2025 年 12 巻 p. 409-414
Introduction: Dural arteriovenous fistula is an abnormal shunt between arteries and veins located within or around the dural venous sinuses, comprising 10%-15% of cerebrovascular malformations. Falcotentorial dural arteriovenous fistula with hydrocephalus is extremely rare, with only a few cases reported. This paper presents the technical approach to managing such a condition.
Case Description: A 56-year-old man presented with gait disturbance and cognitive decline for 3 months. Magnetic resonance angiography revealed hydrocephalus and a vascular malformation near the third ventricle. Digital subtraction angiography confirmed a falcotentorial dural arteriovenous fistula with multiple arterial feeders and deep venous drainage. Trans-arterial embolization was performed, achieving complete occlusion of the fistula while preserving the venous varices. The patient tolerated the procedure well, with both clinical and radiological improvement.
Discussion: Hydrocephalus in dural arteriovenous fistula is often caused by aqueductal compression from dilated venous structures. Treating hydrocephalus before addressing the fistula may risk hemorrhage due to fragile leptomeningeal vessels. In this case, embolization was performed with particular attention to preserving the venous varix located caudally at the fistula site. Embolizing this pouch could have led to acute thrombosis and worsening hydrocephalus. Following embolization, ventricular dilation regressed, and the patient's symptoms improved.
Conclusion: Falcotentorial dural arteriovenous fistula with hydrocephalus is exceptionally rare. During embolization, preserving the venous ectasia compressing the Sylvian aqueduct may help prevent the aggravation of hydrocephalus and support progressive ventricular size reduction.
Dural arteriovenous fistula (dAVF) is an abnormal connection between arteries and veins located around or within the dural venous sinuses, intradural pial, or meningeal veins, accounting for 10%-15% of all cerebrovascular malformations.1,2) Among all dAVFs, falcotentorial dAVF is a relatively rare subtype and is positioned in an intricate anatomical location, typically with multiple feeders and intersections of deep venous drainage formation.1) Falcotentorial dAVF with the development of hydrocephalus is an exceptionally rare condition, with only a handful of cases reported.3) dAVFs in this region also exhibit a highly aggressive clinical presentation, requiring prompt and effective treatment. In this paper, we describe the technical details of the management of falcotentorial dAVF with hydrocephalus.
A 56-year-old male presented to our hospital clinic with walking difficulty and symptoms of dementia that had persisted for 3 months. The symptoms progressively worsened until the patient was unable to walk and became bedridden. Magnetic resonance angiography showed signs of ventriculomegaly with ependymal enhancement on T2-Flair, suggesting hydrocephalus (Fig. 1A). A flow void was detected at the quadrigeminal cistern, with partial compression of the Sylvian aqueduct by an engorged vessel suspected to be the cause of the hydrocephalus (Fig. 1B). Angiography confirmed an arteriovenous fistulous connection at the junction between the falx and tentorium cerebelli (Fig. 2A). The dAVF has multiple shunt points, with feeding arteries from the parietal convexity branch of the middle meningeal artery (MMA) (Fig. 2B), which later became the falcine artery, the superficial temporal artery, the branches of the occipital artery (Fig. 2C), posterior meningeal artery from the vertebral artery (Fig. 2D), and the bilateral artery of Davidoff and Schechter, which branches from both P1 segments. Several draining veins included the bilateral basal vein of Rosenthal, the internal cerebral vein, and the vein of Galen, which subsequently drained into the straight sinus. Venous ectasia was observed at the caudal part of the fistula and was suspected to be the cause of obstructive hydrocephalus (Fig. 2E, F). Based on the angioarchitecture, the dAVF resembles Cognard classification type IIb, Borden type II, due to the antegrade flow from the straight sinus to both transverse sinuses and cortical venous reflux.
(A) Pre-operative MRI T2-Weighted imaging shows ventriculomegaly with trans ependymal edema (white arrowheads) indicating hydrocephalus, with a cluster of flow void configuration at the posterior part of the third ventricle, suggesting vascular malformation. (B) Sagittal T2-weighted image showed obstruction of the Sylvian aqueduct due to venous varix dilation. (C, D) Post-embolization T2-weighted images showed a reduction in the size of the venous varix dilation with subsequent re-establishment of the Sylvian aqueduct patency (white arrow), along with resolution of hydrocephalus, as indicated by the reduction of ventricular size and decreased periventricular edema.
