2026 年 13 巻 p. 281-287
Posterior condylar canal dural arteriovenous fistula is rare, and cases of posterior condylar canal dural arteriovenous fistula directly related to trauma have been reported even less frequently. We describe a case of posterior condylar canal dural arteriovenous fistula that presented with tinnitus soon after head trauma and was successfully treated with transarterial embolization. A 60-year-old man presented with right-sided tinnitus that had persisted for 2 weeks after sustaining a right temporal injury. Digital subtraction angiography revealed a posterior condylar canal dural arteriovenous fistula with venous drainage from the posterior condylar vein to the suboccipital cavernous sinus, without cortical venous reflux. The shunt was supplied by a single feeder, the jugular branch of the occipital artery. Transarterial embolization using N-butyl cyanoacrylate and coils achieved complete occlusion of the shunt. The patient's tinnitus resolved immediately after the procedure, and follow-up angiography demonstrated persistent complete occlusion of the fistula, with no evidence of recurrence. Posterior condylar canal dural arteriovenous fistula is a rare lesion that may occur following head trauma. Bone-window three-dimensional angiographic reconstruction is useful for diagnosis, as it clearly delineates the relationship between the skull base canal and the shunt. Transarterial embolization can be a curative treatment option when performed with a thorough understanding of the relevant vascular anatomy and potentially hazardous anastomoses.
Dural arteriovenous fistula (dAVF) is a relatively rare vascular disorder that can cause intracranial hemorrhage or epilepsy, making early diagnosis and appropriate treatment essential. Posterior condylar canal (PCC) dAVF is an extremely rare subtype, with only approximately a dozen cases reported in the literature.1) Cases of PCC dAVF occurring following head trauma are even rarer. We report a case of PCC dAVF identified after head trauma that presented with pulsatile tinnitus, and was successfully treated with transarterial embolization (TAE).
A 60-year-old man fell from the bed of a truck, sustaining a laceration to the right temporal region, neck contusion, right clavicular fracture, right second to sixth rib fractures, and right upper lobe lung contusion. After undergoing open reduction and internal fixation for the clavicular fracture at another hospital, he was discharged. However, persistent right-sided tinnitus that had been present since the injury prompted referral to our neurosurgical department 2 weeks post-trauma. Neurological examination revealed no focal deficits except for tinnitus, which disappeared when manual pressure was applied posterior to the right auricle. Brain magnetic resonance imaging (MRI) demonstrated abnormal vascular structures around the right foramen magnum, suggestive of an arteriovenous shunt (Figure 1A and B). Computed tomography (CT) revealed no skull fracture or intracranial hemorrhage. Digital subtraction angiography (DSA) and three-dimensional (3D) reconstruction demonstrated that the jugular branch of the right occipital artery (OA), a meningeal branch, passed superiorly and posteriorly through the jugular foramen and formed a shunt near the PCC (Figure 1C-G). Venous drainage was directed from the posterior condylar vein (PCV) to the suboccipital cavernous sinus (SCS), indirectly connecting the posterior fossa dural sinuses with the vertebral venous plexus, without cortical venous reflux. The venous phase confirmed antegrade flow from the sigmoid sinus (SS) to the internal jugular vein (IJV) (Figure 1H). The dAVF was supplied solely by the jugular branch of the OA, and this feeder did not supply the lower cranial nerves (cranial nerves IX, X, and XI). In addition, DSA did not demonstrate a clear connection between the shunt pouch and either the IJV or the SS, suggesting that transvenous embolization (TVE) via the IJV might not be feasible. Therefore, we planned TAE.
A and B: Time-of-flight MR angiography showing an arteriovenous shunt around the right foramen magnum. C and D: Frontal (C) and lateral (D) views of right external carotid angiography demonstrating an arteriovenous fistula (AVF) fed by the right occipital artery (black arrow) and draining through the posterior condylar vein (arrowhead) into suboccipital cavernous sinus (SCS). E-G: Axial reconstructed images from rotational angiography (green color) showing the occipital artery (white arrow) passing through the jugular foramen and coursing posteroinferiorly (E, F), draining into the posterior condylar vein (arrowhead) around posterior condylar canal to form a shunt (G). H: In the venous phase of the lateral angiogram, antegrade venous drainage from the sigmoid sinus to the internal jugular vein was preserved.
