Cervicothoracic Spinal Manipulation, Autonomic and Psychological Response, and Pain-Mediated Quality of Life in Chronic Neck Pain with Forward Shoulder Posture: A Biopsychosocial Mechanism Analysis from a Randomized Controlled Trial

Abstract

Background: Forward shoulder posture in chronic neck pain is associated with autonomic dysregulation, perceived stress, and reduced quality of life, yet randomized evidence on biopsychosocial mechanism is limited.
Purpose: To characterize the autonomic, psychological, and quality-of-life response to adding cervicothoracic spinal manipulation to structured physiotherapy, and to test pre-specified mediation linking the intervention to behavioral-medicine outcomes.
Methods: This assessor-blinded randomized trial allocated 55 adults to manipulation plus physiotherapy (n = 27) or physiotherapy alone (n = 28). Heart rate variability (HRV), Perceived Stress Scale (PSS-10), and WHOQOL-BREF were measured at baseline, 4 weeks, and 8 weeks. Pre-specified mediation tested whether 4-week pain reduction mediated the 8-week effect on physical quality of life; a post-hoc chest-expansion-to-pain path is reported transparently.
Results: Six of eight HRV markers showed significant Group x Time interactions, with a transient parasympathetic boost at 4 weeks (RMSSD 32 to 42 ms) that did not persist at 8 weeks (declined to 28 ms). PSS-10 reduction was large (d = -0.97); WHOQOL-Physical, Social, and Environment improved (d = 0.71, 0.49, 0.64). Pre-specified mediation: pain reduction mediated 67.9% of the effect on physical quality of life (indirect 1.997, 95% confidence interval 0.881 to 3.410). Post-hoc exploratory mediation: chest expansion mediated 43.1% of the effect on pain (indirect -0.865, 95% confidence interval -1.769 to -0.138).
Conclusions: Manipulation produced a transient autonomic response (not a durable HRV shift), large stress reduction, and quality-of-life gains driven by pain reduction. Findings are hypothesis-generating and require replication.