Spinal Cord Stimulation May Treat Axial Low Back Pain

Lexa W Lee

February 22, 2007

February 22, 2007 (New Orleans) — Researchers are reporting encouraging preliminary outcomes with the use of spinal cord stimulation (SCS) as a treatment for axial back pain associated with failed-back-surgery syndrome (FBSS).

Unlike radicular or sciatic nerve pain, "axial pain is nonspecific and more difficult to evaluate," said Todd Gross, PhD, director of biostatistics and lead author of this clinical study at Advanced Bionics. The company makes the stimulator used in this study and was the study sponsor.

This was the largest prospective clinical trial to date assessing the efficacy of SCS for axial low back pain in patients with FBSS, the authors say. Results were reported here at the American Academy of Pain Medicine 23rd Annual Meeting.

Little Evidence in Axial Back Pain

Spinal cord stimulation has been used successfully in a number of painful conditions, the authors point out, but to date there has been little evidence of its utility in axial back pain.

In this multicenter study, subjects with FBSS and a primary complaint of axial low back pain were implanted with an SCS system (Precision, Advanced Bionics). Outcomes were assessed after 5 to 10 days, and those subjects who reported a significant reduction in pain during this initial trial and who were appropriate clinical subjects as assessed by their physicians were considered to have had successful trials; most of these subjects were then implanted with a permanent Precision system according to standard clinical procedure.

There were 226 patients enrolled from 14 sites in the short-term trials. "This was essentially a screen for long-term study," said Dr. Gross. Of these, 176, or 76.1%, had successful 5- to 10-day trials and 159, or 70.4%, received permanent SCS implants. As reported by the patients, pain ratings (on a 0 – 10 scale) during the short-term trial showed an average decrease of 40% (3.9 vs 6.6 at baseline; P < .0001). "What's so impressive is that the results were almost immediate," Dr. Gross said.

SCS resulted in a significant reduction of axial low back pain at all time periods from baseline (P < .001). Pain scores, quality-of-life (QoL) assessments, and disability assessments using the Oswestry disability scale were compared with baseline scores at 3 months and, when available, at 6 and 12 months. At the 3.5-month point, after a 2-week period of no SCS, assessments were repeated. A report including all 12-month data is pending.

Preliminary data indicate that pain reduction continues over the long term and is consistent with that observed during the short-term trial, Dr. Gross said. With SCS off, pain scores returned to near baseline. QoL and disability also showed significant improvement with SCS; however, comparisons of these measures with baseline were not undertaken as part of the short-term study.

Dr. Todd Sitzman, anesthesiologist and medical director of the Forrest General Cancer Center in Hattiesburg, Mississippi, commented, "Chronic refractory low back pain following surgery is probably the number-one condition evaluated and treated by chronic pain physicians. The short-term findings are extremely impressive, but we must await the 12-month follow-up data to assess long-term results."

Dr. Gross is an employee of Advanced Bionics.

American Academy of Pain Medicine 23rd Annual Meeting: Abstract 114.