Selective Bridging Vein Embolization of a Transverse-Sigmoid Sinus Dural Arteriovenous Fistula Draining via the Jugular Foramen: A Case Report

Abstract

Objective

Bridging veins adjacent to the jugular foramen (JF-BVs) are rare drainage pathways in dural arteriovenous fistulas (DAVFs). We report a unique case of a transverse-sigmoid sinus DAVF (TS-DAVF) with retrograde venous drainage via a JF-BV, successfully treated with selective transvenous coil embolization.

Case Presentation

A man in his 60s presented with a 2-month history of right-sided pulsatile tinnitus. Cerebral angiography revealed a high-grade TS-DAVF supplied by branches of the external carotid and vertebral arteries. Venous drainage involved a compartmentalized portion of the sigmoid sinus that drained into a JF-BV, continuing through the retrotonsillar and inferior vermian veins to the confluence of sinuses. Additional reflux occurred via the ipsilateral and contralateral TSs, the superior petrosal sinus, and cortical veins through the vein of Labbé. The right internal jugular vein was occluded at the cervical level. A transvenous approach via the contralateral jugular vein allowed catheter navigation via a compartmentalized portion of the jugular bulb separated by trabecular septations to reach the JF-BV. After superselective angiography confirmed its course, coil embolization was performed from the lateral medullary vein junction back to the sinus. Shunt flow was completely occluded while preserving normal cortical venous drainage. The patient’s tinnitus resolved without neurological deficits.

Conclusion

To the best of our knowledge, this is the first reported case of selective transvenous coil embolization of a JF-BV draining a TS-DAVF. Preprocedural imaging with selective angiography and a multi-catheter system enabled safe and effective treatment. Selective JF-BV embolization may represent a viable therapeutic option for DAVFs with catheter-navigable compartments.

Introduction

Bridging veins (BVs) of the medulla oblongata are important venous pathways that connect the surface of the medulla oblongata to adjacent dural venous sinuses. These veins are increasingly recognized as critical drainers for retrograde pial venous reflux in dural arteriovenous fistulas (DAVFs), particularly those located near the jugular foramen (JF) as well as the foramen magnum.^1–3) The BV adjacent to the JF (JF-BV), one of the major BVs in this region, typically drains into the inferior petrosal or sigmoid sinus via the lateral medullary or inferior peduncular veins.⁴⁾ However, DAVFs with retrograde drainage via a JF-BV are rarely reported in the literature.^5–7) Herein, we present a transverse-sigmoid sinus DAVF (TS-DAVF) exhibiting retrograde venous drainage via a JF-BV and into the ipsilateral dural sinuses.

Case Presentation

Clinical presentation and angioarchitecture

A man in his 60s presented with a 2-month history of right-sided pulsatile tinnitus. A pulsatile bruit was auscultated over the right postauricular region, and no other neurological deficits were observed. A high-grade DAVF located at the center of the jugular bulb, with multiple distinct fistulous points extending into the adjacent sigmoid and transverse sinuses, was confirmed on cerebral angiography. The primary feeders originated from the right external carotid artery branches, including the neuromeningeal trunk of the ascending pharyngeal artery (APA), the posterior convexity branch of the middle meningeal artery, and the transosseous and mastoid branches of the occipital artery. Additional arterial supply arose from the transosseous branches of the right deep cervical artery, derived from the right vertebral artery, and from the branch of the posterior meningeal artery arising from the occipital artery of the left external carotid artery.

A retrograde shunt flow entered a JF-BV and passed through the retrotonsillar and inferior vermian veins before reaching the confluence of sinuses. Another retrograde drainage pathway involved the ipsilateral TS, with venous reflux into the contralateral TS, the superior petrosal sinus, and cortical veins via the vein of Labbé toward the right posterior cerebral hemisphere. Occlusion of the right internal jugular vein was identified at the cervical level. On images obtained from 3D rotational angiography (3DRA), trabecular septations within the jugular bulb delineated a compartment draining into the JF-BV, which is distinct from the compartment draining into the ipsilateral TS. These trabecular septations appeared to act as partial partitions within the jugular bulb, suggesting functional compartmentalization of venous flow. The lesion was classified as Cognard Ⅱa+b. During the venous phase of right cerebral angiography, the vein of Labbé exhibited slow antegrade drainage into the venous sinus, showing a to-and-fro flow pattern with the shunt flow (Figs. 1 and 2).

