When it comes to smog, many people may not know much about it, or even have never heard of it. It is a rare cerebrovascular disease discovered by Japanese medical experts in the 1950s and 1960s. It is caused by chronic progressive narrowing or occlusion of the major bilateral branches of the cerebral artery ring (the siphon section of the internal carotid artery, the anterior cerebral artery, the middle cerebral artery, and sometimes the beginning of the posterior cerebral artery), followed by abnormal growth of the vascular network at the base of the skull. The proliferated vascular network appears as a clump of vascular images on cerebral angiography, resembling the smoke exhaled during smoking, and is therefore called smoky disease by the Japanese. The age of onset of the disease is bimodal, mainly in children under 10 years old and adults around 40 years old. Children with smog disease tend to develop ischemic symptoms, while adults with smog disease have both ischemic and hemorrhagic symptoms in equal proportions. This disease is very dangerous, and in case of acute cerebral infarction or cerebral hemorrhage, it is very dangerous and may even be disabling or fatal. Therefore, once smog is detected and clearly diagnosed, it should be treated promptly. For the treatment of smog, the medical community recognizes that conservative treatment is not very meaningful, that is, the early relief of symptoms, but the later effect is not good, so the consensus is that smog should be treated surgically. Some patients ask how long it takes to operate for smog. Currently, clinically, combined vascular bypass surgery is performed to treat smog and can achieve significant results. This surgery is a dual procedure of direct bypass + patching, which can comprehensively reconstruct a perfect blood bypass channel and provide sufficient blood supply to the brain. The direct vascular anastomosis is accompanied by a multifactorial dressing on the brain surface to further expand the scope of blood supply improvement, and the procedure takes about 3-4 hours to perform.