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

A Case of an Intraosseous Arteriovenous Fistula at the Squamous Part of the Occipital Bone with Spontaneous Occlusion of Diploic Venous Drainage

Objective

An intraosseous arteriovenous fistula (AVF) is a rare fistula with an intracranial shunted pouch. A case of an intraosseous AVF at the squamous part of the occipital bone with spontaneous occlusion of diploic venous drainage is described.

Case Presentation

The patient, a Japanese woman in her 80s, presented with headaches at the back of the head and a history of multiple unruptured cerebral aneurysms but no recent head trauma. MRA showed abnormal signals in the occipital diploic region, and DSA showed an intraosseous AVF with a shunted pouch in the squamous part of the occipital bone near the inion. This was not seen on MRA 6 months earlier. One month later, follow-up examinations showed spontaneous occlusion of the diploic venous drainage, leading to a change in retrograde drainage into the superior sagittal sinus. Transvenous coil embolization was performed, and the shunted pouch was completely occluded. Postoperatively, the patient's symptoms resolved, and subsequent follow-ups showed no recurrence of the AVF.

Conclusion

This case suggested that the vascular architecture of intraosseous AVFs might change over a short period. Transvenous embolization was effective in obliterating the intraosseous shunted pouch.

Bridging veins at the craniocervical junction: from anatomy to clinical significance in dural arteriovenous shunts

PURPOSE

Bridging veins (BVs) serve as a route of pial venous reflux, and its anatomy is essential to understand the pathophysiology of dural arteriovenous shunts (dAVSs) around the craniocervical junction (CCJ) (from the jugular foramen level to the atlantal level). However, the anatomical variations of the BVs and their proximal connections remained poorly elucidated. This study aimed to radiologically investigate the anatomy of the bridging veins around CCJ and discuss the clinical significance of these BVs in the dAVS.

METHODS

We investigated normal venous anatomy of the BVs from the jugular foramen level to the atlantal level using preoperative computed tomography digital subtraction venography in patients undergoing elective neurosurgery. BVs affected by the dAVSs in the same region were also evaluated. The three types of dAVS, craniocervical junction, anterior condylar, and proximal sigmoid sinus, were investigated.

RESULTS

We identified six BV groups: superolateral, anterolateral, lateral, posterior, inferolateral, and inferoposterior. The superolateral and inferolateral groups, connected with the proximal sigmoid sinus and suboccipital cavernous sinus, respectively, were the largest groups. Each group has a specific downstream venous connection. The association with dVASs was observed only in the inferolateral group, which was typically the sole venous drainage in most dAVSs at the CCJ.

CONCLUSION

We reported detailed anatomy of BVs from the jugular level to the atlantal level, which enhanced our understanding of the pathophysiology of dAVSs in the corresponding region.

Prevalence of intra-osseous veins and venous lakes in the posterior skull base on 3T MRI

BACKGROUND

Intra-osseous vessels are normal anatomic structures in the calvarium and skull base. On imaging, these structures-particularly venous lakes-can mimic pathologic abnormalities. This study sought to assess the prevalence of veins and lakes in the skull base on MRI.

MATERIALS AND METHODS

A retrospective review was completed of consecutive patients that underwent contrast-enhanced MRI imaging of the internal auditory canals. The clivus, jugular tubercles, and basio-occiput were assessed for the presence of both intra-osseous veins (serpentine and/or branching vessels) and venous lakes (well-circumscribed round or oval enhancing structures). Vessels in the adjacent synchondroses major foramina were excluded. Three board-certified neuroradiologists performed independent blinded reviews, with discrepancies agreed upon by consensus.

RESULTS

96 patients were included in this cohort (58.3% female). Mean age was 58.4 years (range = 19-85). At least one intra-osseous vessel was identified in 71 (74.0%) patients. 67 (70.0%) had at least one skull base vein, and 14 (14.6%) had at least one venous lake. Both vessel subtypes were observed in 8.3% of patients. Vessels were more commonly observed in women, though this did not reach statistical threshold (p = 0.56). Age was not associated with the presence of vessels (0.59) or vessel location (p values ranged from 0.44-0.84).

