Generality
TENS is the acronym for TransCutaneous Electrical Nerve Stimulation (transcutaneous electrical nerve stimulation), a complementary medical technique, mainly used to control some acute or chronic painful conditions.
TENS consists in the application on the skin of light electrical impulses, which activate large diameter nerve fibers, reducing the perception of pain.
What is TENS
TENS involves passing low-voltage electrical current through the skin in order to stimulate specific nerve fibers. An electrical generator (power unit or stimulator) is used to deliver painless pulses, which should be perceived by the patient as a tingling sensation. A typical TENS stimulator is able to modulate the "pulse width, frequency and intensity. Generally, electric current is applied at a high frequency (> 50 Hz), with a sensory" intensity or low frequency (motor contraction). . The power supply unit is connected at the skin level in the area to be treated by two or more electrodes, applied to the skin with reusable adhesive plasters. The pulses allow to block or reduce pain signals that reach the spinal cord and brain, and can potentially relieve muscle spasms and other painful symptoms.
Low frequencies of electric current are also used to stimulate the body to release neuropeptides and other chemical mediators (such as enkephalins, endorphins, opiates, substance P, etc.), which influence the way the painful stimulus is perceived and transmitted.
The frequency, intensity and site of application of the treatment depend on the specific condition and the therapeutic objectives, and represent the fundamental parameters to be considered in order to obtain optimal effects during and after electrical stimulation. Consequently, the electrodes can be placed in various regions of the body. Generally, when the power supply is turned on, the effects on pain are recorded after approximately 40 minutes. Once the tool is turned off, some people may get long-lasting relief, but this result is not common. Currently, several clinical trials are aimed at demonstrating the reliability and safety of TENS. Experience has shown that this method is effective only for some patients and the therapeutic outcome is fundamentally dependent on the individual clinical condition. Transcutaneous electrical nerve stimulation is often used in subjects who cannot take painkilling drugs, due to intolerances or unwanted side effects.
An alternative application of TENS, called iontophoresis, allows the administration of a drug transcutaneously in the body: a direct current allows the active principle to be conveyed through the skin only to the affected area, where it acts to reduce inflammation and produce a high analgesic effect.
Potential applications
Transcutaneous electrical nerve stimulation (TENS) is used in a variety of clinical settings for the treatment of various conditions associated with acute and chronic pain; over the years it has become popular with both patients and healthcare professionals.
TENS has been evaluated in scientific studies for the following health problems:
- Ache. Several studies support the efficacy of TENS for certain types of pain, making it commonly referred to as complementary physical therapy in the management of a wide range of acute or chronic conditions.
- Joint Disorders. TENS can be applied to relieve various types of joint disorders, such as knee osteoarthritis, patellofemoral syndrome or temporomandibular joint pain. However, the long-term benefits are still unclear.
- Muscle strength (physical performance). TENS is also used with encouraging results for recovery after exercise, suggesting potential benefits in rehabilitation programs as well.
- Dysmenorrhea. Several studies report that TENS can reduce short-term discomfort in the case of menstrual pain by decreasing the need for pain medication.
- Nervous disorders. TENS has been proposed as a treatment for nerve disorders such as hemiplegia (paralysis on one side of the body) and spasticity in multiple sclerosis. The method is also used for neuropathic pain (neuralgia) resulting from bruxism (grinding of the teeth) and in spinal cord injuries.
- Cardiac pathologies. TENS can be used to support the treatment of some cardiovascular diseases, such as angina and cardiac ischaemia. Further studies are needed before any conclusions can be drawn about the efficacy of TENS in this area; therefore, people with heart disease should consult a doctor to evaluate the possibility of benefiting from TENS applied to their condition.
- Pain of labor. The application of TENS for labor pain is controversial. Although several studies have been conducted, the results are not conclusive. In particular, it is not clear whether the passage of electric current can cause harmful effects on the fetus.
- Post-operative recovery. TENS is used for the treatment of pain after various types of surgery, including cardiac surgery and abdominal, pulmonary, gynecological and orthopedic surgery.Some studies report benefits (less pain or less need for painkiller therapy), while others do not find clear improvement.
- Soft tissue injuries. TENS therapy is used to treat soft tissue injuries, such as tendonitis and tendon injuries. However, the results are variable and more research is needed.
- Alzheimer's. A limited amount of research reports suggest that TENS may improve some symptoms of Alzheimer's, such as mood and memory.
