Endovascular management of dural arteriovenous fistulae of the anterior condylar confluence

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Korean J Cerebrovasc Surg. 2025;.jcen.2025.E2024.08.004

Publication date (electronic) : 2025 March 24

doi : https://doi.org/10.7461/jcen.2025.E2024.08.004

David C. Lauzier, Arindam R. Chatterjee, Joshua W. Osbun

Department of Neurosurgery, Washington University School of Medicine, Missouri, USA

Correspondence to David C. Lauzier Department of Neurosurgery, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110-1010, USA Tel +1-828-578-9926 E-mail dlauzier@wustl.edu

Received 2024 July 9; Revised 2025 February 27; Accepted 2025 March 4.

Abstract

INTRODUCTION

Dural arteriovenous fistulae (dAVF) are anomalous connections between arterial feeders and dural venous sinuses that often present with symptoms including hemorrhage, focal neurologic deficits, seizures, and flow-related symptoms [12,13,18]. Surgical approaches can be employed for dAVFs that carry certain anatomical characteristics, however, dAVFs are most commonly treated endovascularly using either the transarterial or transvenous approach [3,8,14].

While large, multi-center efforts are underway to assess the natural history, treatment strategies, and clinical outcomes of dAVFs, large studies of this magnitude can preclude detailed description of treatment strategies and outcomes for rare subtypes of dAVFs [3]. One interesting subtype of dAVF is those affecting the anterior condylar confluence adjacent to the canal of the hypoglossal nerve [9]. Though little is known about these rare dAVFs, a small number of studies have been published describing the treatment of these lesions [9]. Building on these efforts, we share our experience with endovascular management of 3 unique cases of dAVFs affecting the anterior condylar confluence, providing details surrounding presentation, treatment strategy, imaging, and patient outcomes.

CASE DESCRIPTION

For procedural details of the cases reported in this study, see Table 1.

Table 1.

Procedural and technical details for each case

Case 1

A 68-year-old male patient presented following 3 months of right ocular hyperemia and proptosis as well as a whooshing noise in his right ear. Magnetic resonance imaging (MRI) performed at an outside hospital demonstrated an enlarged right superior ophthalmic vein concerning for a cavernous carotid fistula. Initial catheter angiography demonstrated a complex right-sided skull base/foramen magnum region dAVF with arterial supply from multiple right external carotid artery branches including the right ascending pharyngeal artery, right middle meningeal artery, right occipital artery, and right vertebral artery branches (Fig. 1A). Drainage was anterograde into the jugular bulb and paraspinal venous plexuses, and retrograde into the inferior petrosal sinus, cavernous sinus, and superior ophthalmic vein. Additional cortical venous drainage with venous ectasia was noted into the leptomeningeal veins connecting to the straight sinus and draining to the superior sagittal sinus. This dAVF was successfully treated using transvenous coil embolization, with post-treatment angiography demonstrating complete obliteration of the dAVF without any early venous drainage (Fig. 1B). Follow-up angiography performed 5 months post-treatment demonstrated complete obliteration of the dAVF (Fig. 1C). The patient remained asymptomatic at final clinical follow-up.

Fig. 1.

Preoperative angiogram of a right-sided foramen magnum region dAVF (A). Intraoperative angiogram demonstrating complete occlusion (B). Five-month follow-up angiogram demonstrated complete occlusion of the dAVF (C). dAVF, dural arteriovenous fistulae

Case 2

A 73-year-old man presented following 2 weeks of right ocular chemosis and 6th nerve palsy, in addition to 3 months of pulsatile tinnitus. Computed tomography (CT) performed at an outside hospital demonstrated a suspected right-sided carotid-cavernous fistula. Initial catheter angiography demonstrated a right-sided type 2 hypoglossal canal dAVF with an abnormal connection between the right ascending pharyngeal artery and the right inferior petrosal sinus as well as the right internal jugular vein (Fig. 2A). Retrograde flow was present via the right inferior petrosal sinus and antegrade flow was present via the right internal jugular vein. This dAVF was successfully treated using transvenous coil embolization, with post-treatment angiography demonstrating complete obliteration of the dAVF without residual early venous drainage (Fig. 2B). Follow-up angiography performed 6 months post-treatment demonstrated complete obliteration of the dAVF (Fig. 2C). The patient remained asymptomatic at final clinical follow-up.

Fig. 2.

Preoperative angiogram of a right-sided hypoglossal canal dAVF involving an abnormal connection between the right ascending pharyngeal artery and the right inferior petrosal sinus (A). Successful transvenous coil embolization was demonstrated on intraoperative angiogram (B). Six-month follow-up angiogram demonstrated stable occlusion (C). dAVF, dural arteriovenous fistulae

Case 3

A 60-year-old woman presented following 2 months of left-sided pulsatile tinnitus. CT angiography performed at an outside hospital demonstrated a left-sided dAVF. Initial catheter angiography demonstrated a left-sided dAVF of the anterior occipital confluence with arteriovenous shunting from the occipital and ascending pharyngeal arteries to the anterior occipital confluence, occipital veins, left jugular vein, and perimedullary spinal venous plexus (Fig. 3A). This dAVF was treated using partial transarterial embolization with Onyx HD-500 and coils, as well as transvenous coil embolization (Fig. 3B). Follow-up angiography performed 6 months post-treatment demonstrated reduced shunting through the dAVF with persistent arterial supply from the ascending pharyngeal artery (Fig. 3C). The patient reported recurrence of her left-sided pulsatile tinnitus 2 days after the procedure, but this was completely resolved at 8-month clinical follow-up.

