Classification, angioarchitecture and treatment outcomes of medullary bridging vein-draining dural arteriovenous fistulas in the foramen magnum region: a multicenter study

Abstract

Purpose: This study aimed to classify medullary bridging vein-draining dural arteriovenous fistulas (MBV-DAVFs) located around the foramen magnum (FM) according to their location and characterize their angioarchitecture and treatment outcomes.

Methods: Patients with MBV-DAVFs diagnosed between January 2013 and October 2022 were included. MBV-DAVFs were classified into four groups. Jugular vein-bridging vein (JV-BV) DAVF: located in proximity to jugular fossa, Anterior condylar vein (ACV)-BV DAVF: proximity to anterior condylar canal, Marginal sinus (MS)-BV DAVF: lateral surface of FM and Suboccipital cavernous sinus (SCS)-BV DAVF: proximity to dural penetration of vertebral artery.

Results: Twenty patients were included, three JV-BV, four ACV-BV, three MS-BV and ten SCS-BV DAVFs, respectively. All groups showed male predominance. There were significant differences in main feeders between JV (jugular branch of ascending pharyngeal artery) and SCS group (C1 dural branch). Pial feeders from anterior spinal artery (ASA) or lateral spinal artery (LSA) were visualized in four SCS and one MS group. Drainage pattern did not differ between groups. Transarterial embolization (TAE) was performed in three, two, one and two cases and complete obliteration was obtained in 100%, 50%, 100% and 0% in JV, ACS, MS and SCS group, respectively. Successful interventions without major complications were finally obtained in 100%, 75%, 100%, and 40% in JV, ACS, MS and SCS group, respectively.

Conclusion: JV-BV DAVFs were successfully treated using TAE alone. SCS-BV DAVFs were mainly fed by small C1 dural branches of vertebral artery often with pial feeders from ASA or LSA, and difficultly treated by TAE alone.

Keywords: Bridging vein; Dural arteriovenous fistula; Foramen Magnum; Surgical obliteration; Transarterial embolization.

Fig. 1

Schematic illustration of bridging vein (BV) and surrounding vessels around the foramen magnum: 1 shows jugular vein BV; 2, anterior condylar vein BV; 3, marginal sinus BV; 4, suboccipital cavernous sinus BV; 5, cerebellomedullary cistern BV. IPS = inferior petrosal sinus, Bplx = basilar plexus, JV = jugular vein, BV = bridging vein, ACV = anterior condylar vein, AMV = anterior medullary vein, MS = marginal sinus, SCS = suboccipital cavernous sinus, RMV = radiculomedullary vein, SS = sigmoid sinus, OS = occipital sinus

Fig. 2

Representative case of DAVF with fistulous point located lateral to the jugular tubercle: JV-BV DAVF. (A) Sagittal T2 weighted image on admission showing high intensity area in the spinal cord at upper cervical levels. (B) Lateral view of the left ascending pharyngeal angiography showing jugular branch feeding a DAVF. The DAVF draining caudally into the anterior and posterior spinal veins. (C) Lateral view of the left external carotid angiography showing stylomastoid branch of the occipital artery feeding the DAVF. (D) Axial partial MIP image of 3D angiography showing fistulous point (arrow) located laterally to the jugular tubercle. (E) Coronal partial MIP image of 3D angiography showing fistulous point (arrow) close to jugular foramen. The dural feeders from the jugular branch of the APA converge on the fistulous point. The DAVF was classified as JV-BV DAVF. (F) Lateral view of DSA during NBCA injection from a microcatheter whose tip located in a dural feeder from the jugular branch of the APA. Arrow shows tip of the micro catheter. Arrowhead shows that NBCA cast reaches draining vein. The JV-BV DAVF was completely occluded with NBCA. JV = jugular vein, BV = bridging vein, DAVF = dural arteriovenous fistula, NBCA = n-butyl-2-cyanoacrylate