MR: magnetic resonance
Under local anesthesia, TAE was performed using a combination of N-butyl cyanoacrylate (NBCA) and coils. A 6-Fr sheath was introduced into the right femoral artery, and a 6-Fr Launcher (Medtronic; Minneapolis, MN, USA) was advanced to the origin of the right external carotid artery. Under roadmap guidance, a Headway Duo microcatheter (Terumo; Tokyo, Japan) was advanced into the jugular branch of the right OA and was positioned just proximal to the shunt point. To prevent NBCA reflux, an Excelsior SL-10 microcatheter (Stryker; Kalamazoo, MI, USA) was placed proximally, and a coil plug was created using an Axium Prime 2 mm× 8 cm coil (Medtronic; Minneapolis, MN, USA) (Figure 2A). Subsequently, 20% NBCA was injected through the distal microcatheter into the shunt pouch (Figures 2B and 3). Residual shunt flow was observed on post-embolization angiography; therefore, additional coils were deployed to achieve complete occlusion. A hyperattenuating area due to NBCA was observed in the PCC on postoperative head CT (Figure 2C).
A: Unsubtracted lateral view after coil embolization showing two microcatheter tips: distal (arrowhead) for NBCA injection and proximal (arrow) for coil embolization. B: Subtracted lateral view showing NBCA injected from the tip of the microcatheter into the PCV (black arrow), with subsequent extension into the vertebral venous plexus (white arrow). The microcatheter tip, distal to the coil mass, was positioned sufficiently away from the jugular foramen (arrowhead). C: Hyperattenuating area (arrow) due to NBCA is observed in the PCC on postoperative head CT. D: Lateral view of right external carotid angiography at 6 months post-treatment demonstrated complete shunt obliteration.
CT: computed tomography; NBCA: N-butyl cyanoacrylate; PCC: posterior condylar canal; PCV: posterior condylar vein
Schematic lateral view of the transarterial embolization (TAE) procedure. The arteriovenous shunt is located around the posterior condylar canal (PCC) and is supplied solely by the jugular branch of the occipital artery (OA), draining into the suboccipital cavernous sinus (SCS). After coil embolization of the proximal portion of the shunt pouch, N-butyl cyanoacrylate (NBCA) was injected to fill the segment from the posterior condylar vein (PCV) to the SCS.
IJV: inferior jugular vein; SS: sigmoid sinus; TS: transverse sinus
No new neurological deficits occurred postoperatively, and the tinnitus resolved immediately. Follow-up DSA at 6 months showed no recurrence of the dAVF (Figure 2D). Written informed consent was obtained from the patient for the publication of this case report and any accompanying images.
The development of dAVF is thought to involve venous hypertension from sinus thrombosis and induction of angiogenic factors secondary to local inflammation, leading to neovascularization and fistula formation.2,3) Wang et al.4) demonstrated in a rabbit model that artificially induced intracranial venous hypertension upregulated vascular endothelial growth factor and hypoxia-inducible factor-1α within 1-2 weeks, and DSA at 90 days confirmed abnormal arteriovenous shunts. In contrast, intracranial traumatic arteriovenous fistula (AVF) arises from a direct connection between an artery and an adjacent dural sinus or cortical vein, typically developing immediately after injury.5,6) Furthermore, traumatic AVF tends to consist of a single arterial feeder and a single shunt point compared to nontraumatic lesions.7) The patient in this case developed tinnitus immediately after head trauma, and the lesion consisted of a single arterial feeder, which could suggest a traumatic AVF. However, no skull fracture or direct evidence of vascular wall injury was observed. The shunt was located in the PCC, supplied by a meningeal branch of the OA, and drained via an emissary vein, features that are consistent with an acquired dAVF. It is possible that a previously asymptomatic PCC dAVF became hemodynamically aggravated after trauma, or that pre-existing but unrecognized tinnitus became noticeable due to psychological stress or environmental changes associated with hospitalization. These observations indicate that, while a traumatic etiology cannot be excluded, the lesion is compatible with a pre-existing dAVF that either worsened or became clinically apparent following head injury. To our knowledge, only one case of PCC dAVF following head trauma has been previously reported.8)
The PCC is located posterior to the occipital condyle and inferoposterior to the jugular foramen, and serves as the bony canal through which the PCV passes.9,10) The PCV usually arises near the junction of the SS and IJV, draining via the SCS into the vertebral venous plexus or deep cervical vein.10-12)
In PCC dAVF, feeders often arise from the OA, middle meningeal artery, ascending pharyngeal artery (APA), vertebral artery, or posterior auricular artery.1) The shunt typically forms in the dural portion of the PCV, with venous drainage into the SCS or IJV.1) In rare cases, retrograde venous reflux through the bridging vein into the pontomedullary venous system may lead to intracranial hemorrhage.13)
We add our case to the 14 previously reported cases of PCC dAVF1,8,11,13-20) (Table 1). Among these 15 cases (including ours), 12 patients (80%) presented with pulsatile tinnitus, and all achieved complete cure following treatment. The most frequent arterial feeders were the OA and APA, observed in 12 cases (80%) and 10 cases (67%), respectively. The main venous drainage pathways were the SCS in 11 cases (73%) and the internal condylar vein in 7 cases (50%). Three cases (20%) with retrograde drainage into the medullary bridging vein presented with symptomatic intracranial hemorrhage. Endovascular therapy was the mainstay of treatment, including TAE alone in 6 cases (40%), TVE alone in 7 cases (47%), combined TAE and TVE in one case (7%), and conservative management in one case (7%). No cases treated with direct surgery were reported. In the series by Brinjikji et al.,8) one patient had a history of head trauma, suggesting the possibility of a trauma-related dAVF; however, the presence of multiple feeders in that case makes a simple direct-shunt mechanism uncertain.
