Heightened pain facilitation rather than impaired pain inhibition distinguishes those with moderate/severe disability in work-related neck pain

To better understand the mechanisms underpinning work-related neck pain, this cross-sectional and single-blinded study compared somatosensory profiles among sonographers with varied neck disability levels. Based on K-mean cluster analysis of scores on the neck disability index (NDI), participants were classified into no (NDI <= 8%, n = 31, reference group), mild (NDI = 10%-20%, n = 43), or moderate/severe (NDI >= 22%, n = 18) disability groups. Data were collected on bodily pain distribution and severity and psychological measures including depression, anxiety, pain-catastrophizing, and fear-avoidance beliefs using validated scales. Participants attended 1 session of quantitative sensory testing performed according to a standardized protocol, including local and remote thermal and mechanical pain thresholds, temporal summation of pain (TSP), conditioned pain modulation, and an exercise-induced analgesia paradigm. Compared with participants with no and mild disability, those with moderate/severe disability showed more widespread pain, cold and mechanical hyperalgesia at a remote nonpainful site, and significantly higher TSP. Participants with mild disability demonstrated significantly higher TSP than those with no disability. These group differences were attenuated after adjusting for depression or anxiety, indicating these psychological factors may mediate the somatosensory changes associated with neck disability. Group differences were not found for conditioned pain modulation or exercise-induced analgesia. These findings suggest that heightened pain facilitation, rather than impaired pain inhibition may underpin nociplastic pain in participants with moderate/severe disability, and it may be associated with depression and anxiety. Clinicians should be aware that individuals with work-related neck pain presenting with moderate/severe disability display distinct somatosensory features and tailor management strategies accordingly.