Fig. 3

Representative case of the DAVF with fistulous point located on the lateral surface of the foramen magnum: MS-BV DAVF. (A) CT at admission showing subarachnoid hemorrhage. (B) Lateral view of the right external carotid angiography showing a DAVF at the level of foramen magnum. Arrow indicates jugular branch of the APA. (C) Sagittal MPR image of the right vertebral 3D angiography showing the C1 dural branch from VA (arrow) feeding the DAVF. (D) Axial MPR image of the right external carotid 3D angiography showing the feeder from the jugular branch continued to the fistulous points (arrow) on the lateral surface of the foramen magnum and then the medullary bridging vein. The DAVF was classified as MS-BV DAVF. (E) Late phase of the right external carotid angiography showing both cranial and caudal drainage routes from the MS-BV DAVF. Arrow, the anterior spinal vein; double arrows, the posterior spinal vein; arrowhead, the left lateral pontine vein; and double arrowheads, the right lateral pontine vein. (F) Lateral view of selective angiography with contrast injection from a microcatheter shows the tip located deeply in the feeder of the jugular branch of the right APA. Double arrows indicate a 1.3-Fr micro catheter which was coaxially introduced through a 2.7-Fr high-flow microcatheter (arrow). (G) Lateral view of selective angiography with contrast injection from another microcatheter located in the C1 dural branch of the right VA just before NBCA injection. Double arrows indicate a 1.3-Fr microcatheter which was advanced through a 3.4-Fr distal access catheter (arrow). (H) Coronal MPR image after NBCA injection from both feeders showing cast of the NBCA filling in the feeders and the drainage vein. Arrow shows the feeder from the jugular branch of the right APA and double arrow shows the C1 dural branch of the right VA. (I) Postoperative right common carotid angiography showing complete obliteration of the MS-BV DAVF. MS-BV DAVF = marginal sinus bridging vein dural arteriovenous fistula, MS = marginal sinus, BV = bridging vein, VA = vertebral artery, NBCA = n-butyl-2-cyanoacrylate

Fig. 4

Representative case of DAVF with fistulous point located at proximity to the dural penetration of the vertebral artery: SCS-BV DAVF. (A) Sagittal T2 weighted image on admission showing high intensity area (arrow) in the spinal cord. (B) AP view of the left VAG showing C1 dural branch from the left VA (arrow) supplied to fistulous point. (C) AP view of the right vertebral angiography showing ASA (arrow) feed the SCS-BV DAVF. (D-F) Coronal MIP images of rotational angiography of the left VA (D), the left ECA (E, F) showing small C1 dural branches (arrow in D) of the VA, a feeder from the jugular branch (arrow in E) and a small feeder from the hypoglossal branch of the left APA converge on the fistulous point (arrowhead in D) at the level of O-C1. The DAVF was classified as the SCS-BV DAVF. (G)Volume rendering image of the left rotational vertebral angiography showing arteriovenous fistula supplied from dural branches of the left VA. (H) Fusion volume rendering image of the rotational angiographies of the left VA and the left ECA showing APA also supplied the DAVF at the same fistulous point with dural branch of the left VA. (I) Postoperative left vertebral angiography showing disappearance of the fistula. SCS = suboccipital cavernous sinus, BV = bridging vein, VA = vertebral artery, ECA = external carotid artery, APA = ascending pharyngeal artery, MIP = maximum intensity projection, ASA (anterior spinal artery)

Fig. 5

Schematic drawing of each group of MBV-DAVF and relevant feeders on coronal view. JB-BV DAVFs (JV) are usually fed by the jugular branch (jb)of the ascending pharyngeal artery (APA), ACV-BV DAVFs (ACV) are fed by the hypoglossal branch (hgb) of the APA and the C1 dural branch (db). MS-BV DAVFs (MS) are fed by both APA branches and the C1 dural branch. SCS-BV DAVFs (SCS) are fed by the C1 dural branch. The anterior meningeal artery (ama) and pial feeders from the anterior spinal artery (ASA) and lateral spinal artery (LSA) may also supply the SCS-BV DAVFs. PICA, posterior inferior cerebellar artery; pma, posterior meningeal artery; HGC, hypoglossal canal; JF, jugular fossa; OA, occipital artery