Cerebrovascular Malformation

A cerebrovascular malformation is an abnormal blood vessel formation in the brain. At the Cerebrovascular Center, common surgical treatment options include microsurgical resection to remove the lesion, endovascular embolization to block it off or targeted radiosurgery to shrink it over time—usually 18 months to two years.

Cerebrovascular malformations may involve the following vessels:

• Arteries—Blood vessels, generally under high pressure, most of which bring oxygen-rich blood from the heart and lungs to the rest of the body. Medium-sized arteries are called “arterioles.”
• Veins—Blood vessels that return blood to the heart and lungs, generally under lower pressure than arteries. Medium-sized veins are called “venules.”
• Capillaries—The smallest-diameter blood vessels, which connect arterioles and venules. Capillaries spread throughout the body’s tissues, allowing arterial blood to deliver nutrients (such as oxygen and glucose) and pick up waste products (such as carbon dioxide), then sending the blood through the venous system back to the heart and lungs.

There are five common types of cerebrovascular malformation: pial arteriovenous malformation, dural arteriovenous fistula, cavernous malformation, venous malformation and capillary telangiectasia. They differ by location, type of vessels affected and whether or not blood flow through the malformation is rapid.

Arteriovenous malformations (AVM) are characterized by a direct connection between an artery and a vein in the brain. Normally blood travels through large arteries, then smaller arteries and eventually through tiny capillaries before entering a vein. High-pressure arterial blood slows down and loses force during its journey through the small capillaries. But in an AVM, the high-pressure arterial blood rushes directly into a vein without slowing down or losing force first—a situation known as arteriovenous shunting. Blood travels quickly through an AVM, exerting pressure on the vessels, so an AVM is classified as a high-flow vascular malformation.

Veins, which are not built to accommodate high-pressure blood, have weaker walls than arteries. Therefore the venous component of the AVM may bulge, weaken and even rupture and bleed. A bleed in the brain causes a stroke. The risk for a stroke depends on many factors, such as the AVM’s location, size, and blood flow. AVMs are complex malformations that should be treated by experts, like those at Columbia Neurosurgery, who specialize in their care.

A dural arteriovenous fistula (DAVF) is another high-flow vascular lesion. Like an AVM, it is characterized by a direct connection between artery and vein. However, an AVM occurs in the brain itself, while a DAVF occurs in the dural membranes that cover the brain. DAVFs are most often acquired after development of the brain’s vascular system, and most commonly become symptomatic during adult life. There are a number of grading scales that help to characterize the risks and reasons for treatment. Most DAVFs can be treated and cured through open microsurgery or endovascular embolization.

A cavernous malformation (also known as a cavernoma or a cavernous hemangioma) is a group of thin-walled capillaries. These are low-pressure, slow-flow malformations, so they are less likely than AVMs to rupture. Often, cavernous malformations do not require treatment. However, they may grow in size through recurrent episodes of leaking. A cavernous malformation that is leaking or growing in size may compress or irritate the surrounding brain tissue, causing focal neurological deficits or seizures. In such cases, the most common treatment is surgical removal of the cavernous malformation.

A venous malformation (also known as a venous angioma or a developmental venous anomaly) consists of enlarged veins. Venous malformations rarely rupture, leak or cause any symptoms, and usually go undetected. They are sometimes found incidentally on brain scans such as MRI, CT or angiography, where they have a characteristic appearance referred to as caput medusae. Rarely, venous malformations that cause symptoms on the basis of their size may require treatment.

Telangiectasis are enlarged capillaries, often in the brainstem. These are usually small lesions that only rarely cause any problems. Like venous malformations, they are often found incidentally and very rarely require any form of treatment.

At Columbia University Irving Medical Center/NewYork-Presbyterian Hospital, our neurosurgeons specialize in diagnosing, evaluating and treating cerebrovascular malformations. Furthermore, our comprehensive Cerebrovascular Center provides patients with unparalleled access to specialized care thanks to collaboration between our world-class neurosurgeons and radiologists.