Restoration of normal central pain processing following manual therapy in nonspecific chronic neck pain

Abstract Objective to determine if a 4-week manual therapy treatment restores normal functioning of central pain processing mechanisms in non-specific chronic neck pain (NSCNP), as well as the existence of a possible relationship between changes in pain processing mechanisms and clinical outcome. Design cohort study. Methods sixty-three patients with NSCNP received four treatment sessions (once a week) of manual therapy. Pressure pain thresholds (PPTs), conditioned pain modulation (CPM) and temporal summation of pain (TSP) were evaluated at baseline and after treatment completion. Therapy outcome was measured using the Global Rating of Change Scale, the Neck disability Index, intensity of pain during the last 24 hours, Tampa Scale of Kinesiophobia and Pain Catastrophizing Scale. Results Following treatment, an increased CPM response and attenuated TSP were found, along with amelioration of pain and improved clinical status. PPTs at trapezius muscle on the side of neck pain were increased after therapy, but not those on the contralateral trapezius and tibialis anterior muscles. Only minor associations were found between normalization of TSP/CPM and measures of clinical outcome. Conclusion Clinical improvement after manual therapy is accompanied by restoration of CPM and TSP responses to normal levels in NSCNP patients. The existence of only minor associations between changes in central pain processing and clinical outcome suggests multiple mechanisms of action of manual therapy in NSCNP.