Moyamoya Disease | Diagnosis and Treatment

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Contact the Moyamoya Disease Program

How is moyamoya disease diagnosed?

The standard test for both diagnosing moyamoya disease and planning for surgery is a cerebral angiogram, a minimally invasive procedure that produces a “map” of your child’s carotid arteries. During an angiogram, a special dye that shows up on x-rays is injected into the artery. The dye creates a contrast effect in the images, which allows clinicians to see both the extent of narrowing in the brain’s blood vessels and the tangle of thin new vessels generated by moyamoya disease.

Clinicians may also use the following imaging technologies to help diagnose, or confirm a diagnosis of, moyamoya disease:

What are the treatment options for moyamoya disease?

Surgery is the mainstay of treatment for moyamoya. Several surgical treatments for moyamoya disease have been very effective at bypassing narrowed arteries and creating a new blood supply for the affected areas of the brain, decreasing the likelihood of a stroke.

Pial synangiosis

Pial synangiosis is the mainstay of surgical treatment in the Moyamoya Disease Program. It is designed to take advantage of the tendency of the brains of children with moyamoya disease to attract new blood vessels from any source that is made available by the surgeon. During the procedure, the neurosurgeon makes an incision in the child’s scalp, exposing a healthy blood vessel in the scalp and then separates it from the surrounding tissue while ensuring that blood continues to flow through it. A window of bone is opened beneath the artery. Using a microscope to carefully open each of the brain’s coverings, the surface of the brain is eventually exposed.

The neurosurgeon then places the scalp artery directly onto the brain and sews the tissues surrounding the artery’s walls to the surface of the brain using tiny sutures. This keeps the transplanted artery in direct contact with the brain. The neurosurgeon then replaces the window of bone and closes the incision in the skin. The procedure usually takes three to four hours but may be longer if both sides of the brain require surgery.

Pial synangiosis stimulates the development of new blood vessels that grow from the donor scalp artery, providing a vital source of blood to the brain beneath. The new blood vessels emerge not only from the transplanted scalp artery, but also from blood vessels sprouting from the coverings of the brain around the opening in the skull.

It’s still not fully understood why these new blood vessels emerge and flourish. Boston Children’s researchers have discovered that the cerebrospinal fluid that flows over the brains of children with moyamoya disease may have certain growth factors that prompt new blood vessel development.

Indirect procedures

Some procedures for moyamoya disease are considered indirect surgeries, meaning that they encourage and introduce new blood vessel growth to the brain over time. Examples of these procedures are:

  • EDAS (encephaloduroarteriosynangiosis). In this procedure, the superficial temporal artery in the child’s brain is laid over an opening in the cortex. The artery is then sewed to the dura (the firm layer of tissue that covers the brain). Over time, small new arterial vessels begin to develop.
  • EMS (encephalomyosynangiosis). In this procedure, small portions of the temporalis muscle in the jaw are attached in a parallel direction to the surface of the child’s brain. The transplanted muscle gradually generates new blood vessels, forming a supplementary source of blood flow to the brain.
  • Omental transposition/transfer. In this procedure, the child’s omentum — the blood-rich lining that surrounds the organs in the abdomen — is laid over the surface of the brain. New vessels eventually develop and grow into the brain.
  • Dural inversion. In this procedure, neurosurgeons invert the flaps of fibrous dural tissue on the child’s meningeal vessel, a large artery within the skull. This places the outer dural surface, which has plentiful blood vessels, in direct contact with the parts of the brain that were previously deprived of essential blood flow.

Direct arterial bypass

The direct arterial bypass surgery is also known as superficial temporal to middle cerebral artery anastomosis, or STA-MCA bypass. During this procedure, neurosurgeons join a blood vessel from the child’s scalp directly to a vessel in the brain. Blood flow throughout the brain should improve over the next several months.

Medication

While surgery is the only viable treatment for moyamoya disease in the long term, your doctor may also recommend medication to manage some of your child’s symptoms. These may include aspirin (to help prevent blood from clotting) and calcium channel blockers, such as verapamil (to help lower blood pressure).

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