Morphologic Changes of Cervical Musculature in Relation to Chronic Nonspecific Neck Pain: A Systematic Review and Meta-Analysis

Chronic neck pain is a common musculoskeletal disorder. Previous studies have found that chronic neck pain is associated with changes in neck muscle morphology and fat infiltration (FI). This systematic review summarizes and analyzes all studies on neck muscle morphology in patients with chronic nonspecific neck pain (CNNP). The main objective of this study was to review and analyze measurements of neck muscles in all patients with CNNP, including morphologic changes in the multifidus muscle (MF), longus colli muscle (LC), and semis-spinalis capitis muscle (SCa) in patients with CNNP compared with controls.This was a systematic review with meta-analysis A comprehensive search of online databases, including PubMed, Web of Sciences, Embase, and Medline was conducted to identify relevant studies reporting changes in neck muscle morphology in patients with chronic neck pain versus healthy controls. Search scope was from inception to June 30, 2022, with no language restrictions. Two reviewers participated in the screening process independently. Due to the lack of relevant data from other studies, only studies that reported morphologic changes of MF, LC, and SCa in patients with CNNP, including muscle cross-sectional area (CSA), lateral diameter (LD), and anteroposterior diameter (APD), were selected. A modified Newcastle-Ottawa scale was used to assess study quality and risk of bias. A total of 11 studies were included based on inclusion and exclusion criteria, of which 8 were included in the meta-analysis.The results showed that the CSA of LC was slightly smaller in patients with CNNP (mean difference-0.23, 95% confidence interval -0.37 to -0.08), and the multiplied linear dimensions (multiplied linear dimensions: lateral diameter × anteroposterior diameter) of SCa was slightly smaller (mean difference -0.19, 95% confidence interval -0.34 to -0.03). There was no difference in MF muscle size between Patients with CNNP and healthy controls.LC and SCa sizes were slightly smaller in patients with CNNP; there was no difference in MF muscle size between the 2 groups. In addition, no conclusions could be drawn in fat infiltration due to insufficient evidence. In summary, CNNP has influence on neck muscle morphology but the evidence is limited.