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.

Medications used

Steroids commonly used in ESI include triamcinolone, methylprednisolone, betamethasone, and dexamethasone (Table 217-1) and are often combined with a local anesthetic agent, such as lidocaine, bupivacaine, or ropivacaine.

Contraindications and adverse effects

The use of ESI is contraindicated in patients with coagulopathy or who use anticoagulant therapy and in patients who have an active systemic infection or a history of adverse reactions to steroids or any other drug being used. ESI should be used with caution in patients with diabetes.

The use of ESI is associated with a variety of adverse effects (Box 217-1) and is not without risks that must be weighed when assessing the potential benefits. The risks can be divided among those related to placement of the needle and to the adverse effects associated with the drugs. As with the placement of any epidural needle, dural puncture (spinal headache), intrathecal (or intravascular) injection of drug, bleeding and hematoma, infection (e.g., meningitis, abscess), and direct trauma to the cord, nerve roots, or nerves can occur. There are isolated case reports of pneumothorax and quadriplegia or paraplegia occurring.

Conclusion

Limited evidence indicates that ESIs may be effective in treating LBP in some patients, with a long-term success rate of approximately 20%. The best results seem to be obtained in patients with acute radicular symptoms; conversely, the poorest results are in patients with chronic symptoms of axial back pain who have had surgery and those who smoke. In addition, ESIs are being used to provide pain relief from diskogenic pain. Even with all the recent controversies about the lack of randomized controlled studies, ESIs continue to be used and these procedures can be done safely and effectively, providing pain relief to many patients.