Moyamoya disease, which is prevalent in Eastern children, is a disease that the large blood vessels on both sides of the brain gradually become stenosis and occlusion, and leading to a stroke. As the large blood vessels gradually narrow, the brain spontaneously grows many abnormal, winding small blood vessels at the skull base to rescue the brain tissue, forming a smoky pattern, which appears on the cerebral angiography. The termed "moyamoya" in Japanese, i.e. “puff of smoke”, was used to describe this particular disease or syndrome. Moyamoya syndrome is used when the presence of underlying diseases, while moyamoya disease is used when the underlying cause is not known.

The changes in blood vessel blockage are gradual; the moyamoya patients usually experience transient, repeated reversible cerebral ischemia. The transient weakness quickly recovers and is easily overlooked, especially in children who cannot express themselves well, thus may not be diagnosed until the permanent neurological symptoms of obvious or persistent motor deficits, language impairment, epilepsy, developmental delays, and so on occur years after the onset of the disease. Crying may cause excessive hyperventilation, resulting in cerebral vasoconstriction, reducing cerebral blood flow, and causing cerebral ischemia and symptoms such as weakness and hemiplegia in these children. Other activities that commonly cause hyperventilation in school-aged children include blowing a balloon, playing musical instruments, and so on.

Moyamoya disease is a disease that can and should be treated by various revascularization surgeries. The symptoms of cerebral ischemia in patients can be significantly improved after surgery. At National Taiwan University Children’s Hospital, a team of pediatric neurosurgeons, pediatric neurologist, neuro-radiologists, geneticists, neuropsychologists, epidemiologists, and laboratory experts has conducted various studies on the pathogenesis, genetic patterns, diagnostic tools, surgical methods, and cognitive psychology of moyamoya patients. Standardized surgical procedure and study program have been developed to reduce perioperative complication. Through the comprehensive diagnosis and care, the impact of moyamoya disease on children and families is reduced as much as possible.