AVMs are abnormal clusters of arteries and veins located within the brain or spinal cord. The blood flow in AVMs is abnormal since the blood rapidly flows from a complex of feeding arteries directly into a network of draining veins, bypassing the smaller capillary network of vessels that normally connects the arterial and venous circulations. This abnormal blood flow places significant hemodynamic stresses on the blood vessels and can alter oxygen delivery to surrounding tissues.
Most spinal AVMs are believed to arise during embryonic and fetal development. Therefore, patients with AVMs likely have had them since birth. A small subset of spinal AVMs, such as spinal dural fistulas, may actually develop later in life for reasons that are not well understood.
Typically a spinal AVM presents with back pain, sensory loss and weakness in the arms and/or legs that progresses over a period of months to years. The first test to evaluate the patient is usually spinal MRI or CT myelography. Often these initial screening tests will demonstrate dilated blood vessels around the spinal cord and even within the spinal cord. The next step is to obtain a spinal angiogram to study the anatomy of the AVM, which is a critical step in determining treatment options.
The treatment options for a spinal AVM include endovascular occlusion, surgical excision or a combination of both. The therapeutic approach depends greatly on the anatomic features of the malformation.