Transcutaneous Electrical Nerve Stimulation for Pain Control in Women With Primary Dysmenorrhea

Is transcutaneous electrical nerve stimulation (TENS) effective and safe in the treatment of primary dysmenorrhea compared with placebo, no treatment, or other treatments?

TENS, regardless of frequency (low = less than 10 Hz; high = more than 50 Hz), seems to reduce pain associated with primary dysmenorrhea compared with placebo or no treatment. It is uncertain whether TENS has a better analgesic effect than acupressure, acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs), and interferential current therapy. The evidence is uncertain about whether there are more or fewer adverse effects with the use of TENS compared with other treatment options.¹ (Strength of Recommendation: B, inconsistent or limited-quality patient-oriented evidence.)

Primary dysmenorrhea is a common concern of menstruating individuals. It is characterized by painful cramps in the lower abdomen, which start shortly before or at the onset of menses, in the absence of pelvic pathology.² Primary dysmenorrhea negatively affects quality of life and tends to be one of the main reasons for absenteeism from school and work in this population.

A TENS machine is a small, portable device with electrodes that can be attached to the skin over an area of pain. It delivers an electrical current intended to block the pain signaling pathway, thus reducing pain perception.² The authors of this Cochrane review wanted to determine if TENS was a suitable nonpharmacologic alternative for the management of primary dysmenorrhea.¹

The Cochrane review included 20 randomized controlled trials with 585 individuals (ages 12–49 years) who had primary dysmenorrhea.¹ These were published between 1985 and 2009. Most of the studies took place in Brazil, the United States, and Sweden, with others in India, Iran, Japan, South Korea, and Taiwan. Pain measurements were recorded using the visual analog scale and/or a numeric rating scale (both measured as 0 [no pain] to 10 [worst pain imaginable]). A categorical scale delineated the number of participants who experienced some level of pain reduction. Out of 20 trials, 4 reported the number of participants who experienced pain relief and 5 reported adverse effects. The amount of time TENS was used varied per study from 20 to 246 minutes, with a mean time of 30 minutes. The certainty of evidence for all outcomes was rated as low to very low.

High-frequency TENS may reduce pain compared with placebo or no treatment (mean difference [MD] = −1.39; 95% CI, −2.51 to −0.28).¹ High-frequency TENS did not increase the incidence of adverse effects compared with other treatments.

Low-frequency TENS may also reduce pain compared with placebo or no treatment (MD = −2.04; 95% CI, −2.95 to −1.14).¹ No adverse effects were reported with its use. Low-frequency TENS may have reduced the mean number of analgesics taken (MD = −3.07; 95% CI, −5.46 to −0.68) compared with placebo or no treatment.

Comparisons between the two modalities revealed that high-frequency TENS did not appear to have a better effect on pain relief compared with low-frequency TENS.¹ Furthermore, the mean lost hours of work and school did not differ significantly between patients using high- vs low-frequency TENS.