Transcutaneous electrical nerve stimulation and acupuncture for primary dysmenorrhoea

Dysmenorrhoea is the occurrence of painful menstrual cramps of the uterus. Medical therapy for dysmenorrhoea commonly consists of nonsteroidal anti-inflammatory drugs or the oral contraceptive pill both of which work by reducing myometrial (uterine muscle) activity. However, these treatments are accompanied by a number of side effects, making an effective non-pharmacological method of treating dysmenorrhoea of potential value. Transcutaneous electrical nerve stimulation (TENS) is a treatment that has been shown to be effective for pain relief in a variety of conditions. Electrodes are placed on the skin and electric current applied at different pulse rates (frequencies) and intensities is used to stimulate these areas so as to provide pain relief. In dysmenorrhoea. TENS is thought to work by alteration of the body's ability to receive or perceive pain signals rather than by having a direct effect on the uterine contractions. Acupuncture may also be indicated as a useful, non-pharmacological method for treating dysmenorrhoea. Acupuncture is thought to excite receptors or nerve fibres which, through a complicated interaction with mediators such as serotonin and endorphins, blocks pain impulses. Acupuncture typically involves penetration of the skin by fine, solid metallic needles, which are manipulated manually or by electrical stimulation.

To determine the effectiveness of high and low frequency transcutaneous electrical nerve stimulation and acupuncture when compared to each other, placebo, no treatment, or medical treatment for primary dysmenorrhoea.

Electronic searches of the Cochrane Menstrual Disorders and Subfertility Group Register of controlled trials, CCTR (Cochrane Library Issue 3, 2001), MEDLINE, EMBASE, CINAHL, Bio extracts, PsycLIT and SPORTDiscus were performed in August 2001 to identify relevant randomised controlled trials (RCTs). The Cochrane Complementary Medicine Field's Register of controlled trials (CISCOM) was also searched. Attempts were also made to identify trials from the UK National Research Register, the Clinical Trial Register and the citation lists of review articles and included trials. In most cases, the first or corresponding author of each included trial was contacted for additional information.

The inclusion criteria were randomised controlled trials of transcutaneous electrical nerve stimulation and acupuncture that compared these treatments to each other, placebo, no treatment, or medical treatment for primary dysmenorrhoea. Exclusion criteria were: mild, infrequent or secondary dysmenorrhoea and dysmenorrhoea associated with an IUD.

Nine RCTs were identified that fulfilled the inclusion criteria for this review, seven involving TENS, one acupuncture, and one both treatments. Quality assessment and data extraction were performed independently by two reviewers. Meta analysis was performed using odds ratios for dichotomous outcomes and weighted mean differences for continuous outcomes. Data unsuitable for meta-analysis was reported as descriptive data and was also included for discussion. The outcome measures were pain relief (dichotomous, visual analogue scales, descriptive), adverse effects, use of analgesics additional to treatment and absence from work or school.

Overall high frequency TENS was shown to be more effective for pain relief than placebo TENS. Low frequency TENS was found to be no more effective in reducing pain than placebo TENS. There were conflicting results regarding whether high frequency TENS is more effective than low frequency TENS. One small trial showed acupuncture to be significantly more effective for pain relief than both placebo acupuncture and two no treatment control groups.

High frequency TENS was found to be effective for the treatment of dysmenorrhoea by a number of small trials. The minor adverse effects reported in one trial requires further investigation. There is insufficient evidence to determine the effectiveness of low frequency TENS in reducing dysmenorrhoea. There is also insufficient evidence to determine the effectiveness of acupuncture in reducing dysmenorrhoea, however a single small but methodologically sound trial of acupuncture suggests benefit for this modality.