Abstract
BACKGROUND
The standard approach for transvenous embolization (TVE) of a cavernous sinus (CS) dural arteriovenous fistula (DAVF) involves the inferior petrosal sinus (IPS). However, the IPS is often obstructed in many cases. In some cases, the IPS is not connected to the internal jugular vein, making access to the CS via the IPS difficult. The inferior petroclival vein (IPCV) runs through the extracranial petroclival fissures. Although only one case series has reported on the treatment of a CS DAVF via the IPCV, no detailed technical tips have been provided.
OBSERVATIONS
A 76-year-old female presented with right abducens nerve palsy and left ptosis. Angiography revealed a right CS DAVF with bilateral IPS obstructions. Preoperative contrast-enhanced MRI confirmed the IPCV, connecting caudally to the anterior condylar confluence (ACC) and cranially to the internal carotid artery venous plexus of Rektorzik. Intraoperative venography of the ACC revealed the IPCV, allowing easy access to the CS. The patient’s symptoms resolved after TVE.
LESSONS
The IPCV is rarely used due to its low anatomical recognition and narrow, tortuous structure compared to the IPS. However, understanding the course of the IPCV through preoperative contrast-enhanced MRI and visualizing the IPCV using intraoperative ACC venography can facilitate the IPCV approach.
Keywords: anterior condylar confluence, arteriovenous fistula, cavernous sinus, embolization, endovascular, inferior petroclival vein
ABBREVIATIONS: ACC = anterior condylar confluence, ACV = anterior condylar vein, APA = ascending pharyngeal artery, BVR = basal vein of Rosenthal, CS = cavernous sinus, DAVF = dural arteriovenous fistula, ICA = internal carotid artery, IJV = internal jugular vein, IPCV = inferior petroclival vein, IPS = inferior petrosal sinus, LCV = lateral condylar vein, MRA = MR angiography, SOV = superior ophthalmic vein, SPS = superior petrosal sinus, TVE = transvenous embolization.
The standard access route for transvenous embolization (TVE) of a cavernous sinus (CS) dural arteriovenous fistula (DAVF) is through the inferior petrosal sinus (IPS).1,2 However, the IPS is often obstructed in many cases of CS DAVF. Furthermore, in some cases, the IPS does not connect to the internal jugular vein (IJV),3–5 making it difficult to access the CS through the IPS. Alternative approaches, such as TVE through the superior ophthalmic vein (SOV) or superior petrosal sinus (SPS), have been extensively reported;6,7 however, TVE through the inferior petroclival vein (IPCV) is extremely rare.8 The IPCV is not commonly used as an approach route to the CS owing to its complex venous anatomy and the difficulty in navigating the narrow, tortuous vein. However, using several technical tips, we found that accessing the CS through the IPCV can be quite straightforward. In this report, we present the case of a CS DAVF with bilateral IPS occlusion treated with TVE via the IPCV.
Illustrative Case
A 76-year-old female with a history of hypertension and diabetes presented to our hospital with diplopia that had persisted for approximately 1 month. The patient had right abducens nerve palsy and left-sided ptosis. MR angiography (MRA) revealed abnormally high intensity around the CS, implying a CS DAVF (Fig. 1A and B). Right external carotid artery angiography revealed feeders clustered in the right CS (Fig. 1C and D). Similar findings were observed on angiography of the left ascending pharyngeal artery (APA), with feeders converging in the anterosuperior wall of the right CS (Fig. 1E and F). The shunt flow drained retrogradely into the left SOV, the left superficial middle cerebral vein, and the basal vein of Rosenthal (BVR) through the inter-CS. The bilateral IPS was occluded; however, on closer observation, the right IPCV was identified (Fig. 1G and H). Angiography confirmed the diagnosis of a CS DAVF, classified as Borden type II and Cognard type IIa+b. Preoperative contrast-enhanced T1-weighted MRI showed that neither IPS was visible. In contrast, both IPCVs were observed, with their caudal ends connected to the anterior condylar confluence (ACC) and their cranial ends connected to the internal carotid artery (ICA) venous plexus of Rektorzik (Fig. 2A–H). We considered performing TVE via the facial or superior temporal vein to access the SOV; however, the approach route was long and tortuous. Additionally, an approach using the SPS was not feasible because both SPSs were occluded. Therefore, we decided to approach the CS via the IPCV and perform a TVE. The treatment plan was to guide a microcatheter from the right CS to the inter-CS and occlude the inter-CS with coils to stop the retrograde flow into the left SOV and right BVR. We planned to place additional coils around the shunt point on the right CS anterosuperior wall to promote thrombosis.
FIG. 1.