- Autoimmune Diseases. TENS can also be applied as a complementary treatment for numerous autoimmune diseases, including rheumatoid arthritis, ankylosing spondylitis and Sjögren's syndrome.
- Respiratory difficulties. Some evidence suggests that TENS could be useful in case of breathing difficulties, if inserted in combination with other therapies as part of a rehabilitation program for chronic obstructive pulmonary disease (COPD).
- Depression. There is limited evidence that TENS can increase the efficacy of antidepressant drugs and effectively support the treatment of depression, in combination with appropriate therapies.
- Gastroparesis. A study in patients with gastroparesis treated with percutaneous electrical nerve stimulation (PENS) reported positive effects. It is unclear whether these results could also be found using the conventional method.
- Multiple sclerosis. In a small study, multiple sclerosis patients treated with TENS showed a tendency to improve.
- Post-stroke rehabilitation. Some evidence demonstrates the usefulness of TENS in rehabilitation following a stroke. In particular, this technique can help improve motor function in patients.
- Attention Deficit Hyperactivity Disorder (ADHD). One study found moderate benefit in children with ADHD.
- Tinnitus. TENS can relieve symptoms of tinnitus (ringing in the ears), especially when the tinnitus is not caused by other conditions.
- Obesity. The application of therapy to support weight loss in obese subjects has been reported. However, the evidence is limited and the efficacy of TENS in weight loss remains unclear.
- Constipation. TENS is able to relieve constipation without producing negative effects. However, there is limited evidence that this treatment is more effective than other therapeutic measures.
Additionally, some scientific research suggests that transcutaneous electrical nerve stimulation (TENS) may improve symptoms associated with:
- Acute fracture / physical trauma pain;
- Fibromyalgia;
- Headache (migraine, cluster headache and some chronic forms);
- Backache;
- Nausea;
- Peripheral diabetic neuropathy (neuropathic pain);
- Symptoms of menopause;
- Herpes zoster (post-herpetic neuralgia);
- Urinary incontinence, overactive bladder and detrusor instability;
- Circulatory disorders and low blood pressure;
- Spinal muscular atrophy;
- Claudication (pain in the legs due to "impaired blood circulation);
- Carpal tunnel syndrome;
- Raynaud's disease;
- Gout;
- Notalgia paresthetica (sensory neuropathy characterized by localized itching on the back).
Note. Based on several scientific theories, the use of TENS has been suggested for many conditions. However, there is still limited evidence of its safety or efficacy for some of these specific medical conditions. Other applications of TENS have not been sufficiently studied to draw firm conclusions. For this variety of reasons, it is advisable to consult a physician before resorting to transcutaneous electrical nerve stimulation.
Risks and Side Effects
If their doctor or physiotherapist has confirmed the possibility of using this treatment option, the patient should know that TENS is well tolerated and safe. However, some patients cannot resort to this treatment option.
When TENS shouldn't be used:
- If you do not know the cause of the pain or if the diagnosis of your condition has not yet been defined;
- If you have a pacemaker or other implanted electrical devices;
- If you have epilepsy or a heart rhythm disorder;
- If you have a severe skin condition.
The most common side effects include the onset of some skin reactions, such as irritation and redness, found in about one third of people. There are isolated cases in which various other side effects are reported, including loss of sensitivity, pain or unpleasant sensations ( near or far from the application site), headache, muscle aches, nausea, agitation and dizziness. However, it is unclear whether TENS is responsible for these problems. Therapy should only be applied under medical supervision or under the close supervision of an experienced and licensed healthcare practitioner. With excessive or improper use electrical burns can occur and, because of this risk, TENS should be used with caution in people with reduced sensitivity, such as in patients with neuropathy.
Transcutaneous electrical nerve stimulation should not be used in patients with implanted medical devices, such as cardiac defibrillators, pacemakers, intravenous infusion pumps, etc. as they may cause interference or device malfunction. TENS is also contraindicated in patients with malignancy (in According to some in vitro experiments, electricity promotes cell growth), while it must be used with caution in pregnant women. Although several studies show that TENS can be applied to relieve pain during childbirth, the evidence for its safety is limited and the effects of electrical stimulation on the fetus are unknown. In some cases, increases in fetal heart rate and interference with fetal monitoring equipment have been reported. The safety of TENS has not yet been established. in children.
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