Figure 1.

The neurophysiological schematic model of “central sensitization” in humans. Local pain will excite the pathway mediating pain upward to the dorsal horn, while a sensitization process is initiated at the same time. The release of sensitizing substances will cause the opening of latent synaptic connections to the neurons mediating pain from the referred area. Both the direct excitation of the involved neurons and the facilitation of afferent input in the referred area will result in the perception of referred pain (5).