Preoperative MR angiograms (A and B) showing high intensity at the right CS. Digital subtraction angiograms of the right external carotid artery, anteroposterior (C) and lateral (D) projections, showing the right CS DAVF with shunt flow that refluxes into the left SOV, the superficial middle cerebral vein, and the basal vein of Rosenthal. Digital subtraction angiogram (E) and 3D rotational image (F) of the ascending left pharyngeal artery revealing the shunt point located in the anterosuperior wall of the right CS. Digital subtraction anigograms of the right ICA in the venous phase, anteroposterior (G) and lateral (H) projections, revealing the IPCV (arrowheads).
FIG. 2.
Preoperative contrast-enhanced MR images (A–H) and intraoperative angiograms (I–L). The ACC (yellow arrows, A–C) is located medial to the IJV and connects to the IJV. The IPCV (yellow arrowheads, D–G) connects to the ACC caudally and runs along the extracranial petroclival fissure. The IPCV connects cranially to the ICA venous plexus of Rektorzik (double yellow arrow, H). Venograms of the IJV showing the ACC (arrows, I and J) but not the IPCV. Venograms from the ACC (arrows, K and L) revealing the IPCV (arrowheads).
Under general anesthesia, a 7-Fr Shuttle sheath (Cook Medical) was inserted into the left femoral vein and advanced to the right IJV. A 5-Fr catheter was inserted into the left APA for angiographic control. Contrast injection from the guiding catheter into the right IJV revealed the ACC (Fig. 2I and J); however, the IPS was not visualized. The inner catheter (6-Fr JB2 catheter, Medikit Co. Ltd.) was advanced into the ACC, and the IPCV was visualized after injection of contrast media (Fig. 2K and L). Therefore, we attempted to approach the right CS via the right IPCV.
Using the roadmap technique, a CHIKAI 14 microwire (Asahi Intecc Medical) was navigated from the IPCV to the CS. A Headway DUO microcatheter (MicroVention) was successfully advanced into the CS using a microguidewire. Axial rotational imaging revealed that the microcatheter entered the foramen lacerum along the extracranial petroclival fissure (Fig. 3A–F). First, the microcatheter was advanced to the inter-CS, and the coils were deployed. Subsequently, the Headway DUO microcatheter was directed to the anterosuperior shunt point, and additional coils were placed. Postcoiling angiography showed the disappearance of retrograde flow from the left CS to the left SOV and BVR. Although a small residual shunt remained in the right CS (Fig. 3G and H), spontaneous closure was anticipated, and the treatment was concluded.
FIG. 3.
Intraoperative axial noncontrast 3D rotational angiograms (A–F). After the microcatheter is guided to the CS via the IPCV, the axial image shows the microcatheter (white arrowheads) entering the foramen lacerum along the extracranial petroclival fissure, with the tip of the microcatheter guided to the CS. Postoperative angiograms of the left APA, anteroposterior (G) and lateral (H) projections, showing a small residual shunt; however, reflux into the left SOV and intracranial veins has disappeared. Postoperative MR angiograms (I and J) showing that the arteriovenous shunt has disappeared.
Postoperative MRA revealed the disappearance of the shunt and improvement in ptosis (Fig. 3I and J). One month postoperatively, the right abducens nerve palsy had resolved, and 5 months postoperatively, the diplopia had completely resolved.
Informed Consent
The necessary informed consent was obtained in this study.
Discussion
Observations
Previous reports have indicated that the IPS does not connect to the IJV in 1%–7% of cases, making it difficult to access the CS via the IPS in such cases.3–5 In such instances, an approach using the IPCV is considered a viable strategy. TVE for CS DAVF through the IPCV has been reported in only one case series.8 However, no such reports have been published since then. The IPCV is not well known anatomically and is a narrower and more tortuous vein than the IPS, making it difficult to guide a microcatheter to the CS via the IPCV. Therefore, it has not become a popular or widely used approach.
To our knowledge, this is the first instance of TVE via the IPCV using preoperative contrast-enhanced MRI and an intraoperative venographic roadmap from the ACC.
Anatomy of the IPCV
The IPS is a venous sinus that runs along the intracranial petroclival fissure. By contrast, the IPCV runs along the extracranial petroclival fissure that connects cranially to the ICA venous plexus of Rektorzik around the foramen lacerum. This venous plexus communicates with the CS (Fig. 4).9,10 Furthermore, the IPCV can also be used as an outflow route for the shunt flow in some cases of CS DAVF. Therefore, anatomical knowledge of the IPCV is crucial for the treatment of CS DAVF.
FIG. 4.
Illustration of the venous anatomy around the IPCV viewed from the posterior aspect. The IPCV runs along the extracranial petroclival fissure, connecting caudally with the ACC and cranially with the ICA venous plexus of Rektorzik. The yellow line indicates the approach route used in our case. DCV = deep cervical vein; HGC = hypoglossal canal; IPS = inferior petrosal sinus; IVVP = internal vertebral venous plexus; JB = jugular bulb; PCV = posterior condylar vein; SCS = suboccipital CS; SigS = sigmoid sinus.
