A Transcutaneous Electrical
Nerve Stimulation machine is a remarkable device which can help remove
backache extremely effectively at very low cost and with few side
effects. To understand how it works it would be best to explain how
your body recognises pain.
The gate control theory of pain put forward by two scientists called
Melzack and Wall suggested that when body tissues are damaged, messages
carrying information about the injury travel towards the brain along
two quite separate sets of nerve fibres. The larger fibres carry
messages about sensations other than pain, and the smaller fibres
carry the pain messages. The messages which travel along the larger
fibres tend to arrive at the spinal cord before the messages travelling
along the smaller fibres and, if there are enough non painful sensations
travelling, the pain messages won't be able to get through to the
Once this theory had been accepted it was possible to explain all
sorts of natural phenomena which had, up until then, been a mystery.
So, for example, it became clear that when we rub a sore spot what
we are doing is increasing the number of non-pain messages travelling
towards the spinal cord (and thence the brain). If you knock your
elbow you will automatically reach to rub the spot because sub-consciously
you know that by rubbing the area you will be able to cut down the
amount of pain that you feel.
Having realized just how rubbing a sore or painful place can relieve
pain, the next step for scientists was to come up with the idea
of using electrical pulses to produce the necessary stimulus.
When the theory was first put into practice in the late 1960s doctors
suggested that electricity should be introduced into the body through
electrodes surgically implanted in the spine. Although that did
work, the fact that it involved an operation limited the usefulness
and availability of the procedure.
Next, it was discovered that all nerves within an inch or so of
the surface of the skin can be stimulated by electrodes which are
simply stuck onto the skin. That encouraged medical researchers
to start giving patients pocket-sized battery-operated stimulators
which sent out a continous series of electrical pulses which could
transmit those pulses into the large nerves of the body via silicon
electrodes stuck to the skin with a special conducting paste. It
More exciting still, it was discovered that Transcutaneous Electrical
Nerve Stimulation (TENS) did not just stimulate the passage of sensory
impulses designed to inhibit the passage of pain impulses; it also
stimulated the body to start producing its own pain-relieving hormones
known as endorphins.
During the last ten years an enormous number of research projects
have shown that TENS machines are convenient, safe and effective.
They are also cheap to buy and extremely cheap to run.
TENS machines have been shown to be effective in the treatment
of all kinds of pain. For example, a Swedish study has shown that
TENS machines are the only painkillers required by 70 per cent of
women in labour; and backache is one of the types of pain best treated
with TENS machines.
With this sort of success available from a small, cheap, portable,
long-lasting machine that can be used at home without any training
and that does not seem to produce any side effects at all, you might
imagine that doctors would be recommending TENS machines to millions
of patients and that shops would have different models stocked high
on their shelves. But if you try to buy a TENS machine you'll have
difficulty. This problem lays squarely at the door of the drug companies
who don't want patients in pain to be able to deal with their symptoms
so easily, quickly and cheaply. Drug companies make huge amounts
of money out of selling painkillers to pain sufferers and if people
used TENS machines instead it would cost them a fortune in lost
If you want to try a TENS machine ask your doctor to refer you
to the nearest pain clinic. You should be able to get one on loan
and if you find that the machine works for you then you should be
able to obtain one for permanent use.