Moyamoya disease was first reported in 1957 by Japanese scholars Takeuchi and Shimizu because of bilateral internal carotid artery hypoplasia and was officially named Moyamoya disease by Suzuki and Takaku in 1967.Moyamoya means smoky, hazy, and blurred state in Japanese. The annual incidence of this disease is 0.35 per 100,000 people, with a high incidence in Oriental races and a very low incidence in Caucasians. The male to female sex ratio is 1:1.7, with a slight female predominance. Solitary cases are common. It can be seen in all age groups, with a predominance under 10 years of age and a low incidence in 30-40 years of age. Moyamoya disease can cause cerebral ischemia (transient ischemic brain attack and cerebral infarction) and cerebral hemorrhage (intracerebral, intraventricular, and subarachnoid hemorrhage). In children, the symptoms are mainly recurrent or occasional TIA (light paralysis, monoparesis and sensory disturbances), but also headaches, involuntary movements and seizures. All behaviors that can cause hyperventilation, such as crying and playing the harmonica, can lead to constriction of the cerebral arteries and trigger TIA. as the disease progresses, cerebral infarction and lasting neurological impairment and mental retardation can occur. Intracerebral hemorrhage, severe disability and life threatening conditions occur in the later stages. The clinical diagnosis is based on cerebral angiography. The diagnostic criteria are: 1. stenosis or occlusion of the terminal portion of the internal carotid artery and the proximal section of the anterior and/or middle cerebral arteries; 2. abnormal vascular network seen in the arterial phase of angiography near the occluded artery; 3. bilateral involvement. In recent years, MRI and MRA have also been used for diagnosis. Bilateral involvement is a confirmed case and unilateral involvement is a suspected case. Suspicious cases in children may develop bilaterally within 1-2 years, while adults tend to remain unchanged. EEG is a useful test in children with Moyamoya disease. Its characteristic finding is the “reconstruction” of a slow wave of 20-60 s after hyperventilation cessation. This phenomenon is thought to be associated with sub-reduced perfusion of ischemic brain tissue. Histopathology shows that the arterial damage is mainly located in the anterior half of the ring of Willis, due to intimal thickening and narrowing or occlusion of the arterial lumen. Abnormal laminar thickening of the intima of the aorta with marked distortion of the elastic lamina is usually rare with endoelastic disruption and inflammatory cell infiltration, and lipid deposition is rarely seen. Thrombus is often seen in the stenotic segment of the vessel wall, and the etiology of Moyamoya disease remains unclear. Due to the high prevalence in Oriental races and the low prevalence in Caucasian races, familial cases exist. Multifactorial genetic factors should be considered. Treatment of Moyamoya disease is divided into medical and surgical treatment. There is no effective medical treatment to stop the progression of the disease. Direct bypass surgery (superficial temporal artery-middle cerebral artery, STA-MCA vascular anastomosis) and indirect bypass surgery (attachment of vascularized soft tissue to the surface of the brain) can improve ischemic cerebral circulation and clinical symptoms. Indirect bypass surgery is preferred in children. Most patients resolve ischemic attacks several months after bypass surgery.