Cranial and sacral dural arteriovenous fistulas as a cause of myelopathy

Abstract

The authors report a series of seven patients with myelopathy who were found to have spinal dural arteriovenous (AV) fistulas in which the nidus was located at some distance from the spinal cord. The nidus was intracranial in three cases and involved a sacral nerve root sheath in the other four; in each case, the arterialized draining vein led into the coronal plexus of medullary veins. A lack of normal draining radicular veins was noted in all cases. Magnetic resonance images were obtained in four patients and demonstrated spinal cord tissue changes only in the lower thoracic cord in three cases and in the cervical cord in one, all consistent with an ischemic process secondary to venous hypertension. Five patients were managed surgically by division of the draining vein, with improvement of the neurological deficit in all. One patient was treated by embolization alone and had stabilization of her deficit. The remaining patient in the series died of unrelated systemic disease before the spinal dural AV fistula could be treated. These cases support the theory that venous hypertension is the dominant pathophysiological mechanism involved in spinal dural AV fistulas independent of their location. In patients with a suspected spinal dural AV fistula, lumbar and thoracic spinal angiography will reveal the site of the fistula in the majority of cases (88% in this series). In the remaining patients, the possibility of a remote fistula must be considered. The lack of normal venous drainage of the cord following injection in the artery of Adamkiewicz is the most reliable indicator of venous hypertension in the cord and can be helpful in making the decision to proceed with a search for a cranial or sacral arterial supply.

Treatment and outcome of spinal dural arteriovenous fistulas

“…A total of eight patients (23%) underwent a second embolization for recurrent dAVF after adequate initial embolization. Earlier reports about the use of particulate embolization revealed high long-term failure rates in more than 60% of patients [2,10,11]. Recurrence can occur by either recanalization of the embolized vessels, collateralization, or development of the new fistula [10].…”

“…In principle, we distinguish between three types of spinal vascular malformation: extradural, dural, and intradural [2,6,7,11,12]. The intradural malformations can be separated into perimedullary fistulas and the real intramedullary arteriovenous malformations (AVMs).…”

“…Eighty percent of all spinal AVMs are dural fistulas. In contrast to the probably inborn perimedullary fistulas, dAVFs are most likely acquired [11,12]. The fistula itself is located in the dural layer near the penetration point of the nerve root.…”

“…Venous drainage runs along the spinal cord veins on the surface of the cord, because the local radicular venous drainage is missing. The high venous pressure is presumed to be the cause of clinical symptoms [2,6,9,11].…”

“…Venous drainage runs along the spinal cord veins on the surface of the cord, because the local radicular venous drainage is missing. The high venous pressure is presumed to be the cause of clinical symptoms [2,6,9,11].Abstract Spinal dural arteriovenous fistula (dAVFs) are rare and often misdiagnosed entities. The choice between surgical treatment and embolization remains a matter of debate.…”