Skip tests and go straight to radiofrequency zaps for back pain: study

by Brendon Nafziger, DOTmed News Associate Editor | July 26, 2010
New research helps
fill in the holes
screening tests might miss
Skipping screening tests and going straight to zapping nerves to relieve suspected arthritis-related back pain could save thousands of dollars while helping treat patients the screening tests might miss, according to new research.

In diagnosing arthritis-related lower back pain, doctors have been debating for years whether patients need one or two screening tests, called nerve blocks, before they should get treatment. But a study published in the August issue of Anesthesiology suggests it might be more cost-effective, and better for patients, to forgo nerve blocks entirely and instead move straight to nerve ablation therapy for patients suspected of arthritis-related back pain after a clinical exam.

"The question in my mind becomes, what do people want?" asked Dr. Steven P. Cohen, lead author of the study, and associate professor at Johns Hopkins School of Medicine and the Uniformed Services University of the Health Sciences. He also directs chronic pain research at Walter Reed Army Medical Center, where part of the work was carried out. "Do you want pain relief and functional improvement, or do you want increased diagnostic accuracy?"

In the nerve-ablation procedure, doctors insert a needle under the skin and track it to its location using real-time X-ray scans, called fluoroscopy. The needles beam out radiofrequency waves that heat and burn the nerves to temporarily dull the pain. Typically, the procedure has published success rates above 60 percent. Pain relief, when it occurs, can last between six months and two years, as the nerves grow back.

But only patients who suffer from arthritis-related back pain, a degeneration of the facet joints, and who are thought to be about one out of 10 sufferers of chronic back pain, benefit from the procedure. So to screen out patients with other sources of pain, such as damaged discs, doctors use the nerve block screening test. In this, physicians usually inject an anesthetic, such as lidocaine, coupled with a steroid, into nerves leading to the facet joints to see if it brings pain relief.

But the nerve blocks aren't terribly accurate, Cohen said.

"Between 25 and 40 percent of people will get pain relief with one block even though they really don't have arthritis causing their pain," Cohen said. The reasons could be the placebo effect, the anesthetic drug numbing other nerves, or the effects of sedation, when used, he said.

Nerve blocks also potentially miss patients by disqualifying ones who really do have arthritis-related back pain and could benefit from the treatment. Studies on the false-negative, or miss rate are scant, Cohen said, with the only evidence really being a nearly 15-year-old study, which in any case looked at a different area of the back. The study found the miss rate was close to 50 percent, he said.