Venous infarction of the spinal cord resulting from dural arteriovenous fistula: MR imaging findings.

Three patients with spinal dural arteriovenous fistula presented with acute and/or progressive myelopathy. The thoracic cord was focally enlarged and poorly defined on MR images in two of the patients. One individual showed focal cord atrophy, and one demonstrated abnormal intrathecal vessels. In all patients MR studies revealed cord enhancement after IV administration of gadopentetate dimeglumine. The MR findings are believed to represent disruption of the blood-cord barrier associated with cord ischemia and/or infarction, which, in turn, is caused by venous stasis resulting from the fistula. The diagnosis in each case was confirmed by the combined results of myelography, spinal arteriography, and surgery. Surgical excision or embolization of the fistula produced a poor return of lost function but an arrest in the progression of paresis. One of the patients had constant severe back and leg pain postoperatively, and a follow-up MR study 5 months after surgery showed focal atrophy and persistent enhancement of the thoracic cord. The patient with preoperative focal cord atrophy had an MR examination 1 year prior to surgery, which revealed enhancement of the cord similar to that seen on the immediate preoperative MR study. This patient also had severe pain in the back and lower extremities preoperatively, which accompanied her progressive paraparesis. It is believed that long-standing enhancement of the spinal cord in patients with dural arteriovenous fistula probably results from chronic progressive venous ischemia, which may be irreversible and cause pain of a central type.