Preliminary results of a randomized, equivalence trial of fluoroscopic caudal epidural injections in managing chronic low back pain: Part 3--Post surgery syndrome.

BACKGROUND Post surgery syndrome resulting in persistent pain following lumbar spine surgery is common. Speculated causes of post lumbar surgery syndrome include stenosis, degeneration of adjacent segments, internal disc disruption, recurrent disc herniation, retained disc fragment, epidural or intraneural fibrosis, radiculopathy, and various other causes. Epidural injections are most commonly used in post surgery syndrome. There is lack of evidence for the effectiveness of epidural injections in managing chronic low back pain with or without lower extremity pain secondary to post surgery syndrome. 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 in patients with chronic low back and lower extremity pain after surgical intervention with post lumbar surgery syndrome. 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 6 mg non-particulate Celestone. 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 described as 50% or more, whereas significant improvement in the disability score was defined as a reduction of 40% or more. RESULTS Significant pain relief (> or =50%) was recorded in 60% to 70% of the patients with no significant differences noted with or without steroid over a period of one-year. In addition, functional assessment measured by the ODI also showed significant improvement with at least 40% reduction in Oswestry scores in 40% to 55% of the patients. The average procedures per year were 3.4 with an average total relief per year of 31.7 +/- 19.10 weeks in Group I and 26.2 +/- 18.34 weeks in Group II over a period of 52 weeks. LIMITATIONS The results of this study are limited by the lack of a placebo group and the preliminary report size of only 20 patients in each group. CONCLUSION Caudal epidural injections in chronic function-limiting low back pain in post surgery syndrome without facet joint pain demonstrated effectiveness with over 55% of the patients showing improvement in functional status with significant pain relief in 60% to 70%.