Fig. 1. Pre-treatment angiographic findings showing a high-grade dural arteriovenous fistula. (A, B) Right external carotid angiography (anteroposterior and lateral views) revealed a high-grade dural arteriovenous fistula with multiple fistulous points extending from the jugular bulb into the adjacent sigmoid and transverse sinuses. The primary arterial feeders included the neuromeningeal trunk of the ascending pharyngeal artery (A, black arrow), posterior convexity branch of the middle meningeal artery, and transosseous and mastoid branches of the occipital artery. The shunt point was located within the jugular bulb (A, white arrowhead). Retrograde venous drainage occurred via the bridging vein adjacent to the jugular foramen (A, white arrow) into the inferior vermian veins (A, B, asterisk), with additional reflux via the ipsilateral transverse-sigmoid sinus, superior petrosal sinus (B, double arrowhead), and vein of Labbé. (C) A coronal maximum intensity projection image from 3D rotational angiography revealed the shunt point (white arrowhead) within the jugular bulb and the bridging vein adjacent to the jugular foramen (white arrow) as the draining vein. (D) Right vertebral angiography depicted arterial feeders from the transosseous branches of the deep cervical artery with the shunt point located on the dura mater near the jugular bulb (arrowhead). (E, F) The delayed phase of right external carotid angiography and the venous phase of right internal carotid angiography showed a to-and-fro flow pattern in the vein of Labbé, demonstrating retrograde shunt drainage (E, blue dotted arrow) and antegrade normal venous flow (F, red dotted arrow).

Fig. 2. Sequential maximum intensity projection images from 3D rotational angiography. (A–D) Axial views and (E–H) coronal views. Trabecular septations within the jugular bulb delineated a compartment draining into the bridging vein adjacent to the jugular foramen (JF-BV), which was distinct from the compartment draining into the ipsilateral sigmoid sinus. These trabecular septations represented partial partitions within the jugular bulb, suggesting functional compartmentalization of venous flow. (black dot: shunt point; black arrowhead: compartment draining toward the ipsilateral sigmoid sinus; red arrowhead: compartment draining toward the JF-BV; red arrow: JF-BV; white arrow: trabecular septation; white arrowhead: lateral medullary vein).

Treatment

We planned transvenous coil embolization that selectively involved the JF-BV and the affected TS, starting at the JF and extending to its junction with the vein of Labbé, thereby preserving the normal cortical venous drainage.

Prior to performing the venous approach, a 3.4-Fr TACTICS (Technocrat Corporation, Aichi, Japan) was placed into the right APA to enhance JF-BV visualization. Using the contralateral jugular vein approach, a 6-Fr guiding sheath was placed in the left internal jugular vein. Via this sheath, a 6-Fr ASAHI FUBUKI guiding catheter (Asahi Intecc, Aichi, Japan) and a 3.4-Fr Guidepost (Tokai Medical Products, Aichi, Japan) were advanced coaxially. After guiding the 3.4-Fr Guidepost to the JF level of the sigmoid sinus as a distal-access catheter, a 1.7-Fr Headway microcatheter (Terumo, Tokyo, Japan) and Chikai 14 black microguidewire (Asahi Intecc) were inserted coaxially via the system.

After determining the optimal working angle, the microguidewire was advanced via a compartmentalized portion of the jugular bulb separated by trabecular septations to enter the isolated compartment that drained into the JF-BV. Subsequently, the microcatheter was guided into it. The junction with the lateral medullary vein was identified on microcatheter angiography, and coils were deployed from just proximal to the junction with the lateral medullary vein back toward the sinus to occlude shunt flow. After complete interruption of shunt flow into the JF-BV was confirmed (Fig. 3), the affected sigmoid sinus, the superior petrosal sinus, and the remaining transverse sinus up to its junction with the vein of Labbé were sequentially embolized.

Fig. 3. Selective embolization of the JF-BV. (A) Prior to transvenous coil embolization, selective angiography of the right ascending pharyngeal artery (asterisk) showed a dural arteriovenous fistula at the jugular foramen draining into the JF-BV (black arrow) and ipsilateral sigmoid sinus with cortical venous reflux. (B) Microcatheter angiography within the JF-BV revealed the connection to the lateral medullary vein and the shunt drainage pathway via the inferior vermian vein (black double arrows). (C) Fluoroscopic image depicted coil placement within the JF-BV (arrowhead) and the isolated small compartment of the sigmoid sinus. (D) DSA confirmed the absence of a residual shunt drainage into the JF-BV. JF-BV, bridging vein adjacent to the jugular foramen.

Complete occlusion of shunt flow into the JF-BV and preservation of normal cortical venous drainage via the vein of Labbé were observed on the final angiograms. Consequently, the Cognard classification improved to type IIa. The patient did not develop new neurological deficits, and the tinnitus resolved (Fig. 4).