CONCLUSIONS

Intra-osseous skull base veins and venous lakes are relatively common findings on MRI. Both vascular structures should be considered normal anatomy, and care should be taken to not confuse these for pathologic entities.

Treatment of high cervical arteriovenous fistulas in the craniocervical junction region

The craniocervical junction (CCJ) is a complex region. Rarely, arteriovenous fistulas (AVFs) can occur in the CCJ region. Currently, it is accepted that CCJ AVFs should only refer to AVFs at the C1-C2 levels. It is reasonable to assume that high cervical CCJ AVFs are being referred to when discussing CCJ AVFs. High cervical CCJ AVFs can be divided into the following four types: dural AVF, radicular AVF, epidural AVF and perimedullary AVF. Until now, it was difficult to understand high cervical CCJ AVFs and provide a proper treatment for them. Therefore, an updated review of high cervical CCJ AVFs is necessary. In this review, the following issues are discussed: the definition of high cervical CCJ AVFs, vessel anatomy of the CCJ region, angioarchitecture of high cervical CCJ AVFs, treatment options, prognoses and complications. Based on the review and our experience, we found that the four types of high cervical CCJ AVFs share similar clinical and imaging characteristics. Patients may present with intracranial hemorrhage or congestive myelopathy. Treatment, including open surgery and endovascular treatment (EVT), can be used for symptomatic AVFs. Most high cervical CCJ AVFs can be effectively treated with open surgery. EVT remains challenging due to a high rate of incomplete obliteration and complications, and it can only be performed in superselective AVFs with simple angioarchitecture. Appropriate treatment can lead to a good prognosis.

Cone-beam CT-assisted microcatheter tip placement at the shunted pouch entry zone: A technical note for anterior condylar arteriovenous fistula

Accurate microcatheter placement for anterior condylar arteriovenous fistula (AVF) enables selective transvenous embolization (TVE) and helps to avoid hypoglossal nerve palsy. Anterior condylar AVF has a shunted pouch within the condylar vascular and osseous structures. Detailed anatomical comprehension of the shunted pouch is essential, in addition, we believe that it is important to have a strategy for where in the shunted pouch to start filling with coils. Specifically, we consider that it is important to structurally understand the more upstream location (arterial side) within the shunted pouch (called "shunted pouch entry zone"), guide the microcatheter there, and embolize from that site. Although several studies have discussed the usefulness of intraoperative cone-beam computed tomography (CBCT) for treating anterior condylar AVF, there are no studies which have mentioned the importance of microcatheter position before coil embolization in selective TVE as in this study. Intraoperative localization of the shunted pouch entry zone is often difficult. Herein, the authors report that cone-beam computed tomography (CBCT) can assist accurate microcatheter tip placement at the shunted pouch entry zone before staring embolization. This is the novel application of intraoperative CBCT to treat anterior condylar AVF successfully treated with precise and selective TVE.

Targeted transvenous embolization of a dural arteriovenous fistula at the jugular tubercle venous complex

Background

Dural arteriovenous fistulas (dAVFs) occurring near the hypoglossal canal are rare. Detailed evaluation of vascular structures can identify shunt pouches at the jugular tubercle venous complex (JTVC) in the bone near the hypoglossal canal. Although the JTVC has several venous connections, including the hypoglossal canal, there have been no reports of transvenous embolization (TVE) of a dAVF at the JTVC using an approach route other than the hypoglossal canal. This report describes the first case of complete occlusion with targeted TVE using an alternative approach route in a 70-year-old woman presenting with tinnitus diagnosed with dAVF at the JTVC.

Case Description

The patient had no history of head trauma or other preexisting conditions. Magnetic resonance imaging (MRI) showed no abnormal findings in the brain parenchyma. Magnetic resonance angiography (MRA) revealed a dAVF near the ACC. The shunt pouch was located in the JTVC, near the left hypoglossal canal, with feeders from the bilateral ascending pharyngeal arteries and occipital arteries, left meningohypophyseal trunk, and odontoid arch of the left vertebral artery. TVE was performed near the shunt pouch. Localized packing of the shunt point was achieved. The patient's tinnitus improved. Postoperative MRI showed disappearance of the shunt without any complications. No recurrence was observed on MRA 6 months after treatment.

