TENS therapy is an analgesic electrotherapy that uses frequencies between 2Hz and 150Hz to reduce pain caused by many different diseases.
The name is an acronym for Transcutaneous Electrical Nerve Stimulation.
TENS is a therapy that is not widely used because the benefits are temporary.
The technique is to send electrical impulses to the skin through the plates conducting electricity.
By stimulating nerve fibers, TENS can neutralize pain signals that do not reach the brain, so they are not perceived.
In addition, pulses of TENS cause the production of beta-endorphins, ie physiological substances with the same effects of morphine that complete the analgesic action.
In physical therapy, TENS is used for: cervical pain , tendonitis , cervicobrachial neuralgia , sciatica , back pain , back pain , shoulder periarthritis , etc. The recovery function of TENS is the ability to reduce pain and restore normal physiological conditions.
You do not have to go to a physiotherapy center to do TENS, there are portable devices that can be rented or purchased from specialized companies, even online. The difference between the handset and the handset is just the applied power, but the frequencies are the same.
Where does TENS apply?
To ensure maximum effectiveness of the therapy, we must also pay attention to transmitting the impulse that is guaranteed from the plates (electrodes) inside two conductive sponges .
Less effective seem to be the self-adhesive electrodes because they are characterized by greater dispersion.
The plates have a different polarity: the positive electrode (red) is positioned over the point where the pain starts, while the negative (black) electrode is applied to the end where the pain radiates.
The positioning of the electrodes is not as important as the change in polarity occurs continuously.
The electrodes should be positioned so as to form a square in the area where you are feeling the pain, but there are also other methods of placement, so it is advisable to consult your physiotherapist. There are several applications of the electrodes: in the pain area, in the area of reflected projection, along the dermatome or in acupuncture points.
What power and frequency should be defined?
During therapy, it is essential to control the intensity of the current supplied for pain relief: the patient should feel a constant tingling sensation , it should be pleasant for the whole duration of the therapy.
To do this, you must modulate the intensity of the frequency during the session, otherwise the phenomenon of “accommodation”, that is, the habituation to electrical stimulation (disappearance of the sensation of tingling) occurs.
In case the patient feels acute pain, to achieve a rapid easing of pain, you can adjust the higher intensity until you feel that the bluntness is stronger than the pain itself, but only for 1-2 minutes maximum.
Next, it is necessary to set the intensity values to the pleasant tingling, to avoid skin irritations underneath the plates.
Very important is the frequency of the impulses. Typically, a good machine should be able to offer a range of frequencies between 2Hz and 150Hz, with the ability to modulate itself according to the type of pain.
The literature highlights the criteria for the application of different frequencies:
- With high frequencies (80Hz to 150Hz), the effect is immediate, pain decreases significantly after about 10-20 minutes after application, but this tends to occur after about 2-3 hours;
- Using medium frequency (40Hz to 60Hz) takes about 30-40 minutes to obtain pain relief, but the analgesic effect lasts for several hours;
- With a low frequency (2 Hz to 20 Hz) a longer time takes place, about 60-80 minutes to relieve pain, but the analgesic effect will be much more durable. In these frequencies it stimulates the body to release neuropeptides (endorphins are substances similar to morphine). Neuropeptides inhibit the transmission of pain to the level of the spinal cord for a few days.
It is essential to know how to apply TENS palettes according to the patient’s type of pain.
To combat acute pain it is suggested to start with the highest frequency (150 Hz) for approximately 10 minutes, once attenuated the pain must be continued for 10 consecutive minutes with the lowest frequency (80Hz, 60Hz, 40Hz, 20Hz and 2 Hz) that improve the analgesic effect over time, even for 1-2 days. In the presence of chronic pain you may need to repeat the application several times before the pain disappears: a long application (at least 1 hour) is recommended using the average and low frequencies followed by at least 20-30 minutes each time.
What is the duration of therapy?
The total number of sessions varies: it can be used for long periods of time because it is a therapeutic alternative with few side effects or complications.
The medium and long term sessions include longer intervals, while the short sessions can be repeated twice a day.
Generally, sessions are held on alternate days.
In treating patients with chronic pain due to rheumatic processes, it can lead to effective pain control in ten sessions, although further treatment is necessary.
What programs can I use?
Depending on the mechanism used to reduce pain, TENS is divided into some categories:
- TENS conventional or fast analgesic ,
- TENS training type electro-acupuncture or delayed analgesic,
- TENS maximum values, with analgesic action and consequent immediate calming effect,
- TENS Burst, is a mixture between the first two types.
How does it work ?
According to the theory of Melzack and Wall, it is possible to interfere and block pain through the appropriate electrical stimulation of certain nerve fibers.
Which diseases are most appropriate?
The field of application of TENS is very large, it is indicated in numerous problems such as neck pain , tendinitis , rheumatism, bone or nervous pain : lumbago , back pain, sciatica , sprains , dislocations , epicondylitis , medial epicondylitis , postoperative pain, etc.
Taking into account acute pain and the ability to prevent and block pain, therapy contributes significantly to the reduction of pain at the level of the wound, for example in the postoperative period.
In the case of end-stage cancer, the attenuation of pain with induced neuro-stimulation makes it possible to reduce the dose of narcotic drugs that are assumed in the later stages of the disease.
What are the main contraindications?
The use of TENS in pain therapy has no contraindications or special side effects except for patients with certain medical conditions:
- Pacemaker carriers;
- Women who are pregnant or breastfeeding;
- Patients with heart rhythm disorders.
The electrodes should never be placed on wounds or areas with abnormal sensitivity, nor is the use of TENS in the front of the neck not recommended to avoid spasm of the larynx.