Introduction: Widespread pain may be related to psychosocial aspects in several musculoskeletal conditions, but the literature on carpal tunnel syndrome (CTS) is scarce. Objective: To determine the relationship between pain extent and psychological factors (catastrophizing, kinesiophobia, anxiety symptoms, and depression) in people with CTS. Methods: A cross-sectional study was conducted. The independent variables were: pain intensity, disability (QuickDASH), duration of symptoms, anxiety and depressive symptoms, catastrophizing, and kinesiophobia. The main outcome was: pain extent (% of total area and categories "pain within the median nerve-innervated territory" versus "extra-median nerve pain"). Correlation analysis was performed using Spearman's correlation coefficient. A linear regression model and binary logistic regression (both with forward selection) were performed to determine the main predictors of pain extent. Results: Forty-eight participants were included. A moderate positive correlation was found between catastrophizing (r = 0.455; p = 0.024) and disability (r = 0.448; p = 0.024) with total pain extent area. Regression models indicated that catastrophizing explained 22% of the variance in the pain extent (beta = 0.003; 95% CI: 0.002-0.005), while kinesiophobia was the variable that best explained the distribution of pain in the extra-median territory (R-2 Nagelkerke = 0.182). Null or weak correlations were found for the rest of the associations. Conclusion: Catastrophizing and kinesiophobia were the main indicators of pain extent in people with CTS. Clinicians are advised to use specific questionnaires to check for the presence of catastrophizing or kinesiophobia in people with CTS and wider pain extension.
