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Moyamoya Center at Washington University

This angiogram, a front view, shows severe narrowing of the internal carotid and middle cerebral arteries (arrows shown in blue) that provide blood supply to one side of the brain. It also shows tiny arteries (called moyamoya collaterals; arrowheads shown in red) that enlarge and multiply over time in an effort to bypass the blocked arteries. The cause of the artery narrowing or blockage is unknown in moyamoya patients.

Moyamoya disease is a progressive disorder in which the large arteries that carry blood to the brain narrow and often completely close off. The cause of the narrowing is unknown. When the arteries narrow, small branches of these arteries enlarge to bypass the blockage. These small branches, which grow larger (and maybe more numerous) give the disorder its name. "Moyamoya" is a Japanese term that means “puff of smoke,” which is used to describe the hazy appearance of these small vessels on an angiogram.

The Moyamoya Center at Washington University School of Medicine is a leading national program that is advancing the understanding and treatment of moyamoya disease. 

Led by radiologist Colin Derdeyn, MD, and neurosurgeon Gregory Zipfel, MD, the Center was established in 2006 with the receipt of a five-year grant from the National Institute of Neurological Disorders and Stroke (NINDS) to perform a long-term outcomes study of people with moyamoya disease. 

Dr. Zipfel has performed surgical revascularization on hundreds of patients with moyamoya disease with excellent results. Patients with the disease also are treated by vascular neurologists and receive well-coordinated care in the Neuroscience Center at the Center for Advanced Medicine at Washington University School of Medicine.

For a referral or clinic visit with Dr. Gregory Zipfel, call 314-362-3559. 


Moyamoya disease is common in Asia, usually affecting children, and is much less common in North America, where it generally affects women in their 30s, 40s and 50s. 

Untreated, moyamoya disease can cause headaches, speech problems, and progressive cognitive and learning impairments. It can result in strokes, during which blood flow to the brain stops, resulting in weakness or numbness of limbs, speech difficulties, visual or walking problems. Speech deficiencies usually fall into the category of aphasia, or an impaired ability to speak and understand others. The disease also can cause transient ischemic attacks (TIAs), often referred to as “mini-strokes,” with temporary stroke-like symptoms.


Cerebral angiography – an X-ray study of the blood vessels using a dye – is the principal form of imaging used for the diagnosis of moyamoya disease. The characteristic findings of moyamoya disease on an angiogram are traditionally described in stages, which progress from early narrowing of the carotid arteries to the formation of moyamoya vessels and then to the disappearance of these vessels with maintenance of blood flow by the external carotid and vertebral arterial systems.

 Stage I 

Narrowing of carotid arteries

 Stage II

Initial appearance of moyamoya vessels

 Stage III

Intensification of moyamoya vessels

 Stage IV

Minimization of moyamoya vessels

 Stage V

Reduction of moyamoya vessels 

 Stage VI

Disappearance of moyamoya vessels 

  1. Suzuki J. Moyamoya Disease. Tokyo, Japan: Springer-Verlag; 1986.

Noninvasive imaging techniques also may be used in the diagnosis of moyamoya disease. When magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) demonstrate blockage of carotid arteries and moyamoya vessels on both sides, a cerebral angiogram is not needed for a diagnosis.

This magnetic resonance (MR) scan was obtained as part of a research study looking at blood vessel walls in moyamoya. The scan shows the spinal fluid as white. The spinal fluid surrounds the blood vessels at the base of the brain where the narrowing generally occurs. In this patient, the main artery (the carotid artery) on the right of the image is normal (white arrow). The arteries on the left are abnormally small (white arrow head). These pictures show that the narrowing is not from a buildup of material in the wall of the artery, as occurs with atherosclerotic disease and cholesterol plaque.

Once the diagnosis is confirmed, other imaging techniques may be used to measure blood flow and other aspects of the recovery and disease. Washington University neuroradiologists are experts in diagnosing and following moyamoya disease.