Conclusion

Our results suggest targeted TVE is an effective treatment for dAVFs at the JTVC.

Extracranial prevertebral venous network of the craniocervical junction: CT-digital subtraction venography analysis

PURPOSE

Although the craniocervical junction has a complex anatomical structure associated with clinical diseases, its ventral venous network has not been well studied. This study aimed to clarify the extracranial ventral venous structure at the craniocervical junction.

METHODS

Head computed tomography digital subtraction venography (CT-DSV) images of 273 patients (age 6 months to 93 years) taken at our department were retrospectively analyzed. We analyzed the frequency and anatomical features of the venous channels, as well as their upstream and downstream connections with the surrounding channels at the ventral craniocervical junction, from the level of the hypoglossal canal to the second cervical vertebra.

RESULTS

In 54% of the cases, the vein descended from the anterior condylar confluence, running medially along the basioccipital and fusing with its counterpart in the midline at the level of the atlanto-occipital membrane. Furthermore, 24% of this vein was connected caudally to the anterior external vertebral venous plexus. We also identified venous channels, either as a sole vein or venous plexus, on the tip of the odontoid process (10%), which has not been well described previously. The vein around the odontoid process was connected to several veins, including the aforementioned vein anterior to the condyle and the anterior internal vertebral venous plexus.

CONCLUSIONS

CT-DSV analysis revealed a detailed venous architecture ventral to the craniocervical junction. Venous structures identified in this study may be involved in diseases in this area.

Anterior cranial fossa osseous arteriovenous fistula of the crista galli with bone erosion: patient series

BACKGROUND

Although an anterior cranial fossa dural arteriovenous fistula (ACFdAVF) is thought to have a fistula on the dura near the olfactory groove, the detailed angioarchitecture remains unreported.

OBSERVATIONS

In case 1, a 65-year-old man was found to have an asymptomatic ACFAVF. His computed tomography angiography (CTA)-maximum intensity projection (MIP) showed the shunt point in the crista galli (CG), with the intradural drainer penetrating the destroyed bone of the CG. In case 2, a 78-year-old man had a past history of intracerebral hemorrhage and was found to have an ACFAVF. The rotational angiography (RA)-MIP showed the intraosseous fistula in the CG with the drainer passing through a tiny bone defect of the CG. In case 3, a 35-year-old man was investigated for epilepsy. The RA-MIP showed an osseous arteriovenous fistula (AVF) in the anterior cranial base, with the drainer penetrating the skull osteolytic site. In case 4, a 73-year-old woman was found to have an asymptomatic ACFAVF. Her RA-MIP showed the osseous AVF with the drainer penetrating the CG with bone erosion.

LESSSONS

All patients were diagnosed with anterior cranial fossa osseous AVF rather than dAVF, with bone erosion in the CG. These findings should be noted at the time of diagnosis and treatment.

Surgical disconnection of a hypoglossal canal dural arteriovenous fistula demonstrating rapid progression of medulla oblongata disturbance: illustrative case

BACKGROUND

Dural arteriovenous fistulas of the hypoglossal canal (HCDAVFs) with dominant drainage to perimedullary veins are extremely rare. These patients are prone to develop slow and progressive myelopathy, however, their clinical course has not been fully elucidated. We report an unusual case of HCDAVF in which the patient demonstrated rapid progression of hemiplegia and respiratory insufficiency.

OBSERVATIONS

An 82-year-old woman demonstrated motor weakness of the left extremities. T2-weighted magnetic resonance imaging showed a high intensity area in the right medulla oblongata and angiography revealed HCDAVF with dominant drainage to the anterior medullary vein through the anterior condylar vein. Within 3 days, her hemiparesis and respiratory function worsened, and she needed mechanical ventilation. Considering that venous congestion in the medulla oblongata could cause the symptoms, we immediately performed surgical obliteration of the anterior condylar vein. The disappearance of HCDAVF was confirmed by angiography and the patient was weaned from mechanical ventilation 3 days postoperatively. Her left hemiplegia gradually resolved and she was independent in daily life 8 months after the operation.

