Low Intensity Permanent Magnets in the Treatment of Chronic Lumbar Radicular Pain

We assessed the pain-relieving efficacy of static magnetic fields produced by 200 Gauss (G) magnets compared with 50 G magnets in a double-blind, randomized, two-phase crossover study in patients with chronic lumbar radicular pain. The surface field strengths of the magnets were 200 and 50 G. Phase I included four random periods of two-week duration: two periods with 200 G, one period with 50 G, and one period of "no treatment." The magnets were positioned either vertically or horizontally in standard lumbosacral elastic corsets. Phase II consisted of two five-week periods with the most effective magnet from Phase I and its corresponding 50 or 200 G device. The primary outcome was average daily leg pain score (0-10 scale) in each period of Phase II. Thirty-eight of 40 randomized patients completed Phase I, and 28 of 31 Phase II participants completed the study. In Phase I, pain scores did not differ significantly between 200 and 50 G magnets. Phase II average leg pain scores tended to be lower with 200 vs. 50 G magnets (3.2 ± 2.1 for 200 G vs. 3.9 ± 2.2 for 50 G magnets [P = 0.08]) after excluding one unblinded patient. The relative treatment effect of the 200 G magnets appeared to increase throughout the five-week period. Although these data cannot rule out a chance effect, the positive trends suggest that larger, longer-duration, sham-controlled trials with 200 G magnets be considered in patients with chronic lumbar radicular pain.