The effect of post‐surgical neuroplasticity on the stability of systemic pain perception: A psychophysical study

Background Surgery‐induced neuroplasticity at spinal and supra‐spinal levels is assumed to evoke a clinical acute post‐operative pain ( cAPOP ) experience, which is expressed by allodynia and/or hyperalgesia. It remains unclear whether the systemic pain perception measured outside the incision area remains unchanged and whether it is affected by the presence of cAPOP . Aims This study explored whether the systemic perception of experimental pain would be altered towards hypersensitivity following elective gynecological surgery unmasked by opioids. Methods A perioperative psychophysical evaluation of heat pain thresholds ( HPT ) and pain estimations were obtained in a remote bodily area before and after surgery among 35 women. Results The ratings for both pain dimensions of intensity and unpleasantness remained stable following surgery. However, there was a reduction found in HPT the day after surgery (43.6 ± 2.2 ° C to 42.2 ± 3.1 ° C , p  = 0.002). This reduction was associated with lower HPT measured before surgery ( r  = .56, p  < 0.000) and with higher cAPOP intensity obtained at rest ( r  = −.44, p  = 0.008). Conclusions This post‐surgical allodynia, as reflected by the systemic enhancement of pain perception, may represent plasticity in the central pain pathways at the supra‐spinal level. Pre‐surgical assessment of a patient's pain perception profile may predict certain pain dimensions of post‐surgical pain plasticity. The evaluation of individual pain profiles may contribute to a mechanism‐based approach aimed to attenuate the cAPOP .