"Epidural steroids appear to speed the rate of recovery and return to function, however, allowing patients to reduce medication levels and increase activity while awaiting the natural improvement expected in most spinal disorders. Fluoroscopic verification of needle placement, with contrast injection, greatly improves steroid delivery while reducing risks."
McClain RF, Kapural L, Mekhail NA. Epidural steroid therapy for back and leg pain: mechanisms of action and efficacy. The Spine Journal 2005. Volume 5, Issue 2: 191-201

Epidural steroid injections should be done with fluoroscopic guidance. Studies show that even for experienced physicians, nearly one third of 'blind' epidural steroid injections do not truly access the epidural space.
White AH, Derby R, Wynne G. Epidural injections for the diagnosis and treatment of low-back pain. Spine 1980; 5: 78-86.

Compared with interlaminar epidural injections, transforaminal epidural injections have the theoretic advantage of delivering medication to the anterior epidural space where the nerve root traverses.
Vad VB, Bhat AL, Lutz GE, Cammisa F. Transforaminal epidural steroid injections in lumbosacral radiculopathy: a prospective randomized study. Spine 2002; 27(1):11-15.

Recent prospective, controlled studies show that transforaminal epidural steroid injections may help patients avoid surgery and reduce pain in the setting of painful lumbar herniated nucleus pulposus and lumbar radiculopathy.
Riew KD, Yin Y, Gilula L, et al. The effect of nerve-root injections on the need for operative treatment of lumbar radicular pain. A prospective, randomized, controlled, double blind study. The Journal of Bone and Joint Surgery. 2000; 82:1589-93.