Dale Swift, M.D. Answers Questions On: Moyamoya Syndrome

Moyamoya syndrome causes the carotid arteries – the large vessels that supply blood to the brain – to become progressively more narrow (stenosis) as they enter the skull, to the extent that they are eventually blocked (ischemia) completely. The resulting decrease in blood supply can result in strokes.

In addition, as the brain tries to get more blood, it “recruits” new blood vessels to develop at the base of the skull. Those new blood vessels can sometimes hemorrhage later, when people are older.

When an adult with moyamoya syndrome has a blocked artery in the brain, the arteries in the scalp are usually large enough for a surgeon to connect one of them to an artery inside the skull in a surgery called an anastomosis. But because the arteries in children’s scalps are so small, we have to do a different operation to treat the condition. 

To surgically treat moyamoya syndrome in children, we isolate the temporal artery (the one that pulses in the temple) and move it to the surface of the brain through a small window we open in the skull.

We leave the diseased carotid artery intact and don’t attach the repositioned temporal artery to anything. Because the carotid artery is no longer being used to transport blood to the brain, the brain sends out chemical messengers that signal the body to grow new arteries directly from the relocated temporal artery that has taken over its job.