If you develop symptoms or strokes and/or if tests show evidence of low blood flow to your brain, your doctor may recommend revascularization surgery.
In revascularization surgery, surgeons bypass blocked arteries by connecting blood vessels on the outside and inside of the skull to help restore blood flow to your brain. This may include direct or indirect revascularization procedures, or a combination of both.
Direct revascularization procedures. In direct revascularization surgery, surgeons stitch (suture) the scalp artery directly to a brain artery (superficial temporal artery to middle cerebral artery bypass surgery) to increase blood flow to your brain immediately.
Direct bypass surgery may be difficult to perform in children due to the size of the blood vessels to be attached, but it's the preferred option in adults. This intervention can be performed safely and with high efficacy by an experienced surgical team that treat moyamoya patients on a daily basis.
Indirect revascularization procedures. In indirect revascularization, the goal is to lay over the brain surface blood-rich tissues to increase blood flow to your brain gradually over time. In high-volume surgical centers, indirect revascularization is almost always combined with direct revascularization in adult patients.
Types of indirect revascularization procedures include encephaloduroarteriosynangiosis (EDAS) or encephalomyosynangiosis (EMS), or a combination of both.
In encephaloduroarteriosynangiosis (EDAS), your surgeon separates (dissects) a scalp artery over several inches.
Your surgeon makes a small temporary opening on the skin to expose the artery, then makes an opening in your skull directly beneath the artery. The surgeon lays the intact scalp artery to the surface of your brain, which allows blood vessels from the artery to grow into your brain over time. The surgeon then replaces the bone and closes the opening in your skull.
In encephalomyosynangiosis (EMS), your surgeon separates (dissects) a muscle in the temple region of your forehead and places it onto the surface of your brain through an opening in your skull to help restore blood flow.
Your surgeon may perform EMS with EDAS. In this procedure, your surgeon separates (dissects) a muscle in the temple region of your forehead and places it onto the surface of your brain after attaching the scalp artery to the surface of your brain. The muscle helps to hold the artery in place as blood vessels grow into your brain over time.
Possible surgery risks of revascularization procedures for moyamoya disease include changes in pressure in the blood vessels in the brain causing symptoms such as headaches, bleeding and seizures. However, the benefits of surgery largely outweigh the risks.
Some people with moyamoya disease develop a bulge or ballooning of a blood vessel in the brain known as a brain aneurysm. If this occurs, surgery may be necessary to prevent or treat a ruptured brain aneurysm.
To address the physical and mental effects of a stroke on you or your child, your doctor may recommend an evaluation by a psychiatrist or therapist. Without surgery, moyamoya disease can cause mental decline due to narrowing blood vessels. A psychiatrist may look for signs of problems with thinking and reasoning skills, or monitor you or your child for signs that those problems are worsening.
Physical and occupational therapy can help regain any lost physical function caused by a stroke. Cognitive behavioral therapy can help address emotional issues related to having moyamoya disease, such as how to cope with fears and uncertainties about future strokes.
If you or your child has been diagnosed with moyamoya disease, you'll most likely be referred to a doctor who specializes in brain conditions (neurologist). You can prepare to discuss the subject with your doctor at your next appointment.
Some basic questions to ask include:
Your doctor is likely to ask you or your child a number of questions, such as:
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