Transcutaneous Electrical Nerve Stimulation(TENS) is a non-medicine, non-invasive treatment to relief pain. By stimulating the sensory nerves with a mild electrical current(usually less than 25 µC in a specific unit of time), to block the signal of pain transmitting to the brain, pain relief effect is then achieved.

Clinical researches approved that a TENS device made with the principle is effective in the relief of dysmenorrhoea, an alternative to the pain medicine. For the benefit of without the side effects of taking conventional medicine, TENS devices have been widely used in the Western countries for many years.

Symptoms of pain

TENS device is class II medical device defined by the US FDA, it is effective in the relief of pain including symptomatic relief of chronic intractable pain, relief of acute post-surgical and post-traumatic pain, and relief of pain associated with arthritis. [1]

Dysmenorrhoea

Dysmenorrhoea is an experience of lower abdomen pain during a menstrual period of women. Primary dysmenorrhoea is defined as the pain with unclear causes and secondary dysmenorrhoea is defined by the causes of Pathological factors(suggested by Beard and Pearce in 1989). It is believed that dysmenorrhoea is associated with the release of prostaglandin, the prostaglandin causes the muscular layer of the inner wall of the uterus to contract excessively, thus limiting blood supply to certain portion of the uterus. Successful treatment of dysmenorrhoea relief is depending on the use of prostaglandin synthetase inhibitors. Because of unacceptable side effects, some women cannot take these medicine for the treatment of dysmenorrhoea. So, it is valuable to use non-medicine alternatives to relief menstrual pain. [2]

Clinical researches

Clinical researches approved that a TENS device made with the principle was effective in the relief of dysmenorrhoea, TENS devices have been widely used in the Western countries for many years.

In researches, the effects of TENS device were compared with pain medicine and placebo. The pain relieving outcomes of TENS were satisfactory in general. Kaplan conducted a research in 1994, firstly, data of pain scores were collected from a group of 61 women for their two recent cycles of menstrual period, these data were used to calculate the base of pain score. Then, during the next two cycles of period, TENS devices were used, the electrodes of TENS device were applied to the skin over the position of the spinal T10, T11, and T12(ends of sensory nerve fibers of uterus). Collecting pain scores again for the later two periods from the group, the result of analysis were 59% of patients received moderate pain relief, 31.2% were without any pain at all, and 10% were no changes of pain felt.

A study of a sample of 20 patients conducted by Neighbors in 1987, by using TENS of acupunctural type comparing with the group of using placebo, received significant pain relieving effects(p<0.05). The placement of TENS electrodes were 4 acupuncture points, B21, B29, ST35 and SP6.

A research of using typical TENS device compared with placebo TENS was conducted by Mannheimer and Whalen in 1985, electrode pads of two channels were crossly placed on both sides of the patient's navel and the anterior superior spine, while acupunctural TENS at SP6 and SP10 acupunctural points. In the research, all treatment time were set at 30 minutes, patients were advised that they could resume the use of the device at home whenever menstrual pain arisen . The result indicated that either the percentage of score of pain reduced (p<0.05), or the duration of pain reduced (p<0.1), the typical TENS is more effective than the placebo TENS.

The above three researches approved the effect of TENS to relief pain is positive, but how it would compare with the use of menstrual pain reduction medicine? The following two researches could provide answers to the question.

In 1990, a research was done by Dawood and Ramos, in which, 32 patients with symptoms of primary dysmenorrhoea randomly used 3 types of pain reduction methods during 4 consequential menstrual periods, TENS device, placebo TENS, and ibuprofen: use TENS device twice, use placebo TENS once, and ibuprofen once. The electrode placement of TENS was the same as Kaplan did in their 1944, that was the T10-T12 skin positions. The treatment time was set at a longer duration of 8 hours, then, resume use as needed. When using TENS and placebo TENS, to record if "emergency medicine such as ibuprofen" were needed as an extra mean of pain reduction, and the dose of use. The result indicated that compared to the other two methods of treatment, when using TENS device, the need of using "emergency medicine" to reduce pain is much less by the number of patients (p<0.01); also, when TENS was used, the time of needing extra pill of ibuprofen were prolonged (p<0.05).

The last research was conducted by Milsom in 1994, directly compared the use of TENS and a single dose of naproxen, in two menstrual periods. Both treatments significantly reduced the menstrual pain, but interestingly, the active parameters of uterus were significantly reduced(p<0.01) when using naproxen, while no changes during the TENS treatments. That is, the pain relief of TENS is not related to the pressure of the uterus. The authors discussed some possible theories, and figured that pain relief effect of TENS may come from the reduction of the degree of anemia to the muscle of partial uterus due to local blood circulation and supply of oxygen.

Treatment procedure

Connect electrode pads with lead wires to the TENS device made according to TENS principles with accurate electrical stimulation output, place the self adhesive electrodes on the skin at the specific positions of lower abdomen. Pain relief is immediately felt when the device is working properly.

Note:

Only use electrode pads with biocompatible materials;

The electrode pads shall only be applied to intact and healthy skin without wound.

[1]. Class II Special Controls Guidance Document: Transcutaneous Electrical Nerve Stimulator for Pain Relief   ．USFDA．2010-04-05[date of introduction 2015-01-06]

[2]. Deirdre M. Walsh．TENS: Clinical Applications and Related Theory．New York, USA：CHURCHILL LIVINGSTONE, 1997 pages:84 - 86

Reference: this article is an English translation of "痛经的电刺激(TENS)止痛法" from Baidu.com/百度百科