Don't Overlook the Drain: Ruptured Venous Aneurysms in Intracranial Dural AVF

Abstract

Venous aneurysms are typically regarded as secondary vascular anomalies arising from chronically elevated venous pressures and ectatic changes in draining veins, particularly in the setting of dural arteriovenous fistulas (dAVFs). Their presence is often associated with an increased risk of intracerebral hemorrhage. However, the occurrence of a discrete, saccular venous aneurysm resembling an arterial aneurysm—arising from a draining vein without angiographic evidence of venous hypertension or ectasia—is exceptionally rare and poorly characterized. We present an unusual case in which a patient presented with ruptured venous aneurysms in association with dAVFs lacking any evidence of venous outflow restriction or ectasia.

Keywords

venous aneurysm - ICH - embolization - dAVF

Introduction

Intracerebral hemorrhage (ICH) secondary to dural arteriovenous fistulas (dAVFs) is most often attributed to venous hypertension and cortical venous reflux. The development of venous ectasia or aneurysmal dilatation within the draining veins of a dAVF is considered a hallmark of chronic venous pressure elevation and is strongly associated with hemorrhagic presentation.[1] However, the occurrence of a discrete venous aneurysm in the absence of angiographic features of venous hypertension or outflow obstruction remains exceedingly rare.[2] Such lesions can mimic primary hypertensive ICH on imaging, posing significant diagnostic challenges. Recognizing these atypical presentations is critical, as prompt endovascular management can be curative and prevent rebleeding. We report a rare case of a ruptured remote venous aneurysm associated with a tentorial dAVF without evidence of venous ectasia or outflow restriction.

Case Report

A 75-year-old male presented with left-sided weakness with no prior history of hypertension. Computed tomography (CT) brain revealed an acute hematoma in the right frontal subcortical region, predominantly in the lower part of the lentiform and was considered to be a hypertensive bleed as shown in [Fig. 1A]. CT angiography was performed which showed an aneurysm involving the middle cerebral artery perforator origin. However, many dilated veins were noticed on the CT angiography as shown in [Fig. 1B]. On careful evaluation, aneurysm was venous in origin corresponding to the hypodense region that was noticed on the plain CT in the center of the bleed. In view of the multiple dilated veins and no obvious nidus noted, a digital subtraction angiography (DSA) was performed which showed dural arteriovenous fistula (dAVF). Fistula was located along the tent and arterial supply was via transosseous supply from the superficial temporal artery to the posterior division of the middle meningeal artery and also anterograde via the posterior division of the middle meningeal artery. There was also supply from the dural branch of the posterior cerebral artery. The venous drainage was directed anterior along the basal vein into sphenoparietal sinus as shown in [Fig. 1C] and [D]. Although it looked hypertensive bleed at the presentation, CT angiography clearly revealed dilated veins and a DSA showed that it was an arteriovenous fistula that resulted in the venous aneurysm and the bleed. Following that, Marathon 1.5 F microcatheter was navigated from both the posterior division of the middle meningeal artery and as well as the superficial temporal artery over Synchro 10 and Hybrid 0.008' microwire. Onyx 18 was injected and complete occlusion of the fistula was achieved as show in [Fig. 1E] and [F]. On follow-up, patient left side weakness gradually improved with no evidence of recurrence.

Fig. 1 (A) Computed tomography (CT) brain shows bleed in the frontal subcortical region, predominantly in the lower part of the lentiform with focal hypodense area within bleed (white arrow). (B) CT angiography showed an aneurysm in the region of right middle cerebral artery (MCA) with multiple dilated veins, on careful evaluation aneurysm was venous in origin (white arrow). (C) Digital subtraction angiography (DSA) showed dural arteriovenous fistula (white arrow head) located along the tent and supplied by the superficial temporal artery (white solid arrow) and retrograde via posterior division of middle meningeal artery with early venous drainage sac (white arrow). (D) Venous aneurysm noted in the right vertebral artery run suggestive of dural supply of the posterior cerebral artery. (E) Microcatheter selectively into superficial temporal artery feeder with onyx cast. Another microcatheter was kept in middle meningeal feeder (white arrow). (F) Postembolization DSA run shows complete obliteration of fistula.

