The specific cause and pathogenesis are not well understood. At present, we only know that it is due to narrowing and occlusion of the major arteries of the brain, which leads to smoke-like malformations of the vascular network at the base of the skull. Although the cause and pathogenesis are not well understood, there is a consensus in the academic and clinical community that surgery is necessary to build another vascular bypass channel to improve the blood supply to the brain. The traditional surgical method for constructing another blood flow channel is to perform patching surgery, also called indirect vascular bypass surgery. This surgery, which is not technically difficult, mainly involves applying some tissues with strong vascular regenerative capacity to the brain surface to induce them to generate new blood vessels to penetrate deeper into the brain tissue to supply blood flow to the brain tissue. The common tissues used for patching are cranial periosteum, middle meningeal artery, temporalis muscle, dura mater and so on. The patching procedure is used by many hospitals because it is relatively simple. However, there is a drawback or limitation of this procedure, that is, after the patching is completed, it takes quite some time to form the new bypass vessels, usually three to six months, and who can guarantee that the patient will not have another cerebral infarction or cerebral hemorrhage during this period! So this period is still very dangerous. So it seems that smog patch surgery is not the best choice. Instead, there is another method called direct vascular bypass surgery, which generally involves bypassing the superficial temporal artery to anastomose the middle cerebral artery, and sometimes other arteries may be used. This procedure can improve the blood supply very quickly, usually immediately after the bypass surgery, but this procedure also has the disadvantage that the scope of blood supply improvement is rather limited. Therefore, direct vascular bypass is not the best option. There is a more advanced surgical approach called combined vascular bypass surgery. This procedure is a combination of direct vascular bypass and patching in one procedure, which overcomes all the disadvantages and limitations of bypass alone or patch alone, and accomplishes better blood flow reconstruction, which is absolutely beneficial to improve blood supply in patients with smog.