Fig. 4. Post-embolization angiographic and radiographic findings. (A, B) Right external carotid angiography (anteroposterior and lateral views) revealed complete elimination of shunt drainage into the bridging vein adjacent to the jugular foramen and superior petrosal sinus. (C) The venous phase of right internal carotid angiography showed preserved antegrade drainage via the vein of Labbé into the affected transverse sinus. (D, E) Plain skull radiography (anteroposterior and lateral views) depicted coil placement within the proximal bridging vein adjacent to the jugular foramen, jugular bulb, sigmoid sinus, superior petrosal sinus, and transverse sinus. (F) Postoperative cone-beam CT demonstrated coil embolization of the compartmentalized portion of the jugular bulb and the bridging vein (red arrow).

Discussion

To the best of our knowledge, this is the first reported case of selective transvenous coil embolization of the JF-BV serving as the draining vein of a TS-DAVF. Based on previous reports, DAVFs involving the JF-BV are commonly classified as non-sinus type, and sinus-type cases with reflux into the JF-BV are extremely rare.^3,5,7,8) A distinct feature of this case was the presence of a small compartment within the sigmoid sinus, separated by trabecular septations, that drained into the JF-BV. Unlike the most commonly reported cases, in which the JF-BV drained into the perimedullary venous systems, this case showed a unique outflow pattern, the retrotonsillar and inferior vermian veins leading to the confluence. This difference likely contributed to the absence of spinal symptoms, underscoring the clinical relevance of venous drainage patterns.

Anatomy of the JF-BV and clinical implications

With the recent advancements in high-resolution CT scan and 3D rotational angiography, BVs at the foramen magnum and craniocervical junction can be depicted in detail, thereby clarifying their anatomical features.^1–3) These findings are fundamental for understanding the complex pathophysiology of DAVFs in the craniocervical junction and foramen magnum regions, particularly their role as routes for retrograde medullary venous drainage. The JF-BV is a major subtype of BVs around the foramen magnum. Hiramatsu et al. classified it as part of the foramen magnum BV system, and Miyauchi et al. categorized it under the superolateral group.^1,2) The drainage territory of the JF-BV includes the lateral and anterolateral aspects of the medulla oblongata, as well as the region around the inferior cerebellar peduncle. These veins typically drain into the sigmoid sinus or inferior petrosal sinus via the lateral medullary vein, inferior peduncular vein, or vein of the cerebellomedullary fissure. Further, they are the most frequently detected subtype, observed in nearly one-third of radiologic studies, with an average diameter of 0.6 (range: 0.3–0.9) mm.¹⁾

Because of their small caliber, selective angiography and 3DRA are valuable for identifying fistulous points and venous drainage routes in the DAVFs of the lateral foramen magnum region.⁶⁾ In the current case, selective injection of the APA enhanced the visibility of the JF-BV and validated the compartmental structure within the jugular bulb, which directly contributed to the development of a safe treatment strategy.

DAVF and the JF-BV

DAVFs involving the JF-BV have been reported as both sinus and non-sinus types. However, the majority of cases involve the non-sinus type. Byun et al. described a non-sinus-type case in which the JF-BV drained into the lateral medullary vein and subsequently into the superior petrosal sinus.⁵⁾ They performed transarterial embolization with n-butyl cyanoacrylate via the neuromeningeal trunk of the APA, which resulted in medullary infarction. Sugiura et al. reported a sinus-type case in which an isolated sigmoid sinus drained into the JF-BV, with subsequent reflux into the lateral medullary and perimedullary veins. They accessed the isolated sinus via the contralateral venous sinus and achieved sinus occlusion with coils. However, the JF-BV was not selectively embolized.⁷⁾ More recently, Ozaki et al. conducted a multicenter study and classified DAVFs involving medullary BVs at the foramen magnum. Their study reported 3 cases in the JF-BV group (referred to as JV-BV). All cases involved the non-sinus type, with drainage into the anterior or posterior spinal veins or the lateral medullary vein. Further, all were completely cured with transarterial embolization with n-butyl cyanoacrylate via the jugular branch of the APA, with no recurrence.³⁾

Compared with these reports, the current case represents a rare sinus-type lesion associated with a TS-DAVF, in which a compartmentalized portion of the jugular bulb drained into the JF-BV. A key distinction of sinus-type lesions is that catheters can be advanced into the JF-BV via the sinus, which is not possible in non-sinus-type DAVFs. In this case, a detailed evaluation with selective APA angiography and 3DRA enabled transvenous access from the ipsilateral sigmoid sinus to the JF-BV, facilitating selective coil embolization. The venous outflow pattern was also uncommon, draining toward the confluence without involvement of the spinal veins, which likely accounted for the limited clinical symptoms. Table 1 shows the details of previous reports.

