Transcutaneous Electrical Nerve Stimulation (TENS) is a non-invasive method that uses a low-voltage electrical current to help manage pain. This therapy is frequently used to alleviate discomfort associated with Temporomandibular Joint (TMJ) disorder, a chronic condition causing pain and dysfunction in the jaw joint and surrounding facial muscles. The electrical pulses work by blocking pain signals from reaching the brain and promoting the relaxation of hyperactive jaw muscles, which is a major source of TMJ symptoms. Effective relief from TMJ pain relies on the precise placement of the electrode pads to target the correct muscles and nerves.
Essential Safety Precautions Before Use
Using a TENS unit requires careful adherence to safety guidelines, especially when placing electrodes near the head and neck. Certain medical conditions are contraindications for TENS therapy, including having an implanted electronic device such as a cardiac pacemaker or a defibrillator. Individuals who are pregnant or have a history of epilepsy should also consult with a healthcare provider before use. The electrical current should never be applied over areas of broken, infected, or damaged skin.
It is important to avoid placing electrodes directly on the eyes, inside the mouth, or over the front or sides of the neck, where the carotid arteries and sensitive nerve structures are located. To ensure the pads adhere properly and the current is delivered effectively, the skin in the target area should be clean and dry. When beginning a session, always start with the lowest intensity setting and slowly increase the stimulation until a strong but comfortable tingling sensation is felt, stopping immediately if the feeling becomes painful.
Primary Placement: Targeting the Masseter Muscle
The masseter muscle is often the primary source of pain in TMJ disorder because it is one of the main muscles responsible for chewing and clenching. Correct placement over this thick muscle is the most direct way to encourage muscle relaxation and pain relief. To locate the masseter, clench your teeth firmly and feel the bulge of the muscle just above the angle of your jawbone, near the cheek. This is the muscle belly where the pads should be centered.
The goal is to create a current flow that encompasses the entire muscle, typically requiring two pads. Place the first electrode pad directly over the most tender spot or the center of the masseter muscle belly, often about one centimeter above the corner of the jaw. Position the second pad slightly behind and below the first, or along the lower edge of the jawbone toward the neck. This configuration ensures the electrical current passes through the bulk of the muscle.
Addressing Referred Pain: Temporalis and Neck Placement
TMJ pain is often complex, with tension frequently radiating to secondary muscles, which is known as referred pain. The temporalis muscle, located on the side of the head above the ear, is a common secondary target, especially for patients who experience tension headaches with their jaw pain. For this placement, apply one pad over the temporalis muscle in the temple region, being sure to keep the pad safely away from the eye and the hairline. The second pad can be placed on a tender spot on the same side, or sometimes on the masseter muscle to treat both primary and secondary areas simultaneously.
Tension in the upper neck muscles can also contribute significantly to jaw discomfort, making the cervical area a useful location for a complementary treatment. Targeting trigger points in the upper trapezius or suboccipital muscles, located at the base of the skull and upper back, can help relieve tension that refers up to the jaw. When applying pads to the neck, one pad can be placed over a palpable, tight spot on the upper trapezius muscle, and the second pad can be placed a few inches lower on the same muscle.
Optimal TENS Settings and Treatment Duration
The effectiveness of TENS therapy depends on selecting the correct electrical parameters to achieve the desired physiological response. For chronic muscle pain relief associated with TMJ, a low-frequency setting, typically between 2 and 10 Hertz (Hz), is often recommended. This setting is thought to stimulate the body’s natural opioid system, encouraging the release of endorphins for long-lasting pain relief. Alternatively, a higher frequency, such as 50 to 120 Hz, can be used to activate the pain gate control theory, which offers more immediate pain signal interruption.
The pulse width, which determines the duration of each electrical pulse, can be set to a range like 150 to 250 microseconds (µs) for muscle-based pain. The most important setting is the intensity, which should be adjusted until a strong, non-painful tingling or tapping sensation is felt in the muscle. A typical treatment session for TMJ pain relief should last 20 to 30 minutes, and this can be repeated two or three times per day as needed to manage discomfort.