What is Moyamoya?

History of Moyamoya

Moyamoya disease is characterized by a progressive narrowing of the internal carotid arteries leading into the brain, and usually affects both sides of the brain.

The cause of arterial narrowing is unknown, but does not appear related to atherosclerosis or inflammation of the arteries.  

As the vessels narrow the brain receives less blood. This can result in temporary symptoms such as:

• Headaches
• Numbness or weakness in the extremities
• Difficulty speaking
• Stroke

Dr. Steinberg with Moyamoya patient     1993	Dr. Steinberg with the same Moyamoya patient 2004

Symptoms

Children typically have symptoms including:

• Strokes (sustained weakness or numbness in an arm or leg, difficulty speaking, visual abnormalities or problems walking)
• Transient ischemic attacks, or TIA’s (temporary stroke-like symptoms that don’t last long)
• Headaches
• Progressive cognitive or learning impairments

Children also often experience temporary weakness in one or more of their extremities during strenuous physical activity or when crying. Adults can also present with brain hemorrhage causing neurologic symptoms in addition to nonhemorrhagic strokes, TIA’s and headaches.

Moyamoya sometimes occurs along with other disorders such as Down’s Syndrome, brain AVM’s (arteriovenous malformations), and neurofibromatosis. We have also seen it in patients who had previous brain radiation for tumors.

Diagnosis

Based on the patients’ symptoms and history, the physician may order one or all of these tests before making a decision about treatment.

Magnetic Resonance Imaging (MRI)
This allows physicians to examine brain structures and detect any strokes that might have occurred. 

The arrows on this MRI of the brain shows a patient with a large stroke from moyamoya.

 

Cerebral Angiogram
This is the definitive test that confirms the diagnosis of moyamoya. “Contrast” (or dye) is injected into arteries to reveal the anatomy of the arteries of the brain and scalp. This is a minimally invasive test that requires patients to stay at the hospital for several hours. This test assesses the severity of moyamoya and its results guide treatment options, which are determined by how severe the disease is and what the external (scalp) blood supply is. 

 

	Slide view of a normal angiogram. MCA=middle cerebral artery ACA=anterior cerebral artery ICA=internal carotid artery
	Angiogram of a patient with moyamoya disease. You can see the MCA and ACA vessels are imparied and moyamoya vessels have appeared along with other collateral vessels.

Xenon CT Scans
This test reveals blood flow to regions of the brain to determine if enough blood is reaching all areas. Patients breathe xenon (an odorless, colorless gas), which acts as a contrast agent to show regions of low and high blood flow.

Pre-Operative             Post Operative

Pre-Diamox Post-Diamox

Note the areas of red, which indicate a higher volume of blood flow to the brain when challenged with Diamox.