1.What is smog disease: Smog disease is a group of occlusive diseases characterized by progressive stenosis or occlusion of the end of the internal carotid arteries and their large branches, and the formation of an abnormal neovascular network at the base of the skull. The name “smoke” comes from the fact that cerebral angiograms show a blurred reticular shadow at the base of the brain due to abnormal capillary hyperplasia, resembling a puff of smoke from a cigarette. The clinical manifestations are mainly divided into two categories: hemorrhage and ischemia, with a bimodal distribution of the age of onset between 5 and 40 years old, and ischemia as the main clinical manifestation in children, while ischemia and hemorrhage are basically the same in adult patients. The essence of the disease is occlusion of the arterial trunk at the base of the brain with compensatory vascular proliferation. 2. Clinical manifestations: ①TIA type: the most common, about 70% of all idiopathic smoker’s disease. It is characterized by recurrent transient paralysis or weakness, mostly hemiparesis, or alternating right and left hemiparesis or double hemiparesis. There is complete recovery of motor function after an attack. The course of the disease is mostly benign, with a tendency to spontaneous remission or complete cessation of attacks. Very few cases are associated with hemiplegic attacks, headache or migraine. Rarely, there is transient sensory impairment, involuntary movements or mental retardation. (ii) Infarct type: acute stroke resulting in permanent type of paralysis, aphasia, visual impairment and mental retardation. (③Epileptic type: frequent seizures, partial seizures or seizure continuity with EEG epileptiform discharges. (iv) Hemorrhagic type: subarachnoid hemorrhage or brain parenchymal hemorrhage, seen in older children and adult cases. The last three types of the above clinical typing are called “non-TIA type”, which has a complex and variable course and a poor prognosis, and mostly manifests as a mixed type, such as epileptic type plus infarct type and epileptic type plus TIA type. In case of simple seizures, the prognosis is not necessarily poor. Regardless of the type, the prognosis is worse in those with onset before the age of 4 years. In addition, the clinical symptoms and their severity are determined by the compensatory effect of the collateral circulation. If adequate cerebral perfusion is maintained, there may be no clinical symptoms, or only transient TIA seizures, or headaches. If cerebral perfusion is not maintained, the symptoms are severe and cause extensive brain damage.