09/25/2024
Spine implant for back pain
The Food and Drug Administration reported in 2020 that about 50,000 spinal cord stimulators, devices intended to reduce chronic pain using electrical impulses, were being implanted annually — and that over four years the agency had received 108,000 reports of patient injuries, including 497 deaths, and malfunctioning stimulators.
Annual implantations are likely to have risen since, as doctors seek substitutes for prescription opioids. Do these stimulators work?
Here the dilemma is not lack of evidence but contradictory claims and conflicting findings, with researchers arguing about methodologies and results — a confusing landscape for patients desperately seeking relief.
Pain doctors consider a treatment effective if it reduces pain by half in 50 percent of patients. Potentially confounding such results, however, is the potent placebo effect.
For patients, “the more you have invested, the more likely you are to see an effect,” said Dr. Rita F. Redberg, a cardiologist at the University of California, San Francisco, and a co-author of a recent study in JAMA Neurology.
A surgically implanted generator, with wires inserted into the space around the spinal column, constitutes a major investment. Such studies are not easily blinded, as in most clinical drug trials; patients know they have received stimulators.
The new study analyzed insurance claims data for 7,500 patients (average age: 64) suffering chronic pain, most after failed back surgery. “We did careful matching so we could compare outcomes,” Dr. Redberg said.
Over two years, the 1,260 patients using spinal cord stimulators didn’t have lower use of opioids, or most other pain treatments, than did those pursuing conventional medical management without implantation.
“They wanted to feel better, but they didn’t,” Dr. Redberg said. Moreover, about one patient in five had the device removed or required a second surgery to repair or relocate it.
Two Cochrane reviews, meta-analyses by an independent network of researchers, have found “low to very low certainty evidence” that stimulation reduces pain intensity and “little to no sustained benefit” for low back pain.
Pain specialists and professional organizations were quick to criticize the new study’s methodology, however.
“That’s a very imprecise criteria to judge someone’s pain relief by — the amount of medication they take,” said Dr. Konstantin Slavin, a neurosurgeon at the University of Illinois, Chicago, and president of the International Neuromodulation Society.
“That doesn’t correlate with patients’ self-reported experiences.”
Although the technology is improving rapidly, supporters acknowledge that spinal cord stimulation has limitations. It may help some patients with nerve pain but won’t relieve arthritis pain, pointed out Dr. Lawrence Poree, director of the Neuromodulation Service at U.C.S.F.
“When patients have the expectation of being pain-free with spinal cord stimulation, that just doesn’t happen,” Dr. Slavin said. But “improved ability to function, to enjoy life, we definitely can accomplish that.”
Patients should probably proceed with caution. The F.D.A. recommends a stimulation trial for several days, with the generator taped to the body. Only those experiencing substantial pain relief should go ahead with implantation, Dr. Poree said.
For now, disputes continue. “We all want to help patients with pain,” Dr. Redberg said. “This is not the way to do it.”
Some treatments and procedures become routine despite lacking strong evidence to show that they’re beneficial. Recent studies have called a few into question.
