Cerebrovascular malformation is usually due to congenital abnormalities in cerebral vascular development, and is one of the common causes of cerebral hemorrhage, second only to hypertensive cerebral hemorrhage and intracranial aneurysm. Some data show that the annual incidence of cerebrovascular malformation hemorrhage is about 2-4%, the annual mortality rate is about 1%, the incidence of rebleeding within 20 years is 51%, and each hemorrhage has a 10%-15% mortality rate. Because of its special location and its predilection for young people, it is one of the dangerous diseases with a higher rate of death and disability. Intracranial vascular malformation is a developmental malformation of the intracranial vascular bed; it manifests as an abnormal increase of blood vessels in a certain area of the skull. At present, there are 4 types: 1) arteriovenous malformation; 2) capillary dilation; 3) venous hemangioma and varicose veins; 4) cavernous hemangioma. Among them, arteriovenous malformation is the most common, accounting for more than half of them, because some factors during embryonic period affect the normal development of its original cerebral vascular network, capillaries are not sound, and the arterioles and veins are directly connected to form a short circuit, which develops into cerebral arteriovenous malformation. Cerebral arteriovenous malformations are most common in young people, with the highest incidence in young adults between the ages of 20 and 40, and twice as common in men as in women. The lesions can occur in any part of the brain, but the parietal lobe is the most frequent, followed by the frontal and temporal lobes. Most of the malformed vascular masses are conical in shape, with a broad base facing the cerebral cortex and a tip pointing deep into the white matter, close to the wall of the lateral ventricles. There is one or more thickened blood supply arteries, which may come from all cerebral arteries. The draining vein is dilated and twisted and can be directed into superficial cerebral veins or into deep cerebral veins. The brain tissue surrounding the lesion may be atrophic due to ischemia, with surface arachnoid thickening and whitening, and signs of old hemorrhage. According to the size of the lesion, it can be divided into small size (<2.5cm in diameter), medium size (2.5-5cm), large size (5-7.5cm), and extra large size (>7.5cm). The main clinical manifestations are local ischemia and recurrent hemorrhage in the brain. 1, hemorrhage: often no clear cause, patients often rupture and bleed from malformed blood vessels, forming intracerebral hematoma or subarachnoid hemorrhage as the first symptom, accounting for 52%-70%, often sudden onset, related to the patient’s physical activity and mood swings. The symptoms are sudden severe headache and stiff neck, accompanied by nausea and vomiting, and may have a certain degree of impaired consciousness. Different parts of the lesion and hemorrhage may present with localization signs such as hemiparesis, hemianopia, aphasia and hemianopic sensory impairment, ataxia, etc. 2. Ischemia: It is seen in giant lesions, mostly due to long-term blood theft that causes total brain atrophy leading to mental retardation, sometimes manifested as progressive mild hemiparesis and other brain dysfunction. 3. Epilepsy: It is the main clinical manifestation of superficial AVM after hemorrhage, with an incidence of 28%-64%, related to the site and size of AVM. 4.Headache: about 60% of patients usually have vascular headache, which may be caused by vasodilatation. 5.Intracranial murmur: only seen in huge and superficial AVM, or AVM involving dura mater and extracranial tissues. Imaging manifestations 1.CT manifestations: (1) Unruptured cerebral arteriovenous malformation CT manifestations: in plain scan, focal high and low or low mixed density shadow is seen, in the form of spots, clusters or cords, with unclear edges, no obvious occupying effect and no surrounding cerebral edema. In some patients, arteriovenous malformations cannot be detected on plain scan, but after contrast injection, the arteriovenous malformations in the brain show mass-like enhancement, and even tortuous vascular shadow, blood supply arteries and draining veins are visible. (2) CT manifestation of cerebral arteriovenous malformation after hemorrhage: intracerebral hematoma, subarachnoid and ventricular system hemorrhage are present. According to the duration of hemorrhage, high-density shadow, mixed dense shadow and low-density shadow are shown, and there is a low-density edema area around the hematoma. After contrast injection, some of the hematomas may have tortuous reinforcement at the edges of the malformed vessels, while the mixed dense shadow hematomas often have ring reinforcement. Therefore, MRI is the preferred imaging method when a patient is suspected of having cerebrovascular malformation. (1) The vascular component of cerebral arteriovenous malformation is shown as a signal-free flow-void vascular shadow distributed in clusters and networks. (2) Hematoma formed by hemorrhage from arteriovenous malformation is shown as T1- and T2-weighted image changes similar to other causes of hematoma. In the subacute stage, the hematoma is high signal on both T1 and T2-weighted images, and with time, the hematoma gradually changes to equal signal or low signal on T1-weighted images, and remains high signal on T2-weighted images. Cerebral angiography: Cerebral angiography is the most useful method to diagnose this disease. It can not only identify the size and location of AVM, but also show the blood supply arteries and reflux veins, determine the AVM level, which is of great significance to the selection and design of treatment. (1) Showing malformed blood vessels. Mostly seen in the cerebral hemisphere cortex . (2) Abnormally large feeding arteries and draining veins with accelerated local circulation. This is a manifestation of local blood flow short circuit. (3) Blood flow shunt phenomenon: the contrast agent flows into the vein with the blood flow through the short circuit of the malformed vessels. (4) Manifestation of hematoma: intracerebral hematoma caused by rupture and bleeding of blood vessel, and the main manifestation of hematoma is local occupying sign. More than 90% of intracranial vascular malformations are arteriovenous malformations (AVM), and there are three types of AVM: 1) cerebral arteriovenous malformation; 2) meningeal arteriovenous malformation; 3) dural arteriovenous malformation. Among them, cerebral arteriovenous malformation accounts for more than 70% of intracranial arteriovenous malformation. V. Grading of cerebral arteriovenous malformation AVM is often graded according to Spetzler’s grading method, and AVM is scored from the following 3 aspects, which is divided into 5 levels: 1, according to the size of the malformation mass: 1 point for small (less than 3cm in diameter); 2 points for medium (3-6cm); 3 points for large (more than 6cm). 