Moyamoya disease may happen at any age. But symptoms are most common in children between ages 5 and 10 and in adults between ages 30 and 50. Spotting symptoms early is very important to prevent complications such as a stroke.

Moyamoya disease causes different symptoms in adults and children. In children, the first symptom is usually a stroke or recurrent transient ischemic attack, also called TIA. Adults may experience these symptoms, as well. But adults also may experience bleeding in the brain, known as a hemorrhagic stroke. The bleeding happens because of the way blood vessels in the brain formed.

Symptoms of moyamoya disease related to reduced blood flow to the brain include:

• Headache.
• Seizures.
• Weakness, numbness or paralysis in the face, arm or leg. This is typically on one side of the body.
• Vision problems.
• Trouble speaking or understanding others, known as aphasia.
• Cognitive or developmental delays.
• Involuntary movements.

These symptoms can be triggered by exercise, crying, coughing, straining or a fever.

See your healthcare professional if you have any of the symptoms of moyamoya disease. Early detection and treatment can help prevent a stroke and serious complications.

When to see a doctor

Seek immediate medical attention if you notice any symptoms of a stroke or ministroke, even if the symptoms seem to come and go or disappear.

To check for signs of stroke, think "FAST" and do the following:

• Face. Ask the person to smile. Does one side of the face droop?
• Arms. Ask the person to raise both arms. Does one arm drift downward? Or is one arm unable to rise up?
• Speech. Ask the person to repeat a simple phrase. Is the person's speech slurred or strange?
• Time. If you observe any of these signs, call 911 or emergency medical help 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.

The exact cause of moyamoya disease isn't known. Moyamoya disease is most commonly seen in Japan, Korea and China. But it also happens in other parts of the world. Because moyamoya disease is most common in these Asian countries, researchers believe this strongly suggests a genetic factor in some populations.

Sometimes changes to the blood vessels, known as vascular changes, can happen that mimic moyamoya disease. These changes may have different causes and symptoms. This is known as moyamoya syndrome.

Moyamoya syndrome can be linked to certain conditions, such as Down syndrome, sickle cell anemia, neurofibromatosis type 1 and hyperthyroidism.

Though the cause of moyamoya disease is not known, certain factors may increase your risk of having the condition. They include:

• Asian heritage. Although moyamoya disease is found all over the world, it's more common in East Asian countries, especially Korea, Japan and China. This may be due to certain genetic factors in those populations. People with Asian heritage living in Western countries also have a higher risk of moyamoya disease.
• 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. This strongly suggests a genetic link.
• Medical conditions. Moyamoya syndrome sometimes happens with other disorders, including neurofibromatosis type 1, sickle cell disease and Down syndrome, among many others.
• Being female. Moyamoya disease is slightly more common in females.
• Being young. Though adults can have moyamoya disease, children younger than 15 years old are most commonly affected.

Most complications from moyamoya disease are linked to the effects of strokes. They include 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.

There is no way to prevent moyamoya disease. However, moyamoya treatments can prevent strokes and other complications.

Moyamoya disease is usually diagnosed by a doctor who specializes in conditions of the brain, called a neurologist. The neurologist reviews your symptoms and your family and medical history. The neurologist also may perform a physical exam. Several tests are generally needed to diagnose moyamoya disease and any underlying conditions.

Tests may include:

• Magnetic resonance imaging. This imaging test also is known as an MRI. An MRI uses powerful magnets and radio waves to create detailed images of the brain. A healthcare professional may inject a dye into a blood vessel to view your arteries and veins and highlight blood circulation. This type of test is called a magnetic resonance angiogram.

  Your neurologist may recommend a perfusion MRI. This type of imaging can measure the amount of blood passing through the vessels. It can show if there is a decrease in blood supply to the brain.

• Computerized tomography scan. Also known as a CT scan, this imaging test uses a series of X-rays to create a detailed image of your brain. A healthcare professional may inject a dye into a blood vessel to highlight blood flow in your arteries and veins. This is called a CT angiogram. This test can't diagnose early stages of moyamoya disease. But it may help find problems with blood vessels.
• Cerebral angiogram. In a cerebral angiogram, a healthcare professional inserts a long, thin tube called a catheter into a blood vessel in your groin. The healthcare professional then uses X-ray imaging to guide the catheter to your brain and injects dye through the catheter into the blood vessels of your brain. The dye conforms to the shape of the blood vessels to make them more visible under X-ray imaging.
• Positron emission tomography scan or single-photon emission computerized tomography. In these tests, you're injected with a small amount of a safe radioactive material. Positron emission tomography, also called PET, provides visual images of brain activity. Single-photon emission computerized tomography, called SPECT for short, measures blood flow to the brain.
• Electroencephalogram. An electroencephalogram also is called an EEG. It monitors the electrical activity in your brain using small metal disks, called electrodes, attached to your scalp. Children with moyamoya disease often have EEG results that are out of the typical range.
• Transcranial Doppler ultrasound. In surgical transcranial Doppler ultrasound, sound waves are used to obtain images of your head and sometimes your neck. Specialists may use this test to evaluate blood flow in blood vessels in your neck.

If necessary, your neurologist may order other tests to rule out other conditions.

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, known as a neurologist.

Here's some information to help you get ready for your appointment.

What you can do

• Be aware of anything you need to do ahead of time. At the time you make the appointment, be sure to ask if there's anything you or your child needs to do in advance, such as restrict your diet.
• Write down symptoms you or your child has, including any that may not seem related to the reason for which you scheduled the appointment.
• Write down important personal information, including major stresses or recent life changes.
• Make a list of all medicines, vitamins or supplements you or your child is taking and the doses.
• Take a family member or friend along. Sometimes it can be hard to remember all the information provided during an appointment. Someone who goes with you may remember something that you missed or forgot.
• Write down questions to ask your healthcare team.

Your time with your healthcare team is limited, so preparing a list of questions can help you make the most of your time together. List your questions from most important to least important in case time runs out. For moyamoya disease, some basic questions to ask include:

• What is likely causing my or my child's symptoms or condition?
• What tests are necessary? Do they require any special preparation?
• What treatments are available, and which do you recommend?
• What side effects can be expected from treatment?
• Is surgery a possibility?
• Are you prescribing medicine? If so, is there a generic alternative?
• I have other medical problems. How can they be managed together?
• Will I or my child have any restrictions on physical activity?
• Are there brochures or other printed materials that I can take with me? What websites do you recommend?

What to expect from your doctor

Your healthcare professional is likely to ask a number of questions, such as:

• When did symptoms first begin?
• How often do the symptoms occur?
• Do certain activities trigger symptoms?
• Has anyone in your immediate family ever had moyamoya disease?