Fig. 3.

Preoperative angiogram of a left-sided anterior occipital confluence dAVF (A). Partial occlusion demonstrated on intraoperative angiogram following embolization with Onyx and coils (B). Six-month follow-up angiogram demonstrated reduced shunting (C). dAVF, dural arteriovenous fistulae

DISCUSSION

In this work, we report outcomes of endovascularly-treated dAVFs located at the anterior condylar confluence. Among 3 treated dAVFs, there were no technical complications or treatment-related clinical complications. At final follow-up, presenting symptoms had resolved in all patients and there was no angiographic recurrence of any dAVF.

While none have proposed pathophysiology specific to dAVFs in the anterior condylar confluence, it is likely that the etiology of these lesions is shared with dAVFs in other regions. Known risk factors for dAVFs include local infection, cranial trauma, prior intracranial surgery, and venous sinus thrombosis [13,17]. The majority of dAVFs are thought to be acquired lesions, though the presence of dAVFs in infants suggests that there may be a small number that are either congenital or secondary to antecedent insults occurring very early in life [17]. Inceptive studies in dAVF pathophysiology suggested that inflammation secondary to organization of sinus thrombosis was a trigger for the formation of aberrant arterial-venous communications, however subsequent evidence implicated angiogenesis induced by ischemia from venous hypertension as the main driver of dAVF development [4,7]. The etiology of dAVFs continues to be an area of active scientific interest, with recent studies implicating neutrophilic, monocytic, and cell-mediated inflammation as important players in the organization of venous thrombosis that may precede dAVF formation [2,5]. Despite these risk factors and potential etiologies of dAVFs, no patients in our group had a history of any previously described risk factor.

The anterior condylar confluence is an extracranial venous system at the skull base that comprises communications between regional veins and dural sinuses [15]. It is located medial to the jugular vein, anterior to the aperture of the hypoglossal canal, and inferior to the jugular bulb and inferior petrosal sinus [15]. This confluence provides connections between the dural venous sinuses of the posterior fossa, branches of the internal jugular vein, and branches of the vertebral venous system [11]. Prior work has suggested that the ascending pharyngeal artery is the main feeder for dAVFs in this location, and that contralateral arterial contribution is not uncommon [11]. Most cases have feeders from posterior meningeal branch of the VA. In our study, arterial supply was from the ascending pharyngeal artery in 3 dAVFs, from the occipital artery in 2 dAVFs, from the middle meningeal artery in 1 dAVF, and from branches of the vertebral artery in 1 dAVF. All arterial supply for dAVFs included in our study was ipsilateral to the fistula. Venous drainage was to the internal jugular vein in 3 cases, to the paraspinal venous plexus in 2 cases, to the inferior petrosal sinus in 2 cases, to the cavernous sinus in 1 case, and to the ophthalmic veins in 2 cases. Venous ectasia was present in 1 dAVF, while cortical venous reflux was not observed in any dAVFs.

The proximity of the anterior condylar confluence to important structures is easily correlated with presenting symptoms of patients in our study and prior studies. Two patients in our study had auditory symptoms at presentation (1 case each of pulsatile tinnitus and audible bruit), and two had ocular symptoms (1 patient with 6th nerve palsy and ocular chemosis, and 1 patient with proptosis and ocular hyperemia). Prior studies have reported similar ocular symptoms and auditory symptoms, in addition to hoarseness from 12th nerve compression and facial droop from 7th nerve compression [1,9,11]. The shunting that occurs near the petrous bone can be the cause of the tinnitus and pulsatile bruit, while ocular symptoms are likely due to the anterior draining pattern of these dAVFs [6]. It has been noted that the drainage and anatomy of these dAVFs make them similar to carotid-cavernous fistulae (CCF) [11]. In our series, 2 of 3 were initially diagnosed as CCFs before being re-classified due to catheter angiography studies. The proximity of the anterior condylar confluence to crucial structures also influences treatment approaches. Besides favoring endovascular approaches to avoid approach-related complications, exquisite caution must be taken when performing these interventions. When embolizing these lesions, dense packing of the anterior condylar vein with embolics should be avoided in order to minimize the risk of postoperative cranial nerve XII palsy, which has been observed in previous studies [11]. Additionally, transvenous approaches are commonly favored over transarterial approaches given the risk of embolic stroke in the latter [10,16]. Because of the inherent risk of treating dAVFs in this region, even when using minimally invasive endovascular approaches, further work is necessary to identify additional therapeutic avenues.

There are several limitations to this study that are common to studies of this type. Our study is an observational case series including a small number of cases due to the overall rarity of these lesions. Therefore, it is unclear if our findings are generalizable to all dAVFs of the condylar canal. In addition, our single-center perspective leads to treatment approaches described to reflect preferences of a small group of operators, further limiting the generalizability of our findings. Finally, this small series reflects careful patient selection and therefore our experience may not reflect all the technical nuances of treatment of dAVFs found in this location.

CONCLUSIONS

Treatment of dAVFs located in the anterior condylar confluence can be achieved endovascularly using both transarterial and transvenous approaches. No dAVF recanalization or treatment-related complications were observed.

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