Navigating the epidural plexus: a venographic classification system to predict technical feasibility in cerebrospinal fluid-venous fistula embolization.

BACKGROUND

Navigating the epidural plexus (EP) is a key step in transvenous embolization of cerebrospinal fluid-venous fistulas (CSFVFs) in spontaneous intracranial hypotension (SIH). However, no standard venographic classification currently exists to predict procedural complexity. This study proposes a venographic classification of the EP and evaluates its correlation with technical outcomes.

METHODS

From November 2022 to May 2025, 85 patients underwent transvenous embolization for CSFVF. In 75 cases, detailed EP venography was available and categorized as: Type I (55%), homogeneous EP, Type II (34.5%), septated channels, and Type III (10.5%), complex, narrow pathways. Of the 75 cases with available EP venography, EP microcatheter navigation was performed in 65 cases: technical endpoints were extracted from these cases.

RESULTS

Overall, embolization was technically successful in all cases. EP navigation was performed in 65/75 cases (87%), with a 91% success rate overall: highest in Type I (97.5%)-Type II (90%), and lowest in Type III (50%). Type III EPs were associated with longer fluoroscopy times per level (510 vs 60-70 s, p=0.0008) and a higher rate of EP perforation (66% vs 10% Type I and 0% Type II; p<0.001). EP navigation time per segment decreased over time, from 130 s (first year) to 60 s (after 24 months), reflecting a learning curve.

CONCLUSIONS

The proposed EP classification correlates with procedural complexity and outcomes. It may aid in preprocedural planning and improve the safety and efficiency of transvenous CSFVF embolization.