Surgical management of dural arteriovenous fistulas with transosseous arterial feeders involving the jugular bulb

Multidisciplinary approach to the craniovertebral junction. Historical insights, current and future perspectives in the neurosurgical and otorhinolaryngological alliance

Historically considered as a nobody’s land, craniovertebral junction (CVJ) surgery or specialty recently gained high consideration as symbol of challenging surgery as well as selective top level qualifying surgery. The alliance between Neurosurgeons and Otorhinolaringologists has become stronger in the time. CVJ has unique anatomical bone and neurovascular structures architecture. It not only separates from the subaxial cervical spine but it also provides a special cranial flexion, extension, and axial rotation pattern. Stability is provided by a complex combination of osseous and ligamentous supports which allows a large degree of motion. The perfect knowledge of CVJ anatomy and physiology allows to better understand surgical procedures of the occiput, atlas and axis and the specific diseases that affect the region. Although many years passed since the beginning of this pioneering surgery, managing lesions situated in the anterior aspect of the CVJ still remains a challenging neurosurgical problem. Many studies are available in the literature so far aiming to examine the microsurgical anatomy of both the anterior and posterior extradural and intradural aspects of the CVJ as well as the differences in all the possible surgical exposures obtained by 360° approach philosophy. Herein we provide a short but quite complete at glance tour across the personal experience and publications and the more recent literature available in order to highlight where this alliance between Neurosurgeon and Otorhinolaringologist is mandatory, strongly advisable or unnecessary.

Dural arteriovenous fistula formation following bilateral middle meningeal artery embolization for the treatment of a chronic subdural hematoma: a case report

Here is reported a case of dural arteriovenous fistula (DAVF) formation following middle meningeal artery (MMA) embolization. A 64-year-old male patient was operated for a bilateral CSDH by burr-hole craniostomy. Prophylactic post-operative MMA embolization was performed with 300-500-μm calibrated microparticles. The patient was admitted 3 months later for a left CSDH recurrence. Digital subtraction angiography demonstrated formation of a superior sagittal sinus DAVF fed by both superficial temporal arteries. This case highlights the possible role of local tissue hypoxia as a significant component of DAVF pathogenesis. Moreover, it has potential implications for MMA embolization as a management strategy for CSDH.

Arteriovenous fistula of the clival diploic vein associated with arteriovenous fistula of the posterior condylar canal

We herein report a rare case of a patient with a clival diploic vein arteriovenous fistula (AVF) associated with a posterior condylar canal AVF and discuss the radiological features of clival diploic vein AVF during decision-making on treatment strategies. A 69-year-old male patient with one-year history of pulsatile tinnitus was evaluated with magnetic resonance angiography, which revealed a dilated venous structure. Digital subtraction angiography revealed AVFs located in the clivus and posterior condylar canal. The clival diploic vein AVF was fed by the right internal maxillary artery and the petrous branch of middle meningeal artery and shed to the posterior condylar canal only through an intraosseous vein in the jugular tubercle. Although a catheter could not be navigated into the venous pouch in the clivus, the AVFs were successfully obliterated by transvenous embolization of the venous pouch in the posterior condylar canal.

A 360° Approach to the Craniovertebral Junction in a Cadaveric Laboratory Setting: Historical Insights, Current, and Future Perspectives in a Comparative Study

BACKGROUND

We herein outline the experience matured in our equipped Cranio-Vertebral Junction Laboratory for anatomic dissection.

METHODS

An extreme lateral approach (ELA) was performed on 4 fresh cadavers and submandibular approach was performed on 5. An endoscope and navigation-assisted far lateral approach (FLA) was performed in 5 injected specimens. In these specimens, a transoral approach was also performed, as well as a neuronavigation-assisted comparison between transoral and transnasal explorable distances.

RESULTS

As calculated with neuronavigation, statistically significant differences both in the explored craniocaudal (P = 0.003) and lateral (P = 0.008) distances were observed between the transoral approach and endoscopic endonasal approach. In FLA, neuronavigation facilitated identification and partial removal of the occipital condyle; in one case, during endoscopic intradural exploration, tearing of the emerging roots of the 11th cranial nerve occurred. In ELA, the site where the accessory nerve pierces into the sternocleidomastoid muscle was found at a distance from the tip of the mastoid between 3 and 4 cm.

CONCLUSIONS

During dissections, as in the clinical setting, endoscope and image guidance give the surgeon a constant orientation, increasing the accuracy and the safety of the approach. Nonetheless, the encumbrance of the endoscope could represent a limit in deep and narrow corridors as those running across the craniovertebral junction, especially in "oblique" FLA and ELA, in which the surgical target is often hidden by a delicate tangle of nerves and vessels. Its use appears more suitable and safer in "straight" approaches as transoral and transnasal in which there are no neurovascular structures interposed.