Colin Derdeyn, MD, co-director of the Moyamoya Center at Washington University, uses positron emission tomography (PET) in an NINDS*-sponsored clinical trial to study blood flow to the brain and oxygen use in patients with moyamoya.

The PET scan is from a patient who had a stroke and then surgical revascularization. The before surgery scan is the top row. CBF is cerebral blood flow, the delivery of blood to the brain. It is reduced on both sides of the brain (white arrows). OEF is oxygen extraction fraction. When blood flow falls, the brain can compensate by increasing the amount of oxygen from the blood. This helps keep oxygen metabolism normal and keeps the brain alive. The OEF is increased on both sides of the head (white arrows).The bottom row is from one year after surgery on both sides (EDAS procedure). CBF and OEF are both improved and are normal now (white arrows).


Surgical revascularization has become the treatment of choice for patients with moyamoya disease. Although various drugs have been investigated for the treatment of this disease, at this point all have proven ineffective.

In adults, surgical revascularization that directly bypasses blocked arteries is the most common treatment, if feasible. Indirect revascularization procedures are more frequently used in children.

STA-MCA bypass

The superficial temporal artery to middle cerebral artery (STA-MCA) bypass for adult patients with moyamoya disease is performed by neurosurgeon Gregory Zipfel, MD, co-director of the Moyamoya Center at Washington University School of Medicine.

After opening of the scalp, the STA is cut along its length. Care is taken to gently move the STA out of the operative field, and a portion of the skull is removed to expose the brain. The dura – the outermost membrane enveloping the brain – is opened in a way that preserves the main branches of the middle meningeal artery (MMA), which delivers blood to the meninges, or connective tissues that cover the brain. Once the MCA is identified, the arachnoid – the middle layer of membrane surrounding the brain – is opened and the MCA is positioned so that the bypass can be completed. The MCA is opened, and the STA is connected to it.

In contrast to indirect revascularization procedures, the direct STA-MCA bypass provides an immediate increase to blood flow in the brain. Dr. Zipfel has performed hundreds of these direct bypass procedures with relief of symptoms and excellent results for patients.

STA-MCA bypass steps

STA-MCA bypass 1

STA-MCA bypass 2

After opening of the skin, the superficial temporal artery is dissected free along its length.
Craniotomy is performed with multiple burr holes to preserve the middle meningeal artery (MMA), and the dura is opened to find a recipient branch of the middle cerebral artery (MCA).


STA-MCA bypass 3

STA-MCA bypass 4

STA-MCA bypass 5

The arachnoid is opened and the recipient vessel is dissected free.
The recipient vessel is opened and a graft is anchored into place.
A connection is made surgically from the superficial temporal artery to middle cerebral artery (STA-MCA).


Illustrations from: Zipfel GJ, Fox DJ Jr, Rivet DJ. Moyamoya disease in adults: the role of cerebral revascularization. Skull Base. 2005 Feb;15(1). Pages 33-36. Reprinted with permission from Thieme Medical Publishers.


Indirect revascularization procedures

Indirect revascularization procedures involve laying an artery or muscle on the surface of the brain. This can lead to blood vessel formation and increased blood flow to the brain over a longer period of time. Indirect procedures are more frequently used in children and are performed in adults only when direct surgical bypass is not feasible. Two of the most common indirect procedures are:

  • Encephaloduroarteriosynangiosis (EDAS): During this procedure, one of the main scalp arteries, usually the STA, is laid directly on the surface of the brain. Over time (6-8 weeks), this may cause the growth of new arteries in the brain and provide more blood flow. Once an EDAS is performed, the STA cannot be used for a direct bypass procedure.
  • Encephalomyosynangiosis (EMS): This procedure involves taking the temporalis muscle, which is in the temple region of the forehead, opening the skull, and placing the muscle on the brain. Once again, over 6-8 weeks, this may result in the development of arteries and increased blood flow.



Dedicated Moyamoya Center

Washington University School of Medicine is the site for a research study on Moyamoya sponsored by National Institute of Neurological Disorders and Stroke (NINDS). For more information, contact study coordinator Lina Shinawi at or call 314-362-3466.