Nursing theories

• 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.

• 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.