Epidural steroid injection for low back pain

Published on 07/02/2015 by admin

Filed under Anesthesiology

Last modified 07/02/2015

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Epidural steroid injection for low back pain

Caridad Bravo-Fernandez, MD

Low back pain (LBP) is common among those seeking medical care; the lifetime prevalence of LBP varies between 60% and 80%. Recurrent episodes of LBP are also common, especially within 12 months of the first occurrence. For manual laborers, LBP may cause absence from work from 30 weeks to 140 weeks over an entire 40-year career.

Multiple therapeutic measures and techniques have been used to treat acute episodes of LBP, and almost all are equally effective—whatever the intervention, the LBP usually resolves within 2 weeks. However, an alternate treatment path may be appropriate for those patients whose pain persists longer than 2 weeks and who, on evaluation, are found to have evidence of radicular pain or of a radiculopathy and whose imaging studies are indicative of spinal stenosis, spondylolysis, or a protruding nucleus pulposus of an intervertebral disk. Many believe that a herniated disk causes radicular pain only if it initiates an inflammatory process mediated through interleukins and tumor necrosis factor-α. In these patients, a course of 1 to 3 epidural steroid injections (ESIs) with or without a local anesthetic (occasionally also with an opioid or clonidine) may be indicated to inhibit the release of these cytokines and to diminish inflammation, subsequently diminishing pain.

Site of injection

The translaminar approach has been the traditional approach to the epidural space—using anatomic landmarks and a loss-of-resistance technique to place a Tuohy needle in the epidural space—and is still commonly used in many academic pain departments. The practice is changing, however, and many anesthesia providers especially those in private practice, are more likely to use fluoroscopy and the transforaminal approach to deposit solution at the site of the nerve root that is involved in the radiculopathy or radiculitis. When administering epidural injections under fluoroscopic guidance, nonionic radiographic dyes, such as iopamidol (Isovue) and iohexol (Omnipaque), are used to confirm location but may precipitate an allergic response. The use of fluoroscopy and contrast dye provides evidence of delivery of medication to the appropriate nerve root. When the transforaminal approach is used, the volume of injectate is smaller than that used for the translaminar approach; with the latter, saline is usually used to increase the injectate volume, increasing the likelihood that the active medications—steroids, local anesthetic agents, or a combination of both—will reach the affected site.

The caudal approach from the sacral canal was used frequently in the past, but it is not commonly used in current practice. However, good results have been demonstrated with the lumbar approach.

Technique

Few studies have evaluated the use of sedation in performing ESIs, but the existing evidence suggests that many practitioners provide some sedation, with appropriate monitoring, using either small amounts of midazolam or fentanyl. Translaminar needle placement is usually performed with the patient in the sitting, lateral, or prone position. The patient is usually prone for transforaminal injections, using the fluoroscope to take lateral images of the spine. As with any invasive procedure, documentation of the appropriate patient, site, and intervention are mandatory, as is the use of sterile technique.

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