Preliminary results of a randomized, equivalence trial of fluoroscopic caudal epidural injections in managing chronic low back pain: Part 1--Discogenic pain without disc herniation or radiculitis.

Background: Intervertebral discs, facet joints, ligaments, fascia, muscles, and nerve root dura have been described as tissues capable of transmitting pain in the low back. The pathophysiology of spinal radicular pain is the subject of ongoing research and controversy with discogenic pain assuming a major role as a cause of non-specific low back pain. Even though epidural injections are frequently administered in managing axial low back pain, the evidence is lacking.

Study Design: A randomized, double-blind, equivalence trial.

Setting: An interventional pain management practice, a specialty referral center, a private practice setting in the United States.

Objectives: To evaluate the effectiveness of caudal epidural injections with or without steroids in managing chronic low back pain without disc herniation or radiculitis in providing effective and long-lasting pain relief and to evaluate the differences between local anesthetic with or without steroids.

Methods: Patients were randomly assigned to one of 2 groups, Group I patients received caudal epidural injections with local anesthetic (lidocaine 0.5%), whereas Group II patients received caudal epidural injections with 0.5% lidocaine 9 mL mixed with 1 mL of steroid. Randomization was performed by computer-generated random allocation sequence by simple randomization.

Outcomes Assessment: Multiple outcome measures were utilized which included the Numeric Rating Scale (NRS), the Oswestry Disability Index 2.0 (ODI), employment status, and opioid intake with assessment at 3 months, 6 months, and 12 months post-treatment. Significant pain relief was defined as 50% or more, whereas significant improvement in disability score was defined as reduction of 40% or more.

Results: Significant pain relief (> or =50%) was demonstrated in 72% to 81% of patients and functional status improvement was demonstrated by a reduction of 40% in the ODI scores in 81% of the patients. The overall average procedures per year were 3.6 +/- 1.05 in Group I and 3.9 +/- 1.33 in Group II with an average total relief per year of 32.3 +/- 16.93 weeks in Group I and 30.7 +/- 17.94 weeks in Group II over a period of 52 weeks.

Limitations: The results of this study are limited by lack of a placebo group and a preliminary report of 36 patients in each group.

Conclusion: Caudal epidural injections with or without steroids may be effective in patients with chronic function-limiting low back pain without facet joint pain, disc herniation, and/or radiculitis in over 70% of the patients.