At first glance, pain may seem to be a straightforward example of cause and effect. Touching a hot pan, for instance, results in pain. Although this is generally true for acute pain, chronic pain can be much different.
In the case of chronic pain, a closer look reveals a much more complex process. For many years, theories of pain did not adequately address chronic pain and the variations in responses to pain—even for the same person.
Much of modern medicine's understanding of the process of chronic pain stems from the Gate Control Theory, which takes into account many factors that influence chronic pain, including sensory (actual physical influences including activities), cognitive (including thoughts and beliefs about the pain), and emotional (including feelings about the pain). This article reviews the Gate Control Theory of pain and how it can be helpful in treating pain.
Gate Theory Explains Pain Variations
In an effort to improve scientific understanding, the Gate Control Theory of pain was advanced by psychologist Ronald Melzack and biologist Patrick Wall in 1965.1 Since that landmark paper, the Gate Control Theory was modified in 19782 and subsequently refined over the years.3 Although the theory has gone through some critiques and modifications to take into account new findings, its heuristic value has held up to this day.4,5 Most the modifications of the Gate Control Theory have to do with the complicated physiologic nervous system details that explain the pain experience and not the results that are observed clinically (e.g. the individual’s experience of the pain).
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In the Gate Control Theory, pain messages travel from the periphery of the body through nerve “gates” in the spinal cord and up to the brain. The theory uses the concept of “gates” in the central nervous system to describe how some pain messages are allowed get through and reach the brain, while others are blocked.
Aside from just allowing and blocking pain signals completely, these gates can also amplify or diminish a signal as it travels to the brain, as illustrated in the Gate Control Theory image on this page.
- Melzack R, Wall PD. Pain mechanisms: a new theory. Science. 1965;150(3699):971-9.
- Wall PD. The gate control theory of pain mechanisms. A re-examination and re-statement. Brain. 1978;101(1):1-18.
- Melzack, R. Gate control theory: On the evolution of pain concepts. Pain Forum. 1996; 5, 128-138.