Volume 70, Issue 3, May 2024, 101534Author links open overlay panel, AbstractBackground

Dural arteriovenous fistulas of the marginal sinus (DAVFms) are uncommon and complex, with varied symptoms. Their complexity is heightened by the region's dense anastomotic network, posing risks for endovascular treatment. Surgical intervention can be effective, but this depends on thorough pre-operative understanding and optimal intra-operative visualization of the fistula.

Objective

To review the relevant anatomy, presentation patterns of DAVFms, and provide insights for surgical treatment.

Methods

Recent literature on DAVFms was reviewed, and three surgical cases are discussed to highlight treatment principles.

Results

The symptoms of a DAVFms vary depending on its venous drainage pattern. Drainage may be either ascending towards the cranial compartment or descending towards the spinal canal. Patients suffering from DAVFms may experience hemorrhage, particularly when venous drainage is directed upwards. Congestive symptoms of the spinal cord or brainstem can occur in cases of downward venous drainage. Compared to the endovascular approach, open surgery has a higher success rate in obliterating the fistula and yields better outcomes in cases of perimedullary venous drainage. Achieving surgical success necessitates thorough preoperative evaluation and adequate surgical exposure. Brainstem hyperintensity observed on T2-weighted MRI scans is linked to a poorer prognosis for recovery.

Conclusion

Treating complex DAVFms often requires surgery, as endovascular methods may not be feasible. Successful surgery hinges on a precise understanding of the fistula's venous architecture and its spatial relationships, assessed using digital substraction angiography (DSA), angio-MRI, and angio-CT. Optimal intraoperative exposure is crucial for effective surgery.

Section snippetsBackground

DAVFs consist of branches of meningeal arteries connecting to an arterialized intra-dural vein through a dural shunt point [1]. DAVFms are rare intracranial malformations in which the drainage vein exits at the dura mater forming the inner border of the marginal sinus (MS) [2], [3]. DAVFms appear in the literature under various names, including DAVF of the foramen magnum (FM), anterior condylar confluence, hypoglossal canal, or condylar veins. Sometimes, these DAVFms are classified within the

Anatomy

The MS is a circular fold of dura mater located at the inner edge of the FM. It has connections with the basilar plexus anteriorly, the jugular bulb laterally, via the anterior condylar vein, and indirectly via the suboccipital cavernous sinus and the middle and posterior condylar veins. Posteriorly, it is connected to the occipital sinus, and inferiorly it drains extracranially to the suboccipital cavernous sinus and vertebral venous plexus [6], [10], [11].

The FM is a circular bony opening

Clinical manifestations

The symptoms of a fistula vary depending on its venous drainage pattern. Drainage may be either ascending towards the cranial compartment or descending towards the spinal compartment [4], [7].

In a systematic review the main clinical presentation of a DAVFcvj is myelopathy, accounting for 39% of cases and varies in its progression [4]. This occurs when the venous drainage is descending towards the medullary veins and coronal venous plexuses.

Ascending intracranial venous drainage involves the

Work-up

A thorough assessment of DAVF necessitates the use of a CT scan, MRI, and DSA. A CT scan is effective in detecting SAH, while MRI best demonstrates neural tissue edema in T2-weighted MRI images. Additionally, abnormal and tortuous vessels can be detected using angiographic CT or MRI techniques.

DSA is the preferred and most reliable method for the definitive diagnosis and detailed understanding of DAVF. A comprehensive approach using DSA to evaluate the ICA, the ECA, and the VA bilaterally is

Treatment

The treatment consists of interrupting the high blood flow in the arterialized cortical veins. Fistulas that drain directly into venous sinuses are thought to pose a lower risk of hemorrhage. However, in cases of disabling symptoms caused by changes in venous flow, treatment may be necessary.

Treatment can be achieved by stopping the arterial supply at the shunting point, or by obliterating the arterialized vein at its dural exit point.

Arterial embolization may be challenging due to the small,

Illustrative casesA

DAVF with SAH presentation (Fig. 2):

A 63-year-old woman presented with progressive occipital headache. Diagnostic imaging revealed a complex bilateral DAVFms supplied by branches of both VA (V2, V3, V4 segments), the OA bilaterally, and the neuromeningeal trunk of the right APhA. Venous drainage involved cortical veins connecting with peri-truncular veins, leading to a venous aneurysm in the right lateral mesencephalic vein (Fig. 3).

Due to the lesion's complexity and the high risks associated

Conclusion

DAVFms is a rare condition with diverse presentations ranging from myelopathy and brainstem dysfunction to SAH. Compared to the endovascular method, open surgery offers a higher success rate in completely closing the fistula, especially when dealing with perimedullary venous drainage. Successful surgery requires comprehensive preoperative assessment and proper surgical exposure. The presence of brainstem hyperintensity on T2-weighted MRI scans indicates a less optimistic prognosis for recovery.

Funding sources

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Ethics declaration

The present work has been carried out in accordance with the Declaration of Helsinki for experiments involving human participants. Patients’ rights to privacy have been observed and all data has been anonymized.

Declaration of generative ai and ai-assisted technologies in the writing process

During the preparation of this work the authors used Chat-GPT 4 in order to improve clarity of English language in some sections of the text. After using this tool, the authors reviewed and edited the content as needed and take full responsibility for the content of the publication.

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