MOYAMOYA DISEASE: CAUSES, SYMPTOMS, DIAGNOSIS, TREATMENT AND MORE

Moyamoya disease is a rarely-diagnosed cerebrovascular disorder that negatively impacts blood vessels in the brain. The condition's hallmark is the progressive narrowing or blockage (stenosis) of the carotid artery and its extensions that supply blood to the brain. Arterial occlusion reduces blood flow and oxygen to the affected areas. The disrupted brain blood supply can result in many symptoms, from mild headaches to severe strokes, in both adults and children affected by the condition.^[1]

The phrase "Moyamoya" translates to "puff of smoke" in Japanese, which describes the appearance of abnormal blood vessel tangles that form in the brain due to the disease. These abnormal blood vessels (known as collaterals) are fragile and prone to bleeding, which gives rise to strokes and other serious complications associated with the disease.

The condition was first described in Japan in the 1960s. It is mainly found in young Japanese females under 20 years of age, with prevalence of around 1 in 300,000. It has also been observed in other populations from different parts of the world, including Asia, Europe, and the Americas.^[2]

Primary Moyamoya disease is often idiopathic. When the disease occurs due to an underlying vascular condition, it is known as Moyamoya syndrome. Children are more susceptible to Moyamoya syndrome.

This article examines MMD causes, symptoms, diagnosis, and treatment options.

Causes of Moyamoya Disease

The exact cause is not yet known. Research indicates that several genetic and environmental factors are responsible for causing MMD.

Various factors can cause blood vessel narrowing and damage, resulting in Moyamoya disease or syndrome. These include autoimmune diseases, infections, and exposure to excessive radiation.^[3]

Some of the most frequent occurrences include:

1. Sickle cell disease: Sickle cell disease yields abnormal red blood cells, which can block the smallest blood vessels in the brain, resulting in Moyamoya syndrome.
2. Neurofibromatosis type I: Neurofibromatosis type I is a genetic condition that results in tumor growth on the nerves. These tumors can affect the blood vessels in the brain, increasing the risk of Moyamoya syndrome.
3. Down syndrome: A genetic condition associated with an increased risk of developing Moyamoya syndrome. The specific mechanism is not entirely understood, yet researchers suspect that an extra chromosome 21 can lead to abnormalities in the brain's blood vessels.
4. CNS infections: Central nervous system (CNS) infections and their complications, such as meningitis or encephalitis, cause inflammatory damage to the brain’s blood vessels. This inflammation and damage can contribute to the development of Moyamoya syndrome. Commonly implicated infections include Epstein-Barr virus and shingles (varicella-zoster virus)^[4].
5. Autoimmune conditions: Autoimmune diseases can trigger brain blood vessel inflammation, causing thickening and narrowing. This effect reduces blood flow and leads to collateral vessel formation. Autoimmune conditions linked to Moyamoya syndrome include Grave's disease and Systemic Lupus Erythematosus.

Genetics

In approximately 10% of cases in Japan, Moyamoya disease is genetic with an autosomal recessive inheritance pattern. There are a few gene mutations that can cause Moyamoya disease^[5]:

• One variant is the ACTA2 gene R179 variant, which links to a distinct subtype of Moyamoya disease. Similar variations in this gene can cause other cardiovascular diseases and increase the risk.
• Variants in the RNF213 gene (involved in blood vessel development) correlate with East Asian Moyamoya^[6]. Up to 70% of East Asian cases acquire this type from carrier parents. This type affects both sides of the brain, with symptoms occurring in adulthood.

Several other mutations relate to other diseases that cause Moyamoya syndrome.

Risk Factors

Specific risk factors for Moyamoya disease include being a young female and having a family history of the condition or any other condition that can lead to the condition.

Those with Moyamoya disease are at a much higher risk of strokes. These may occur more frequently in those with the following risk factors^[7]:

• High blood pressure
• Smoking
• Diabetes
• High cholesterol
• Physical inactivity
• Obesity
• Excessive alcohol consumption
• Atrial fibrillation
• Sleep apnea
• Poor nutrition

Symptoms of Moyamoya Disease

The symptoms of Moyamoya disease vary depending on the severity of the condition and the brain areas it affects. Some common symptoms include^[8]:

• Headaches
• Seizures
• Weakness or numbness
• Difficulty with speaking or comprehension
• Vision problems
• Cognitive impairment and decline
• Strokes

In children, the most common symptoms are seizures and mini-strokes, known as transient ischemic attacks (TIAs). Adults tend to experience full hemorrhagic strokes more frequently than children with a higher degree of cognitive decline and speech difficulties^[9].

