Relative Risk of Operation between Lumbar Far Lateral Disc Herniation and Posterolateral Disc Herniation: A Retrospective Cohort Study

Abstract

Purpose:We reported relative risk of operation between patients who were diagnosed with lumbar far lateral disc herniation and posterolateral disc herniation after transforaminal epidural block. Materials and Methods: A retrospective cohort study was performed on 295 patients (131 male and 164 female) who underwent transforaminal epidural block for unilateral radiculopathy caused by lumbar intervertebral disc herniation. Among these 295 patients, 34 patients were diagnosed with far lateral disc herniation and 261 patients with posterolateral disc herniation. The median follow-up period was 23.9 months, with an average age of 55.7 years. Results: Fifty-one patients underwent surgical treatment. Among them, 38 patients had posterolateral disc herniation and 13 patients had far lateral disc herniation. Patients with far lateral disc herniation, when compared with posterolateral disc herniation, had a relative risk of operation of 2.67 (1.59-4.48, 95% confidence interval) with statistical significance (p=0.0002). At the final follow-up, the average visual analogue scale (VAS) score for radicular pain in the surgical and non-surgical groups was 0.69 and 1.50, respectively; the average KoreanOswestry Disability Questionnaire (K-ODI) score was 11.7 and 9.6, respectively. The difference of average VAS score showed a statistical significance (p=0.035), however, that of K-ODI showed no statistical significance (p=0.266). Conclusion: In the case of far lateral disc herniation, the relative risk of surgery after transforaminal epidural block was 2.67, which is higher than that of posterolateral disc herniation. Therefore, we should consider surgical treatment more aggressively.