Janna Friedly (Department of Rehabilitative Medicine, University of Washington, Seattle, USA) and others report in The New England Journal of Medicine that epidural injections of glucocorticoids and lidocaine provide little or no benefit compared with epidural injections of lidocaine alone for patients with lumbar spinal stenosis.
Friedly et al write that although uncontrolled studies suggest that epidural injections of glucocorticoids and lidocaine provide short-term pain relief for patients with lumbar stenosis, data from “rigorous, randomised, controlled trials” are lacking. Therefore, the aim of the LESS (Lumbar epidural steroid injections for spinal stenosis) trial was to compare the effectiveness of epidural injections of glucocorticoid and lidocaine with that of epidural injections of lidocaine alone.
At 16 sites across the USA, 400 patients aged 50 or older and with evidence of central lumbar spinal stenosis on MRI or computed tomography were randomised to receive an epidural injection of glucocorticoids plus lidocaine (200 patients) or to an epidural injection of lidocaine alone (200). The primary outcome was the Roland-Morris Disability Questionnaire (RMDQ) score at six weeks and the patient’s rating of average buttock, hip, or leg pain in the previous week (questioned at six weeks).
At three weeks, there was a significant—albeit small—difference between groups favouring epidural injection of glucocorticoids in the RMDQ score (p<0.0001 for the comparison) and in intensity of leg pain (p<0.02). Friedly et al report that at six weeks, both groups had a significant improvements in RMDQ score (compared with their respective baseline levels) but add that there were no significant differences between groups in either the RMDQ score (p=0.07) or in the leg pain score (p=0.48). Nor were there, at six weeks, any significant differences between groups in the proportion of patients who had a 30% improvement in RMDQ score (p=0.24), 50% improvement in RMDQ score (p=0.39), a 30% improvement in rating of leg pain (p=0.88) or who had a 50% improvement in rating of leg pain (p=0.97). Friedly et al report: “Post-hoc adjustment for the baseline duration of pain resulted in a statistically significant but small between-group difference in RMDQ score (average treatment effect, 1.2 points; p=0.03) at six weeks.”
Also, although adverse events were rare overall, there were significantly more adverse events in the group taking glucocorticoids—58 vs. 38 for the lidocaine alone group (p=0.02). The authors add: “Among the patients who received glucocorticoids plus lidocaine, the rate of adverse events was higher among patients who received transforaminal injections (0.46) than among patients who received interlaminar injections (0.22).”
Friedly et al conclude: “Our large, controlled trial, in which both patients and clinicians were unaware of the treatment assignments, provides no evidence of a treatment effect at six weeks with fluoroscopically guided epidural injections of glucocorticoids plus lidocaine as compared with lidocaine alone.” They add that possible reasons for the similar improvements in the two groups include placebo effects, regression to the mean, the natural history of spinal stenosis, and other factors present in both study groups. “We did not include a sham injection group and thus cannot assess whether lidocaine alone conferred a benefit. Although it has been proposed that epidural lidocaine alone have longer-term therapeutic effects, a sustained benefit from lidocaine injection has not been rigorously demonstrated,” the authors note.