The Far Lateral Approach to the Craniovertebral Junction: An Update

INTRODUCTION

Since 1972, when Hammon first described the far lateral approach (FLA) for treatment of vertebral artery aneurysms, it has undergone numerous modifications, including drilling of the occipital condyle, removal of the laminas of upper cervical vertebrae and so on. Also, the range of indications has increased exponentially.

OBJECTIVE

In this paper we discuss state-of-the-art advances in the FLA, such as promising minimally invasive variants where an endoscope is used, and many others.

METHODS

We reviewed all articles touching upon the FLA in the modern era (from the year 2000 onward) and selected those that presented a significant contribution to the development of the relevant approach. The database used was PubMed.

RESULTS AND CONCLUSION

We found several new caveats not mentioned in other reviews or book chapters. The FLA is an ever-changing field of battle where the common and ultimate goals are to minimize the risk of injuring the major vessel in the region-the vertebral artery-and to provide such an angle of attack upon the tumours in the anterior and anterolateral foramen magnum that it is feasible to ensure gross total resection. This paper is an update on the knowledge about this approach, which we feel is necessary.

Dural arteriovenous fistula of the lateral foramen magnum region: A review

The lateral foramen magnum region is defined as the bilateral occipital area that runs laterally up to the jugular foramen. The critical vasculatures of this region are not completely understood. Dural arteriovenous fistulas that occur in this region are rare and difficult to treat. Therefore, we searched PubMed to identify all relevant previously published English language articles about lateral foramen magnum dural arteriovenous fistulas, and we performed a review of this literature to increase understanding about these fistulas. Four types of dural arteriovenous fistulas occur in the lateral foramen magnum region. These include anterior condylar confluence and anterior condylar vein dural arteriovenous fistulas, posterior condylar canal dural arteriovenous fistulas, marginal sinus dural arteriovenous fistulas, and jugular foramen dural arteriovenous fistulas. These dural arteriovenous fistulas share similar angioarchitectures and clinical characteristics. The clinical presentations of lateral foramen magnum dural arteriovenous fistulas include pulsatile tinnitus, intracranial hemorrhage, myelopathy, orbital symptoms, and cranial nerve palsy. Currently, head computed tomography, computed tomography angiography, magnetic resonance imaging, magnetic resonance angiography and digital subtraction angiography (DSA) are useful for diagnosing dural arteriovenous fistulas, and of these, DSA remains the "gold standard." Most lateral foramen magnum dural arteriovenous fistulas need to be treated due to their aggressive symptoms, and transvenous embolization presents the best options. During treatment, it is critical to accurately place the microcatheter into the fistula point, and intraoperative integrated computed tomography and DSA data are very helpful. Other treatments, such as transarterial embolization, microsurgery or conservative treatment, can also be chosen. After appropriate treatment, most patients with lateral foramen magnum dural arteriovenous fistulas achieve satisfactory outcomes.

Intraosseous venous structures adjacent to the jugular tubercle associated with an anterior condylar dural arteriovenous fistula

PURPOSE

Although involvement of the osseous component with an anterior condylar dural arteriovenous fistula (AC-DAVF) has been frequently described, osseous venous structures in which AC-DAVFs develop have not been fully elucidated. We investigated osseous venous structures adjacent to the hypoglossal canal in normal controls and patients with AC-DAVFs.

METHODS

The study included 50 individuals with unruptured aneurysms as normal controls and seven patients with AC-DAVFs. Osseous venous structures adjacent to the hypoglossal canal in normal controls were analyzed using computed tomography (CT) digital subtraction venography. In patients with AC-DAVFs, the fistulous pouches, draining veins, and surrounding venous structures were examined using cone beam CT.

RESULTS

In 46.0% of laterals in normal controls, osseous venous structures were visualized within the jugular tubercle superomedially to the hypoglossal canal. We named these structures the jugular tubercle venous complex (JTVC). The JTVC was always continuous with the anterior condylar vein and was sometimes connected to surrounding venous channels. We detected nine fistulous pouches in the seven patients with AC-DAVFs. The fistulous pouches were in the JTVC (33.3%), anterior condylar vein (33.3%), and other venous channels within the exoccipital region (33.3%).

CONCLUSION

Although the JTVC is a venous structure frequently found in normal people, it had not been investigated until now. The venous channel between the anterior condylar vein and JTVC is a common origin site for AC-DAVFs, and it was associated with 66.6% of the AC-DAVF cases in the current study.

