1. What is DAVM? Dural arteriovenous malformation (DAVM) is an arteriovenous communication or arteriovenous fistula within the dura mater that is supplied by the dural artery or the dural branch of the intracranial artery and returns to the venous sinus or arterialized meningeal vein. Essentially DAVM is based on one or more arteriovenous fistulas in the dura mater, hence the term dural arteriovenous fistula (DAVF) in the past. However, the vast majority of arteriovenous fistulas are acquired lesions, and the name “dural arteriovenous malformation” better reflects the congenital origin of some of these lesions. 2.Why does DAVM occur? (What is the pathogenesis of DAVM/DAVF)? There is no uniform understanding of the mechanism of its occurrence, which can be summarized into two categories: congenital factors and acquired factors. Most scholars emphasize the close relationship between dural arteriovenous malformation and phlebitis, which is due to the formation of neovascularization after venous sinus embolization. Some believe that dural arteriovenous malformations are related to congenital dilatation of small arteriovenous circuits. In addition, it is also believed that dural arteriovenous malformation is related to venous sinusitis, and any external factors such as trauma and surgery can cause the opening of reticular traffic between dural arterioles and venous sinuses to form arteriovenous fistulas. 3.What symptoms can occur in DAVM/DAVF? 1.Intracranial vascular murmur 2.Headache 3.Increased intracranial pressure 4.Intracranial hemorrhage 5.Other: Seizures, tinnitus, mild hemiparesis, aphasia, transient blackness, etc. may occur in a few cases. (Dural arteriovenous malformation of cavernous sinus may present with frontal orbital or retrobulbar pain, proptosis, decreased visual acuity, diplopia, oculomotor nerve disorder, etc.) 4.Can DAVM/DAVF be prevented? There is no effective preventive measure for this disease, early detection and diagnosis is the key to prevention and treatment of this disease. 5.How is DAVM/DAVF diagnosed? Sudden subarachnoid hemorrhage under the age of 40 with a history of epilepsy or mild hemiplegia, aphasia, or headache before the hemorrhage without obvious increase in intracranial pressure should be highly suspected of arteriovenous malformation. However, a clear differential diagnosis depends on cerebral angiography, CT and MRI examinations. Among them, cerebral angiography is the most important tool for diagnosis and typing of DAVM, which can clearly show the manifestation of malformed vessels from arterial to venous stages, which is beneficial to the typing of lesions and understanding the relationship between angiographic changes and clinical manifestations and prognosis, especially to observe whether the involved venous sinuses are embolized and the direction of venous return flow, which has a decisive role in the design of treatment plan. 6.How to treat DAVM/DAVF? The treatment plan should be selected and developed according to the patient’s past clinical manifestations, current clinical condition and angiographic manifestations, respectively. At present, minimally invasive interventional treatment is mainly used. 7.What is suitable for medical treatment? How to treat? (1) Indications: ①Mild symptoms or incidental findings; ②No cerebral cortical venous drainage on angiography. (2) Methods: ①Since the chance of rupture and bleeding of DAVM is small, and individual patients can even heal spontaneously, only follow-up observation is needed, and annual cranial MRI examination should be performed, except for the appearance of cortical drainage veins. Cerebral angiography can be repeated within a few years if cortical drainage veins are suspected or if clinical symptoms change. ② Pain and intracranial murmur are the most common subjective symptoms that affect the patient’s quality of life. In mild cases, symptomatic treatment such as non-steroidal anti-inflammatory drugs, carbamazepine or short-term hormonal therapy can be given, which is effective in relieving pain and pulsating murmurs. However, for pain in the trigeminal nerve distribution area, percutaneous puncture to destroy the nerve root should not be used to avoid puncturing the malformed blood vessels and causing hemorrhage. 8.What needs non-medical treatment? Indications: ① single cortical draining vein, especially if the draining vein has tortuous and aneurysmal expansion, needs immediate treatment to prevent rupture and bleeding; ② history of intracranial hemorrhage; ③ increased intracranial pressure, optic disc edema, affecting vision; ④ focal neurological dysfunction, progressive aggravation; ⑤ headache and intracranial murmur that affects life. It is important to analyze the specific situation, and there are different treatment strategies for different lesion sites 9. which are suitable for surgical treatment of DAVF Surgical surgery is only used for patients who have no way to perform interventional treatment. The aim is to isolate, electrocoagulate, and excise the dural flap and adjacent venous sinuses involved in DAVM, and to cut off the access to the arterialized cortical drainage veins. If the involved venous sinus is arterialized or the collateral circulation has been established, removal of the venous sinus will not cause venous cerebral infarction. 10.What are suitable for endovascular intervention? The vast majority of patients are suitable for interventional treatment. The effect is good. 11.What are suitable for radiation therapy? Radiosurgery: In recent years, radiosurgery such as γ-knife and linear gas pedal have been applied to the treatment of certain types of dural AVM. For example, DAVM at the transverse sigmoid sinus, superior sagittal sinus and middle skull base without recent bleeding, or other lesions with high treatment risk. It has been reported that intra-dural aberrant vessels can self-occlude within 2 years, but there is no definitive conclusion on the dose of irradiation or indications for treatment. Currently, radiation therapy can be tried for lesions that cannot be managed by intervention and surgery. 12.Common complications of DAVF/DAVM Some patients with mixed dural arteriovenous malformations may develop scalp vascular rage, distortion, or even formation of vascular masses. When the dural arteriovenous malformation in the posterior cranial fossa drains into the spinal veins, it can cause intravertebral venous hypertension, leading to spinal cord ischemia and spinal cord damage manifestations. High blood flow can also be accompanied by heart enlargement and heart failure. 13.Prognosis of DAVF/DAVM Intracranial hemorrhage and progressive neurological dysfunction are the most important factors affecting the prognosis of DAVM. Once intracranial hemorrhage occurs, the prognosis is poor. Approximately 30% of patients die or become severely disabled at the time of the first bleed. The prognosis is worse for patients undergoing anticoagulation therapy.
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