A-delta fibers and 60 percent were C fibers.17 Clearly, from a clinical and research perspective, we are being urged to focus on nociception. We can no longer avoid it. Consider some of the nociceptive processes chiropractors encounter on a daily basis. It is well known that nociceptors themselves and nociceptive activities in the spinal cord can become sensitized. However, the presence of chemical irritants, which are released after tissue injury, can lower nociceptor thresholds.
Peripheral sensitization refers to the lowering of a normally high nociceptor threshold.
Now innocuous stimuli, such as turning the head, bending over, and gentle palpation can activate nociceptors. It happens all the time. First, it should be understood that central facilitation and wind-up are generally considered to be synonyms of central sensitization. It is now believe that neuronal plasticity is the process which creates central sensitization. The end result is an amplification or an increase in the excitability of dorsal horn neurons, such that the experience of pain can be magnified by noxious and innocuous stimuli.