2.Scoring according to the location of the deformity mass: 1 point in the functional area; 0 points in the non-functional area. 3.Scoring according to the drainage vein drainage mode: 1 point for deep vein drainage; 0 points for brain surface drainage. The above 3 scores are added up to the corresponding level. Diagnosis of cerebrovascular malformation In young patients with cerebral hemorrhage at atypical sites, in young people with seizures, especially those with vascular lesions detected by CT or MRI, AVM should be considered as a possibility, and whole brain angiography (DSA) should be performed to confirm or exclude the diagnosis of this disease. In addition to confirming the diagnosis of the disease, whole brain angiography can also reveal the location, size, blood supply arteries, number and direction of draining veins, and the presence of aneurysms and venous aneurysm-like dilatation, so as to determine the appropriate treatment plan. Treatment of cerebral arteriovenous malformation The main purpose of cerebral arteriovenous malformation is to prevent hemorrhage, remove hematoma, improve blood theft and control epilepsy, and the treatment methods include: 1, malformation vascular resection; 2, intravascular embolization treatment; 3, gamma knife radiation therapy. 1, arteriovenous malformation resection Microscopic craniotomy is a surgical method to remove arteriovenous vessels directly, i.e. craniotomy. During the operation, the blood supplying artery of the malformation vessel is cut off to strip the malformation vessel mass, and finally the draining vein is cut off. 2.Arteriovenous malformation embolization Interventional embolization therapy is currently the preferred method, especially for intracerebral or huge lesions located in important functional areas and in particularly deep locations, intra-arterial embolization under digital subtraction can be adopted to reduce the blood supply of the malformed vascular lesion, so that the lesion disappears, is reduced or facilitates further surgical or radiological resection. (1) Indications for surgery ① Simple malformed vessel and supply artery embolization: Applicable to non-functional area, small vessel malformation, and simple lesion with only one supply artery. ②Embolysis of supply artery of preoperative malformed vessels: applicable to extensive or multiple lesions with high blood flow that cannot be resected, or used before resection of extensive vascular malformations as a preparatory procedure that can prevent postoperative hyperperfusion complications. (3) Pre-treatment before γ-knife radiotherapy: preoperative γ-knife radiotherapy is performed after the malformed vessels are reduced to a certain size (less than 3 cm) by embolization of the malformed vessels. (2) The advantages of arteriovenous malformation embolization ① Low erosivity to the whole body. It can be performed under local anesthesia by puncturing the femoral artery at the root of the thigh and introducing the treatment catheter. ②Low trauma to brain tissue, no craniotomy. ③Short operation time. ④No damage to the normal perivascular penetrating vessels, which can reduce surgical complications. (3) Surgical method: The microcatheter is used to introduce various embolic substances (real wire segments, NBCA, ONYX gel, etc.) into the blood supply artery or malformation mass of the arteriovenous malformation to eliminate the lesion or reduce the size of the malformation mass. Transarterial embolization: only transarterial injections of liquid embolic agents can be curative In transarterial embolization, liquid embolic material must be used if the patient is to be cured or to obtain relatively long-term remission, and the liquid embolic material enters the fistula, even to the proximal end of the draining vein. It is commonly used in patients in whom the venous route is difficult to reach or in whom the draining vein cannot be occluded. In general, NBCA can be embolized via arterial injection except in the cavernous sinus area ② Transvenous route embolization treatment: safe, effective, and can be done by visualized venous sinus embolization, non-visualized venous sinus embolization, and direct puncture filling by drilling. Any cerebral angiography proves that the draining vein no longer drains normal brain tissue, i.e., it does not have normal drainage function can be occluded, but the premise of occlusion is that the microcatheter can enter the draining vein near the fistula. Drilling direct perforation and filling: applicable to venous sinus occlusion, can not enter the drainage venous sinus, or through the venous sinus path is too long, difficult to place. 3.Comprehensive treatment Recently, the embolization method has been changed by placing the catheter directly inside the malformed vascular mass and injecting NBCA gel, which can increase the anatomical cure rate of the malformed mass to 27%. This, coupled with the introduction of finer, ultra-smooth microcatheters, has reduced embolization complications even further. Embolization of large, functional AVMs can reduce their size and improve hemodynamic distribution for microsurgical resection or radiation therapy, and is an important adjunct to the latter two; i.e., embolization to reduce the size of the malformed mass or reduce the risk of overperfusion before surgery or gamma knife treatment.