Stress-induced hyperalgesia instead of analgesia in patients with chronic musculoskeletal pain

TL;DR

This study reveals that patients with chronic musculoskeletal pain experience hyperalgesia instead of analgesia following stress, indicating altered pain modulation mechanisms that may contribute to their chronic pain condition.

Contribution

It demonstrates that stress-induced analgesia is impaired in CMP patients, leading to hyperalgesia, which is a novel insight into pain modulation in chronic pain conditions.

Findings

Patients with CMP show no increase in pain threshold after stress

CMP patients exhibit hyperalgesia instead of analgesia post-stress

Altered stress-induced pain modulation may be key in CMP pathology

Abstract

Many individuals with chronic musculoskeletal pain (CMP) show impairments in their pain-modulatory capacity. Although stress plays an important role in chronic pain, it is not known if stress-induced analgesia (SIA) is affected in patients with CMP. We investigated SIA in 22 patients with CMP and 18 pain-free participants. Pain thresholds, pain tolerance and suprathreshold pain ratings were examined before and after a cognitive stressor that typically induces pain reduction (SIA). Whereas the controls displayed a significant increase in pain threshold in response to the stressor, the patients with CMP showed no analgesia. In addition, increased pain intensity ratings after the stressor indicated hyperalgesia (SIH) in the patients with CMP compared to controls. An exploratory analysis showed no significant association of SIA or SIH with spatial pain extent. We did not observe significant changes in pain tolerance or pain unpleasantness ratings after the stressor in patients with CMP or controls. Our data suggest that altered stress-induced pain modulation is an important mechanism involved in CMP. Future studies need to clarify the psychobiological mechanisms of these stress-induced alterations in pain processing and determine the role of contributing factors such as early childhood trauma, catastrophizing, comorbidity with mental disorders and genetic predisposition.