Elsevier

The Spine Journal

Volume 5, Issue 2, March–April 2005, Pages 191-201
The Spine Journal

Review Article
Epidural steroid therapy for back and leg pain: mechanisms of action and efficacy

https://doi.org/10.1016/j.spinee.2004.10.046Get rights and content

Abstract

Background context

Epidural steroid injection (ESI) is one of the most common nonsurgical interventions prescribed for back and leg pain symptoms. Although the use of ESI is widespread, proof of efficacy among the broad population of low back pain patients is lacking and use is predicated to a great extent on the cost and morbidity of the perceived “next step” in many patient's care—surgery.

Purpose

To review the relative indications and clinical features that predict success with ESI therapy, and to provide a physiological rationale to guide clinical decision-making.

Study design/setting

Review of literature and clinical experience.

Results

Clinical studies have alternately supported and refuted the efficacy of ESI in the treatment of patients with back and leg pain. Steroid medications do benefit some patients with radicular pain, but the benefit is often limited in duration, making efficacy difficult to prove over time. 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. Although it is assumed that the benefit of steroids is related to their effect on inflammation, that remains unproven, and it is possible that benefit is gained through an unrecognized action.

Conclusions

Randomized, controlled trials are needed to conclusively identify those patients most likely to benefit from ESI, and when and for how long. Until then, epidural steroids provide a reasonable alternative to surgical intervention in selected patients with back and/or leg pain, whose symptoms are functionally limiting. When appropriate goals are established and proper patients are selected, sufficient short-term benefit has been documented to warrant continued use of this tool.

Introduction

Whereas mechanical compression of the spinal nerve root is usually the precipitating cause of sciatic pain in patients with lumbar disc herniation, it is unlikely that pressure on the nerve root is the only cause of radicular pain in patients with disc disease [1], [2], [3]. The association between pressure and pain is not so direct. Severe nerve root compression may not produce pain in every patient, and surgical decompression may fail to relieve symptoms in others. Although decompression may provide more rapid improvement than nonsurgical care, nonoperative modalities can provide excellent pain relief in many patients [4], [5]. The key factor determining the extent and severity of leg and back pain in these patients is often inflammation, in combination with nerve root pressure or mechanical irritation. Modalities that alleviate this inflammatory process can reduce pain symptoms and improve function in patients with a variety of spinal disorders.

Section snippets

History of epidural steroid use

Medications were first injected into the epidural space to treat back and leg pain in the early part of the last century. Viner began injecting large volumes of saline and procaine into the lumbar epidural space to treat back pain and lumbar radiculopathy in the 1920s [6]. Evans reported results with a similar procedure in 1930, but achieved only a 14% clinical success rate in 40 patients [7]. The effects of epidural steroid injection were first reported in 1960. Brown reported complete

Causes of sciatica

Nerve root compression, through disc herniation or stenosis, is the most common cause of sciatic pain symptoms [17], [18], [19]. Other factors contribute significantly to the overall experience of radicular pain, however. Although Lindblom and Rexed proposed nerve root compression as a cause of radicular pain after demonstrating pathological changes in nerve roots compressed by herniated disc material [20], other investigators have revealed disc protrusion or herniation on post-mortem

Scientific rationale for corticosteroid use

Lindahl and Rexed first noted inflammation, edema, and proliferative or degenerative changes in biopsy samples from posterior nerve roots of patients undergoing laminectomy [29]. Berg, using myelography, observed a consistent reduction in the swelling of involved nerve roots coincident with improvement in the patient's sciatic symptoms [30]. Green [31] reported a similar improvement in a patient treated with intramuscular dexamethasone.

In 1990, Saal et al. demonstrated an immunocompetent

Clinical effectiveness

Proving that steroid injections are effective has been difficult. Systematic reviews (such as the Cochrane Collaboration) depend on high-quality randomized controlled studies for data, putting emphasis on the methods and criteria of the studies selected. Clinical studies of epidural steroid therapy have, by and large, suffered from one or more of the following flaws:

  • 1)

    Lack of appropriate controls;

  • 2)

    Lax treatment protocols, introducing a variety of concurrent therapies along with the epidural

Causes of treatment failure

Considering the inconsistent outcomes reflected in these studies, surprisingly little has been said about factors predisposing patients to failure of epidural steroid therapy. Although psychosocial factors have long been recognized with respect to surgical and overall outcomes, only a few studies have specifically addressed these issues with respect to epidural injections.

Jamison et al. identified four factors that predicted a poor outcome among patients with chronic low back pain [80]: 1)

What constitutes an adequate epidural injection?

Treatment approaches vary from center to center, but some basic principles are generally observed. As in any treatment of spine patients, patient selection often dictates the likelihood of success. For the most part, epidural steroid therapy should be reserved for patients with symptoms of radiculopathy. Even then, patients with radicular symptoms resulting from spinal stenosis are less likely to benefit than those with disc herniation [77]. Patients with diabetes, or with any signs of

Transforaminal epidural injection

In the transforaminal approach, a smaller gauge blunt needle is used to introduce the steroid into the epidural space via the intervertebral foramen [93]. This technique allows placement of pharmacological agent very close to the irritated nerve root. Unlike the translaminar approach, transforaminal epidural injections have been considered the most advantageous in reaching the ventral thecal sac, the cardinal site of the pathology. The procedure is done with the patient in prone position and

Summary

Clinical studies have alternately supported and refuted the efficacy of epidural steroids in the treatment of patients with back and leg pain. Groups studied have had mixed pathologies, some of which present no inflammatory component on which steroids might be expected to act.

Steroid medications do benefit some patients with radicular pain, but the benefit is often limited in duration, making efficacy difficult to prove over time. Steroids appear to speed the rate of recovery and return to

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