Steroid injections' value for spinal stenosis questioned

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Steroid injections' value for spinal stenosis questioned

UW-led study is largest to evaluate common treatment of low back pain
Michael McCarthy

Epidural injections with a corticosteroid in combination with the local anesthetic lidocaine appear to be no better than injections of lidocaine alone for reducing pain and physical limitations in patients with spinal stenosis, new research suggests. 

UW Medicine
An epidural injection, guided by high-resolution imaging instruments, is a common treatment to relieve stenosis, or narrowing, of the spinal canal.
fluoroscopic image of a spinal injection

Corticosteroids, also known as glucocorticoids, are commonly used to treat inflammation.

The study, which appears in the July 3 New England Journal of Medicine, is the largest, double-blind, randomized clinical trial to examine the effectiveness of this commonly administered treatment. 

In the study, 400 patients with back and leg pain caused by lumbar spinal stenosis were randomly assigned to receive epidural injections containing either the local anesthetic alone or the anesthetic plus glucocorticoids.

"Compared to injections with local anesthetic alone, injections with glucocorticoids provided these patients with minimal or no additional benefit." said lead author Dr. Janna L. Friedly, an assistant professor of rehabilitation medicine at the University of Washington.

The findings call into question the routine use of epidural injections for spinal stenosis, she said. "If patients are considering an epidural injection, they should talk with their doctor about a lidocaine-only injection, given that corticosteroids do pose risks and this study found that they provided no significant added benefit at six weeks."

Lumbar spinal stenosis is often caused by age-related changes in the spine. The spinal canal narrows and compresses the nerves, causing back and leg pain, numbness, tingling, and weakness.

Injections into the epidural, or outermost, space of the spinal canal are common; more than 2.2 million lumbar epidural injections are performed each year in the Medicare population, data indicates. Proponents of the treatment hypothesize that the glucocorticoids relieve pain by reducing swelling and inflammation around the compressed spinal nerves. However, the efficacy of the treatment has been in doubt because it has never been evaluated in a large, multi-center, double-blind, randomized trial.

The new study's main goal was to determine whether any differences in pain or physical limitations emerged six weeks after the injections in the two patient groups. The researchers also looked secondary outcomes including differences at three weeks, patient satisfaction, and depression. 

Clare McLean
Dr. Janna Friedly, a rehabilitation medicine specialist, examines an amputee's leg for the fitting of a prosthesis.
Dr. Janna Friedly, a rehabilitation medicine specialist, examines an amputee's leg for the fitting of a prosthesis.

The extent of pain and physical disability were assessed by asking patients to rate the intensity of their pain on a 0-10 scale and to complete a questionnaire that assesses physical limitations caused by back or leg pain, called the Roland-Morris Disability Questionnaire. Patients completed these measures before the injections and again at three and six weeks afterward.

The study was conducted at 16 medical centers across the United States. Neither the patients nor their doctors knew whether the injections contained the combination of glucocorticoid and lidocaine or lidocaine alone. The study was funded by the U.S. Agency for Healthcare Research and Quality.

Symptoms improved in both groups. At three weeks, those who received glucocorticoid reported slightly less leg pain and slightly better function, but by six weeks, no significant differences existed between the two groups in either pain or function.

Patients who received glucocorticoid reported greater satisfaction with treatment: 67 percent reported being "very" or "somewhat" satisfied, compared with 54 percent of those who received lidocaine alone. They also improved more in depressive symptoms.

The researchers speculate that the higher satisfaction reported by patients with corticosteroid injections may have stemmed from the small benefit experienced at three weeks. Glucocorticoids are also known to improve mood and reduce fatigue. 

However, patients who received corticosteroids also reported more adverse events and were more likely to have low morning serum cortisol levels three and six weeks after the injections. This suggests that the corticosteroid was being absorbed in the general circulation and may have had broad systemic effects, the researchers note. Systemic effects of corticosteroids include reduced bone mineral density, increased risk of bone fractures, and immunosuppression.

Additional studies are needed to ascertain whether the lidocaine-only injections are of any true benefit, Friedly added. "It's unclear how a short-acting anesthetic like lidocaine could have a sustained effect on pain and mobility," she said.