About moya-moya disease
What is moya-moy Disease?
Moyamoya syndrome is a progressive disorder that affects the blood vessels in the brain (cerebrovascular). It is characterized by the narrowing (stenosis) and/or closing (occlusion) of the carotid artery inside the skull, the major artery that delivers blood to the brain. At the same time, tiny blood vessels at the base of the brain open up in an apparent attempt to supply blood to the brain distal to the blockage. These tiny vessels are the "moyamoya" vessels for which the disease was named. Inadequate blood supply then leads to reduced oxygen delivery to the brain, and it is this oxygen deprivation that causes the signs of moyamoya. One of the symptoms is typically stroke, which results in paralysis of the face, arms or legs, loss of speech, etc., or temporary loss of neurologic function of body parts or speech (transient ischemic attacks). Other symptoms that may result include headaches, visual disturbances, developmental delay, and seizures. Approximately 10% of cases of moyamoya in Asian countries have a genetic cause. Patients with this arteriopathy that occurs either on a familial or idiopathic basis are said to have moyamoya disease. 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 syndrome. In this report, we use the term "moyamoya syndrome" as a shorthand for both forms.
What are the symptoms for moya-moy Disease?
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:
- Weakness, Numbness or Paralysis in your face, arm or leg, typically on one side of your body
- Visual disturbances
- Difficulties with speaking or understanding others (aphasia)
- Cognitive or developmental delays
- Involuntary movements
These symptoms can be triggered by exercise, crying, coughing, straining or a fever.
What are the causes for moya-moy Disease?
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.
What are the treatments for moya-moy Disease?
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:
- How early the disease was diagnosed
- How much damage has occurred when you seek treatment
- Whether or not you undergo treatment
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:
- Blood thinners. After you're diagnosed with moyamoya disease, if you have mild or no symptoms at first, then your doctor may recommend that you take aspirin or another blood thinner to prevent strokes.
- Calcium channel blockers. Also known as calcium antagonists, this type of medication may prove helpful in managing symptoms of headaches and possibly reduce symptoms related to transient ischemic attacks. These drugs can help manage blood pressure, which is essential in people with moyamoya disease to prevent blood vessel damage.
- Anti-seizure medications. These medications could be helpful for those who have had seizures.
Moya-Moya Surgery Types
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.
What are the risk factors for moya-moy Disease?
Though the cause of moyamoya disease is unknown, certain factors may increase your risk of having the condition, including:
- Asian heritage. 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. This same higher prevalence has been documented among Asians living in Western countries.
- Family history of moyamoya disease. If you have a family member with moyamoya disease, your risk of having the condition is 30 to 40 times higher than that of the general population — a factor that strongly suggests a genetic component.
- Medical conditions. Moyamoya syndrome sometimes occurs in association with other disorders, including neurofibromatosis type 1, sickle cell disease and Down syndrome, among many others.
- Being female. Females have a slightly higher incidence of moyamoya disease.
- Being young. Though adults can have moyamoya disease, children younger than 15 years old are most commonly affected.
Is there a cure/medications for moya-moy Disease?
Moyamoya is a progressive disease and without treatment patients will not improve. Moyamoya itself is not curable, but revascularization surgery that allows for alternative blood supply to the brain prevents symptoms and can reduce the risk of future strokes.
Without surgery, most patients with Moyamoya disease will suffer from multiple stokes and a mental decline because of the progressive narrowing of arteries. If left untreated, Moyamoya disease can be fatal as the result of intracerebral hemorrhage (bleeding within the brain).
In general, the earlier patients are diagnosed and treated, the better the outcome. Patients who are diagnosed early and treated promptly with surgical intervention can have a normal life expectancy.
Moyamoya disease is progressive, and patients who are not treated often suffer cognitive and neurologic decline due to repeated ischemic stroke or hemorrhage.