Gate Control Theory of Chronic Pain

In gate control theory, experiencing pain can be caused by a complex interaction of the central and peripheral nervous system and how they process pain signals. Pain is more complex than was previously understood, gate control theory of pain was created in the 1960s by Ronald Melzack and Patrick Wall. Gate control theory of pain states that non-painful signals closes the “gates” to painful signals, preventing pain sensation from traveling to the central nervous system. And it gives reason to believe there can be psychological factors that influence the experience of pain. Depending on the situation pain can be experienced differently and can be caused by a variety of different variables, like stress. 

The brain commonly blocks out sensations that it knows are not dangerous, such as when the feel of tight-fitting shoes that are put on in the morning has all but vanished by the second cup of coffee. A similar process is at work in processing some moderately painful experiences.

The following outlines two brief case examples of how the gate control theory of pain may be experienced.

1. This case example shows how the experience of pain may change as information is processed in the brain.

  • Applying a clothespin to one’s arm initially produces pain that may be quite intense as the skin and surface muscles are compressed. Peripheral nerve fibers detect this pressure and transmit a pain signal to the spinal cord and on to the brain. At first it is the fast pain signals that get through, and the intensity of the pain experience is fairly proportional to the amount of pressure applied. Everyone would agree that this is acute pain.
  • The slower pain signals are not far behind, however, and a dull ache may soon be noticed. After a short while, the pain coming from the pinched tissue will begin to be decreased by the closing of the spinal nerve gates. This is because the brain begins to view the pain signals as non-harmful. The pressure may be painful initially but it is not injuring the person in any way. As time goes on, the pain message is given less priority by the brain and the person’s awareness of it decreases greatly.
  • The brain knows that the clothespin is not causing any injury. Therefore, the brain gradually “turns the volume down” on the pain message to the point of it being barely noticeable after about thirty minutes. The compression on skin and muscle is still occurring, but it is now perceived as a mild discomfort if it is noticed at all.

By: William W. Deardorff, PhD, ABPP

03/11/2003

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