Literature Review of Previously Reported PCC dAVFs
| Age/sex | Presentation | Feeder | Drainer | Treatment | Result/compliment | History of trauma | |
|---|---|---|---|---|---|---|---|
| A: artery; AMA, accessory meningeal artery; APA: ascending pharyngeal artery; CO: complete obliteration; dAVF: dural arteriovenous fistula; ECA, external carotid artery; F: female; ICH: intracerebral hemorrhage; IJV: internal jugular vein; IPS, inferior petrosal sinus, IVH: intraventricular hemorrhage; LCV: lateral condylar vein; M: male; MMA, middle meningeal artery; NBCA: N-butyl-2-cyanoacrylate; NR: not reported; OA: occipital artery; PAA, posterior auricular artery; PCC: posterior condylar canal; PMA: posterior meningeal artery; SAH: subarachnoid hemorrhage; SCS: suboccipital cavernous sinus; TAE: transarterial embolization; TVE: transvenous embolization; VA: vertebral artery | |||||||
| Kiyosue et al. (11), 2007 | 54/M | Tinnitus | APA, OA, lateral clival A, AMA | IJV, SCS | TVE | CO/None | No |
| Mondel et al. (14), 2014 | 43/M | SAH, IVH | APA, VA, PMA | Medullary bridging vein | TAE (Onyx) | CO/None | No |
| Maus et al. (15), 2014 | NR | Tinnitus | VA, Ascending cervical artery, ECA | IJV, SCS | TVE | CO/None | No |
| Shambanduram et al. (13), 2017 | 72/M | SAH, IVH | PMA | Medullary bridging vein | TAE (NBCA) | CO/Brainstem infarction | No |
| Brinjikji et al. (8), 2020 | NR | Tinnitus | VA, OA, APA | IJV, SCS | TVE | CO/None | Yes |
| Matsuda et al. (16), 2021 | 71/F | Tinnitus | APA, OA, AMA, VA, Dorsal meningeal artery | SCS, IJV, IPS | TVE | CO/None | No |
| Yokogawa et al. (17), 2022 | 30/F | Tinnitus, Radiculopathy | OA, MMA, VA, APA, PAA | SCS | TAE (Onyx) and TVE | CO/None | No |
| Suyama et al. (18), 2022 | 39/M | Tinnitus | APA, OA, AMA, PMA | SCS, LCV | TVE | CO/None | No |
| Prasad et al. (19), 2023 | 30s/M | ICH | OA | Medullary bridging vein | TAE (Onyx) | CO/None | No |
| Maekawa et al. (20), 2024 | NR | Tinnitus | OA | IJV, SCS | TAE (coil) | CO/None | NR |
| NR | Tinnitus | PMA, APA | SCS | TAE (coil) | CO/None | NR | |
| NR | Tinnitus | OA, PMA, APA, Lateral clival A | IJV | TVE | CO/None | NR | |
| NR | Tinnitus | PAA, OA, APA | SCS | Conservative treatment | - | NR | |
| Su et al. (1), 2025 | 43/F | Tinnitus | MMA, PAA, OA, VA, APA | IJV, SCS | TVE | CO/None | No |
| Present case | 60/M | Tinnitus | OA | SCS | TAE (NBCA) | CO/None | Yes |
In this case, the jugular branch of the OA served as the sole feeder. The OA arises from the posterior aspect of the external carotid artery and gives rise to several meningeal branches that enter the cranial cavity through the mastoid foramen, foramen magnum, and parietal foramen, and occasionally through the jugular foramen.21) Embryologically, the OA represents a remnant of the proatlantal artery and therefore possesses potential anastomoses with the vertebral artery at the C1-C2 level.21) In addition, the OA mastoid branch is known to anastomose with the neuromeningeal branch of the APA near the sigmoid sinus, which supplies the lower cranial nerves.22) When performing TAE via the OA, it is essential to prevent the migration of liquid embolic material into these dangerous anastomoses. Although there is no documented evidence demonstrating an anastomosis between the OA jugular branch and the APA, the close anatomical relationship within the jugular foramen suggests the possibility of such a connection.
