Last updated: Sat, Aug 17, 2024
Sensitivity to stroking in the area of secondary hyperalgesia is also called allodynia, a general name used when a stimulus that is not normally perceived as painful becomes painful. The intense barrage of messages that is received in the cord when the injury occurs excites interneurons so that synaptic connections between low-intensity sensory neurons and pain pathways that are normally silent become active. This increases the frequency of action potentials in these pathways.
Stroking hyperalgesia lasts for one to two hours, after which the interneurons recover their normal state of excitement. If the area of primary hyperalgesia is anesthetized, it puts an end to the stroking hyperalgesia. The stroking hyperalgesia is dependent on ongoing messages from the primary injury zone.