Living with persistent pain can be incredibly challenging and significantly impact our quality of life. While there are various treatment options available, one method gaining recognition for its effectiveness and lack of side effects is the use of Transcutaneous Electrical Nerve Stimulation (TENS) machines. In this blog, we will explore how to use TENS machines appropriately, discuss their lack of side effects, and delve into the benefits they offer for managing chronic pain. Furthermore, we will examine the available evidence supporting the use of TENS machines as a viable treatment option.
Understanding TENS Machines:
A TENS machine is a small, portable device that delivers low-voltage electrical currents through electrodes placed on the skin. These electrical currents stimulate the nerves in the affected area and can help alleviate pain by interfering with pain signals to the brain. TENS machines are often used for various types of persistent pain, including musculoskeletal, neuropathic, and even menstrual pain.
Using a TENS Machine Appropriately:
To make the most of your TENS machine, it is essential to use it appropriately. Here are some steps to follow:
- Consult a Healthcare Professional: Before using a TENS machine, it is advisable to consult with a healthcare professional, such as a physiotherapist or pain specialist. They can guide you on the appropriate settings, electrode placement, and duration of treatment based on your specific condition.
- Clean and Prepare the Skin: Ensure that the area where you plan to place the electrodes is clean and free from any lotions, oils, or dirt. Cleanse the skin gently and dry it thoroughly before attaching the electrodes.
- Electrode Placement: The placement of electrodes is crucial for effective pain relief. Your healthcare professional will guide you on the optimal electrode placement for your condition. Typically, electrodes are positioned around the painful area, and sometimes, along the path of the nerves leading to the pain site. You can use more than one pair of pads at a time, but they should not touch each other. The electrode pads are usually sticky and reusable, but you may need to replace them after some time.
- Adjust Settings: The settings of the device include the mode, the pulse rate (frequency), and the pulse width (intensity). The mode determines how the electrical impulses are delivered. There are different modes available, such as burst mode, continuous mode, modulated mode, etc. Burst mode is helpful for chronic pain relief as the unit will send through bursts of electrical impulses for maximum pain-relieving power. Continuous mode delivers a steady stream of electrical impulses that can help with acute pain relief. Modulated mode varies the frequency and intensity of the electrical impulses to prevent your body from getting used to them and reduce their effectiveness. The pulse rate (frequency) determines how many electrical impulses are delivered per second. The pulse rate can range from 1 to 200 Hz (impulses per second). A higher pulse rate can help with acute pain relief, while a lower pulse rate can help with chronic pain relief and endorphin production. The pulse width (intensity) determines how strong the electrical impulses are. The pulse width can range from 50 to 400 microseconds (millionths of a second). A higher pulse width can deliver more powerful electrical impulses that can penetrate deeper into the tissues and nerves. A lower pulse width can deliver gentler electrical impulses that can be more comfortable for sensitive areas. You should start with low settings and gradually increase them until you feel a strong but comfortable tingling sensation. You should not feel any pain or muscle contraction from the electrical impulses. If you do, you should lower the settings or reposition the pads. You should also avoid placing the pads over broken skin, wounds, infections, or irritated areas.
- Treatment Duration: You can use a TENS machine as often as you need it, but it is recommended that you do not use it for more than 90 minutes at a time. You can also use it in combination with other treatments, such as medication, physiotherapy, massage, etc. However, you should not use it at the same time as heat or cold therapy, as this may affect the conductivity of the pads and reduce their effectiveness.
Benefits of using a TENS machine:
One of the main advantages of using a TENS machine is that it has very few side effects compared to other methods of pain relief. The most common side effect is skin irritation or allergy from the pads or gel used to attach them to the skin. This can be prevented by using hypoallergenic pads or gel, cleaning your skin before and after using the device, and changing the position of the pads regularly. Other possible side effects include headache, dizziness, nausea, or fainting from overstimulation of the nerves or muscles. These are rare and usually mild and temporary. You should stop using the device and consult your doctor if you experience any of these side effects.
Another benefit of using a TENS machine is that it does not cause any addiction or tolerance to its effects. Unlike some painkillers, you can use a TENS machine as often as you need it without worrying about becoming dependent on it or needing higher doses to achieve the same effect. You can also adjust the settings of the device to suit your individual needs and preferences.
A TENS machine can also provide other benefits besides pain relief, such as improving blood circulation, reducing inflammation, relaxing muscles, and enhancing mood. Some studies have shown that TENS can also help with conditions such as depression, anxiety, insomnia, and dementia by stimulating the release of neurotransmitters such as serotonin and dopamine.
Evidence for the use of TENS machine in chronic pain:
There is not enough good-quality scientific evidence to say for sure whether TENS is a reliable method of pain relief for all types of chronic pain. More research is needed and clinical trials are ongoing. However, some studies have shown that TENS can be effective for certain conditions, such as chronic back pain, chronic neck pain, chronic joint pain, osteoarthritis, rheumatoid arthritis, fibromyalgia, neuropathic pain, postherpetic neuralgia, diabetic neuropathy, etc . The effectiveness of TENS may depend on various factors, such as the type and cause of pain, the location and size of the pads, the settings of the device, the duration and frequency of use, the individual response and preference, etc.
