Identification of Subgroups of Women with Carpal Tunnel Syndrome with Central Sensitization

Objective. Identification of subjects with different sensitization mechanisms can help to identify better therapeutic strategies for carpal tunnel syndrome (CTS). The aim of the current study was to identify subgroups of women with CTS with different levels of sensitization. Methods. A total of 223 women with CTS were recruited. Self-reported variables included pain intensity, function, disability, and depression. Pressure pain thresholds (PPT) were assessed bilaterally over median, ulnar, and radial nerves, C5-C6 joint, carpal tunnel, and tibialis anterior to assess widespread pressure pain hyperalgesia. Heat (HPT) and cold (CPT) pain thresholds were also bilaterally assessed over the carpal tunnel and the thenar eminence to determine thermal pain hyperalgesia. Pinch grip force between the thumb and the remaining fingers was calculated to determine motor assessment. Subgroups were determined according to the status on a previous clinical prediction rule: PPT over the affected C5-C6 joint < 137 kPa, HPT on affected carpal tunnel < 39.6A(0)C, and general health > 66 points. Results. The ANOVA showed that women within group 1 (positive rule, n = 60) exhibited bilateral widespread pressure hyperalgesia (P < 0.001) and bilateral thermal thresholds (P < 0.001) than those within group 2 (negative rule, n = 162). Women in group 1 also exhibited higher depression than those in group 2 (P = 0.023). No differences in self-reported variables were observed. Conclusion. This study showed that a clinical prediction rule originally developed for identifying women with CTS who are likely to respond favorably to manual physical therapy was able to identify women exhibiting higher widespread pressure hyper-sensitivity and thermal hyperalgesia. This subgroup of women with CTS exhibiting higher sensitization may need specific therapeutic programs.