Moyamoya Disease: Causes, Symptoms, Risk Factors, Diagnosis, Treatment and Complications

Moyamoya disease is an uncommon blood vessel ailment that results in constriction or obstruction of the carotid artery in the head. The carotid artery is a significant blood vessel that provides blood to the brain. When the brain's blood flow is blocked, it is reduced. Then, tiny blood vessels start to grow at the base of the brain, trying to supply it with blood.

The sickness may cause a ministroke, also known as a transient ischemic attack or a stroke. Furthermore, it could cause bleeding in the brain. Developmental and cognitive impairments, as well as delays in development, can be the outcome of Moyamoya disease.

The disease moyamoya most commonly affects children. But the sickness can also affect adults. The disease moyamoya exists throughout the world. Nonetheless, the prevalence is higher in East Asian countries, including China, Japan, and Korea. This could be due to some genetic factors present in those populations.

Causes Of Moyamoya Disease

What specifically causes moyamoya sickness is uncertain. China, Korea, and Japan are home to the majority of moyamoya disease cases. It does, however, also occur in other parts of the world. Researchers say that the increased frequency in various Asian countries strongly suggests that some populations have a genetic component.

Sometimes the blood arteries can have vascular changes, often known as mimicking moyamoya disease. These changes may have a range of causes and symptoms. This is referred to as the Moyamoya syndrome.

In addition, there are several medical conditions that are associated with Moyamoya syndrome, such as hyperthyroidism, sickle cell anemia, and neurofibromatosis type 1.

Symptoms Of Moyamoya Disease

The disease moyamoya can affect anyone at any age. However, the likelihood of experiencing symptoms is higher in adults between the ages of 30 and 50 and children between the ages of 5 and 10. In order to prevent complications such as a stroke, early symptom detection is essential.

The moyamoya illness has different symptoms in adults and youngsters. In children, recurrent transient ischemic attacks (TIAs) or strokes are usually the first signs. Adults are prone to similar symptoms as well. Hemorrhagic strokes, on the other hand, are strokes that result in bleeding within the brain and can also occur in adults. The bleeding is caused by new blood vessels forming in the brain.

When cerebral blood flow is reduced, the following symptoms are indicative of Moyamoya disease:

• Pain
• Convulsions
• Numbness
• Weakness, or paralysis in your face, arm, or leg.
• Headache, convulsions, numbness, or weakness in your arm, leg, or face. This typically just affects your body's left side.
• Visual problems.
• Lack of comprehension or speech is known as aphasia.
• Cognitive or developmental deficiencies.
• Actions that are not freely chosen.

These symptoms may arise after physical activity, crying, coughing, straining, or a fever.

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Risk Factors Of Moyamoya Disease

There are a few factors that can increase your risk of developing moyamoya disease, even if its precise etiology is unknown. They include:

• Asian origin: Although the disease is found all throughout the world, East Asian countries like China, Japan, and Korea have higher rates of moyamoya infection. This may be the result of some genetic factors present in those populations. It has been discovered that Asians living in Western countries exhibit the same elevated frequency.
• A hereditary history of Moyamoya disease: If any member of your family has Moyamoya disease, you are 30 to 40 times more likely to get the illness than the general population. This unequivocally indicates a genetic component.
• Health problems: Sometimes, a number of diseases, including neurofibromatosis type 1, sickle cell disease, and Down syndrome, coexist with moyamoya syndrome.
• Sex: Moyamoya is a condition that affects women significantly more frequently.
• Age: Although it can occasionally affect adults, moyamoya sickness primarily affects children under the age of fifteen.

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Diagnosis Of Moyamoya Disease

Usually, a neurologist with experience in moyamoya disease makes the diagnosis. Your symptoms, family history, and medical history will all be examined by the professional. It's likely that the specialist will also perform a physical examination. Usually, several tests are needed to diagnose moyamoya disease and any underlying problems.

Tests might include:

• Magnetic resonance imaging is referred to as MRI: In an MRI, radio waves and strong magnets are utilized to produce exact images of the brain. A doctor may inject a dye into a blood vessel to look at your arteries and veins and emphasize blood circulation. An MRI is the medical term for this type of test.
  • Your neurologist might recommend a perfusion MRI if one is available. This type of imaging allows one to measure the volume of blood moving through the veins. It can show the extent of blood supply deprivation to the brain.
• Computerized tomography, or CT scan: An intravenous dye may be used by a medical practitioner to highlight the blood flow in your veins and arteries. This is known as a CT angiography. This test is not able to diagnose moyamoya disease in its early stages. Nonetheless, it could be helpful in identifying problems with blood vessels.
• Cerebral angiography: A long, thin tube called a catheter is inserted by a doctor into a blood vessel in your groin during a cerebral angiography. The doctor then uses X-ray imaging to point it in the direction of your brain. Using the catheter, the doctor injects dye into the cerebral blood vessels. The contrast fills in the blood vessel outlines, increasing their visibility during X-ray imaging.
• PET scans are also known as single-photon emission computed tomography (SPECT) scans. You receive a tiny injection of a safe radioactive substance during these tests. PET shows the activity of the brain visually. SPECT measures blood flow to different parts of the brain.
• The electroencephalogram, or EEG: An EEG measures the electrical activity in your brain by using little metal discs called electrodes that are applied to your scalp. Children with moyamoya illness frequently have aberrant EEG findings.
• Doppler ultrasound of the brain: Surgical transcranial Doppler ultrasound uses sound waves to produce images of your head and, rarely, your neck. Specialists can evaluate blood flow in your neck's blood vessels with this exam.

