Is "Transcutaneous electrical nerve stimulation" (TENS) effective?

Question

I have recently become aware of TENS, but have yet to find any definitive evidence it is either a legitimate treatment or a full-blown pseudo-science.

The closest was this BBC article:

Some of the claims made for TENS could lead you to think it's the miracle cure for pain. Back pain, arthritis, migraine, sports injuries, period pains and even non-painful conditions such as sleeplessness and stress are said to improve with its use.

But while TENS is widely recommended in the UK as a way of controlling labour pain, a review by the Pain Research Unit at Oxford University, published in 1997, found that evidence for it having an analgesic effect in such circumstances was weak. The unit could find no study of note showing any difference in pain intensity or pain relief scores between TENS and a placebo treatment during labour. There has not been any substantial study since, supporting its use.

Can anyone link or summarise some decent papers investigating TENS?

Is this a niche treatment that salespeople are trying to push into the mainstream?

Edit: With out any research my own rational explanation for pain relief in child birth is due to a placebo effect combined with allowing the mother to "control" the pain the same way hypnobirthing works.

Answer 1

I can link you to an excellent article¹, but unfortunately it is in dutch. I shall try to translate parts, and provide the linked articles too.

The article starts with some history and explanation. It seems that the makers of the TENS apartus claim it has some evidence. In 1950 it was banned by the FDA (the provided link is in dutch also). A new theory² about how pain works was introduced and claimed to be the working of TENS, but this was never proven at this point.

As of the proof, the point is made that it's not easily possible to perform a double blind test, as the electrical stimulation is felt. One can do meta-studies about the studies that are published (PubMed etc), and these are laid out in the artcicle (making it a meta-meta article). One of the good studies (score of '3', if that says anything to you) concludes that there is not much difference³

There are several other studies mentioned which are either concluding that there is no effect, or do find an effect, but have a low quality.

As a final thought, one of the referenced books' writer (who was first claimed to point to accupuncture as a valid scientific treatment) responded to the article. In this part he references some different studies. Using the words "TENS" and "clinical trial" and "human" he finds 210 'effectiveness studies'. These studies are measured using "systematic reviews".

He references a study that concludes there is short term diminishing of pain⁴, some research that says more research is to be done⁵. He cites some other research, but this rings some warning bells in my head: (rough translation, sorry)

TENS can, when used informed and guided correctly, lead to an active role of the patient, lowering of cost and improvement of functioning

More of the references linked to this part of the article are found under "more references"

This article of the dutch skeptical society leads me to believe that although there is some research in favor of TENS, that just as with accupunture, the evidence leads one to think it is more of an alternative medicine, and not real Science Based Medicine.

Labour pain
On this point I can link you to an article ⁶ which does a systematic review of excisting research. The results are that the quality on a scale of 1 to 5, there was only 1 that got a good grade, with a typical 2.1 average. The conclusion is that there is no evidence of pain-relief with TENS in labour.

^{[1]: http://www.skepsis.nl/tens.html
[2]: Melzack R, Wall PD, Pain mechanisms: a new theory. Science 150 (1965), p.971- [3]: Aker PD, Gross AR, Goldsmith CH, Peloso P, Conservative management of mechanical neck pain: systematic overview and meta-analysis. BMJ 313 (1996), p.1291-1296.}

^{[4]: Osiri M, Welch V, Brosseau L et al. Transcutaneous electrical nerve stimulation for knee osteoarthritis (Cochrane review). Cochrane Library, Issue 4, 2000.}

^{[5]: Carroll D, Moore RA, McQuay HJ et al. Transcutaneous electrical nerve stimulation for chronic pain (Cochrane review). Cochrane Library, Issue 4, 2001.}

^{[6]: Caroll D et al, Transcutaneous electrical nerve stimulation in labour pain: a systematic review. Br J Obstet Gynaecol 104 (1997), p.169-175.}

More references

^{Scherder E. Peripheral nerve stimulation in Alzheimer's disease (thesis). Vrije Universiteit, Amsterdam, 1995.}

^{Jongste MJL de. Neurostimulation as an adjunct therapy for patients with intractable angina pectoris (thesis). Rijksuniversiteit Groningen, 1994.}

^{Fishbein DA, Chabal C, Abbott A et al. Transcutaneous electrical nerve stimulation: treatment outcome in long term users. Clin J Pain, 1996, 12: 201-14.}

Answer 2

From what i've read about pain, it's very susceptible to placebos and distraction therapy. there's a good general pain article at http://www.myelitis.org/pain.htm and to quote from another, http://www.medindia.net/news/view_news_main.asp?x=210

"at Controlling pain in patients following surgeries has been effectively taken care of by a new therapy called distraction therapy. Doctors at the Johns Hopkins Medical Institutions in the US have distracted patients with images and sounds from nature and have successfully controlled pain in patients following a painful procedure called bronchoscopy, which involves inserting the tube into the nose or the throat to see the lungs."

I couldn't see any evidence that TENS is more than a distraction therapy.

Answer 3

There doesn't seem to be anything definitive anywhere. Some people claim it works, some people claim that it doesn't. Pain is subjective enough that you can get away with that sort of result. There is plenty of research dealing with people who have debilitating pain without any sort of obvious problem, so it stands to reason that there could be a device that could deal with pain without any obvious mechanism.

Historically, electricity has been a very fruitful resource for quack medicine: Electropathy, electric hairbrushes to grow hair, belts to build muscles and fix (hem) "male problems", toothbrushes to stop toothaches, etc, etc, etc. This is a very common trend within scientific advances: I saw "stem cell anti-aging cream" on TV yesterday, and ordered enough to grow my own pizza parlor.

I'll say this: any medical claim that claims to be applicable to that many different types of pain should be viewed with extreme skepticism. I'm also very leery of anything medically electrical that can be bought without a prescription...That suggests to me that it's pretty much impossible to hurt yourself with it, which suggests that it can't be doing very much.