Dural arteriovenous fistulas of the hypoglossal canal: systematic review on imaging anatomy, clinical findings, and endovascular management

Dural arteriovenous fistulas (DAVFs) of the hypoglossal canal (HCDAVFs) are rare and display a complex angiographic anatomy. Hitherto, they have been referred to as various entities (for example, “marginal sinus DAVFs”) solely described in case reports or small series. In this in-depth review of HCDAVF, the authors describe clinical and imaging findings, as well as treatment strategies and subsequent outcomes, based on a systematic literature review supplemented by their own cases (120 cases total). Further, the involved craniocervical venous anatomy with variable venous anastomoses is summarized. Hypoglossal canal DAVFs consist of a fistulous pouch involving the anterior condylar confluence and/or anterior condylar vein with a variable intraosseous component. Three major types of venous drainage are associated with distinct clinical patterns: Type 1, with anterograde drainage (62.5%), mostly presents with pulsatile tinnitus; Type 2, with retrograde drainage to the cavernous sinus and/or orbital veins (23.3%), is associated with ocular symptoms and may mimic cavernous sinus DAVF; and Type 3, with cortical and/or perimedullary drainage (14.2%), presents with either hemorrhage or cervical myelopathy. For Types 1 and 2 HCDAVF, transvenous embolization demonstrates high safety and efficacy (2.9% morbidity, 92.7% total occlusion). Understanding the complex venous anatomy is crucial for planning alternative approaches if standard transjugular access is impossible. Transarterial embolization or surgical disconnection (morbidity 13.3%–16.7%) should be reserved for Type 3 HCDAVFs or lesions with poor venous access. A conservative strategy could be appropriate in Type 1 HCDAVF for which spontaneous regression (5.8%) may be observed.

Cranial dural arteriovenous shunts. Part 1. Anatomy and embryology of the bridging and emissary veins

We reviewed the anatomy and embryology of the bridging and emissary veins aiming to elucidate aspects related to the cranial dural arteriovenous fistulae. Data from relevant articles on the anatomy and embryology of the bridging and emissary veins were identified using one electronic database, supplemented by data from selected reference texts. Persisting fetal pial-arachnoidal veins correspond to the adult bridging veins. Relevant embryologic descriptions are based on the classic scheme of five divisions of the brain (telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon). Variation in their exact position and the number of bridging veins is the rule and certain locations, particularly that of the anterior cranial fossa and lower posterior cranial fossa are often neglected in prior descriptions. The distal segment of a bridging vein is part of the dural system and can be primarily involved in cranial dural arteriovenous lesions by constituting the actual site of the shunt. The veins in the lamina cribriformis exhibit a bridging-emissary vein pattern similar to the spinal configuration. The emissary veins connect the dural venous system with the extracranial venous system and are often involved in dural arteriovenous lesions. Cranial dural shunts may develop in three distinct areas of the cranial venous system: the dural sinuses and their interfaces with bridging veins and emissary veins. The exact site of the lesion may dictate the arterial feeders and original venous drainage pattern.

Endovascular treatment and computed imaging follow-up of 14 anterior condylar dural arteriovenous fistulas

We report our experience in treating the anterior condylar dural arteriovenous fistula (DAVF) and confirm the location of the coils in the follow-up images after successful endovascular treatment. We retrospectively reviewed the 14 patients with anterior condylar DAVF treated successfully in our institute. Twelve of them had CT or MR follow-up images. All the patients had intravascular coiling of the fistula. Seven of our patients had retrograde drainage to different sinuses. Three had ocular symptoms as a clinical manifestation. We treated nine patients with coils alone (eight transvenous, one transarterial), four with adjuvant transarterial treatment with particles or liquid embolic for minimal residual after coiling packing. One patient had failed onyx treatment and successful treatment by following transvenous packing. All patients had total obliteration of the DAVF fistula on immediate post-procedure angiogram or on the follow-up images and no evidence of recurrence clinically. The mean follow-up period was 34.2 months (standard deviation=39.8). Twelve patients had computed images (CT alone in four, MR alone in five, both CT and MR in three). These findings were analyzed by four certified neuroradiologists. We found 100% of the coils at the anterior condylar veins inside the hypoglossal canal, 54.2% at the lateral lower clivus, and only 14.2% at the anterior condylar confluence which is ventrolateral to the anterior orifice of the hypoglossal canal. Intravascular coiling is the treatment of choice in patients with anterior condylar DAVF. All the coils were found at the anterior condylar veins inside the hypoglossal canal after successful treatment.