Table 1. Reported cases of DAVF draining via the JF-BV.

Case	Author (Year)	Age/sex	Type of DAVF*	Arterial feeder	Drainage route via JF-BV	Treatment	Angiographic results	Complication
1	Byun et al.5) (2009)	62/M	V	APA nmt	LMV, TPV, SPS, SS	TAE (APA nmt) with NBCA	Complete	Medullary infarction
2	Sugiura et al.7) (2009)	65/M	IIb	OA tob	LMV, ASV, PSV, SPS	TVE with coil	Complete	—
3	Ozaki et al.3) (2025)	68/M	V	APA hgb, VA pma, OA jb	LMV, ASV	TAE (OA jb) with NBCA	Complete	—
4	Ozaki et al.3) (2025)	62/M	V	APA jb, OA smb	ASV, PSV	TAE (APA jb) with NBCA	Complete	—
5	Ozaki et al.3) (2025)	65/M	V	APA hgb and jb	LMV	TAE (APA jb and hgb) with NBCA	Complete	—
6	Present case	60s/M	IIa+b	APA jb, OA tob and pma, VA db, others	LMV, RTV, IVV, confluence	TVE with coil	Residual (with no cortical and medullary venous reflux)	—

* Cognard classification.

APA, ascending pharyngeal artery; ASV, anterior spinal vein; DAVF, dural arteriovenous fistulas; db, dural branch; hgb, hypoglossal branch; IVV, inferior vermian vein; jb, jugular branch; JF-BV, bridging vein adjacent to the jugular foramen; LMV, lateral medullary vein; M, male; NBCA, n-butyl-2-cyanoacrylate; nmt, neuromeningeal trunk; OA, occipital artery; pma, posterior meningeal artery; PSV, posterior spinal vein; RTV, retrotonsillar vein; smb, stylomastoid branch; SPS, superior petrosal sinus; SS, sigmoid sinus; TAE, transarterial embolization; tob, transosseous branch; TPV, transverse pontine vein; TVE, transvenous embolization; VA, vertebral artery

Compartmentalization within the jugular bulb

The compartmental structure observed within the jugular bulb in this case is of particular interest. Piske et al. introduced the concept of a “dural sinus compartment” in dural arteriovenous shunts, emphasizing that some shunts develop within a restricted portion of a dural sinus that is anatomically separated from the main lumen by a dural septum.⁹⁾ They further speculated that this intraluminal septation was likely formed secondary to partial thrombosis and subsequent organization within the sinus. Arteriovenous shunts are thought to become established within the thrombosed segment after clot reabsorption and recanalization, thereby creating multiple venous channels within the sinus lumen. Consistent with this concept, the compartmentalized portion of the jugular bulb connecting to the JF-BV was considered to have developed secondary to thrombosis. The trabecular structures observed on axial images of 3DRA demonstrated a reticular arrangement, suggesting that partial lysis of an organized thrombus might have resulted in the formation of a porous and complex internal septal architecture. Although the possibility of a calcified or bony septation cannot be completely excluded, no calcified components were identified on axial images, and the measured attenuation values were lower than those of the adjacent osseous structures. Such anatomic variation could lead to localized pressure elevation and preferential drainage into the JF-BV, ultimately predisposing to retrograde cortical venous reflux despite patency of the sigmoid sinus.

Technical considerations for selective JF-BV embolization

Three elements were essential for the achievement of a successful selective JF-BV embolization: 1) selective APA injection, which clearly delineated the course of the JF-BV and the compartmentalized anatomy of the jugular bulb; 2) the use of a multi-catheter system with an intermediate catheter and a contralateral transjugular approach, which ensured catheter alignment with the horizontal course of the JF-BV and enabled safe passage via septations within the jugular bulb; and 3) precise coil placement, with microcatheter angiography confirming the lateral medullary vein junction and coils deployed proximally toward the JF using soft devices with minimal kickback, thereby preserving normal medullary venous drainage while completely occluding the shunt. Compared with liquid embolic agents, coil embolization allows precise control of the occlusion site and decreases the risk of spinal cord infarction.

Conclusion

Selective transvenous coil embolization of the BV adjacent to the JF is a safe and effective method for transverse-sigmoid DAVFs when preprocedural imaging confirms a catheter-navigable compartment.

Informed Consent

We obtained informed consent from the patient to publish this clinical report.

Disclosure Statement

The authors declare that they have no conflicts of interest.