July/August 2008
Volume 4, Issue 4

Click on the icon to view the newsletter as a pdf.

Lumbar Epidural Steroid Injections

An Original Contribution by Nilusha Fernando, D.O.

Lumbar epidural steroid injections (ESIs) are a commonly used minimally invasive treatment for low back pain and lumbosacral radicular pain. Radicular pain is often described as a sharp pain that radiates from the spine into an extremity in the distribution of a particular nerve root. Radicular pain often results from inflammation of the nerve root in the epidural space secondary to leakage of herniated disc material or compression of the nerve root secondary to conditions such as spondylolysis or spinal stenosis.

The efficacy of epidural steroids is based on the fact that inflammation of the epidural space and nerve roots secondary to mechanical compression is a significant factor in radicular pain. The analgesic effects of corticosteroids may be due to several factors including the inhibition of phospholipase A2, an important inflammatory mediator, resulting in decreased inflammation. Corticosteroids are also thought to play a role in inhibiting nerve transmission in nociceptive C-fibers as well as in reducing capillary permeability. An advantage of steroids placed directly into the epidural space is the avoidance of the systemic effects of orally administered steroids. Studies have demonstrated that ESIs are most effective in the treatment of acute nerve root inflammation.

An ESI involves the injection of a corticosteroid and, often a local anesthetic, into the epidural space. Lumbar ESIs can be performed using three different approaches to the epidural space: the transforaminal, interlaminar and caudal approaches. The interlaminar approach involves a paramedian or midline approach with the needle entering the skin, the subcutaneous tissue, the paraspinal muscles or the interspinous ligament, and finally the ligamentum flavum which is traversed using a “loss of resistance” technique. The transforaminal approach is employed by placing a needle in the neural foramen just ventral to the exiting nerve root. The advantage of this approach lies in its ability to deliver the corticosteroid in close proximity to the site of pathology, presumably onto an inflamed nerve root. A transforaminal ESI can be diagnostic as well as therapeutic and may help to determine symptomatic from asymptomatic levels of nerve compression in patients with imaging demonstrating multiple levels of involvement or in those patients with a confounding clinical presentation. Caudal ESIs are performed by inserting a needle through the sacral hiatus into the sacral epidural space. Caudal ESIs are indicated for patients with chronic low back pain and/or leg pain who have failed to respond to conservative treatment. The caudal approach is the preferred approach for sacral pain in patients with a history of back surgery. Most pain specialists prefer to use fluoroscopic guidance in directing the epidural needle position, as a blind injection may result in 30%-40% needle misplacement. Fluoroscopic guidance in addition to the use of a contrast medium allows for documentation of appropriate placement of epidural steroids and helps to ensure safety, accuracy and potential efficacy.

Patients who have low back pain, radiculopathy or neurogenic claudication associated with spinal stenosis may be potential candidates for a lumbar ESI. In conjunction with a through history and physical examination, available imaging and electrodiagnostic studies should be reviewed prior to the procedure to help guide the interventionalist as to the best approach for a particular patient. Contraindications to ESIs include uncontrolled bleeding or the use of anticoagulation, local cellulitis near the injection site, systemic infection, a history of significant allergic reaction to any component of the injectate, uncontrolled diabetes mellitus, progressive neurologic deficit and cauda equina syndrome.

When performed by a skilled and experienced clinician in an appropriate setting in carefully selected patients, the risk of complications from ESIs is minimal. The more common risks associated with lumbar ESIs include backache, pain at the injection site, post-procedure headache with or without dural puncture, and bleeding along the trajectory of the injection. Other complications include infection, nerve injury and epidural hematoma.

Although numerous studies exist to support the use of ESIs in the treatment of back pain, other studies have disputed the efficacy of these procedures. Most of the earlier studies that failed to demonstrate the efficacy of ESIs had significant methodological limitations, including the lack of use of fluoroscopic guidance and contrast medium to ensure accurate placement of the steroids. Many of these procedures also failed to document that the injection was performed at the presumed level of pathology, a factor that is critical to the success of ESIs. Several more recent studies have supported the benefits of lumbar ESIs including relief of radicular and low back pain, with radicular pain more improved than low back pain. Other demonstrated benefits include increased quality of life, reduced need for pain medications, improvements in work status and decreased requirements for hospitalization and surgery.

Lumbar ESIs are a commonly used, non-surgical option in the arsenal of treatment available to the pain specialist. These procedures are particularly effective in a well-selected patient population and are best performed in an appropriate setting incorporating the use of fluoroscopic guidance and contrast media to guide accurate needle placement. Lumbar ESIs are often considered after more conservative measures, including medications and physical therapy have failed. These procedures should be considered in patients in whom a physical therapy program has failed or been prematurely terminated due to pain and may be effective in reducing pain and allowing these patients to resume their previous level of activity.§