Mechanisms of Local CSF-Venous Fistula Persistence after Transvenous Embolization for Spontaneous Intracranial Hypotension.

CSF-venous fistulas (CVF) are an important cause of spontaneous intracranial hypotension (SIH) and are increasingly treated with transvenous embolization (TVE). Based on the current published literature, approximately 8% of patients experience symptomatic recurrence due to local CVF persistence at the same site and level of prior TVE. The mechanisms responsible for persistent local CVF after TVE are unknown. Among 10 patients with local CVF persistence/recurrence after TVE, we found two mechanisms: 1) CVFs that occur at the margin of the Onyx cast, typically within the external venous plexus or the basivertebral vein; and 2) CVFs that occur due to inadequate occlusion of the internal epidural venous plexus, though not necessarily at the distal end of the Onyx cast. These findings may facilitate technical optimization of TVE for CVF and may also enable localization of persistent CVF in patients with symptomatic recurrence after TVE.