If more testing is required, your neurologist may ask for it in order to rule out other illnesses.

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Treatment Of Moyamoya Disease

Medical specialists determine the best course of action after assessing your situation. Moyamoya is an incurable disease. Nonetheless, there are therapeutic approaches to avert strokes.

Reduction of symptoms and improvement of cerebral blood flow are the goals of treatment. Another aim of treatment is to lower your risk of problems. A lack of blood flow can cause a brain hemorrhage, an ischemic stroke, or possibly cause death.

The prognosis for Moyamoya disease is influenced by the following factors:

• How soon the disease was discovered.
• How much damage is done when you seek medical attention.
• Whether you are given medical care or not.
• Age.

Some of the options for your care are: 

Drugs 

Prescription medications may be administered to address symptoms, reduce the risk of a stroke, or assist in managing seizures. Among them are:

• Blood thinners: Blood thinners are typically recommended if you have been diagnosed with Moyamoya disease and your symptoms are mild or nonexistent. Your doctor may suggest taking aspirin or another blood thinner to help prevent strokes.
• Calcium channel blockers: These drugs, which are also known as calcium antagonists, may help relieve headaches. Additionally, they may minimize the symptoms and indicators of transient ischemic events. For individuals with Moyamoya disease, controlling blood pressure is essential to avoiding blood vessel damage. These drugs can help with this.
• Medications that stop seizures: Individuals who have gone through seizures might find these medications beneficial.

Surgery

Early surgical surgery can reduce the progression of Moyamoya disease. Your neurologist may recommend surgical revascularization if you have symptoms or strokes. Surgery may also be recommended if testing shows signs of decreased blood flow to your brain.

The surgeon avoids occluded arteries during revascularization surgery. By connecting the blood arteries on the outside and interior of the skull, they assist restore blood flow to your brain. This can include both direct and indirect revascularization procedures. On the other hand, it may combine the two.

• Direct revascularization: During direct revascularization surgery, doctors stitch the scalp artery directly to a brain artery. This process is also known as middle cerebral artery to superficial temporal artery bypass surgery. Your brain receives more blood flow right away after this surgery.
  • Direct bypass surgery may be difficult to perform on children due to the size of the blood veins that need to be connected. Adults, however, favor taking this approach. An experienced surgical team that regularly cares for patients with moyamoya may be able to perform this procedure safely.
• Indirect revascularization: The objective of indirect revascularization is to gradually enhance the blood supply to the brain by covering areas of the brain's surface that are rich in blood. In high-volume surgical centers, indirect revascularization is almost often combined with direct revascularization for adult patients. 
• Indirect revascularization techniques include encephaloduroarteriosynangiosis (EDAS), encephalomyosynangiosis (EMS), or a combination of the two.During EDAS, a surgeon divides a scalp artery across a few inches. 

The surgeon makes a small, temporary incision in the skin to expose the artery. The surgeon next makes an incision in your skull directly beneath the artery. Your brain's surface is surgically connected to your intact scalp artery, which permits blood vessels to progressively grow inside of your brain. Subsequently, the surgeon repairs the fractured skull and replaces the missing bone.

Your surgeon performs EMS through a hole in your skull by slicing a muscle in the temple area of your forehead and placing it on the surface of your brain. This makes it easier for blood flow to return. 

Your surgeon might provide EMS utilizing EDAS. During this procedure, your surgeon will split a muscle in the temple region of the forehead. The surgeon puts the scalp artery into your brain after it has been connected to its surface. The muscle helps to hold the artery in place as blood arteries gradually enlarge into your brain.

Possible medical procedures changes in cerebral blood artery pressure are one of the risks connected to revascularization therapy for Moyamoya disease. This may cause symptoms like headaches, bleeding, and convulsions. However, the benefits of surgery typically outweigh the drawbacks. 

A brain aneurysm, which is a ballooning or bulging of a cerebral blood vessel, can happen to some people who have Moyamoya disease. If this occurs, a ruptured brain aneurysm may need to be prevented or treated surgically.

Therapy

To address the psychological and physical effects of a stroke, your doctor may suggest that a psychiatrist or therapist evaluate you or your child. In the absence of surgery, moyamoya disease can cause cognitive decline due to blood vessel narrowing. A psychiatrist may be watching for signs of problems with cognition and reasoning. The psychiatrist may also be on the lookout for any signs that your child's problems are growing worse. 

Cognitive behavioral therapy can help with the emotional issues related to having Moyamoya disease, such as managing fears and anxieties about having more strokes.

Physical and occupational therapy can help regain any lost physical function after a stroke.

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Complications Of Moyamoya Disease

The majority of the aftereffects of moyamoya disease are associated with strokes. These include convulsions, paralysis, and vision problems. Additional concerns include speech difficulties, movement impairments, and developmental delays. Moyamoya disease can cause serious, irreparable brain damage.

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