Dural arteriovenous fistula is an acquired vascular shunt. It is well known due to its relatively high occurrence in clinical practice, and its frequency is treated by endovascular techniques. However, several points including its etiology and pathophysiology have not been clarified yet. In this paper, we discuss the dural arteriovenous fistula from the view point of the vascular anatomy and angioarchitecture. Based upon comparative vascular anatomy between spinal and cerebral area, spinal dural arteriovenous fistula is corresponded to the non-sinusal type intracranial dural arteriovenous fistula which does not drain into the dural sinuses. Spinal epidural arteriovenous fistula is corresponded to the sinusal type of intracranial dural arteriovenous fistula which directly drains into the dural sinuses. The former forms the arteriovenous shunt in the dura matter and drains into the bridging vein. The latter frequently forms the arteriovenous shunt in the bone as well as dura matter and drains into the dural sinus or epidural venous plexus. Variation of the cerebral and spinal veins are associated with the hemodynamic status and symptoms in each cases of dural arteriovenous fistula, and furthermore it is potentially associated with the development of the dural arteriovenous fistula.

Dural arteriovenous fistulas (DAVFs) are not distributed homogeneously on the surface of the dural membrane, but there are certain areas susceptible to DAVFs. The dura maters of the olfactory groove, falx cerebri, inferior sagittal sinus, tentorium cerebelli, falx cerebelli, and the spinal cord are composed only of dura propria derived from neural crest cells. The dura maters of the cavernous, transverse, sigmoid sinus, and anterior condylar confluence (hypoglossal canal) are composed of both dura propria and osteal dura derived from mesoderm. Although the cause of the segmental susceptibility has not yet been determined, it is important to analyze DAVFs based on the embryology to understand the pathoetiology for the future's treatment.

Cavernous sinus (CS) is a dural sinus located at the bilateral sides of the pituitary fossa, in which arteriovenous shunt and/or other neoplastic disease may occur. CS plays a role of the cross-road receiving the orbital, meningeal and neuronal venous drainage, and the venous drainage may show some anatomical variations. The knowledge about the venous drainage patterns is important for the treatment of the vascular and neoplastic lesions involving the CS and surrounding venous structures.

The major neuronal venous systems, including the superficial middle cerebral vein (SMCV) and uncal vein (UV), may be a route of the cortical venous reflux from the CS in case with the dural arteriovenous fistula (DAVF) or direct carotid-cavernous fistula. SMCV and UV often terminate directly at lateral wall of CS or at the anterolateral aspect of CS through the sphenoparietal sinus. However, they sometimes terminates at the laterocavernous sinus (LCS). LCS itself may show the anatomical variation of the drainage pattern and may be involved in the CSDAVF. It is important to know about the angioarchitectures of CSDAVF and the surrounding venous drainage patterns. In this paper, the anatomy of CS and variations will be described with focusing on the anatomy of LCS and CSDAVFs.

Retrograde leptomeningeal venous drainage (RLVD) of a dural arteriovenous fistula (dAVF) is well known to cause serious brain damage due to intracranial hemorrhage or venous congestive encephalopathy. However, detail of the underling mechanism has not been elucidated well. In this manuscript, angiographic features and hemodynamic and metabolic disturbances of dAVF were reviewed. On angiography, RLVD, varicose dilatation of venous drainage, direct drainage into cortical vein, drainage into so called ‘isolated sinus’, and pseudophlebitic pattern are the risk factors for intracranial hemorrhage or non-hemorrhage neurological deficits. Modalities such as positron emission tomography, single-photon emission computed tomography and MRI were adopted for the evaluation of hemodynamic and metabolic disturbance of dAVF. We demonstrated the reduction of regional cerebral blood flow was strongly correlated with the severity of venous congestive encephalopathy, and loss of the cerebral vascular reactivity with acetazolamide challenge was an indicator of irreversible venous infarction caused by RLVD.

Objective: The purpose of this study was to provide an update on recent developments in the diagnosis and treatment of arteriovenous fistulas at the craniocervical junction (CCJ AVFs).

Methods: Associated literature published between 2009 and 2018 on the PubMed database was reviewed.

Results:The systematic review identified 97 lesions in 92 cases of CCJ AVFs. These lesions were divided into three groups according to their angioarchitecture: 56 lesions of dural AVFs, 34 of intradural AVFs, and 7 of extradural AVFs. Clinical features, neuroimaging findings, treatments, and outcomes were compared among the three groups. Cases of dural AVFs were commonly associated with myelopathy and/or brainstem dysfunction due to venous congestion in the spinal cord (38%) and/or brainstem (21%). Cases of intradural AVFs had a more complex angioarchitecture than those of dural AVFs and were associated with a hemorrhagic presentation (83%). Of the 34 intradural AVFs, 25 lesions (74%) had a feeder aneurysm (n = 20) or varix (n = 5). The development of the aneurysm/varix may be attributed to hemodynamic and flow-related phenomena. The surgical obliteration of the intradural drainer and/or feeder was effective in most cases of dural and intradural AVFs. Endovascular embolization may be more effective in cases of extradural AVFs than in those of dural or intradural AVFs. No permanent neurologic complications occurred in 80 cases treated by surgery; however, brain infarction occurred in 2 (9%) of 22 cases treated by endovascular embolization. Good recovery was more frequently achieved in cases of intradural (79%) and extradural AVFs (100%) than in those of dural AVFs (61%) because cases with hemorrhagic presentation had fewer permanent neurologic deficits than those with venous congestion.

Conclusion: A differential diagnosis among dural, intradural, and extradural AVFs is important because clinical features, neuroimaging findings, and treatment outcomes markedly differ among the three groups.

The anterior condylar arteriovenous fistula (AC-AVF) is a relatively rare AVF that affects the vasculatures adjacent to the hypoglossal canal. We aimed to discuss the etiology and definition of the AC-AVF from the viewpoint of the osseous venous anatomy. Our recent study, which used modern imaging technology (CT digital subtraction venography and cone beam CT reconstructed from 3D rotational angiography), elucidated the intraosseous venous anatomy in this region and the precise fistulous locations of AC-AVFs. Those findings suggest that the AC-AVF is a group of “osseous” AVF that involves the anterior condylar vein and jugular tubercle venous complex (JTVC), and the osseous veins connected to them. The AC-AVF develops in osseous veins adjacent to the hypoglossal canal, and it is one of the most common subtypes of osseous AVFs. The angioarchitectures and etiology of AC-AVFs discussed herein are essential to understand this clinical entity.

Regarding dural arteriovenous fistula after cerebral venous sinus thrombosis (DAVF after CVST), not only its clinical characteristics but the mechanism of its onset and progress have remained unelucidated yet. This report attempted to clarify them as possible as we can.

We analyzed previously reported cases and our cases of DAVF after CVST, focusing on (1) frequency, (2) required condition of the previous CVST, (3) difference based on sex, (4) clinical characteristics and mechanism of its onset and progress.

We summarized the following four points: 1. DAVF after CVST occurred in cases of CVST with residual thrombus after treatment. 2. Its clinical features were multiple complicated DAVF, or non-sinus type of convexity DAVF. 3. In its early stage, DAVF occurred around the residual CVST and draining inside of the thrombus to the patent part of sinus. In next stage, the secondary DAVF appeared based on the venous hypertension. 4. More than 3 years' MRI follow-up is required in cases of CVST with residual thrombosis in the sinus.