In a cadaveric study, the IPCV was present in 83.3% of cases, with the average length and width of the IPCV being 18 mm (range 15–21 mm) and 1.5 mm (range 1–1.8 mm), respectively.11 Additionally, in cases in which the IPCV was present, the diameter of the IPS was reported to be significantly smaller.11
In a previous radiographic report, contrast-enhanced fat-suppressed T1-weighted MRI in 26 patients (51 sides) showed that the IPCV was present bilaterally in all cases.9 Additionally, the caudal end of the IPCV passed through the ACC.12 Our evaluation of random contrast-enhanced T1-weighted MRI of 40 sides from 20 cases confirmed the bilateral presence of the IPCV in all cases (Table 1). The width of the IPCV was 1.94 mm (range 1.40–2.66 mm). Connections to the ICA venous plexus were observed on all sides of the cranial end of the IPCV. Additionally, communication with the clival diploic vein was identified on 6 sides (15%) at the cranial end. The caudal end of the IPCV was connected to the ACC on all sides. The ACC was connected to the IJV, anterior condylar vein (ACV), and prevertebral veins on all sides. The lateral condylar vein (LCV) was present on 34 sides (85%) and communicated with the ACC. Interestingly, while the IPCV was present bilaterally on all sides, the IPS was absent on two sides (5%). Mitsuhashi et al. similarly reported that the IPS was absent in 16.9% of cases on 3D rotational venography.5 These findings suggest that the IPCV is a nearly ubiquitous vein with significant anatomical importance as a potential route for transvenous access to the CS. Furthermore, catheter guidance through the ACC is essential for accessing the IPCV.
Table 1.
IPCV and surrounding veins: findings from contrast-enhanced T1-weighted MRI of 40 sides
| Mean Age ± SD (yrs) | No. of IPCVs (%) | No. of IPSs (%) | Mean IPCV Width, mm (range) | No. of Cranial IPCV Cx (%) | No. of Caudal IPCV Cx w/ ACC (%) | No. of Cx w/ ACC (%) | ||||
|---|---|---|---|---|---|---|---|---|---|---|
| w/ ICA Venous Plexus | w/ Clival Diploic Vein | IJV | ACV | LCV | Prevertebral Vein | |||||
| 49.7 ± 18.8 | 40 (100) | 38 (95) | 1.94 (1.40–2.66) | 40 (100) | 6 (15) | 40 (100) | 40 (100) | 40 (100) | 34 (85) | 40 (100) |
Cx = connections.
Approach for CS via the IPCV
Kurata et al. reported a new transvenous approach via the IPCV for CS DAVF in a case series but did not provide detailed technical tips.8 For TVE of the CS DAVF via the IPCV, preoperative anatomical evaluation of the IPCV by contrast-enhanced MRI and intraoperative roadmap support from venography of the ACC are extremely useful.
Contrast-enhanced MRI is useful preoperatively to confirm the entire course of the IPCV. In the present case, preoperative contrast-enhanced MRI confirmed the access route from the IJV to the CS via the ACC and IPCV. After reviewing the contrast-enhanced CT or MR images of the 8 previously treated CS DAVF cases, the IPCV was confirmed in all cases. This suggests that the IPCV remains patent in many cases of CS DAVF with an obstructed IPS.
Furthermore, in our case, venography of the ACC was useful for confirming the course of the IPCV intraoperatively. As the caudal end of the IPCV connects to the ACC, contrast injection from the catheter to the ACC allowed for visualization of the IPCV and facilitated microcatheter guidance along the roadmap. Using this roadmap, the CS was easily reached using a microcatheter.
Lessons
The IPCV approach for TVE in CS DAVF is not commonly used; however, anatomical confirmation of the IPCV by preoperative contrast-enhanced MRI and visualization of the IPCV by venography from the ACC facilitates easier access to the CS via the IPCV. However, these cases are limited, and it is necessary to obtain more cases using these techniques in the future.
Disclosures
The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.
Author Contributions
Conception and design: Suenaga, Iida, Shimizu, Nakai, Yamamoto. Acquisition of data: Iida, Shimizu, Morinobu, Yoshida. Analysis and interpretation of data: Iida. Drafting the article: Suenaga, Iida, Yamamoto. Critically revising the article: Suenaga, Iida. Reviewed submitted version of manuscript: Suenaga, Iida, Akimoto, Nakai. Approved the final version of the manuscript on behalf of all authors: Suenaga. Administrative/technical/material support: Iida, Nakai. Study supervision: Akimoto, Nakai, Yamamoto.
Correspondence
Jun Suenaga: Yokohama City University School of Medicine, Yokohama, Kanagawa, Japan. suenaga@yokohama-cu.ac.jp.
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