High cervical arteriovenous fistulas fed by dural and spinal arteries and draining into a single medullary vein: report of 3 cases.

OBJECT: The authors previously reported a case of complex arteriovenous fistula (AVF) at C-1 with multiple dural and spinal feeders that were linked with a common medullary venous channel. The purpose of the present study was to collect similar cases and analyze their angioarchitecture to gain a better understanding of this malformation.

METHODS: Three such cases, affecting 2 males and 1 female in their 60s who had presented with hematomyelia (2) or progressive myelopathy (1), were treated surgically, and the operative findings from all 3 cases were compared using digital subtraction angiography (DSA) to determine the angioarchitecture.

RESULTS: The C-1 and C-2 radicular arteries and anterior and posterior spinal arteries supplied feeders to a single medullary draining vein in various combinations and via various routes. The drainage veins ran along the affected ventral nerve roots and lay ventral to the spinal cord. The sites of shunting to the vein were multiple: dural, along the ventral nerve root in the subarachnoid space, and on the spinal cord, showing a vascular structure typical of dural AVF, that is, a direct arteriovenous shunt near the spinal root sleeve fed by one or more dural arteries and ending in a single draining vein, except for intradural shunts fed by feeders from the spinal arteries. In 2 cases with hemorrhagic onset the drainer flowed rostrally, and in 1 case associated with congestive myelopathy the drainer flowed both rostrally and caudally. Preoperative determination of the shunt sites and feeding arteries was difficult because of complex recruitment of the feeders and multiple shunt sites. The angioarchitecture in these cases was clarified postoperatively by meticulous comparison of the DSA images and operative video. Direct surgical intervention led to a favorable outcome in all 3 cases.

CONCLUSIONS: A high cervical complex AVF has unique angioarchitectural characteristics different from those seen in the other spinal regions.