CSF-venous Fistulas Arising in the Absence of Nerve Root Sleeve Diverticula: A Multi-Center Review.

CSF-venous fistulas are an increasingly recognized cause of spontaneous intracranial hypotension. Most CSF-venous fistulas arise from meningeal diverticula along the nerve root sleeves. Therefore, the presence of diverticula on spine MRI may serve as an important predictor for the presence of a CSF-venous fistula on decubitus myelography. Rare cases of CSF-venous fistulas that occur without an associated meningeal diverticulum have been identified. These occur in two varieties: 1) fistulas that arise from a nerve root sleeve that does not harbor a diverticulum and 2) fistulas that arise directly from the common thecal sac, separate from the nerve root sleeve complex. In this multi-institutional, retrospective case series, we identified patients with these two variants of CSF-venous fistulas. We sought to describe the clinical and imaging characteristics of these patients and elucidate how they may differ from those with typical CSF-venous fistulas arising from meningeal diverticula.