Percutaneous transfacial direct embolization of an intraosseous dural arteriovenous fistula

BACKGROUND AND IMPORTANCE

An intraosseous dural arteriovenous fistula (DAVF) is a rare cerebrovascular disease. The fistulous connection occurs within intraosseous diploic or transosseous emissary veins causing dilated intraosseous vascular pouches. To the authors' knowledge, this report describes the first percutaneous transfacial direct embolization of an intraosseous DAVF.

CLINICAL PRESENTATION

A man in his 50s with blue rubber bleb nevus syndrome presented with headaches, imbalance, decreased visual acuity bilaterally, and left eye proptosis and chemosis. Imaging demonstrated an extensive intraosseous DAVF with dilated intraosseous vascular pouches throughout his cranial base and intraorbital venous congestion. He underwent staged endovascular treatment with the goal to improve his ocular symptoms. Transarterial and transvenous approaches failed to provide adequate access to the intraosseous vascular pouches. A direct, percutaneous transfacial approach was used to access the pouches for embolization with coils and liquid embolic material. Postoperative angiography demonstrated successful embolization of the pouch within the left pterygoid wing, reduced opacification of the intraosseous fistula, and elimination of intraorbital venous congestion. At 9-month follow-up, the patient's headaches had resolved, and his ocular symptomatology had improved.

CONCLUSION

Endovascular access to an intraosseous DAVF is limited by the size and location of the intraosseous vascular pouches. In this case, a direct transfacial approach under image guidance facilitated access and embolization, which led to an improvement in the patient's symptoms. This technique is a novel approach for DAVF management.

Endovascular therapy of hypoglossal canal AVFs presenting with orbital symptoms

OBJECTIVE

Dural arteriovenous fistulae (DAVF) of the hypoglossal canal region are rare lesions. We describe three cases of DAVF of the hypoglossal canal presenting with ocular symptoms and discuss the endovascular management options.

METHODS

Three consecutive patients with DAVF of the hypoglossal canal region presented with proptosis, chemosis and disturbances of extra-ocular mobility. Each patient was treated using a different endovascular approach, based on variations of the vascular access.

RESULTS

The cases and treatments are reviewed, with a literature review on the subject. Endovascular treatment, transvenous or trans-arterial was curative in all cases.

CONCLUSION

DAVF of the hypoglossal canal region can present with ocular manifestations very similar to DAVF of the cavernous sinus or carotid-cavernous fistulas. Endovascular treatment is usually feasible and effective, but an understanding of the vascular anatomy and pathophysiology of the disease are of utmost importance when planning the approach.

SURGICAL TREATMENT OF HIGH-RISK INTRACRANIAL DURAL ARTERIOVENOUS FISTULAE

OBJECTIVE

An increasing number of intracranial dural arteriovenous fistulae (DAVFs) are amenable to endovascular treatment. However, a subset of patients with high-risk lesions requires surgical intervention for complete obliteration. We reviewed our experience with the surgical management of high-risk intracranial DAVFs and offer recommendations to minimize complications based on fistula location and type.

METHODS

Hospital records for 53 patients (16 women, 37 men) with high-risk intracranial DAVFs treated surgically between 1995 and 2004 were reviewed to determine their presenting symptoms, location, endovascular and surgical interventions, angiographic outcome, and treatment complications. Most patients (76%) presented with intracranial hemorrhage, progressive neurological deficits, or seizures. All patients had high-risk angiographic features such as cortical venous drainage or venous varix. Preoperative embolization was performed in 27 patients. Surgical approaches were tailored to the lesion location. Fistulae were located in the transverse-sigmoid junction (n = 18), tentorium (n = 17), ethmoid (n = 7), superior sagittal sinus (n = 6), torcula (n = 4), and sphenoparietal sinus (n = 3).

RESULTS

At the time of the last follow-up evaluation, 49 patients (92%) had good or excellent outcomes (Glasgow Outcome Scale score, 4 or 5) and three (6%) were deceased. Five patients had a residual fistula. One residual spontaneously thrombosed, one was treated with gamma knife radiosurgery, and two were successfully embolized. The overall morbidity and mortality rate was 13%.

CONCLUSION

Despite fulminant presenting symptoms, high-risk intracranial DAVFs can be successfully managed with good outcomes. When anatomic features prevent endovascular access, or embolization fails to obliterate the lesion, urgent surgical treatment is indicated. Patients with residual filling of the DAVF should be considered for adjuvant therapy, including further embolization or radiosurgery.