Brain imaging

Moyamoya Disease

Moyamoya Disease is a Rare Neurovascular Condition

Moyamoya disease is a rare neurovascular condition that can affect both children and adults and is caused by progressive narrowing or blockage of the major blood vessels supplying the brain.

The result is a lack of necessary blood flow to the brain, which can cause stroke, mini-stroke (TIA – transient ischemic attack) or bleeding into the brain. Numerous tiny vessels develop around the blockage in an attempt to compensate for the lowered blood flow, leading to a smoky appearance of these vessels on imaging. This smoky appearance is what gives the disease its name, as “moyamoya” means puff of smoke in Japanese.

3D vascular imaging of the brain showing successful revascularization surgery for moyamoya disease with extracranial-to-intracranial bypass.
Brain perfusion heatmap demonstrating successful changes (reduction in amount of red areas representing less blood flow) after revascularization surgery.


Patients with Moyamoya disease experience the symptoms of ischemic or hemorrhagic stroke or TIA. Symptoms can include:

  • Weakness or numbness in an arm or leg
  • Difficulty speaking
  • Paralysis affecting one side of the body
  • Seizures
  • Cognitive difficulty
  • Headache


Diagnosis is typically made by imaging using Magnetic Resonance Imageing (MRI) and angiogram. Computed Tomography Angiography (CTA) or CT Perfusion may also be used.While Moyamoya disease is often diagnosed in people of Asian descent, it has now been recognized worldwide across all ethnic groups. It is unclear why Moyamoya disease develops although there is a genetic component in many cases.


The narrowing of the arteries to the brain is irreversible, thus no medications will help restore adequate blood flow. Minimally invasive (keyhole) revascularization surgery is recommended. Extracranial-to-intracranial (EC-IC) bypass (encephalo-duro-arterio-synangiosis EDAS) is performed to create normal blood flow to the brain.

Contact Us

The Pacific Stroke and Neurovascular Center’s state-of-the-art facilities are located at:

Providence Saint John’s Health Center
2125 Arizona Ave., Santa Monica, CA 90404

Providence Little Company of Mary Medical Center Torrance
4201 Torrance Blvd., Suite 520, Torrance, CA 90503

Providence Saint Joseph Medical Center
501 S. Buena Vista Ave., Burbank, CA 90505

Providence Holy Cross Medical Center
15031 Rinaldi St, Mission Hills, CA 91345