Peripheral sensitization occurs when persistent noxious stimuli result in which of the following?

Peripheral sensitization occurs when persistent noxious stimuli result in which of the following?

• A. Enhanced sensitivity with lower stimulation thresholds.
• B. Decreased sensitivity and higher thresholds.
• C. Only central nervous system involvement.
• D. Increased conduction velocity of all fibers.

Answer: (A)

Peripheral sensitization means the ends of peripheral pain fibers become more excitable after ongoing noxious input. In inflamed or damaged tissue, inflammatory mediators lower the activation threshold of nociceptors and boost their responsiveness, so even milder or normally non-painful stimuli can trigger pain. This explains hyperalgesia (increased pain from painful stimuli) and allodynia (pain from non-painful stimuli) that often accompany persistent noxious input. The changes arise from peripheral nerve terminal sensitization—altered ion channel activity and receptor responsiveness—rather than changes in conduction speed, which is not what sensory sensitization primarily involves.

Peripheral sensitization means the ends of peripheral pain fibers become more excitable after ongoing noxious input. In inflamed or damaged tissue, inflammatory mediators lower the activation threshold of nociceptors and boost their responsiveness, so even milder or normally non-painful stimuli can trigger pain. This explains hyperalgesia (increased pain from painful stimuli) and allodynia (pain from non-painful stimuli) that often accompany persistent noxious input. The changes arise from peripheral nerve terminal sensitization—altered ion channel activity and receptor responsiveness—rather than changes in conduction speed, which is not what sensory sensitization primarily involves.