Stanford Moyamoya Center

Surgical Treatments for Moyamoya

Surgery for moyamoya disease is offered to prevent neurologic deterioration from strokes. Two types of surgical approaches are offered for patients with moyamoya: direct and indirect revascularization.

Direct revascularization

Direct revascularization (STA-MCA bypass) involves use of a branch of a scalp artery (STA) for direct anastomosis (connection) to a branch of the brain artery (MCA) on the outer surface of the brain. This procedure benefits patients by providing an immediate improvement in blood supply to the brain. It's also known as an extracranial to intracranial bypass graft (EC-IC bypass). By virtue of doing the STA-MCA bypass and laying the STA directly on the brain surface, an indirect revascularization is achieved as well. Through enlargement of the STA and increased indirect revascularization, blood flow is expected to continue improving over a period of several months. In the series of patients who have had direct bypass grafts at The Moyamoya Center, results indicate a greater than 95 percent graft patency with excellent long term outcomes. Patients are typically hospitalized for 3 - 5 days, with overall recovery taking between 2 - 6 weeks before returning to all pre-surgery activities. This procedure is our first line recommendation in patients who are eligible. Many children under 5 often don't have arteries large enough to bypass, and may not be candidates for this particular surgery.

STA-MCA bypass surgery illustrations
©Stanford School of Medicine Department of Neurosurgery. Unauthorized use, distribution and duplication of below illustrations are prohibited.

STA-MCA bypass surgery  STA-MCA bypass surgery  STA-MCA bypass surgery 
STA-MCA bypass surgery  STA-MCA bypass surgery  STA-MCA bypass surgery 
A branch of a main scalp artery (superficial temporal artery, or STA) is sewn to a branch of a brain artery (middle cerebral artery, or MCA) lying on the brain's surface in order to provide an immediate improvement in blood flow.

Indirect revascularization

There are various indirect surgical methods used for providing more blood flow to the brains of moyamoya patients.

EDAS (encephalo-duro-arterio-synangiosis) uses a branch of the superficial temporal artery which is laid directly on the surface of the brain without doing a direct anastomosis. The expectation is that it will eventually grow new arteries into the brain and therefore provide more blood flow. This surgery is done at Stanford only when a direct bypass graft is not feasible. In our experience, children tend to have better results with this procedure than adults. Once used for an indirect bypass, the STA branch cannot be used again for direct bypass, even if the indirect bypass is not successful. It usually requires at least 3-6 months for new blood supply to develop from this procedure.

EMS (encephalo-myo-synangiosis) is another indirect bypass operation. The temporalis muscle, which is in the temple region of the forehead, is dissected. Then, through an opening in the skull, the muscle is placed on the surface of the brain. Like the EDAS, 3-6 months are required for a new blood supply to develop from the transposed muscle.

Omental bypass

Omentum is a rich source of blood flow from the lining in the abdomen. Transferring this to the brain can provide an alternative source of flow to patients, when other bypass procedures are not possible or have not been effective enough. Dr. Steinberg has had very good success in providing improved blood flow for some of his moyamoya patients, using omentum for bypass procedures.

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