Introduction
- Gate control theory was described by Melzack and Wall in 1965.
- This theory explains about a pain-modulating system in which a neural gate present in the spinal cord can open and close thereby modulating the perception of pain.
- The gate control theory suggested that psychological factors play a role in the perception of pain.
Terms
- Pain - an unpleasant sensory and emotional experience associated with actual or potential tissue damage.
- Analgesia - the selective suppression of pain without effects on consciousness or other sensations.
- Nociceptors - sensory receptor whose stimulation causes pain
- Pain threshold: the point at which a stimulus is perceived as painful.
- Phantom limb pain – feelings of pain in a limb that is no longer there and has no functioning nerves.
- Sensation – the process of receiving, converting, and transmitting information from the external and internal world to the brain.
Major Concepts
- The three systems located in the spinal cord act to influence perception of pain, viz;
- the substantia gelatinosa in the dorsal horn,
- the dorsal column fibers, and
- the central transmission cells.
- The noxious impulses are influenced by a “gating mechanism.”
- Stimulation of the large-diameter fibers inhibits the transmission of pain, thus “closing the gate.” Whereas, when smaller fibers are stimulated, the gate is opened.
- When the gate is closed signals from small diameter pain fibres do not excite the dorsal horn transmission neurons.
- When the gate is open pain signals excite dorsal horn transmission cells.
- The gating mechanism is influenced by nerve impulses that descend from the brain.
- Factors which influence opening and closing the gate are:
- The amount of activity in the pain fibers.
- The amount of activity in other peripheral fibers
- Messages that descend from the brain.
- A specialized system of large-diameter fibers that activate selective cognitive processes via the modulating properties of the spinal gate.
- Gate is opened by
- Physical Factors - Bodily injury
- Emotional Factors - Anxiety & Depression
- Behavioural Factors - Attending to the injury and concentrating on the pain
- Gate may be closed by:
- Physical Pain - Analgesic Remedies
- Emotional Pain - Being in a ‘good’ mood
- Behavioural Factors - Concentrating on things other than the injury
Conclusion
- The theory guided research toward the cognitivebehavioral approaches to pain management.
- This theory helps to explain how interventions based on somatosensory (auditory, visual and tactile) stimulation such as friction,music therapy and distraction provide pain relief.
- Melzack (1996) extended the gate control theory explaining phantom limb pain.
References
- Dickenson AH, (2002). Gate Control Theory of pain stands the test of time. Br. J. Anaesth., 88 (6):755-757.
- Smeltzer SC, & Bare BG. [Edrs] (2004) . Brunner and Suddarth's Textbook of Medical-Surgical Nursing. 10th edition. Philadelphia: Lippincott Williams & Wilkins.
- Melzack, R. (1996). Gate control theory: On the evolution of pain concepts. Pain Forum, 5(1), 128–138.
- Melzack R, & Wall PD. ( 1965). Pain mechanisms: a new theory. Science, 150: 971–9 (Free access)
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