Moyamoya diseas (MMD) is a group of cerebrovascular diseases characterized by narrowing or occlusion of the siphon section of the internal carotid artery and the beginning of the anterior and middle cerebral arteries, and the presence of an abnormal network of small vessels at the base of the brain. It is called smoker’s disease because the cerebral angiogram shows many dense piles of small blood vessel shadows, which resemble the smoke exhaled when smoking. Some scholars have found that individual families may have similar diseases in mothers and sons or siblings, which may be related to genetic factors. However, some scholars believe that this is a group of acquired occlusive cerebrovascular disease, which may be related to metaplastic cerebral vasculitis. Clinical manifestations 1. Transient ischemic attack (TIA) type is the most common and is seen in 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, and there is a tendency of spontaneous remission or complete cessation of attacks. 2. Infarct type Acute stroke, resulting in permanent paralysis, aphasia, visual impairment and mental retardation. 3. Hemorrhagic brain parenchymal hemorrhage or cerebral hemorrhage breaking into the ventricles is most common and is seen in older children and adult cases. Other clinical manifestations include: cognitive impairment (memory, calculation, spatial orientation, mental decline), headache or migraine, involuntary movements, etc. (1) Electroencephalography (EEG) There are generally no specific changes. Both patients with hemorrhage and patients with infarction have roughly the same EEG performance, which shows increased slow waves on the side or both sides of the lesion and extensive moderate or severe rhythm disorders. (2) Cerebral angiography Cerebral angiography is the main means to confirm the diagnosis of this disease, and its manifestations are characterized as follows: ① Severe stenosis or occlusion of bilateral internal carotid arteries in the supratentorial segment and proximal anterior and middle cerebral arteries. The distal vessels of the occluded segment have normal morphology, and the cerebral angiography is basically the same on both sides, but the two sides are not completely symmetrical, and in a few cases, the abnormalities of the above-mentioned vessels appear on only one side. occlusion of the arteries, forming an abnormal vascular compensatory collateral circulation at the base of the brain. (ii) There is a remarkable capillary dilated network at the basal ganglia, i.e., a collateral circulation centered on the internal and external striate arteries and the thalamic arteries, thalamic geniculate arteries, and anterior and posterior choroidal arteries. (iii) There is extensive and abundant formation of collateral circulation, including the establishment of intracranial and extracranial anastomotic vessels. There are three types of collateral circulation pathways: when the siphon end of the internal carotid artery is occluded, the collateral circulation is formed through the anastomosis between the posterior cerebral artery and the terminal branches of the anterior and middle cerebral arteries. The undamaged arterial ring and all arterial branches of the siphon participate in the blood supply to the basal ganglia, forming a collateral circulation to supply the branches belonging to the anterior and middle cerebral arteries. Therefore, the formation of a very rich anomalous vascular network in the basal ganglia is the most important collateral circulation pathway in this disease. The anastomosis between the branches of the external carotid artery and the soft meningeal vessels on the surface of the brain forms a network. (3) CT scan The following manifestations of smoker’s disease may appear in CT scan alone or in combination. (1) Multiple cerebral infarcts: This is due to repeated occlusion of blood vessels at different sites. Multiple cerebral infarcts may be old or recent and may have foci of cerebral softening of varying sizes. Secondary cerebral atrophy: mostly limited cerebral atrophy, which is directly related to the extent of internal carotid artery occlusion, and the more severe the internal carotid artery stenosis and the poorer the blood supply, the more obvious the cerebral atrophy is. In contrast, there may be no cerebral atrophy on CT in those with good collateral circulation. Cerebral atrophy occurs in the temporal lobe, frontal lobe, and occipital lobe, peaks at 2-4 weeks, and then gradually improves. The reason for its improvement may be related to the establishment of collateral circulation. (iii) Ventricular enlargement: More than half of the patients have ventricular enlargement, and the enlarged ventricles are ipsilateral to the lesion, or bilateral. Ventricular enlargement often coexists with cerebral atrophy and has a relationship with intracranial hemorrhage. In severe cerebral atrophy with ventricular enlargement, there is no previous history of intracranial hemorrhage. In contrast, those with mild cerebral atrophy with significant ventricular enlargement have a history of intracranial hemorrhage in the past. This may be due to adhesions after subarachnoid hemorrhage that affect the circulation of cerebrospinal fluid. Intracranial hemorrhage: 61,6% to 77,3% of patients with smog can have intracranial hemorrhage, with subarachnoid hemorrhage being the most common, accounting for about 60%. Intraventricular hemorrhage is also more common, accounting for 28.6%-60%, mostly combined with subarachnoid hemorrhage, of which 30% are primary intraventricular hemorrhage, which is caused by rupture of the thin abnormal vascular network. Intracerebral hematoma is more common in the frontal lobe, irregular in shape and size, and may rupture and bleed when adjacent to the ventricles, or form subarachnoid hemorrhage after rupture when adjacent to the brain pool. (4) Magnetic resonance imaging (MRI) can show the following pathomorphological changes in smoldering disease: (1) long T1 and long T2 in both old and recent cerebral infarcts, and long T1 and long T2 in cerebral softening foci, with hypointense signal on T1-weighted images and high signal on T2-weighted images. (ii) Intracranial hemorrhage showed high signal in all imaging sequences. (③Limited brain atrophy is most evident in the base of frontal lobe and temporal lobe. ④Anomalous vascular network at the base of the skull appears as foveal or reticular low-signal vascular images due to the flow-space effect. Diagnosis At present, the internationally accepted diagnostic criteria for smoldering disease are adopted, i.e. the criteria established by the Japanese Society for Smoldering Disease Research in 1997: the cause is unknown and the DSA or MRA presentation is consistent with progressive stenosis and/or occlusion of the terminal internal carotid artery and the beginning segment of the anterior and middle cerebral arteries, the artery shows an abnormal smoky vascular network, and the lesion is bilateral. The following diseases should also be excluded: atherosclerosis. Autoimmune disease. Meningitis. Brain tumor. Down’s syndrome. Traumatic brain injury. Radiation head exposure and hyperthyroidism, etc. Possible smog, i.e., unilateral lesions in children or adults, also need to be excluded. Imaging is currently the main tool for the diagnosis of smog. The application of transcranial Doppler ultrasound (TCD) screens for a number of patients with clinically suspicious or unanticipated smog. tCD is able to detect more adult patients with ischemic and adult smog presenting with clinical signs of atypical vascular disease. In terms of confirming the diagnosis, digital subtraction angiography (DSA) is still the most accurate and reliable diagnostic method, and magnetic resonance imaging/magnetic resonance angiography (MRI/MRA) can make a definitive diagnosis in most patients with smog. V. Treatment 1. Internal medicine treatment Patients with infarcts are generally treated with standardized drugs according to neurology. Treatment with volume expansion, vasodilators and calcium antagonists is available. In case of ischemia, vasodilators are used, and in case of hemorrhage, lowering cranial pressure and stopping hemorrhage are the main treatments. If the cause is clear, the cause should be treated actively. 2.Surgical treatment Smoky disease can be treated with intracranial and extracranial vascular anastomosis, cerebral muscle vascular combination and other surgical procedures to reconstruct blood flow and improve the prognosis. Prognosis The prognosis of this disease depends on the natural development of the disease in most cases, that is, it is related to the age of onset, the primary cause, the severity of the disease, the degree of brain tissue damage and other factors. Whether the treatment is timely and appropriate also has a certain impact on the prognosis. The mortality rate is high in adults with intracranial hemorrhage, but most of them do not have sequelae if the coma period passes quickly.