Final answer:
Secondary hyperalgesia refers to the increased sensitivity to pain beyond the area of tissue damage, whereas the flare is the immediate redness and temperature increase surrounding an injury.
Step-by-step explanation:
The concept being referred to in the question is secondary hyperalgesia, which is related to an increased sensitivity to pain, often surrounding an area of injury. Secondary hyperalgesia represents the heightened sensitivity that occurs outside of the damaged tissue area. A related phenomenon is the "flare," which is the redness and increase in temperature around the area of injury. The statement indicates that secondary hyperalgesia covers a broader area than the flare, suggesting that the pain experienced goes beyond the visually inflamed area.
For example, if someone were to sustain a burn on their hand, they may experience a red and warm area surrounding the burn (flare), but the pain could extend beyond this red area due to secondary hyperalgesia. This broader area of sensitivity is due to the sensitization of the nervous system, particularly the spinal cord neurons, which become more responsive to stimuli that are normally not painful (allodynia) or to painful stimuli (hyperalgesia).