Moyamoya disease is a rare, progressive disorder that causes a blockage to the main blood vessels serving the brain as they enter the skull.
In Japanese, "moyamoya" means "puff of smoke," which describes the look of the tangle of small blood vessels that forms to compensate for the blockage.
Symptoms of moyamoya disease vary depending on the age of the patient. Adults with the condition experience bleeding or strokes. Other symptoms in adults include:
- Fainting or blacking out
- Loss of sight in one eye
- Blurry vision
- Poor vision in both eyes
- Inability to recognize objects
The condition tends to get worse without treatment, and can lead to severe brain damage or death.
In children, moyamoya disease tends to cause transient ischemic attacks (TIA), also known as microstrokes or "warning strokes." In children, it also may cause seizures.
Other symptoms may include:
- Uncontrolled movements
- Developmental disabilities
- Speech difficulties
- Periods of being unable to move their feet, legs or arms
Because this condition involves bleeding, patients may also experience a shortage of red blood cells (anemia), which has symptoms such as fatigue and pale skin.
Causes and Risk Factors
The cause of moyamoya disease is unknown. The narrowing of the brain's blood vessels may be due to injuries or genetic abnormalities. There may be some links between the condition and neurofibromatosis, or to procedures such as X-rays of the skull or heart surgery, or treatments such as chemotherapy.
Moyamoya disease is most commonly diagnosed in children, but it can affect adults as well. There appears to be a higher rate of incidence in Japan and other Asian countries; however cases have been diagnosed in the United States, Europe, Australia and Africa.
Because moyamoya disease can cause severe brain damage or even death, it is important to diagnose and treat the condition as quickly as possible. Diagnosis of the condition generally begins with a physical exam and a review of the patient's medical history. The patient's physician may recommend one or more of the following tests or image diagnostic tools in order to more clearly understand the patient's condition
- Computed tomography (CT) scan
- Magnetic resonance imaging (MRI) for the brain or spine
- Single photon emission computerized tomography (SPECT)
These imaging tools can assist the physician in finding the blockage and the tangle of blood vessels, as well as see how much damage may have been done by the condition.
Surgery is the preferred treatment for moyamoya disease. However drug therapy may be used as an alternative when surgery is not an option.
The goal of surgery is to go around the blockage and allow new blood vessels to develop to bring blood and oxygen to the brain. With experienced neurovascular surgeons, such as those at Cedars-Sinai, the risks of this surgery generally are low and the long-term outlook for children who have been treated for the disease is good.
Full recovery from surgery may take six to 12 months, though many patients see an improvement in their symptoms almost immediately. If a patient has had major bleeding into the brain, the damage may be permanent, and prompt treatment is important to preserve as much brain function as possible.
Surgical procedures used to treat moyamoya disease include:
- Encephaloduroarteriosynangiosis (EDAS): This procedure requires freeing up, without severing, a scalp artery over a course of several inches and then making a small temporary opening in the skull directly beneath the artery. The artery is then sutured to the surface of the brain and the bone replaced.
- Encephalomyosynangiosis (EMS): In this procedure, a muscle from the temple region of the forehead is freed from some attachments. A hole is then made in the skull through which this muscle is directed and then placed onto the surface of the brain.
- Superficial temporal artery-middle cerebral artery (STA-MCA): This procedure directly sutures a scalp artery to a brain surface artery. Multiple small holes (burr holes) are placed in the skull to allow for growth of new vessels into the brain from the scalp.
When surgery is not an option, medication may be used as treatment. Medicines that prevent clots from forming, including aspirin, may be helpful. No drug, however, can prevent the arteries to the brain from narrowing. Because medications do not offer a permanent solution, surgery is the preferred treatment option whenever possible.