Dural arteriovenous malformation, also known as dural arteriovenous fistula (DAVF), is a condition where the arteries and veins are connected abnormally. The abnormal connectivity itself is called fistula; under normal circumstances, the arteries and veins do not connect at all. The specific blood vessels usually involved in dural arteriovenous malformation are the meningeal artery and meningeal vein, which are located in the central nervous system (CNS). In some cases, it might involve a meningeal and a dural venous sinus, which is a venous channel situated in the dura mater, or the leathery meningeal layers surrounding the brain and spinal cord. Some patients might experience more than one occurrence of the condition.
There are two types of dural arteriovenous malformation: cranial DAVF and spinal DAVF. Cranial DAVF occurs in the brain and is supplied by the carotid artery's branches. This type of dural arteriovenous malformation is typically found in the convexity dura, the part of the dura mater that overlies the brain hemisphere; or in the tentorial dura, the portion of the meningeal layer located between the forebrain and hindbrain. The other type of dural arteriovenous malformation, spinal DAVF, occurs in the spinal cord and originates from the dural arterial branches. It usually resides at the lower section of the spine.
The cause of dural arteriovenous malformation is unknown, which may be due to the fact that it is an exceedingly rare condition; less than one out of one million people get it. It most commonly affects people over the age of 40, with cranial DAVF more common in women and spinal DAVF more common in men.
Symptoms of dural arteriovenous malformation usually depend on the type of fistula. People with cranial DAVF may experience bruit, where they hear a whooshing sound; pulsatile tinnitus, or ringing in the ears; pulsatile proptosis, or bulging of the eyes; severe headache; or stroke-like signs. People with the spinal DAVF variant are more likely to experience spinal cord swelling, which results in signs such as slow and progressive loss of the use of the limbs and erectile dysfunction in men. More serious complications, particularly in cranial DAVF cases, include brain hemorrhage.
The golden diagnostic standards for dural arteriovenous malformation are cerebral angiography for cranial DAVF and spinal angiography for spinal DAVF. Using these medical imaging techniques, physicians can examine the affected blood vessels, particularly the arteries and veins. The two types of treatments used are open surgery or endovascular surgery. Open surgery involves disconnection of the fistula, while endovascular surgery is used to destroy the fistula by blocking the affected blood vessels.