TENS indications

TENS (transcutaneous electrical nerve stimulation) produces analgesia via stimulation of large afferent fibers. This is generally used for mild-moderate acute pain and chronic pain such as low back pain, arthritis, and neuropathic pain.

Theories:

1. Gate Theory: afferent input from large epicritic fibers competes out input from small pain fibers.
2. Conduction block theory: high rates of stimulation exhaust the small nerve fiber ability to transmit signal.

Conventional use: TENS electrodes are applied to the same dermatome as the pain. The electrodes are periodically stimulated by a direct current generator (typically for 30 minutes several times a day). The usual current is 10-30 mA with a pulse width of 50-80 microseconds at a frequency of 80-100 Hz.

Alternative use (for patient’s refractory to Conventional use): Low-frequency TENS: a stimulus with a pulse width >200 microseconds and a frequency of < 10 Hz (for 5-15 minutes). Note, the effect of low-frequency stimulation is at least partially reversed by naloxone suggesting a role for endogenous opioids.

Indications:

• Musculoskeletal pain

• Acute postoperative pain and acute post traumatic pain – A study showed that TENS used in the postoperative cardiac patient significantly reduced both spontaneous and cough induced pain. It improved pulmonary mechanics and lead to demonstrable increases in thoracic and girdle muscle function.
• Chronic pain: e.g. (rheumatoid arthritis, osteoarthritis, etc.) a recent Cochrane review article suggests an overall positive analgesic outcome in favor of TENS. However, due to poor and inconsistent reporting of methods and results, no meta-analysis was able to be done.
• Chronic low back pain: Two Class I studies demonstrating that TENS is ineffective
• Painful diabetic neuropathy: Two Class II studies demonstrating that TENS is most likely effective
• Neuropathic pain – A recent article suggests that conventional TENS may be better placebo (level C); however’ is most likely not as good as other types of electrical stimulation including acupuncture-like stimulation (level B).
• Visceral pain and dysmenorrhea – A small study of 34 women showed improvement from baseline primary dysmenorrhea pain shortly after application of TENS.
• FDA approval – “Specific indications for use for the TENS device that we consider to be for pain relief include symptomatic relief of chronic intractable pain, relief of acute post-surgical and post-traumatic pain, and relief of pain associated with arthritis”