MRI: magnetic resonance imaging
(A) The AP view of the ECA injection shows multiple feeders mainly from convexity branches of MMA (multiple black arrowheads), which further become the falcine artery, supplying the fistula. Lateral view of ECA (B) and CCA injection (C) shows multiple feeding arteries from branches of the occipital artery (multiple black arrowheads) and branches of MMA (black arrow). Venous drainage is shown to the straight sinus (white arrow). (D) The VA injection shows a feeder from the posterior meningeal artery (black arrow). (E-F) 3D ECA angiography shows multiple feeders from branches of the occipital artery (dashed arrow), along with a venous pouch at the most caudal part of the fistula (white arrow).
3D: three-dimensional; AP: anteroposterior; CCA: common carotid artery; ECA: external carotid artery; MMA: middle meningeal artery; VA; vertebral artery
Trans-arterial embolization was performed using radial access for angiographic control through the right external carotid artery (ECA) and femoral access for the intervention via the left ECA. A Benchmark 6 Fr (Penumbra, Alameda, CA, USA) guiding catheter was advanced to the left ECA, with an intermediate catheter, Fubuki 4 Fr (ASAHI Intecc, Aichi, Japan) positioned on the proximal MMA. A long microcatheter, Marathon 170 cm (Medtronic, Minneapolis, MN, USA), was then advanced to the most distal part of the falcine artery through the parietal convexity branch of the MMA, directly adjacent to the fistula point (Fig. 3A). Onyx18 (Medtronic) was slowly injected into the fistulous connection (Fig. 3B). Care was taken not to embolize the venous ectasia pouch at the most caudal part of the fistula. After several rounds of injection, Digital subtraction angiography evaluation showed complete occlusion of almost all fistulous connections and feeder arteries, with preservation of the venous ectasia pouch (Fig. 3C-F).
Trans-arterial embolization procedure showing (A) MMA selection for embolization (multiple white arrowheads). (B) Embolization with Onyx with preservation of the venous varix at the most caudal part of the dAVF. (C, D) Post-embolization AP and lateral views of ECA injection show no fistula remains. (E, F) AP and lateral view of vertebral artery injection show no fistula remains.
AP: anteroposterior; dAVF: dural arteriovenous fistula; ECA: external carotid artery; MMA: middle meningeal artery
A single fistula connection from the bilateral artery of Davidoff and Schechter was identified and later embolized 2 weeks after the first embolization. The left feeder of the artery of Davidoff was selected to access the remaining fistula, and embolization was performed with Onyx18 (Medtronic). A small fistulous connection remained from the right PCA injection through the right branch of the artery of Davidoff, which could only be appreciated during the late phase of angiographic injection, suggesting a profoundly low-flow fistula that may spontaneously regress without further intervention. Observation for this remaining lesion was therefore decided.
Outcome and follow-upThe patient tolerated both procedures well with no postoperative complications. After the first embolization, magnetic resonance imaging (MRI) evaluation at 2 weeks post-intervention showed a decreased size of the ventricular system and diminished ependymal edema, suggesting resolution of the hydrocephalus (Fig. 1C, D). Motor function was significantly improved, and the Mini-Mental State Examination score improved significantly from an initial score of 14 to 24 two weeks after the first embolization, and further improved to 29 after 1 month, suggesting recovery from cognitive impairment symptoms. The patient was then discharged to a rehabilitation hospital for further care.
dAVF is a relatively rare vascular malformation, comprising 10%-15% of all vascular malformations. Among these, the falcotentorial location of dAVF is a considerably more infrequent subtype of this malformation. Symptoms of dAVF generally depend on the location of the fistula and the pattern of venous drainage. Symptoms of hydrocephalus are remarkably rare in dAVF cases, representing only 28% of all cases.4) Falcotentorial dAVF presenting with hydrocephalus is exceptionally rare, with only 3 cases previously reported (Table 1).2,3,5) The cause of hydrocephalus in the dAVF case is mainly obstruction of the Sylvian aqueduct by venous dilation.2,3) Other possible causes include posterior fossa congestion,5) brainstem or cerebellar hemorrhage causing obstruction, or dilation of either the vein of Galen or the straight sinus, leading to blockage of the ventricular system.2) In our case, venous congestion was not severe on MRI, and obstructive hydrocephalus associated with venous ectasia was considered; treatment was required to improve the venous ectasia. This patient presented with gait abnormality and dementia, which are not typical symptoms of acute hydrocephalus and more likely represent a case of normal pressure hydrocephalus. Another case of dAVF shows bilateral thalamic hyperintensities caused by deep venous congestion, which further developed into a rare clinical presentation of thalamic dementia.6,7) In that case, the dementia symptoms improved after obliteration of the fistula, suggesting a reversible nature of the symptom. This aligns with our case, where the patient's MMSE score improved after the obliteration of the fistula, owing to improvement of the hydrocephalus and venous congestion.