Anything that places pressure on the blood vessels supplying the brain can trigger a TIA or other cerebrovascular event that leads to symptom onset. Examples of triggers include exercising, straining, and coughing.

Moyamoya disorder outcomes and life expectancy vary considerably. Within a five-year duration, progression is evident in two-thirds of patients. Early surgical treatment can enhance prognosis favorably.

Complications of Moyamoya Disease

Most complications of MoyaMoya disease pertain to the frequency of strokes, seizures, or internal bleeding.

These events often result in temporary or permanent brain damage. The damage done varies and can lead to a variety of consequences, including:

• Speech problems
• Movement issues
• Delayed developmental milestones
• Memory loss
• Difficulty with problem-solving
• Changes in behavior

In the event of a stroke, making timely intervention is critical for ensuring best possible outcome.

When to See a Doctor

If you experience any symptoms of Moyamoya disease, you must see a doctor for an accurate diagnosis. Early identification and prompt treatment can deter serious complications and improve outcomes.

FAST to Identify a Stroke

If you think someone is having a stroke, you need to act FAST (face, arms, speech, time) to assess their condition^[10]:

• Face: Does the person's face droop on one side when they try to smile?
• Arms: Can they lift their arms?
• Speech: Can the person respond, articulate, and comprehend you?
• Time: Dial emergency medical services immediately if these symptoms are present.

Diagnosis

Diagnosis of Moyamoya disease is often challenging, as the manifestations are similar to other conditions. A thorough medical history, physical examination, and imaging tests are necessary for an accurate diagnosis.

Some standard tests used to diagnose Moyamoya disease include^[11]:

• MRA (magnetic resonance angiography): This type of MRI looks explicitly at the blood vessels in the brain.
• CTA (computed tomography angiography): This test comprises X-rays and a contrast dye to render images of the brain’s blood vessels. This technique may help a specialist save time during an emergency.

A neurologist may order other blood tests to check for the presence of other health conditions, including a blood count and kidney.

Treatment Options for Moyamoya Disease

Moyamoya disease currently has no cure. Available treatment can manage the symptoms, improve brain blood supply, and prevent complications like strokes.

The most common treatment options include:

Medications

In some cases, medication may manage symptoms and prevent complications. These may include^[12]:

• Blood thinners that can prevent clots and lower the risk of stroke (not advisable for those at risk of bleeding)
• Anti-seizure medications
• Calcium channel blockers (calcium agonists) can help with headaches and symptoms of transient ischemic attacks. They also control blood pressure and prevent blood vessel injury in Moyamoya disease.

Revascularization Surgery

This surgical procedure involves creating new blood vessels to bypass the blocked or narrowed arteries in the brain. These surgeries improve the prognosis for patients substantially, lowering the risk and frequency of strokes and seizures.

There are two types of revascularization surgery: direct and indirect.

Direct bypass surgery: Direct revascularization surgery, also called an EC-IC or STA-MCA bypass, is a process where a scalp artery is surgically attached to a cerebral artery located on the brain's exterior. This operation enhances cerebral blood supply and indirectly improves revascularization over the months afterward.^[13]

Children under five may not qualify due to lacking suitable scalp arteries.

Indirect bypass surgery: This involves implanting a blood vessel or tissue to promote new blood vessel growth that helps enhance the overall brain blood supply.

There are two main types of indirect revascularization surgery:

1. EDAS (encephalo-duro-arterio-synangiosis) is a surgical procedure that uses a branch of the superficial temporal artery to provide additional blood flow to the brain. It is performed when a direct bypass graft is not possible. Children typically have better outcomes than adults with this procedure. It takes approximately 3-6 months for a new blood supply to develop after the procedure.
2. EMS (encephalo-myo-synangiosis) is an indirect bypass operation involving placing a temporalis muscle section on the brain's surface. It also takes 3-6 months for the muscle to develop a new blood supply to the area.

