The enhanced responsiveness of spinal dorsal horn neurons, including spinothalamic tract (STT) cells, that follows peripheral tissue injury or inflammation is thought to account for secondary hyperalgesia and allodynia and is referred to as “central sensitization” because the increases in excitability do not appear to depend on continued activity of peripheral nociceptors. One well-documented model of secondary hyperalgesia and The enhanced responsiveness of spinal dorsal horn neurons, including spinothalamic tract (STT) cells, that follows peripheral tissue injury or inflammation is thought to account for secondary hyperalgesia and allodynia and is referred to as “central sensitization ” because the increases in excitability do not appear to depend on continued activity of peripheral nociceptors. One well-documented model of secondary hyperalgesia and