April 8, 2009
Can TENS Provide Back Pain Relief? Transcutaneous Electrical Nerve Stimulation – is it just a placebo?
Transcutaneous Electrical Nerve Stimulation (also known as TNS or TENS) involves passing an electric current through the body via electrodes taped to your skin. The TENS unit itself is a small battery-operated box about the size of a Walkman radio or a PDA.
TENS is considered by some to be the electrical equivalent of acupuncture or acupressure. It reportedly can provide pain relief for anywhere from a few hours up to several days.
How does a TENS unit provide pain relief?
There are two basic theories that proponents of TENS use to explain how pain relief is accomplished with the TENS unit. The first is known as the gate theory and the second is called the endorphin theory. And, if they are valid, it would seem that both probably play a part in the process.
TENS and the Gate Theory
The gate theory hypothesizes that nerves are only able to carry one signal at a time. By over-stimulating those nerves with electrical current the TENS unit is able to confuse the brain and, thereby, block the real pain signals from getting through.
TENS and the Endorphin Theory
The second theory is that the TENS unit stimulates the production of the body’s own natural morphine-like substances known as endorphins. It is believed that electric current stimulates certain nerves, which in turn send messages to the brain causing it to release these natural pain relief chemicals. These endorphins then act in a similar manner to conventional narcotics to provide the body with overall pain relief.
Do TENS units really work?
If you do much study into TENS you will find that it falls into a category of pain relief modalities known as hyperstimulation analgesia. These hyperstimulation treatments include such things as acupuncture, acupressure, massage and vibration and all have one thing in common. They all produce about the same pain relief results as a placebo.
A study published in the New England Journal of Medicine in June 1990 casts considerable doubt upon the effectiveness of TENS. The study found “that for patients with chronic low back pain, treatment with TENS is no more effective than treatment with a placebo, and TENS adds no apparent benefit to that of exercise alone.”
And most recent studies all seem to confirm this assessment:
There were no statistically significant differences between the active TENS group when compared to the placebo TENS group for any outcome measures… 
A meta-analysis of studies of TENS therapy… found that both TENS and sham TENS significantly reduced pain intensity; no significant differences were found between the two for either analgesic use or pain intensity. These results suggest that, just as with some other interventions, part of the efficacy of TENS can be attributed to a placebo effect. [2,3]
TENS vs. Sham TENS… Fourteen trials were included. None found any difference. 
Seven trials compared opioid plus TENS with opioid alone, four of which also included sham TENS. Five of seven trials reported no difference between groups. 
They could find no study of note showing any difference in pain intensity or pain relief scores between TENS and a placebo treatment during labor. 
In other words, fake TENS – just like fake acupuncture – is just as effective as the real thing. At least as far as the scientific studies have been able to ascertain. This doesn’t mean that they don’t work. Only that the benefit appears more likely to be a psychological one than a real reliable means of achieving pain relief.
To put it another way, there is no concrete proof that TENS actually works and there is a great deal of doubt.
TENS and lower back pain
Almost all the studies are in agreement that TENS does not seem well suited for the treatment of low back pain:
The results of the meta-analysis present no evidence to support the use of TENS in the treatment of chronic low back pain. 
For acute back pain, there is no proven benefit. Two small studies produced inconclusive results, with a trend toward improvement with TENS. In chronic back pain, there is conflicting evidence regarding its ability to help relieve pain. One study showed a slight advantage at 1 week for TENS but no difference at 3 months and beyond. Other studies showed no benefit for TENS at any time. There is no known benefit for sciatica. 
Transcutaneous electrical nerve stimulation (TENS) has been used to treat a variety of pain conditions… It is generally used in chronic pain conditions and not indicated in the initial management of acute low back pain. 
And yet some doctors do prescribe TENS for low back pain and some people do seem to find it to be helpful.
Should you stop using TENS?
Does this mean you should stop using your TENS unit if you are achieving satisfactory results with the device? No, of course not. If you’ve already invested in one and you’re happy with it who cares how or why it works?
The bottom line is if something works for you and you are happy with the results then by all means stick with it. What does it matter if TENS is, in fact, just a placebo?
On the other hand, if you’re just now considering the purchase of a TENS unit, you may want to dig deeper into the research before you make that leap. TENS units aren’t cheap and there are better alternatives available.
What we do know about TENS
What we do know about TENS is that it is completely safe when used as directed and non-addictive. Something that conventional narcotics can’t match.
But perhaps most importantly, TENS cannot correct an underlying mechanical problem. It does not actually fix or heal anything and the effects – if any – are only temporary. Rebuilding your back is still the only real solution for long-term back pain relief.