Transcutaneous Electrical Nerve Stimulation (TENS) is a non-invasive, drug-free method for managing pain. It involves using a small device to deliver low-voltage electrical currents through electrodes placed on the skin. Tennis Elbow, medically known as Lateral Epicondylitis, is a common condition causing pain on the outer part of the elbow. This article explores how TENS therapy works and how it can be applied for individuals seeking relief from the chronic discomfort associated with Lateral Epicondylitis.
Understanding Tennis Elbow Pain
Lateral Epicondylitis is an overuse injury that affects the tendons connecting the forearm muscles to the bone on the outside of the elbow, known as the lateral epicondyle. This condition is most often caused by repetitive strain from activities that involve gripping or repeated wrist extension. The pain is typically felt right over the bony prominence of the elbow and can sometimes radiate down the back of the forearm.
The underlying issue is often a degenerative process of the tendon tissue, correctly termed tendinosis, rather than inflammation. This means the tendon develops microscopic tears and disorganized collagen, making the pain chronic and persistent. The pain can vary from a mild ache to severe discomfort that makes simple tasks like holding a coffee cup difficult.
Mechanism of TENS Therapy for Pain Relief
The pain-relieving effects of TENS therapy are attributed to two distinct mechanisms that interrupt the body’s pain signaling pathway. The first is the Gate Control Theory, which involves high-frequency electrical stimulation (80 to 120 cycles per second). This high-frequency input activates large, non-pain-carrying nerve fibers, which effectively “close the gate” in the spinal cord. By closing this figurative gate, the TENS impulses block pain signals from smaller fibers from reaching the brain, thereby reducing the perception of pain.
The second mechanism involves the release of the body’s natural painkillers, known as endogenous opioids, such as endorphins. This effect is stimulated by low-frequency TENS, which uses a lower pulse rate (1 to 20 cycles per second). These naturally occurring chemicals bind to opioid receptors in the brain and spinal cord, producing an analgesic effect that provides longer-lasting pain relief.
TENS may also promote localized muscle relaxation and increase blood flow to the treated area. The electrical impulses can stimulate motor nerves, helping to relax the tense forearm muscles associated with the condition. Increased circulation helps facilitate the delivery of oxygen and nutrients to the tissue, although TENS is primarily a symptomatic treatment.
Practical Application for Lateral Epicondylitis
Applying a TENS unit for Lateral Epicondylitis requires careful electrode placement to ensure the electrical current targets the painful area effectively. The most effective placement is to position the electrodes around the region of maximum tenderness on the outside of the elbow. The goal is to bracket the pain, with the electrical current running through the affected extensor carpi radialis brevis tendon origin.
A typical configuration involves placing one electrode slightly above the lateral epicondyle and the other slightly below it, on the muscle belly of the forearm extensors. It is recommended to avoid placing the pads directly on the elbow joint itself. For maximum effect, the user should adjust the intensity until a strong, comfortable tingling sensation is felt, without causing muscle contraction or discomfort.
For managing acute pain flares, a high-frequency setting (80-120 Hz) is recommended, as it leverages the fast-acting Gate Control Theory. For a chronic pain relief approach, a low-frequency setting (1-20 Hz) may be used to encourage the release of endorphins. A standard session length is between 20 to 30 minutes, and the treatment can be used up to four times daily.
Important Safety Considerations and Limitations
Before beginning TENS therapy, a consultation with a healthcare provider is important. TENS is a symptomatic treatment that suppresses the sensation of pain, meaning it should be used as one component of a broader rehabilitation plan that includes rest and physical therapy.
There are several safety contraindications that must be observed. The most serious is the presence of implanted electronic devices, such as a cardiac pacemaker, as the electrical impulses could interfere with their function. TENS should also be avoided on the front of the neck, over the eyes, or near the heart.
The safety of TENS during pregnancy has not been definitively established, so it should be avoided, especially on the abdomen or pelvic region. Patients with epilepsy should exercise caution, as electrical stimulation may potentially trigger a seizure. Furthermore, electrodes should never be placed over areas of broken or irritated skin.