Two systematic reviews and meta-analyses have demonstrated no long-term benefit for back pain, leg pain, or disability using epidural steroid injections for either sciatica or lumbar spinal stenosis.
The first systematic review and meta-analysis in 2012 analyzed 23 trials of epidural steroid injections performed in patients with sciatica. The authors concluded that although epidural steroid injections did provide a small short-term benefit for leg pain, there was no long-term benefit for back pain, leg pain, or disability for epidural steroid injections compared with conservative management.
Now, a multicenter, double-blind US study, researchers randomized 400 patients with symptomatic central lumbar spinal stenosis to receive an epidural injection of either lidocaine alone or lidocaine plus a glucocorticoid. All patients had moderate-to-severe pain (with pain in the buttock or leg greater than that in the back) and functional disability. The pain and disability scores improved in patients in BOTH groups during the first 6 weeks; however, there was no significant difference between the two groups at 6 weeks.
We now have two good studies that demonstrate the ineffectiveness of epidural steroid injections for the long-term management of back pain, leg pain, and disability related to either sciatica or lumbar spinal stenosis.
 Pinto RZ et al. Epidural Corticosteroid Injections in the Management of Sciatica: A Systematic Review and Meta-analysis. Ann Intern Med. 2012;157(12):865-877.
 Friedly JL et al. A randomized trial of epidural glucocorticoid injections for spinal stenosis. N Engl J Med 2014 Jul 3; 371:11.