Activation in the Hypothalamic-Pituitary-Adrenocortical Axis and Sympathetic Nervous System in Women with Carpal Tunnel Syndrome

Objective. The aim of this study is to investigate the differences in salivary cortisol (hypothalamicpituitary- adrenocortical [HPA] axis), alpha-amylase activity (sympathetic nervous system [SNS]), and immunoglobulin A (IgA; immune system) concentrations between women with carpal tunnel syndrome (CTS) and healthy women. Design. A cross-sectional study. Setting. Activation of HPA, SNS, and immune system in CTS has not been clearly determined. Patients. One hundred two women (age: 45 +/- 7 years) with electrodiagnostic and clinical diagnosis of CTS and 102 matched healthy women. Outcome Measures. The intensity of the pain was assessed with a Numerical Pain Rating Scale (0-10), and disability was determined with Boston Carpal Tunnel Questionnaire. Salivary cortisol concentration, alpha-amylase activity, salivary flow rate, and IgA concentration were collected from nonstimulated saliva. Results. Women with CTS exhibited lower salivary flow rate (P < 0.001) and higher alpha-amylase activity (P < 0.01) than controls. No significant differences for cortisol and IgA concentrations (P > 0.2) were found between groups as a total. Women with severe CTS exhibited lower salivary flow rate (P < 0.001), higher alpha-amylase activity (P = 0.002), and higher cortisol concentration (P = 0.03) than healthy women and than those with minimal/moderate CTS (P < 0.05). Within women with CTS, significant positive associations between alpha-amylase activity and the intensity of pain were found: the highest the level of pain, the higher the alpha-amylase activity, i.e., higher SNS activation. Conclusions. These results suggest that women with severe CTS exhibit changes in activation in the HPA axis and SNS but not in the humoral immune system. Activation of the SNS was associated with the intensity of pain. Future studies are needed to elucidate the direction of this relationship.