This systematic review and meta-analysis examined the evidence for altered central pain processing in people with non-traumatic neck pain and the relationship between central pain processing, demographics and pain-related characteristics. Case-control studies reporting measures of altered central pain processing using quantitative sensory testing were reviewed. Standardized mean differences (SMDs) and 95% confidence intervals (CIs) between people with non-traumatic neck pain and controls were calculated. Meta-analysis was performed using random-effects models when appropriate. Associations between SMDs with demographics and pain-related characteristics were explored on a study level using meta-regression. Twenty-six studies were eligible with 25 included for meta-analysis. Meta-analysis demonstrated mechanical hyperalgesia at remote non-painful sites in the full sample [sample size (n)=1305, SMD=-0.68] and in the subgroup with moderate/severe disability [n=165, SMD=-0.86] (moderate-quality evidence). Meta-regression indicated that remote mechanical hyperalgesia was negatively associated with age (R=25.4%, P=0.031). Very-low- to low-quality evidence of remote cold and heat hyperalgesia and dysfunctional conditioned pain modulation were identified. This review suggests that altered central pain processing is present in people with non-traumatic neck pain and may be associated with disability levels and age. Perspective: This review found moderate-quality evidence of mechanical hyperalgesia at remote non-painful sites in patients with non-traumatic neck pain compared to controls, indicating altered central pain processing. However, more studies are needed to confirm findings from dynamic quantitative sensory testing.
Copyright © 2020. Published by Elsevier Inc.