Risks and Side Effects: Surgery complications can include blood pressure changes in the brain, headaches, bleeding, and seizures. The side effects are rare. In severe instances, corrective surgery is necessary.

Recovery: Patients usually remain hospitalized for 3-5 days post-operation, with a complete recovery period of 2-6 weeks before returning to activities before surgery^[14].

• During hospitalization, patients may need a liquid or tube-fed diet and pain medications to manage the side effects. Adults will have their staples or sutures removed after a week, while children often receive dissolvable sutures.
• During recovery, patients may feel exhausted and require more rest than usual. Contact sports and similar activities are advised against while in recovery. Blood thinning medications can improve blood flow through the grafts.

There is no special diet, yet remaining hydrated and avoiding blood clotting medications like birth control pills is essential. Those who had a bypass graft surgery should avoid wearing eyewear or other gadgets around the temple area, as this can compress the grafts.

Follow-Up: It is recommended to go for regular checkups with a doctor to monitor blood pressure and to consult over any unusual symptoms that may arise, such as more severe headaches or pain.

Experts suggest opting for the below follow-up tests:

• Follow-up tests after surgery: Angiogram, MRI, Blood flow studies, Neuropsychological testing
• Timing of follow-up tests: 6 months, 3 years, 10 years, and 20 years
• Additional follow-up for patients with unilateral moyamoya: Annual CT angiogram or MRI/MRA
• Contact the doctor for updates and report new or recurring symptoms at least once a year.

Supportive Care

Supportive care involves managing the symptoms and complications of Moyamoya disease and strokes.

Helpful therapies for post-stroke rehabilitation include^[15]:

• Speech therapy assists individuals who have difficulties in speech production or comprehension.
• Physical therapy facilitates the relearning of movement and coordination skills after a stroke.
• Occupational therapy aims to enhance routine activities, like eating, drinking, dressing, bathing, reading, and writing.
• Psychotherapy and medication could be beneficial in dealing with depression or other psychological health issues after a stroke.

Becoming a member of a patient support group may assist you in coping with life post-stroke. Consult your healthcare team about local support groups or inquire about a nearby medical facility.

Lifestyle Changes

Making lifestyle changes may lessen complication risks and improve overall health. These include^[16]:

• Quit smoking
• Eating a healthy diet
• Exercising regularly
• Managing underlying health conditions, including cardiovascular disease, diabetes and hypertension

Outlook: Living with MoyaMoya Disease

Living with Moyamoya disease can present significant emotional and psychological challenges due to the potential impact on daily life. With proper treatment and management, it is possible for those with the condition to lead a fulfilling life.

Regular medical follow-up is essential for individuals with Moyamoya to monitor disease progression, assess treatment effectiveness, and manage associated risks. This care ensures early detection of changes and enables timely interventions for better outcomes and quality of life.

Some tips for living with MoyaMoya disease include:

• Follow your treatment plan: Taking any prescribed medications and attending follow-up appointments with your doctor is crucial.
• Make lifestyle changes: Healthy lifestyle changes can help reduce the risk of complications, such as quitting smoking and eating a healthy diet.
• Seek support: Connect with others with MoyaMoya disease for support and insightful guidance.
• Stay informed: Keep up with current treatment options for MoyaMoya disease and related complications.

Future Research

Research focuses on finding new treatment options and improving outcomes for those with the condition. Some areas of ongoing research include:

• Genetic screening for MoyaMoya disease: Researchers are working to identify the genetic mutations that may cause MoyaMoya disease, uncovering the potential for improving diagnosis and treatment options.^[17]
• Improved Surgical Techniques: Refinement of existing procedures for better blood flow restoration and minimized complications.
• Endovascular Treatments: Investigating techniques to improve blood flow through existing vessels, such as coil embolization, potentially as an adjunct to surgery.^[18]

Conclusion

MoyaMoya disease is a rare cerebrovascular disorder that affects the blood vessels in the brain. While there is no cure, available treatments can manage symptoms and prevent complications. Cooperating with a healthcare team and making lifestyle changes are essential to improving outcomes and quality of life. With ongoing research and advancements in treatment, the outlook for those living with MoyaMoya disease is bright.

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