OBJECTIVE: Fibromyalgia (FM) is characterized by pain and fatigue, particularly during physical activity. Transcutaneous electrical nerve stimulation (TENS) activates endogenous pain inhibitory mechanisms. This study was undertaken to investigate if using TENS during activity would improve movement-evoked pain and other patient-reported outcomes in women with FM.
METHODS: Participants were randomly assigned to receive active TENS (n = 103), placebo TENS (n = 99), or no TENS (n = 99) and instructed to use it at home during activity 2 hours each day for 4 weeks. TENS was applied to the lumbar and cervicothoracic regions using a modulated frequency (2-125 Hz) at the highest tolerable intensity. Participants rated movement-evoked pain (primary outcome measure) and fatigue on an 11-point scale before and during application of TENS. The primary outcome measure and secondary patient-reported outcomes were assessed at baseline (time of randomization) and at 4 weeks.
RESULTS: After 4 weeks, a greater reduction in movement-evoked pain was reported in the active TENS group versus the placebo TENS group (group mean difference -1.0 [95% confidence interval -1.8, -0.2]; P = 0.008) and versus the no TENS group (group mean difference -1.8 [95% confidence interval -2.6, -1.0]; P < 0.0001). A reduction in movement-evoked fatigue was also reported in the active TENS group versus the placebo TENS group (group mean difference -1.4 [95% confidence interval -2.4, -0.4]; P = 0.001) and versus the no TENS group (group mean difference -1.9 [95% confidence interval -2.9, -0.9]; P = <0.0001). A greater percentage of the patients in the active TENS group reported improvement on the global impression of change compared to the placebo TENS group (70% versus 31%; P < 0.0001) and the no TENS group (9%; P < 0.0001). There were no TENS-related serious adverse events, and <5% of participants experienced minor adverse events from TENS.
CONCLUSION: Among women who had FM and were on a stable medication regimen, 4 weeks of active TENS use compared to placebo TENS or no TENS resulted in a significant improvement in movement-evoked pain and other clinical outcomes. Further research is needed to examine effectiveness in a real-world setting to establish the clinical importance of these findings.
Most patients noticed that they received verum TENS, so a large placebo effect can be expected. The effects are relatively small and only regard pain. All of the many other outcome measures did not show any difference. Improvement is only shown during TENS; no long term effects are studied.
Almost every kind treatment may be effective in the short term in fibromyalgia, but the major problem is that the disease is chronic.
Although the authors did not measure this, apparently the difference between the active TENS group and the TENS placebo group is of similar magnitude to those between the TENS placebo group and the non-TENS group. In other words, does the TENS placebo have an effect? Real world study is really needed.
The paper is of peripheral interest to general neurologists, who would refer such patients to rheumatologists or pain clinics. The study was reasonably well conducted. However, there were a number of concerns as participants were not very well blinded, (70%) could tell they were receiving active treatment. Also there is a strong placebo effect in that the sham treatment cases did quite well compared to the "no treatment" group. However, the authors are to be commended for taking this to the step of using TENS during activity. It may be beneficial and worth considering for fibromyalgia patients with at least moderate pain and associated problems.
This phase II double blind placebo controlled trial of the use of TENS machines in patients with Fibromyalgia looked at movement related pain and fatigue before and while using a TENS machine. There was a significant improvement in both outcome measures in patients using TENS machines compared to sham TENS and no TENS patient groups. The trial only lasted 4 weeks so it is unclear how durable these results are and whether this could be a viable long term treatment for Fibromyalgia patients. However, given the limited efficacious treatment options available for such patients, this treatment modality is worthy of further research to establish its place in the management of Fibromyalgia.
With pharmacologic treatment being not very effective, it becomes frustrating both for the patients and the treating physicians. I hope TENS works.
The placebo effect is very important even in fibromyalgia; this is similar as with treatment.
This is a small trial with little clinically important benefit. Placebo TENS is almost as good as real TENS. It's safe and inexpensive though, so there may be a place for its use for some patients.