Clinical features, angio-architectural phenotypes, and treatment strategy of foramen magnum dural arteriovenous fistulas: a retrospective case series study

Abstract

Background: The rarity and complex angioarchitecture of foramen magnum dural arteriovenous fistulas (DAVFs) make its treatment difficult and controversial. We aimed to describe their clinical features, angio-architectural phenotypes, and treatments, through a case series study.

Methods: We first retrospectively studied cases of foramen magnum DAVFs treated in our Cerebrovascular Center, and then reviewed the published cases on Pubmed. The clinical characteristics, angioarchitecture, and treatments were analyzed.

Results: A total of 55 patients were confirmed with foramen magnum DAVFs, which included 50 men and 5 women, with a mean age of 52.8 years. Most patients presented with subarachnoid hemorrhage (SAH) (21/55) or myelopathy (30/55), depending on the venous drainage pattern. In this group, 21 DAVFs were supplied by only the vertebral artery (VA), three by only the occipital artery (OA), three by only the ascending pharyngeal artery (APA), and the remaining 28 DAVFs were supplied by two or three of these feeding arteries. Most cases (30/55) were treated with only endovascular embolization, 18 cases (18/55) with only surgical disconnection, five cases (5/55) with combined therapy, and two cases rejected treatment. The angiographic outcome of complete obliteration was achieved in most patients (50/55). In addition, two cases of foramen magnum DAVFs were treated by us in a Hybrid Angio-Surgical Suite (HASS) with good outcomes.

Conclusions: Foramen magnum DAVFs are rare and their angio-architectural features are complicated. The treatment option (microsurgical disconnection or endovascular embolization) should be weighed carefully, and combined therapy in HASS could be a more feasible and less invasive treatment option.

Keywords: Hybrid Angio-Surgical Suite; dural arteriovenous fistula; foramen magnum DAVF foramen magnum; myelopathy; subarachnoid hemorrhage.

Figure 1

Perioperative neuroimages of Case 12. A cervical spine MRI showed an expanded spinal brain stem and a longitudinal extensive cervical cord enlargement with obvious edema, and vascular flow voids was also demonstrated in front of the cervical cord (A). The cerebral DSA demonstrated a DAVF located at the foramen magnum supplied by the meningeal branch of left VA, and the fistula was draining through the bridge-medullary veins into the dilated tortuous anterior spinal vein (B), lateral view; (C), anteroposterior view; (D), oblique view with magnification. (E) showed the incision line and the operation position (park bench position). F demonstrated a large tortuous vein was visible at the level of the foramen magnum, and it originated near the dural penetration of the left vertebral artery and formed a “C” pattern crawling between the vertebral artery and the medulla. (F) showed an aneurysm min-clip was temporarily applied to the origin of the fistula to occlude the shunt. Intraoperative DSA revealed the complete disappearance of the DAVF (G). After electrical coagulation and disconnection of the fistula at its origin from the dura, repeat cerebral DSA confirmed the complete obliteration of the fistula (H).

Figure 2

Perioperative neuroimages of Case 13. Emergent cranial CT revealed diffuse SAH and 4th ventricular hematoma (A). Emergent cerebral DSA revealed a DAVF located at the foramen magnum supplied by the meningeal branch of the right VA, draining into the enlarged tortuous medullary vein (B). During the procedure, the microcatheter tip was advanced to reach the optimal position (C); the injection of Onyx was continued until the DAVF was completely obliterated (D). Follow-up angiography at 6 months did not reveal any fistula residual or recurrence (E), lateral view; (F), anteroposterior view.