Moyamoya is a progressive blood vessel disorder that involves the blood vessels in the brain – the carotid artery, in particular, a major artery that delivers blood to the vain.
The artery narrows and closes inside the skull while tiny blood vessels at the base of the brain open up in an attempt to supply blood to the brain.
These small vessels are known as the “moyamoya” vessels for which the disease is named. Oxygen delivery to the brain is reduced due to an inadequate supply of blood.
The condition may result in stroke, which causes paralysis of the arms and legs, face, loss of speech. It may also cause transient ischemic attacks (ITA) which involves a temporary loss of neurologic function of speech and body parts.
Bleeding in the brain is another symptom of the moyamoya disease. Other symptoms include seizures, developmental delay, visual impairment, and headaches.
Moyamoya disease can be found all over the world but more commonly found in Asian countries such as Japan, Korea and China. This may be due to genetic factors present in those populations.
Signs and Symptoms of Moyamoya disease
Moyamoya disease symptoms may occur at any age, although the disease is more common between 5 and 10 years in children and 30 and 50 years in adults.
Adults may experience strokes and bleeding (hemorrhagic stroke) due to abnormal brain vessels, while recurrent transient ischemic attacks (ITA) are common in children.
Other signs and symptoms of moyamoya disease include:
- Fainting or blacking out
- Paralysis on one side of the body, usually the face, arm, or leg
- Blurry vision
- Difficulties with speaking or understanding others (aphasia)
- Inability to recognize objects
- Developmental delays
The symptoms can be triggered by exercise, crying, coughing, straining or fever. Moyamoya disease can worsen without treatment, and it can lead to severe brain damage or death. Patients may also suffer from anemia due to excessive bleeding in the brain.
Causes and Risk Factors of Moyamoya disease
There is no known cause for moyamoya disease. Genetic abnormalities and head injuries may cause the brain’s blood vessel to narrow and close up.
There may also be some connection between moyamoya disease and neurofibromatosis. Procedures such as X-rays of the skull, heart surgery or chemotherapy may be possible causes.
The disease is commonly diagnosed in children but can be found in adults too. There is an apparent high incidence of the disease in China and other Asian countries. However, cases of the disease have been discovered in Africa, Europe, Australia and the United States.
It is necessary to seek medical attention immediately if you notice any sign of a stroke. These include:
- Paralysis and drooping of one side of the face
- Inability to raise one or both hands
- Slurred speech
The doctor will review your symptoms and your medical and family history to diagnose the disease. They will also perform a physical examination to diagnose the disease and any underlying conditions.
The tests may include:
- Computerized tomography (CT) scan: This procedure uses a series of X-rays to create a detailed image of your brain. The doctor may inject a dye into the vessels to highlight blood flow in your arteries and veins (CT angiogram).
- Magnetic resonance imaging (MRI): This involves using powerful magnets and radio waves to create detailed images of your brain.
- Cerebral angiogram: involves inserting a long, thin tube, called a catheter, into a blood vessel in your groin. The tube is guided to your brain using X-ray imaging. The doctor then injects dye through the catheter into the blood vessels of your brain to make them visible under X-ray imaging.
- Electroencephalogram (EEG): This device monitors the brain’s electrical activity through a series of electrodes attached to the scalp. Children living with moyamoya disease often exhibit abnormalities on EEG.
- Transcranial Doppler ultrasound: This procedure uses sound waves to obtain images of the brain. Doctors may use this test to get information about the blood vessels in the brain.
Surgery: This is the most preferred treatment for moyamoya. Surgery aims to bypass the blockage and allow new blood vessels to develop and deliver blood and oxygen to the brain. This is the job of a neurovascular surgeon, and the risks of the surgery are low.
It may take up to 6 to 12 months to recover fully from the surgery, although patients may see their symptoms improve almost immediately. Surgical procedures used in treating the disease include:
- Encephalomyosynangiosis (EMS): A muscle from the forehead’s temple region is freed from some attachments. A hole is then made in the skull through which this muscle is directed and then placed onto the brain’s surface.
- Encephaloduroarteriosynangiosis (EDAS): This procedure involves freeing up, without severing, a scalp artery throughout several inches and making a small temporary opening in the skull directly below the artery. The artery is then stitched to the surface of the brain, and the bone replaced.
- Superficial temporal artery-middle cerebral artery (STA-MCA): This involves stitching a scalp artery to a brain surface artery. Many small holes are placed in the skull to allow for growth of new vessels into the brain from the scalp.
Medication may be used as treatment if surgery is not an option. Medicines that prevent clots from forming may be helpful. Because drugs do not offer a permanent solution, surgery is the preferred treatment option whenever possible. Medications that can be used include:
- Blood thinners: Following diagnosis, the doctor may recommend taking aspirin or another blood thinner to prevent strokes.
- Anti-seizure medications: These drugs may be prescribed if you or your child experience seizures.
- Calcium channel blockers: These are also known as calcium antagonists. The medication is used to improve symptoms of headache and possibly reduce symptoms related to transient ischemic attacks.