Predictive Value of Epidural Gas Spread Pattern Following Transforaminal Ozone Injection for Clinical Outcomes in Cervical Radiculopathy: A Prospective Cohort Study

Background: Percutaneous interventions for cervical radiculopathy (CR) show variable efficacy, lacking reliable prognostic predictors. We hypothesized that epidural gas spread patterns during CT-guided ozone injection—using ozone as a native contrast agent—can functionally assess epidural adhesions and predict clinical outcomes. Methods: This prospective, observational cohort study enrolled 185 patients with single-segment CR completing a 6-month follow-up. During CT-guided transforaminal ozone injection, epidural gas spread was evaluated before administering the therapeutic dose. Patients were classified into Good Spread (GS; n=98) or Poor Spread (PS; n=87) groups. Primary (Neck Disability Index, NDI) and secondary (Visual Analog Scale, VAS) outcomes were assessed at baseline and multiple post-intervention time points up to 6 months. Results: Both groups showed significant NDI and VAS improvements from baseline (p< 0.001). However, the GS group exhibited significantly greater improvement at all follow-ups (p< 0.01). At 6 months, treatment success (≥ 50% NDI reduction) was 89.8% in the GS group versus 44.8% in the PS group (p< 0.001). Multivariate analysis identified a good spread pattern (OR=9.80, 95% CI: 4.51– 21.30; p< 0.001) and shorter symptom duration (OR=4.50, p=0.004) as independent predictors of treatment success. Conclusion: This study suggests that the epidural diffusion pattern of ozone gas during CT-guided transforaminal injection may be a useful predictor for clinical outcomes in CR. These findings highlight the potential role of epidural adhesions in treatment response. However, due to the single-center observational design, our findings may lack broad generalizability, and future randomized controlled trials are necessary to confirm these results. Keywords: cervical radiculopathy, ozone therapy, CT-guided, transforaminal injection, gas spread, prognostic prediction, epidural adhesion