Study Overview
Objective. To determine the effectiveness of epidural injections of glucocorticoids plus anesthetic compared with injections of anesthetic alone in patients with lumbar spinal stenosis.
Design. The LESS (Lumbar Epidural Steroid Injection for Spinal Stenosis) trial—a double-blind, multisite, randomized controlled trial.
Setting and participants . The study was conducted at 16 sites in the United States and enrolled 400 patients between April 2011 and June 2013. Patients at least 50 years of age with spinal stenosis as evidenced by magnetic resonance imaging (MRI) or computed tomography (CT) were invited to participate. Additional eligibility criteria included an average pain rating of more than 4 on a scale of 0 to 10 (0 being the lowest score) for back, buttock, or leg pain. Patients were excluded if they did not have stenosis of the central canal, had spondylolisthesis requiring surgery, or had received epidural glucocorticoid injections within the previous 6 months. Patients were randomly assigned to receive a standard epidural injection of glucocorticoids plus lidocaine or lidocaine alone. At the 3-week follow-up they could choose to receive a repeat injection. At the 6-week assessment they were allowed to cross over to the other treatment group. Patients were blinded throughout the study. The treating physicians were also blinded through the use of 2 opaque prefilled syringes provided by the study staff—one marked “inject” and one marked “discard.”
Main outcome measures . The 2 outcomes, measured at 6 weeks, were the Roland-Morris Disability Questionnaire (RMDQ) score (range, 0 to 24, with higher scores indicating greater physical disability) and the patient’s rating of average buttock, hip, or leg pain in the previous week (scale of 0 to 10 with 0 indicating no pain and 10 indicating “pain as bad as you can imagine”).
Eight secondary patient-oriented outcomes were also measured: (1) at least minimal clinically meaningful improvement (≥ 30%), (2) substantial clinically meaningful improvement (≥ 50%), (3) average back pain in the previous week, and scores on the (4) Brief Pain Inventory (BPI) interference scale, (5) 8-question Patient Health Questionnaire (PHQ-8), (6) Generalized Anxiety Disorder 7 scale (GAD-7), (7) EQ-5D (a health status measure) and (8) Swiss Spinal Stenosis Questionnaire (SSSQ).
Main results . The 2 groups were similar with respect to baseline characteristics, except that the duration of pain was shorter in the lidocaine-alone group. At 6 weeks, both groups had improved RMDQ scores (glucocorticoid –4.2 points vs. no glucocorticoid –3.1 points, respectively). However, the difference in RMDQ score between the 2 groups was not statistically significant (–1.0 points [95% CI, –2.1 to 0.1]; P = 0.07). In addition, there was no difference in treatment effect at 6 weeks as measured by patient’s reported leg pain (–0.2 points [95% CI, –0.8 to 0.4]; P = 0.48). Furthermore, there were no significant differences in the secondary outcomes of clinically meaningful improvement, BPI, SSSQ symptoms and physical function, EQ-5D, and GAD-7 scales at 6 weeks. Among the secondary outcomes, only symptoms of depression and patient satisfaction showed a statistically significant improvement in the glucocorticoid plus lidocaine group. Of note, though not statistically significant, there were more adverse events in the glucocorticoid plus lidocaine group compared to the lidocaine alone group (21.5% vs. 15.5%, respectively). Finally, the glucocorticoid plus lidocaine group also had a significantly higher proportion of patients with cortisol serum suppression compared to the lidocaine alone group.
Conclusion. The authors concluded that there was no difference in pain-related functional disability (as measured by the RMDQ score) and pain intensity between patients receiving fluoroscopically guided epidural injections with glucocorticoids plus lidocaine compared with lidocaine alone for lumbar spinal stenosis. The injection of glucocorticoid should be avoided due to its potentially systemic effects, including suppression of the hypothalamic-pituitary axis and reduction in bone mineral density, which may increase the risk of fracture.
Commentary
Lumbar spinal stenosis is one of the most common causes of spine-related back and leg pain; it disproportionally affects older adults due to degenerative changes resulting in narrowing of the spinal canal and nerve-root. Epidural glucocorticoid injections containing a glucocorticoid and an anesthetic are commonly used to relieve symptoms of lumbar stenosis. While this treatment approach is controversial, more than 2.2 million lumbar epidural glucocorticoid injections are performed in the Medicare population each year [1,2]. Previous uncontrolled studies suggest that epidural glucocorticoid injections provide short-term pain relief for some patients with spinal stenosis [3]. While complications from the procedure are rare, a multistate outbreak of fungal meningitis due to contaminated glucocorticoid injections affected at least 751 patients with 64 deaths in 2012 [4].
The purpose of the current study by Friedly et al was to determine whether adding a glucocorticoid to an anesthetic in epidural spinal injections is superior to anesthetic alone for symptom relief and functional improvement in patients with lumbar spinal stenosis. In contrast to previous studies, the authors defined short-term results as 3 weeks after injection, and long-term results as 6 weeks after injection. Despite the shorter follow-up period, results were similar to previous studies, in that adding glucocorticoid to anesthetic in epidural spinal injection reduced pain and improved patient’s functionality short-term, but improvements were not sustained long-term. Based on these results, the authors concluded that there is no benefit in adding glucocorticoid epidural injections for back pain arising from lumbar spinal stenosis.
One major limitation of this study is the lack of a placebo arm. Because of the lack of a placebo arm, it cannot be ascertained whether epidural injection with lidocaine alone conferred a benefit. However, this study provides robust evidence that epidural steroid injections are not beneficial for treatment of back and leg pain associated with lumbar spinal stenosis.
Applications for Clinical Practice
Epidural steroid injection is long accepted in medical communities as a safe and effective treatment for lumbar spinal stenosis symptoms. In light of the potential dangers of epidural steroid injections, including meningitis, coupled with the increasing cost of the procedure, other potential side effects, and demonstrated ineffectiveness of the treatment, providers should stop recommending epidural steroid injections for lumbar spinal stenosis.
—Ka Ming Gordon Ngai, MD, MPH