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Pial Synangiosis

What is pial synangiosis?

Pial synangiosis reroutes a section of artery that is normally connected to the scalp onto the surface of the brain. New blood vessels grow from this section of artery into the brain itself. The goal of pial synangiosis is to provide a new source of blood for an ischemic area of the brain.

When is this procedure performed?

Pial synangiosis is performed to treat a condition of progressively restricted blood flow to the brain known as moyamoya.

When moyamoya restricts blood flow, certain areas of the brain are deprived of the oxygen and glucose they need to function well. In an attempt to compensate, the body grows a network of thin, fragile blood vessels. As the restriction progresses, however, the compensatory vessels will not provide enough blood flow.

Pial synangiosis revascularizes the brain by allowing it access to a healthy artery with a robust blood supply. Over the course of approximately three to six months, vessels grow like roots from this healthy artery into the brain, restoring blood flow.

Pial synangiosis is a modification of a closely related procedure called EDAS. The difference is that in pial synangiosis, the healthy artery is sutured to the innermost of the brain’s three protective coverings. In EDAS, the healthy artery is sutured into an incision in the outermost of the three protective layers. Both procedures are termed indirect revascularization procedures—procedures in which the brain gradually grows vessels from a new blood supply.

Indirect revascularization procedures like EDAS and pial synangiosis are performed most often in children, though in certain cases they may be the procedures of choice for adults. (Due to the larger size of their arteries, adults are more commonly treated with EC-IC bypass, a form of direct revascularization.)

How is this procedure performed?

Usually, the patient is admitted to the hospital the night before the procedure for intensive hydration and intravenous steroids.

When it is time for the procedure, the patient receives general anesthesia. Hair is shaved at the surgery site, on the side of the head. Neuromonitoring is used to monitor brainwaves during the surgery and ensure there is enough blood flow.

To perform most of the surgery, the surgeon uses an operating microscope and delicate instruments.

First the surgeon makes an incision in the scalp and exposes the target artery, usually the superior temporal artery (STA). As its name implies, this artery is in the region of the temple. Along a distance of several inches, the surgeon releases the artery from its attachments to the scalp, leaving a ribbon of tendon-like material attached to the vessel.

Next the surgeon exposes the bone of the skull beneath the course of the artery. The surgeon makes two burr holes where the artery will enter and exit the skull, and then temporarily removes a small window of bone through which to perform surgery.

Beneath the bone are the three snug layers of protective covering over the brain. The surgeon opens the dura and arachnoid layers, exposing the pia. The surgeon uses the ribbon of tendon-like material to suture the healthy artery to the pia. This establishes the artery on its new course, ensuring that it will remain in close contact with the surface of the brain.

The arachnoid is left open, as is the dura. In fact, the surgeon may fold under leaf-like flaps of dura, so that the surface of the dura (which also has a blood supply) is in close contact with the brain, promoting more new vessel growth.

Then the surgeon replaces the small window of bone, minus openings through which the artery now enters and exits the skull. The bone is secured with thin metal plates and screws to hold it in place as it heals. (The plates and screws can remain in place permanently, even after the bone has knit together.) Then the surgeon closes the incision.

How should I prepare for this procedure?

Make sure you understand the risks and goals of your or your child’s procedure. It may help to write down questions as you think of them and bring your questions to your appointments.

Give your surgeon a complete list of your or your child’s medications and their schedule. Ask if the schedule should be changed in any way for surgery. If children are taking aspirin, it will need to be stopped about a week before the surgery.

What should I expect after the procedure?

After surgery, the patient moves to the pediatric ICU, and then to the neurosurgical floor.

The post-surgical period generally is not painful. Adequate pain control is achieved through medication. Young children may also receive sedation.

Pre- and post-surgical care for the emotional health of our young patients and their families is provided by the caring, dedicated pediatric staff and the Child Life Team.

How long will I stay in the hospital?

Hospital stay is an average of four to five days.

Will I need to take any special medications?

No special medications are required after pial synangiosis.

Will I need rehabilitation or physical therapy?

No rehabilitation is required. Patients usually return to school between two weeks and a month after surgery, with some restrictions on the types of activity in which they can safely engage. Physically demanding activities can usually be resumed by three months after surgery.

Will I have any long-term limitations due to pial synangiosis?

There are no long-term limitations. It will always be important for the patient to stay well-hydrated and to protect the head from trauma. Discuss these recommendations with your neurosurgeon.

patient journey

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