Review of Cases of Hydrocephalus Associated with Falcotentorial dAVF
| Reference | Patient | Cognard | Cause of hydrocephalus | Treatment | Extent of embolization | Complications |
|---|---|---|---|---|---|---|
| Abbreviations; F: female; M: Male; TAE: Trans-arterial embolization | ||||||
| Zhang et al. (2) | 55 F | IV | Venous ectasia | TAE | Unknown | |
| Wajima et al. (3) | 54 M | IV | Venous ectasia | TAE | Complete occlusion of the fistula, along with the venous ectasia | Acute thrombosis of the varix |
| Nejadhamzeeigilani et al. (5) | 40 M | III | Congestion of the posterior fossa | TAE | Complete occlusion of the fistula | |
| Current case | 56 M | IIb | Venous ectasia | TAE | Complete occlusion of the fistula with preservation of the venous ectasia | |
Falcotentorial dAVF is located near critical deep veins, including the vein of Galen, the basal vein of Rosenthal, internal cerebral veins, and the straight sinus, which may serve as the draining vein of the fistula. The fistula in this region typically develops a cortical draining vein with an aggressive clinical progression.6) Wen et al.8) strongly recommend treating the dAVF before performing cerebrospinal fluid diversion, as treating hydrocephalus prior to downgrading or curing the dAVF may instigate intracranial hemorrhage by damaging the distended leptomeningeal vessels. Thus, unless signs of a severe increase in intracranial pressure are observed, Cerebrospinal fluid diversion may be delayed until the embolization procedure succeeds.8) In their case, as in ours, embolization of the fistula actually alleviates the hydrocephalus and improves patient symptoms. Open surgery is a more traditional approach that should be reserved for anatomically complex fistulae, which may pose considerable difficulty for endovascular treatment.9) Endovascular treatment is the standard approach for dAVF cases. In the case of falcotentorial dAVF, the complex and considerably tortuous venous access favors the trans-arterial route for embolization.6) While there were multiple feeders for this fistula, we chose the MMA, which follows the convexity to the midline and becomes the falcine artery, due to the lesser tortuosity of this particular vessel. Compared to other embolic agents, Onyx has a better mechanical filling effect, which is more suitable for the embolization of a complex fistula,1) such as in our case.
In our case, as we embolize the fistula point along with the multiple feeders, we are particularly careful to avoid embolizing the venous varix, which was located at the most caudal part of the fistula and was presumed to be the cause of aqueduct obstruction. We believed that embolizing the fistula would induce shrinkage of the venous varix, naturally resolving the obstruction of the aqueduct. This was true in our case, as the hydrocephalus improved just after the first embolization procedure, along with the associated symptoms. Embolization of the venous pouch may cause acute thrombosis and acute dilation of the varix due to thrombosis formation, which may worsen the occlusive hydrocephalus. This is demonstrated in one of the reports,3) in which an endoscopic third ventriculostomy had to be performed emergently after symptom progression due to hydrocephalus aggravation following the embolization procedure in which the venous varix pouch was embolized.
The second embolization was performed through the artery of Davidoff and Schechter, a purely meningeal branch that does not supply the brainstem or adjacent parenchymal tissues.9) The last remnant of the fistula was visible in the venous phase, indicating a slow flow that may spontaneously thrombose.10) After embolization of the fistula, the venous varix eventually disappeared on the angiographic image, indicating spontaneous thrombosis.
ConclusionsFalcotentorial dAVF with hydrocephalus is an exceptionally rare case. Preservation of the venous ectasia pouch compressing the Sylvian aqueduct during the embolization procedure may prevent exacerbation of hydrocephalus and subsequently reduce ventricular volume.
Ethics approval was not required for this case report. However, written informed consent was obtained from the patient to publish this case report and accompanying images.
The authors declare that important data supporting the findings of this study are available within the article. Further data are available on request from the corresponding author. The data are not publicly available due to privacy reasons.
All authors have no conflict of interest.