LESSONS

HCDAVFs with dominant drainage to the perimedullary veins can demonstrate rapid progression of medulla oblongata disturbance. Early disconnection should be considered to provide an opportunity for substantial recovery.

A Case of the So-Called Posterior Condylar Canal Dural Arteriovenous Fistula with an Osseous Shunt

Objective

The authors describe a case of the so-called dural arteriovenous fistula (DAVF) around the posterior condylar canal (PCC).

Case Presentation

A 71-year-old woman presented with pulse-synchronous bruit on the left side. Conventional DSA demonstrated the following: There were many feeders, including the ascending pharyngeal artery (APA), the occipital artery (OA), and the vertebral artery (VA), to the DAVF around the PCC. Shunt flow from the posterior condylar vein (PCV) drained the suboccipital cavernous sinus (SCS) and sigmoid sinus (SS), and there was venous reflux into the inferior petrosal sinus (IPS). The patient was diagnosed with PCC DAVF and underwent transvenous embolization (TVE) with coils. Intraoperative 3D-rotational angiography (RA) and axially reconstructed images revealed an osseous shunt within the occipital bone adjacent to the PCC. The arteriovenous (AV) shunt and other symptoms disappeared after occluding the drainage route from the osseous shunt to the PCV.

Conclusion

There are only three previous reports of PCC DAVF, being rare. However, no report clearly described the shunt point of PCC DAVF. 3D-RA and axially reconstructed images were useful to find and treat the shunt point.

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.

Angio-anatomical study of the pterygovaginal artery based on cone-beam computed tomography

PURPOSE

To investigate the anatomical characteristics and clinical implications of the pterygovaginal artery (PtVA), a recurrent branch from the distal internal maxillary artery (IMA), which courses through the pterygovaginal canal that connects the pterygopalatine fossa and nasopharynx.

METHODS

Eighty-two patients with 90 sides of cone-beam computed tomography (CBCT) reconstructed from rotational angiography of the external or common carotid artery with a field of view covering the pterygopalatine fossa were retrospectively reviewed. The origin from the IMA, branching type, distribution, and anastomoses was evaluated. The underlying lesions were 36 hypervascular lesions with possible supply from PtVA (17 cavernous sinus arteriovenous fistulas (AVFs), 6 anterior condylar AVFs, and 13 nasopharyngeal, parasellar, or paraclival tumors) and 46 other diseases.

RESULTS

PtVA was identified in 75 sides (83%). It originated from the pterygopalatine segment of the IMA in 45 sides (60%) and from the pterygoid segment in 30 sides (40%). It arose independently (77%), sharing the common trunk with the Vidian artery (15%) or with other branches. It ran posteromedially through the pterygovaginal canal to supply the mucosa over the nasopharyngeal roof, the choanae, and the pharyngeal ostium of the eustachian tube. It anastomosed with the ascending pharyngeal artery (n=37), the accessory meningeal artery (n=7), and the mandibular artery from the petrous internal carotid artery (n=2). It served as a feeder of osseous AVFs and skull base tumors.

CONCLUSION

PtVA was often identified by CBCT even in normal anatomy. Its detailed angio-anatomy could be evaluated in the presence of parasellar or paraclival hypervascular lesions.

Intraosseous Arteriovenous Fistula Around the Anterior Condylar Confluence as an Occipital Bone Fracture Sequela

BACKGROUND

Although traumatic dural arteriovenous fistula (AVF) is a rare condition, dural injury associated with skull fracture is one of the major factors for the formation of dural AVF at the skull fracture area. We report a case of de novo intraosseous AVF around the anterior condylar confluence after head injury associated with skull base fracture.

