Type II spinal AVM

Findings

MRI Spine Thoracic: Focal area of low T2 signal with in the spinal cord at the T7 level. There is increased T2 signal within the surrounding cord without mass effect. No clearly abnormal T1 signal or enhancement is seen. No abnormal flow voids are present.
CT Chest: There is a tortuous vessel within the posterior spinal canal which enters at the T9-T10 level from the right and terminates in a blush of contrast at the T7 level in the spinal cord.
Angiogram: T8 arterial injection shows an abnormal vessel extending superiorly to the T7 level with a small nest of abnormal vessels and a very early draining vein which extends inferiorly to the T9-10 level.

Differential diagnosis:
- Cavernous angioma
- Ependymoma
- AVM
- AVF


Diagnosis: Type II spinal AVM


Key points

There are four types of spinal AVMs, this is a type II which means there is abnormal intramedullary vasculature with a nidus. Type III lesions are also true AVMs; they are just larger and more complex. Type I and IV lesions are actually AVFs. Type I is the most common spinal AVM; it is a dural arteriovenous fistula. Type IV is an intradural extramedullary AVF from spinal artery to the coronal venous plexus.
Type II AVMs are generally diagnosed in the early 20s. Patients have a progressive course of myelopathy with severe sudden neurologic deficits when the lesions hemorrhage. Males and females are equally affected.
MRI is very useful in localizing the lesion. A definitive diagnosis is difficult as in this case if the vessels are too small to be visualized. Angiography is the gold standard for making the diagnosis. Both CT and MRI can help with angiogram planning.
Treatment is often embolization with good responses; however, the lesions can return. Surgery is often performed in order to prevent reoccurrence of the lesion.