Electrotherapy and T.E.N.S Machines

Do you ever wonder if those Dr. Ho machines that you see on T.V. really work? I regularly get asked by patients if they really work, or are they just a gimmick. The answer is that they do work and can be quite effective. Dr. Ho’s pain-relieving machine is not new however, it is actually what is called a T.E.N.S (TENS) machine which stands for Transcutaneous Electrical Nerve Stimulation and they have been around for many years.

TENS machines are actually part of a whole category of types of treatment referred to as electrotherapy. As the name implies these types of therapies use electricity to stimulate the nerves of the body and are employed to help relieve pain or stimulate muscles. Dr. Ho’s machine is a TENS unit that has been simplified so that the average person can use it at home on their own but other TENS machines do exist that do the same thing and, in some cases, may be just as easy to use. If you’ve ever been to a chiropractor’s or physiotherapist’s office you may have had interferential current (IFC) or electrical muscle stimulation (EMS) therapy. These are more advanced forms of electrotherapy.


So how does TENS help with pain? Much of the theory behind the use of TENS for pain control is based on something called “the gait control” theory of pain that was first proposed by two researchers, Ronald Melzack and Patrick Wall in 1965. The summary of the complicated theory is that non-painful stimulation of nerve fibers can override and reduce other painful sensations. A simple example of this occurs when one accidently bumps their elbow. Instantly, one will grab the elbow and start rubbing it. For some reason, this seems to help reduce the painful stimulus. The action of rubbing the elbow stimulates other “non-pain” sensing neurons which then reduces or overrides the pain signals going to the spinal cord. TENS may work in a similar fashion by stimulating neurons thereby reducing the painful sensation.

Neurostimulation via TENS may also have an effect at the level of the brain. By causing a recurrent or constant sensation the signals will bombard the area of the brain responsible for interpreting the signals. This constant bombardment may trigger the brain to then release our bodies own natural pain- relieving chemicals called endorphins. These chemicals have a similar effect on our nervous system as some types of pain-relieving drugs thereby reducing pain. These chemicals are released and work through what are termed descending inhibitory pathways. The same mechanism happens when a marathon runner experiences the “runner’s high”. This is also why the pain relief from a TENS treatment will continue even after the machine is turned off.

TENS is only a pain-relieving modality and as such it may be appropriate for a variety of conditions including arthritis, back pain, neck pain, headaches, diabetic neuropathy, sciatica and a variety of tendon conditions like tennis elbow or rotator cuff problems. The devices are about the size of a cell phone and many are designed with additions such as belt clips so that they may be used while you are going about your everyday activities. The machines usually come with two or four leads that attach to sticky electrode pads that are placed around the painful area. TENS is an exceedingly safe type of home therapy and it is very difficult to do it incorrectly. It is advisable to avoid placing the electrodes directly over the heart, front of the neck or on the face as these areas may be adversely affected by the current.

This type of home therapy can be very effective and allow you to take back control of your pain. It can reduce the dependency on medications and help to increase function and ultimately improve quality of life. Consulting with a health care practitioner like a chiropractor or physiotherapist can be a good way to access this type of therapy.