TRANSCUTANEOUS ELECTRICAL NERVE STIMULATION (TENS)
Transcutaneous electrical nerve stimulation (TENS) is one of the most commonly used and beneficial forms of pain control. This form of therapy has been known as electro analgesia. There are numerous research studies that have been done showing the benefits of TENS for many different types of pain including low back pain, myofascial pain, sympathetically mediated pain, neurogenic pain (pain from nerve dysfunction), visceral pain (pain related to internal organs), post surgical pain, of many kinds, and arthritic pain. This modality of pain treatment is safe and non-invasive and best of all, it is does not involved medications.
The mechanisms produced by the use of TENS include:
- Inhibition of abnormally excited nerves.
- A stimulation of and secretion of endorphins and enkephalins.
- Other direct effects on nerves.
A TENS unit consists of an electrical signal generator, generally battery powered, and a set of electrodes connected to the signal generator. The TENS units are small, about the size of a small transistor radio, and they can deliver electrical stimulation with variable pulse rates and current strengths. The normal settings for stimulus variables include:
- Amplitude, generally at a low intensity that is above threshold, yet comfortable.
- A pulse duration of between 10 and 1,000 micro-seconds.
- A pulse frequency between 80 and 100 impulses per second.
When using TENS for pain control, one needs to be particularly observant of electrode placement. The effectiveness of the TENS unit will depend to a significant extent on finding the best skin locations for placing the electrodes. Both the stimulus settings and the locations of the electrode patches are determined by trial and error, and one must experiment with both. To start with, the electrodes are placed over the painful area, but this may not give the best pain control. Sometimes other locations such as over nerves, acupuncture sites, or trigger points will give the best pain relief.
Comfort level is very important in terms of continued use and compliance with the use of the TENS. The intensity of the sensations that are produced is dependent upon both the amplitude of the electrical stimulus as well as the frequency or rate of stimuli.
Adverse medical reactions related to the use of TENS are not very common, thankfully.
Skin irritation is a potential problem. This is generally because of drying of the conductant gel on the surface of the electrode. Another problem can arise if the individual is allergic or sensitive to the type of tape that is used to secure the electrodes to the skin surface. In some cases, the use of self-adhesive disposable electrodes can be beneficial.
The most important contraindication for patients using TENS is the presence of a demand - type pacemaker for their heart. In this case, the TENS unit may interfere with the proper function of the pacemaker.
Generally, it is believed that TENS can provide relief of pain in 70 to 80% of patients, but these percentages vary from researcher to researcher. When used properly, at the proper settings and with the proper electrode locations for best results, the time from start of stimulation until pain relief begins, can vary from almost immediate to one hour or more. The duration of the pain relief also can vary from individual to individual; in some persons the relief is only for the duration of stimulation and in other individuals the pain relief continues sometimes for a considerable prolonged time after the stimulation has been discontinued.
TENS has been found effective in neurogenic pain, musculoskeletal pain, visceral pain, post-surgical pain, arthritic pain and in other and varied pain disorders.
At this time, it is believed that TENS should not be used in patients with pacemakers, during pregnancy, and that the electrodes should not be placed in areas where there is significant sensory impairment, or over the anterior neck, or the carotid artery areas.
Clearly, Transcutaneous Electrical Stimulation is a valuable and non-invasive modality of pain control and can benefit many people. Check with your doctor to see if you would be appropriate for a trial of TENS to better control your pain.