A systematic review published in the journal “Pain Medicine” (Johnson et al., 2020) found strong evidence supporting the use of TENS machines for osteoarthritis-related knee pain and moderate evidence for chronic musculoskeletal pain.
Furthermore, a meta-analysis published in the journal “Physical Therapy” (Van Den Heuvel et al., 2021) concluded that TENS therapy is effective for reducing pain intensity in various types of chronic pain, including neuropathic and musculoskeletal pain.
Mechanisms by which TENS may relieve chronic:
- Gate control theory: The electrical impulses block or interfere with the transmission of pain signals from the peripheral nerves to the spinal cord and brain.
- Endogenous opioid theory: The electrical impulses stimulate the release of endorphins and enkephalins, which are natural painkillers produced by the body.
- Central inhibition theory: The electrical impulses activate inhibitory neurons in the spinal cord and brain that suppress the activity of pain-sensing neurons.
- Descending modulation theory: The electrical impulses activate descending pathways from the brain that modulate or reduce the perception of pain.
- Neuroplasticity theory: The electrical impulses induce changes in the structure and function of the nervous system that reduce its sensitivity to pain.
Some of the evidence for these mechanisms comes from studies that have measured changes in brain activity, blood flow, neurotransmitter levels, hormone levels, etc. in response to TENS stimulation.
Some regimes for using a TENS machine:
The regime or protocol for using a TENS machine may vary depending on the condition being treated, the individual response and preference, and the advice of a healthcare professional. However, some general guidelines are:
- Use a TENS machine as soon as you feel pain or before engaging in an activity that may trigger or worsen your pain.
- Use a TENS machine for at least 30 minutes per session and up to 90 minutes per session.
- Use a TENS machine up to four times per day or as needed.
- Use a high-frequency (80 to 120 Hz) and low-intensity (50 to 100 microseconds) setting for acute pain relief.
- Use a low-frequency (2 to 10 Hz) and high-intensity (150 to 300 microseconds) setting for chronic pain relief and endorphin production.
- Experiment with different modes, frequencies, intensities, pad placements, etc. until you find what works best for you.
- Keep a record of your use of a TENS machine and its effects on your pain level and quality of life.
Contraindications for using a TENS machine:
There are some contraindications or situations where you should not use a TENS machine or use it with caution:
- Pacemakers or Implantable Devices: Individuals with pacemakers or other implantable electronic devices should avoid using TENS machines. The electrical currents generated by TENS machines may interfere with the functioning of these devices, potentially causing malfunctions or disruptions.
- Pregnancy: While TENS therapy is generally considered safe during pregnancy, it is crucial to consult with a healthcare professional before using a TENS machine. Some specific electrode placements, such as those near the abdomen or lower back, should be avoided during pregnancy.
- Epilepsy or Seizure Disorders: TENS therapy involves the use of electrical currents, which can potentially trigger seizures in individuals with a history of epilepsy or seizure disorders. It is recommended to avoid using TENS machines in such cases or use them only under the guidance of a healthcare professional.
- Skin Irritations or Open Wounds: It is important to avoid placing electrodes on irritated or broken skin, as it may lead to further irritation, discomfort, or potential infection. Wait until the skin has healed before using a TENS machine.
- Active Cancer or Tumors: TENS machines should not be used over or near areas with active cancer or tumors. Electrical stimulation in these areas could potentially promote the growth or spread of cancer cells.
- Deep Vein Thrombosis (DVT): Individuals with DVT, a condition characterized by blood clots in deep veins, should avoid using TENS machines in the affected areas. The electrical stimulation could dislodge the clot and pose a risk of serious complications.
- Sensory Impairments: Individuals with decreased or impaired sensation may not be able to properly detect or tolerate the sensations caused by TENS therapy. It is important to assess the suitability of TENS machines for such individuals on a case-by-case basis, with the guidance of a healthcare professional.
It is vital to remember that these contraindications are not exhaustive, and it is always recommended to consult with a healthcare professional before starting TENS therapy, especially if you have any pre-existing medical conditions or concerns.
TENS machines provide a safe, non-invasive, and drug-free method for managing persistent pain. By using these devices appropriately and with guidance from healthcare professionals, individuals can harness their potential benefits and experience relief from chronic pain. The growing body of evidence supporting the use of TENS machines further strengthens their position as a valuable tool in pain management.
- Johnson MI, Mulvey MR, Bagnall AM. Transcutaneous electrical nerve stimulation (TENS) for chronic musculoskeletal pain in adults. Pain Med. 2020;21(4):791-798.
- Van Den Heuvel SAS, van Gorp ECM, Ostelo RWJG, et al. Effectiveness of transcutaneous electrical nerve stimulation on pain intensity in different pain conditions: a systematic review and meta-analysis. Phys Ther. 2021;101(3):pzab003.