Techniques of TENS Treatment
TENS is a non-invasive electrical stimulation technique used to relieve pain. Patients can use TENS themselves and adjust their own treatment levels as there is no risk of overdose and very few side effects. Physiotherapists are trained in the use of TENS and other modalities, so consulting your local physio can be useful for guidance on the purchase and use of a TENS machine.
Different techniques are used to target particular nerve types to stimulate different methods of pain relief. The three main ways of using TENS are:
This is the commonest technique and the one chosen first to try out the treatment.
The International Association for the Study of Pain (IASP) gives the definition of conventional TENS as:
“High frequency (50 – 100Hz), low intensity (paresthesia, not painful), small pulse width (50-200 microseconds). Electrode localization: cover the painful region. Duration: about 30 minutes”.
The treatment idea here is to stimulate the large diameter nerves which deal with non-painful stimuli and are located in the same nerve region as the pain problem. This inhibits the nerves in the central nervous system, which take over incoming pain impulses as they come in, from being as active as they would normally be.
The way to get this effect is to increase the strength of treatment until you get a strong but comfortable feeling of pins and needles under the electrodes. If you increase the intensity further this becomes painful by stimulating pain-related nerves and is not helpful.
This kind of TENS can be used for long periods and whenever the pain becomes a problem.
The International Association for the Study of Pain (IASP) gives the definition of Acupuncture-like TENS as:
“Low frequency (2–4 Hz), higher intensity (to tolerance threshold), longer pulse width (100–400μs). Alternating low (2–4 Hz) and high (50–100 Hz) frequency, each lasting for 3 seconds). Electrode localization: usually at traditional Chinese acupuncture points, or trigger points, but one can also use it at the painful region. Duration: about 30 minutes.”
This is a much stronger form of stimulation which can be tried if conventional TENS does not work well. It is meant to stimulate small pain nerves, triggering nerve pathways coming down from the brain to inhibit the transmission of pain beyond the spinal cord.
Twitching of the muscles can occur during treatment and the electrodes are placed over the relevant muscle groups, trigger points and acupuncture points. It is usually used less than conventional TENS and for shorter periods.
This technique is intended to stimulate the small pain nerves again, causing similar mechanisms to occur as with the previous two techniques. Short periods of time are used as the intensity and the frequency employed are high and uncomfortable.