A commonly used treatment for patients who still suffer chronic back and leg pain after having back surgery is essentially no better than specialized pain treatment or standard medical treatment, a study performed in individuals on workers’ compensation shows.

But the findings do not mean that the procedure - spinal cord stimulation - will not help some people, Dr. Ajay D. Wasan of Brigham and Women’s Hospital and Harvard Medical School in Boston notes in a written commentary published with the study in the journal Pain.

Spinal cord stimulation, in which implanted electrodes send small electrical impulses into the spine, has been used since the 1960s for patients with so-called “failed back surgery syndrome,” Dr. Judith A. Turner of the University of Washington in Seattle and her colleagues note in their report. However, questions remain about the procedure’s risks and long-term effectiveness.

Also, they point out, no studies done to date have included patients on workers’ compensation, who are known to fare worse with any type of pain treatment.

To investigate, Turner and her team studied a group of patients with a workers’ compensation claim who had persistent low back and leg pain following previous back surgery.

They compared the outcomes of 51 people who had at least a trial of spinal cord stimulation (27 went on to have the electrodes implanted permanently) with those of 39 people who underwent evaluation at a pain clinic, and 68 who received neither spinal cord stimulation nor specialized pain treatment.

Fewer than 10 percent of the patients in any of the groups showed notable improvements in leg pain and function, or were able to step down from daily use of opioid painkillers, the researchers found.

While the spinal cord stimulation group showed slightly better improvements in leg pain and function at six months, these patients used more opioids than patients in the other two groups. At 12 and 24 months, there were no differences among the three groups.

While the researchers did not compare the outcomes for people who only had a trial of spinal cord stimulation and those who went on to have electrodes implanted permanently, Wasan points out, results for these two groups were “distinctly different,” with 30 percent of people who underwent permanent implantation showing improvement in leg pain and function at two years.

“The average mental health scores in each of the three groups were quite low,” Wasan notes, “suggesting that any study in this patient population is unlikely to find group differences with pain treatment unless psychiatric treatment is part of the intervention.”

While the findings show that spinal cord stimulation is clearly not appropriate for every person with persistent back pain after surgery, Wasan adds, people with radiating pain on one side of the body, those who are functioning better before undergoing the procedure, and those in better psychological health are more likely to benefit.

SOURCE: Pain, January 2010.