CSF-Venous Fistulas Arising Intraosseously within Bone Remodeled by Meningeal Diverticula

SUMMARY: CSF-venous fistulas (CVFs) are a common and increasingly recognized type of spinal CSF leak. Most of these fistulas occur in the setting of spontaneous intracranial hypotension, though nonspontaneous cases have been described as well. In most instances, CVFs arise from the dome or neck of nerve root sleeve diverticula (also called meningeal diverticula). Venous drainage typically involves some combination of the internal epidural venous plexus and external vertebral venous plexus. Not uncommonly, venous drainage into the basivertebral venous plexus or other intraosseous veins can be seen. However, the drainage is usually a secondary finding related to normal communication between intraosseous and extraosseous veins. We have recently observed unique cases in which CVFs arise directly within the vertebral elements, resulting in primarily intraosseous drainage. It is possible that this phenomenon is secondary to prominent meningeal diverticula remodeling the adjacent vertebral elements. In this clinical report, we reviewed a multi-institutional series of CVFs exhibiting primary intraosseous drainage, with the goal of illustrating the imaging findings, treatment strategies, and outcomes of the patients. Nine cases were identified demonstrating this phenomenon. We show that intraosseous CVFs can arise in virtually any part of the vertebrae and describe how this feature affects treatment.