The Gate Control Theory, suggested by Melzack and Wall in 1965, is the most accepted theory of pain today — although it still has its critics. This theory suggests that a control mechanism exists in the back horn of the butterfly-shaped spinal cord’s inner structure. It particularly applies to an area called the substantia gelatinosa — a jelly-like substance. Melzack and Wall believe that a ‘gate’ is present in this area and, when open, pain messages can pass through to the brain and make their impact.

American Professor Ronald Lawrence suggests that his students imagine two men running for the same narrow gate. The ‘fat man’ (messages travelling along the thick nerve fibres) can run much faster than the ‘thin man’ (messages travelling along thin fibres). He can get to the gate first and can thus block the gate. The thin man can pass through the open gate as do the pain messages when the gate is not blocked. But when the gate is closed, for whatever reason, the pain signal is not received by the brain and is thus effectively blocked. The gate receptors appear to be special spinal nerve cells.Thus signals travel slowly to ‘keep the gate open’ along the small uncoated nerve fibres, and the larger, coated fibres, with their rapid signals, ‘close the gate’. To better understand this, imagine you stub your toe. The pain signal travels slowly along the thin A delta fibres. By rubbing your toe, you send messages along the thicker beta fibres causing the gate to ‘close’. Thus, the pain decreases. This partially explains the effectiveness of acupuncture and TENS (Transcutaneous Electrical Nerve Stimulation), a treatment derived initially from the observation that electricity applied to the skin could have profound effects in controlling pain. The smaller fibres seem able to increase the effect of the input of sensory information into different parts of the brain. These increased signals may initiate reactive signals that descend into the spinal cord. When enough of these signals are activated, another system comes into play — the avoidance system (a reflex phenomenon), performed without thinking of pain — (rubbing your stubbed toe, wagging the finger you’ve mistakenly hit with a hammer, withdrawing your hand from a hot stove.)

*19\37\8*

Share and Enjoy:
  • Digg
  • Sphinn
  • del.icio.us
  • Facebook
  • LinkedIn
  • Reddit
  • StumbleUpon
  • Twitter
  • Yahoo! Bookmarks

Related Posts

Tags:

Comments are closed.