NBCA is a liquid embolic agent that undergoes ionic polymerization and has strong thrombogenic properties, allowing reliable occlusion of the shunt when it reaches the venous side.23) However, premature polymerization before reaching the shunt may result in proximal occlusion, and in cases with multiple feeders, fragmentation of NBCA may carry the risk of distal venous embolization.23) In our patient, no bridging veins were located near the shunt, and neither the PCV nor the SCS was involved in normal venous drainage on the venous phase of DSA. Therefore, the risk of venous infarction due to NBCA migration was considered extremely low. Furthermore, the presence of a single feeder allowed for curative embolization with little risk of reflux from other arteries or fragmentation of the NBCA. To achieve safe TAE, we advanced the microcatheter sufficiently distal to the jugular foramen and created a proximal coil plug before NBCA injection. This strategy minimized the possibility of lower cranial nerve palsy due to potential anastomosis to the neuromeningeal branch of the APA, and allowed for safe and complete occlusion of the shunt pouch and its arterial supply. In this case, the proximal coil reduced the flow in the feeder to a moderate level. Therefore, using a higher NBCA concentration could have prevented it from reaching the shunt pouch adequately, potentially resulting in feeder occlusion. For this reason, the NBCA concentration was set at 20%. However, since the tip of the microcatheter had reached just proximal to the shunt pouch, using a higher NBCA concentration might have allowed more compact, curative embolization over a shorter segment. Onyx was not available at our institution at the time of this treatment and therefore, it was not used.
Although TVE is generally regarded as the most established curative treatment for dAVF, venous access may be challenging in some cases. In dAVF with simple shunt architecture and a single, clearly identifiable feeder, as demonstrated in this case, TAE can serve as a viable therapeutic option when meticulous attention is paid to dangerous anastomoses, and an appropriate distal catheter position and embolization strategy are secured. Furthermore, if the microcatheter can be advanced beyond the fistulous point into the venous pouch, via the arterial route, loose coil packing within the pouch may improve the likelihood of complete occlusion and allow embolization over a shorter segment.
Taken together, this case is characterized by the immediate onset of symptoms following head trauma with a clear temporal association, a relatively simple angioarchitecture consisting of a single feeder from the jugular branch of the OA, and successful treatment with TAE alone, using a carefully planned embolization strategy. Although performing TAE after proximal coil occlusion has been reported previously, its application specifically for PCC dAVF is extremely rare and may represent a potential treatment option in selected cases. These features may provide additional clinical and technical perspectives in the context of previously reported PCC dAVF cases.
The recurrence rates of dAVF vary among reports. A large multicenter study published in 2021 reported recurrence in approximately 7% of patients with angiographically cured dAVF, with a mean time to recurrence of approximately 1 year.24) Possible mechanisms include residual unembolized branches and revascularization secondary to post-treatment venous occlusion.25) In dAVF treated with TAE, proximal occlusion alone may lead to recanalization; therefore, complete occlusion of the shunt point is essential.26) In this case, the patient had a single arterial feeder, and injection of NBCA through this feeder achieved complete occlusion of the shunt pouch.
The main limitation of this report is the relatively short follow-up period of 6 months. Although dAVFs following trauma tend to have lower recurrence rates, longer follow-up would be valuable to confirm the durability of the treatment.
ConclusionsWe report a rare case of PCC dAVF that developed following head trauma and was successfully treated with TAE. PCC dAVF is extremely rare and most commonly presents with pulsatile tinnitus. Bone-window 3D angiographic reconstruction is useful for diagnosis, as it clearly delineates the relationship between the skull base canal and the shunt. For simple shunts, including traumatic direct shunts, TAE can be a curative treatment option when performed with a thorough understanding of the relevant vascular anatomy and potentially hazardous anastomoses.
We thank all staff of Toki Municipal General Hospital. We would like to thank Editage for English language editing.
All authors have no conflict of interest.
Ethics approval was waived by the intstitusional review board due to the nature of this case report.
