Epidural venous access to CSF venous fistulae: an alternative route to fistulae inaccessible from the segmental vein

Objective Endovascular transvenous embolization is the preferred modality for treatment of patients with spontaneous intracranial hypotension (SIH) identified with a leak of cerebrospinal fluid (CSF) from the spinal nerve root foramen to the venous plexus (CSF venous fistula (CVF)). However, challenging access to the individual paraspinal vein makes endovascular embolization difficult. Methods A retrospective review was performed of 69 consecutive fistulae in 65 patients treated via the endovascular transvenous route at our institution from January 2022 to March 2026. Results Of the 69 CVFs treated, in 12 the primary venous channel was inaccessible for microcatheterization. The mean±SD age of the patients was 60.3±9.2 years and six (54.5%) were women. Eight of the fistulae were eventually accessed and treated using an epidural approach from an adjacent level paraspinal vein with epidural venous plexus and intersegmental venous microcatheterization. Technical feasibility of embolization was demonstrated in all eight fistulae (100%). No intraprocedural complications or postoperative issues related to Onyx embolization or access-level complications were noticed. Short-term (3 months) freedom from SIH-type headache was reported in all patients, but rebound intracranial hypertension occurred in three patients (42.8%), recurrent SIH-type headache in two (28.5%), and one patient with a recurrent leak at the embolized level required additional surgical intervention (12.5% clinical failure). The median follow-up was 5 months. Conclusion In pursuit of endovascular transvenous routes to the spinal foramen, the epidural plexus and intersegmental vein provide a useful alternative when the paraspinal vein is not approachable directly via the azygous/vertebral/lumbar vein.