MATERIAL and METHODS: Subsynovial connective tissue samples of 51 idiopathic CTS patients (Group 1), 58 diabetic CTS patients (Group 2) and 16 hypothyroid CTS patients (Group 3) were evaluated in this study. The histopathological examination parameters were; number of fibroblasts, size of collagen fibers, vascular changes (vascular proliferation, intimal thickening and changes of vessel structures), edema and inflammatory infiltration.

RESULTS: In the majority of patients in all 3 groups, non-inflammatory fibrosis was observed in subsynovial connective tissue. Number of fibroblasts, collagen fiber diameter and lengths were statistically different in diabetic CTS patients (Group 2) when compared with other groups. Considering the overall results, neovascularization in subsynovial connective tissue was observed significantly more intensely in diabetic CTS patients (Group 2) and severe edema was found in hypothyroid CTS patients (Group 3).

CONCLUSION: Increased pressure in the carpal tunnel may be a result of reduction of the space or volume increase of the tunnel contents secondary to fibrosis or edema. It may be helpful for the physicians to better understand the causes of this entrapment neuropathy, and these etiological factors should be taken into consideration during the preoperative evaluation of the patients. Keywords : Carpal tunnel syndrome, Diabetes mellitus, Hypothyroidism, Histopathology, Subsynovial connective tissue, Idiopathic carpal tunnel syndrome