Transcutaneous electrical nerve stimulation reduces pain, fatigue and hyperalgesia while restoring central inhibition in primary fibromyalgia. Pain. 2013 Nov;154(11):2554-62. Dailey DL, Rakel BA, Vance CG, Liebano RE, Amrit AS, Bush HM, Lee KS, Lee JE, Sluka KA.
Because transcutaneous electrical nerve stimulation (TENS) works by reducing central excitability and activating central inhibition pathways, we tested the hypothesis that TENS would reduce pain and fatigue and improve function and hyperalgesia in people with fibromyalgia who have enhanced central excitability and reduced inhibition. The current study used a double-blinded randomized, placebo-controlled cross-over design to test the effects of a single treatment of TENS with people with fibromyalgia. Three treatments were assessed in random order: active TENS, placebo TENS and no TENS. The following measures were assessed before and after each TENS treatment: pain and fatigue at rest and in movement; pressure pain thresholds, 6-m walk test, range of motion; 5-time sit-to-stand test, and single-leg stance. Conditioned pain modulation was completed at the end of testing. There was a significant decrease in pain and fatigue with movement for active TENS compared to placebo and no TENS. Pressure pain thresholds increased at the site of TENS (spine) and outside the site of TENS (leg) when compared to placebo TENS or no TENS. During active TENS, conditioned pain modulation was significantly stronger compared to placebo TENS and no TENS. No changes in functional tasks were observed with TENS. Thus, the current study suggests TENS has short-term efficacy in relieving symptoms of fibromyalgia while the stimulator is active. Future clinical trials should examine the effects of repeated daily delivery of TENS, similar to the way in which TENS is used clinically on pain, fatigue, function, and quality of life in individuals with fibromyalgia.
In practical terms it’s not exactly breaking news, as just about every fibromyalgia patient I see already owns one or more TENS machines. However, this is an interesting study because it showed immediate positive effects on central sensitization. After my last blog on central sensitization and chronic pain, I looked up more research with regards to the effects of TENS, since central sensitization sounded like the opposite effect of gate control theory. TENS was designed specifically to make use of gate control theory to reduce pain, and as expected, here’s a study that showed a single treatment of TENS decreased pain, fatigue, and hyperalgesia (pain sensitivity) by lessening central sensitization/restoring central inhibition of pain.
Parameters in this study were:
- Waveform: not given
- Rate: 100 Hz
- Pulse duration: 200 uS
- Treatment Duration: 30 minutes
- Pulse amplitude: maximum tolerable without pain (average 39.93 mA
- Duty cycle: continuous
The researchers agree they need to test for cumulative improvements over time. They also noted that they did not decrease pain at rest but did decrease pain with movement. They recommended wearing the device while exercising, which sounds reasonable. While TENS had positive effects in this study, in my physical therapy clinic I notice even greater reductions in pain and improvements in function with EMS parameters (electric stimulation parameters designed to increase muscle strength), rather than with TENS parameters. The benefits of EMS over TENS parameters (even for pain) are great enough that I always search for research on EMS first for a given condition. Unfortunately with fibromyalgia I have yet to find any studies, so you have to take what you can get. Anecdotally though, EMS works so much better that I almost never use TENS anymore. The difference between them is only a few button pushes on the same machine anyway.
As always, if you have any further questions or need for clarifications, please don’t hesitate to ask. Being aware that some of my blog ideas are contentious and occasionally a bit out of the field of my expertise, I encourage my readers to come forth with any questions/comments that are of interest or concern. Your comments are valued and welcomed.
Chad Reilly is a licensed physical therapist, located in North Phoenix, practicing science based medicine with treatment protocols unique and effective enough to proudly serve patients from Phoenix, Scottsdale, Mesa, Chandler, Tempe, Peoria, and Glendale.