Physiological Effects of TENS

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TENS, also known as transcutaneous electrical nerve stimulation, is a form of pain management that uses electrodes placed on the skin to send electrical pulses to nerves and muscle groups. TENS is often used to treat arthritis pain, migraine pain and other chronic pain disorders.

Doctors also may prescribe TENS for pain following surgical procedures. TENS is often an alternative to narcotic-based pain relief, and a physical therapist can administer it, or the patient can administer it at home. The use of TENS therapy has both theorised and documented physiological effects on the body.

Gate Theory

The gate theory of pain perception, proposed by Melzak and Wall in 1965, is that there is a "gate" through which nerves send pain messages to the brain. TENS treatment based on this theory sends electrical impulses flooding along larger nerve pathways and close the gate so the brain never receives the pain messages from the smaller nerves in the affected part of the body.

Endorphin Theory

Some of the research into the physiological effects of TENS relates to stimulation of endorphins. Endorphins are the natural pain-relieving hormones secreted by the pituitary gland. The theory holds that the electrical stimulation from the TENS machine encourages the brain to secrete more endorphins, reducing the perception of pain.

Ischemic Theory

Ischemia is a reduction of blood flow to a particular area of the body. TENS proponents say it helps increase the blood flow for some patients through vasodilatation, or widening of the blood vessels. The theory is that electrical stimulation from TENS causes the blood vessels to dilate and reduce pain.

Physical Side Effects

TENS form of pain management presents few side effects. However, patients may experience redness or irritation at the sites where electrodes attach for treatment. Overuse of TENS may cause muscle twitching due to overstimulation. Some patients may experience a tingling sensation near the electrode site.