Discussion

Intracranial hemorrhage (ICH) occurs in approximately 35 to 42% of dAVF cases, with the venous drainage pattern serving as a critical determinant of hemorrhagic risk. The clinical presentation of dAVF can vary widely, ranging from no symptoms at all to serious complications like ICH. Studies have consistently shown that the presence of cortical venous drainage (CVD) significantly increases the likelihood of bleeding, particularly when accompanied by cortical venous ectasia or aneurysmal changes.[1] [2] For instance, Cognard et al reported a 40% incidence of hemorrhage in cases with direct CVD, which escalated to 65% when venous ectasia was also observed.[3] Furthermore, sinus outflow obstruction or thrombosis may accelerate the development and expansion of venous ectasia, thereby predisposing the vessel to rupture.

Although venous ectasia or aneurysms are often linked to venous hypertension—such as in cases of venous outlet thrombosis—they can also form or enlarge even without any evident venous hypertension or alterations at the venous outlet. Hashiguchi et al documented a case of a ruptured venous aneurysm associated with a dAVF in the anterior cranial fossa, where the aneurysm had developed at the junction of two primary venous drainage pathways.[4] [5] This location may be subject to elevated hemodynamic stress despite normal venous pressure. Similarly, Im et al found that venous aneurysms related to dAVFs in the anterior cranial fossa could arise due to increased hemodynamic stress alone, even when the venous outlet remains unchanged.[6] [7] [8] In the present case, the venous aneurysm was observed in the absence of angiographic signs typically associated with venous ectasia or outflow obstruction. This finding challenges the prevailing notion that sustained venous hypertension is a prerequisite for venous aneurysm formation. Instead, akin to cerebral arterial aneurysms, venous aneurysms may arise in regions subjected to localized hemodynamic stress induced by dAVFs. Elevated focal intravenous pressure in these regions may be sufficient to initiate aneurysmal dilation, progressive enlargement, and potential rupture. This observation broadens the understanding of the pathophysiological mechanisms underpinning venous aneurysm formation in the context of dAVF.

Conclusion

In conclusion, venous aneurysms associated with dAVFs represent a potentially life-threatening complication and should be considered in cases with atypical imaging findings. While uncommon, venous aneurysms linked to dAVFs may arise in the absence of prior venous ectasia or hypertension. In managing such lesions, it is essential to carefully assess radiologic signs within the draining veins, as these may offer critical clues regarding potential aneurysmal growth and risk of rupture, as observed in our cases.

Conflict of Interest

None declared.

Note

The article is not under consideration for publication elsewhere. Each author participated sufficiently for the work to be submitted. Publication is approved by all authors.

• References

• 1 Kim YS, Yoon W, Baek BH, Kim SK, Joo SP, Kim TS. Ruptured venous aneurysm associated with a dural arteriovenous fistula: two case reports. World J Clin Cases 2024; 12 (29) 6314-6319
• 2 Song W, Sun H, Liu J, Liu L, Liu J. Spontaneous resolution of venous aneurysms after transarterial embolization of a variant superior sagittal sinus dural arteriovenous fistula: case report and literature review. Neurologist 2017; 22 (05) 186-195
• 3 Cognard C, Gobin YP, Pierot L. et al. Cerebral dural arteriovenous fistulas: clinical and angiographic correlation with a revised classification of venous drainage. Radiology 1995; 194 (03) 671-680
• 4 Hashiguchi A, Mimata C, Ichimura H, Morioka M, Kuratsu J. Venous aneurysm development associated with a dural arteriovenous fistula of the anterior cranial fossa with devastating hemorrhage–case report. Neurol Med Chir (Tokyo) 2007; 47 (02) 70-73
• 5 Hamada J, Yano S, Kai Y. et al. Histopathological study of venous aneurysms in patients with dural arteriovenous fistulas. J Neurosurg 2000; 92 (06) 1023-1027
• 6 Della Pepa GM, Parente P, D'Argento F. et al. Angio-architectural features of high-grade intracranial dural arteriovenous fistulas: correlation with aggressive clinical presentation and hemorrhagic risk. Neurosurgery 2017; 81 (02) 315-330
• 7 Im SH, Oh CW, Han DH. Surgical management of an unruptured dural arteriovenous fistula of the anterior cranial fossa: natural history for 7 years. Surg Neurol 2004; 62 (01) 72-75 , discussion 75
• 8 Chung SJ, Kim JS, Kim JC. et al. Intracranial dural arteriovenous fistulas: analysis of 60 patients. Cerebrovasc Dis 2002; 13 (02) 79-88

Publication History

Article published online:
06 November 2025