Another study is raising questions about the value of epidural steroid injections in treating chronic back pain. Researchers at the Agency for Healthcare Research and Quality (AHRQ) say the addition of a corticosteroid to a common anesthetic used in epidural injections does not enhance pain relief in patients with lumbar spinal stenosis.
Over 10 million epidural injections are performed annually in the U.S. to treat spinal stenosis, sciatica and other types of back pain. The practice has become more common in recent years, in part because of a growing reluctance by physicians to prescribe opioid pain medication to their patients. It is also a more lucrative procedure for doctors to perform.
A research team led by Janna Friedly, MD, an assistant professor in the Department of Rehabilitation Medicine at the University of Washington, studied 400 patients with lumbar stenosis being treated at 16 hospitals in the United States. Half of the patients received epidural injections of lidocaine combined with a corticosteroid, while the other half received injections of the anesthetic without a corticosteroid.
The researchers found that patients who received a combination of corticosteroids and lidocaine were more likely to report side effects, and were more likely to absorb the corticosteroid into their bloodstream. Repeated injections of corticosteroids can also result in reduce bone density, increased risk of bone fracture and immunosuppression.
“This is the first large, multicenter randomized trial to look at epidural steroid injections for spinal stenosis, and we found that injection with corticosteroids and lidocaine provided these patients with minimal or no additional benefit over lidocaine injections,” said Friedly, whose study is being published in the New England Journal of Medicine.
Lumbar spinal stenosis is caused by gradual changes in the spine that cause the spinal canal to narrow and press against nerves. This leads to lower back and leg pain, a tingling sensation in the legs and muscle weakness. Stenosis is the leading reason for back surgery in older adults.
“The pain associated with lumbar stenosis can be excruciating, and patients are understandably looking for relief,” said AHRQ Director Richard Kronick, PhD. “This study raises questions about the benefits of combining corticosteroids with an anesthetic for patients with lumbar stenosis, and it will help patients and their physicians make better informed decisions about treatment options.”
The combination of an anesthetic with a corticosteroid in an epidural has been hypothesized to relieve pain by reducing nerve swelling and increasing blood flow. Rates and associated costs of the injections have increased nearly 300 percent over the last two decades.
“Although many injections are used for indications other than spinal stenosis, epidural injections have become almost an expected part of a comprehensive nonoperative treatment protocol in patients with this condition. Yet, evidence to support this practice is incomplete and conflicting,” wrote Gunnar B.J. Andersson, MD, in an editorial also published the New England Journal of Medicine.
In April, the Food and Drug Administration issued a warning about epidural steroid injections, saying they “may result in rare but serious adverse events, including loss of vision, stroke, paralysis, and death.”
The FDA began investigating the safety of the injections after concerns were raised by physicians and patient advocates, and after reviewing its own adverse event database. The agency said an advisory committee will also be formed later this year to discuss the benefits and risks of epidural injections, and whether further FDA action is needed.
Several recent studies have found that epidural steroid injections raise the risk of spinal fractures and often do little to control back pain.