CASE DESCRIPTION

A woman in her 70s presented with pulsatile tinnitus 3 months after cerebellar infarction and occipital bone fracture. The appearance of de novo intraosseous AVF was confirmed by magnetic resonance imaging and magnetic resonance angiography and treated with coil embolization, which led to symptomatic relief without recurrence on follow-up.

CONCLUSIONS

There is no previous report to our knowledge of intraosseous AVF around the anterior condylar confluence proven to appear after skull fracture. This case demonstrates that head injury associated with skull base fracture could be one etiology of dural AVF around the anterior condylar confluence.

Venous Anatomy of the Cavernous Sinus and Relevant Veins

The cavernous sinus (CS) is a dural sinus located on each side of the pituitary fossa. Neoplastic and vascular lesions, such as arteriovenous fistulas, frequently involve the CS. This sinus plays a role as a crossroad receiving venous blood flow from the facial, orbital, meningeal, and neural venous tributaries. The relationship between these surrounding relevant veins and the CS, as well as the CS itself, varies anatomically. For safe and effective surgical and endovascular treatment of lesions involving the CS, knowledge of the anatomy and variations of the CS and the relevant surrounding veins is highly important. In this section, the anatomy and variations of the CS and the relevant surrounding veins are outlined.

Osseous arteriovenous fistulas in the dorsum sellae, clivus, and condyle

PURPOSE

Arteriovenous fistulas (AVFs) located in the cavernous sinus (CS), clivus, and condyle can be osseous shunts in nature. Here, we reviewed the angioarchitecture, clinical characteristics, and treatment results of AVFs in these lesions.

METHODS

Twenty-five patients with 27 lesions who underwent rotational angiography in our department between May 2013 and December 2019 were reviewed. We examined 20 CS AVFs, 2 clival AVFs, and 5 condylar AVFs. We divided the anatomical shunted pouches into five locations: the dorsum sellae (posteromedial of the CS), posterolateral wall of the CS, lateral wall of the CS, clivus, and condyle. We divided the AVFs into three categories: intraosseous, transitional, and nonosseous shunts. We analyzed the characteristics and treatment results.

RESULTS

A total of 33 shunted pouches or points were identified in 27 lesions. The dorsum sellae (n = 16) was the most frequent location. Fourteen AVFs (88%) in the dorsum sellae were osseous (intraosseous or transitional) shunts. All AVFs in the clivus or condyle were also osseous shunts. Eleven lesions (92%) of intraosseous and all lesions of transitional shunts exhibited bilateral external carotid artery involvement as feeders. Ten lesions (83%) of intraosseous shunts were treated with selective transvenous embolization of the shunted pouch with or without additional partial embolization of the sinus. Eleven (92%) intraosseous shunts were completely occluded, and symptom resolution was achieved in all intraosseous shunts.

CONCLUSION

Most of the CS AVFs with shunted pouches in the dorsum sellae and all of the AVFs in the clivus and condyle share similar characteristics.

Embryological Consideration of Dural AVFs in Relation to the Neural Crest and the Mesoderm

Intracranial and spinal dural arteriovenous fistulas (DAVFs) are vascular pathologies of the dural membrane with arteriovenous shunts. They are abnormal communications between arteries and veins or dural venous sinuses that sit between the two sheets of the dura mater. The dura propria faces the surface of brain, and the osteal dura faces the bone. The location of the shunt points is not distributed homogeneously on the surface of the dural membrane, but there are certain areas susceptible to DAVFs. The dura mater of the olfactory groove, falx cerebri, inferior sagittal sinus, tentorium cerebelli, and falx cerebelli, and the dura mater at the level of the spinal cord are composed only of dura propria, and these areas are derived from neural crest cells. The dura mater of the cavernous sinus, transverse sinus, sigmoid sinus, and anterior condylar confluence surrounding the hypoglossal canal are composed of both dura propria and osteal dura; this group is derived from mesoderm. Although the cause of this heterogeneity has not yet been determined, there are some specific characteristics and tendencies in terms of the embryological features. The possible reasons for the segmental susceptibility to DAVFs are summarized based on the embryology of the dura mater.