Spinal arteriovenous malformations

Spinal arteriovenous malformations (AVM) can be divided into dural and intramedullary types. The most common type is the dural arteriovenous fistula which is found on the outside of the dura or along a rootsleeve, most common in the thoracic or lumbar region. The fistula is drained intrathecally by perimedullary veins. This disease most frequently affects elderly men and causes a slowly progressive myelopathy which is thought to be caused by increased pressure in the medullary veins. Intramedullary arteriovenous malformations are predominantly seen in younger individuals and most often in the cervical or thoracic region. They are usually discovered by acute neurological symptoms caused by an intramedullary bleeding. Spinal AVMs can usually be diagnosed by myelography, because enlarged tortuous vessels are found in the subarachnoid space. On MRI intramedullary components can be visualized and when there are large AVMs, vessels are seen in the subarachnoid space (Fig. 55). In dural AVMs, MRI is, however, unreliable and sometimes falsely negative. It should also be mentioned that flow artefacts often create a pattern which might mimic vessels, especially on fast spin-echo T2-weighted sequences. For definite diagnosis angiography is, however, necessary. This examination is also a prerequisite for therapy. The blood supply to the spinal cord is complicated and catheterization of a large number of vessels is required. Following angiography these diseases can successfully be treated by embolization.

Stig Holtås, Maximilian F. Reiser and Axel Stäbler