TENS therapy is an electrical pain therapy that uses frequencies between 2 Hz and 150 Hz to combat pain of various origins.
The name stands for Transcutaneous Electrical Nerve Stimulation.
TENS therapy is not used very often because it only provides temporary relief.
The method is based on the fact that electrical impulses are transmitted to the skin via electrodes.
By stimulating the nerve fibers, TENS can neutralize the pain signals so that they do not reach the brain and are therefore not perceived.
In addition, the brain is stimulated by the impulses to release beta-endorphins, which are physiological substances with a morphine-like effect that complement the pain-relieving activity.
In physiotherapy, TENS therapy is mainly used in the following cases: neck pain, tendinitis, cervicobrachialgia, lumboischialgia, intercostal pain, back pain, periarthritis of the shoulder, etc. The characteristic of TENS relevant for rehabilitation is that it can fight pain and restore the normal physiological state.
You do not necessarily have to go to a rehabilitation center to perform TENS therapy, there are portable devices that can be rented or purchased from specialized companies, also via the Internet. The difference between portable and professional devices is only in the attached power, the frequencies are the same.
Where are the electrodes installed?
In order for the therapy to bring maximum benefit, the impulse transmission must be optimal; this is guaranteed by current-conducting rubber plates (electrodes), which are attached to the skin with a conductive gel.
Self-adhesive electrodes seem to be less effective because they have a higher dispersion.
The electrodes are polarized differently: the positive electrode is positioned where the pain originates, while the negative (black) electrode is placed at the end of the body region into which the pain radiates.
The positioning of the electrodes is not of fundamental importance, as their polarity is constantly changing.
The electrodes are arranged in such a way that they form a rectangle in the painful area; however, there are also other placement options, so the treating physiotherapist should be consulted.
There are several ways to attach the electrodes: at the painful area, in the area of the reflected projection, along the nerve pathway that supplies the area (dermatome) or at the acupuncture points.
Which potency and frequency should be adjusted?
During therapy, it is important to control the current intensity delivered in order to relieve the pain: the patient must feel a constant tingling sensation, which must always be a pleasant sensation throughout the application. For this purpose, the intensity of the impulse must be adjusted during the session, otherwise a habituation effect occurs and the tingling disappears.
If the patient has severe, acute pain, the intensity can be increased for rapid pain relief until the “pinching” is stronger than the pain itself, but only for a maximum of 1-2 minutes.
After that, a value must be set that causes a “pleasant tingling” to avoid skin irritation under the electrodes.
The pulse frequencies are of great importance. A good device usually offers a frequency spectrum between 2 Hz and 150 Hz, the desired frequency can then be set depending on the type of pain.
In the literature, criteria for the application of the different frequencies are defined:
- At high frequencies (80-150 Hz) an immediate effect occurs, the pain decreases noticeably after about 10-20 minutes of treatment, but tends to become stronger again after 2-3 hours.
- At medium frequencies (40-60 Hz), 30-40 minutes are needed to achieve pain reduction, but the effect lasts a few hours longer.
- At low frequencies (2-20 Hz) the application time is even longer, it takes about 60-80 minutes for the pain to subside, but the analgesic effect lasts much longer. At these frequencies, the organism is stimulated to release neuropeptides (endorphins are morphine-like substances). The neuropeptides inhibit pain transmission at the level of the spinal cord, even for several days.
It is essential to know how to adapt TENS therapy to the type of patient and pain.
To combat acute pain, it is recommended to first apply the highest frequency (10 Hz) for about 150 minutes; when the pain subsides, the frequency is gradually reduced every 10 minutes (80 Hz, 60 Hz, 40 Hz, 20 Hz and 2 Hz) and thus the analgesic effect is extended to 1-2 days. In the case of chronic pain, repeated use may be necessary before the pain disappears: here an increased session duration (at least 1 hour) at medium and low frequencies is recommended, which are applied in succession for 20-30 minutes each.
How long does the therapy take?
The total number of applications required varies; this alternative form of therapy can be used over a long period of time because it has few side effects and complications.
For medium and long sessions, the intervals are longer, while the short sessions can also be done twice a day.
Normally, the treatment cycles are scheduled every two days. In patients with chronic pain of a rheumatological nature, effective pain control can be achieved within 10 sessions, even if treatment must be continued.
Which programs can be used?
The TENS method can be divided into certain categories based on the mechanism used to reduce pain: conventional TENS with rapid analgesic effect, TENS training by electro-acupuncture with delayed analgesic effect, TENS grid with variation of stimulation parameters during treatment, TENS at maximum values with immediate analgesic and sedative effect, TENS burst, a mixture of the first two forms.
What is the mode of action behind it?
According to Melzack and Wall’s theory, pain can be affected or blocked by appropriate electrical stimulation of certain nerve fibers.
For which diseases is the TENS method mainly used?
The TENS method has a wide range of applications, it is used for problems such as: neck pain, tendon disease, rheumatism, bone or nerve pain, such as low back pain, back pain, sciatica, sprains, dislocations, tennis elbow, golfer’s elbow postoperative pain and many more.
Since acute pain can be hindered or blocked, the therapy can make a significant contribution to reducing wound pain, for example in the Phase immediately after surgery.
In the case of terminal cancers, pain relief achieved through electrical nerve stimulation can reduce the dosage of narcotic drugs taken at the last stage of the disease.
What are the main contraindications?
The use of TENS pain therapy has no significant contraindications or side effects, except for patients with the following clinical peculiarities:
- pacemaker wearer;
- pregnant or lactating women;
- People with cardiac arrhythmias.
The electrodes must never be placed directly on wounds, diseased skin or in regions with impaired sensitivity; Also, the TENS method should not be used at the front of the neck because there is a risk of laryngeal spasm.