The purposes of the present study were to assess the outcome of surgery for carpal tunnel syndrome (CTS), to evaluate histological findings of subsynovial connective tissue (SSCT) of patients with CTS in comparison with a control group, and to assess whether the histologic appearance of the flexor tenosynovium is correlated with clinical history, preoperative or postoperative physical examination, general health, symptoms and function as assessed by validated tools, or nerve conduction studies.

Materials and Methods: We studied 30 consecutive patients who had idiopathic CTS and were referred to our institution for surgery. All patients had had diagnostic neurophysiological testing. A study specific questionnaire, a historical-objective scale (Hi-Ob), the Boston Carpal Tunnel Questionnaire (BCTQ), the SF-36 questionnaire were administered to the patients preoperatively and six months after surgery. A standard open carpal tunnel release was performed and 1 cm 3 of tickened synovium was removed from the flexor digitorum superficialis tendons. Specimens of SSCT from flexor tendon at wrist were also obtained from ten fresh-frozen cadavers witrh no history of CTS. Seriated hematoxylin and eosin stained sections were obtained and conventional light microscopy at a magnification of 20X was performed. The number of cells, the number of vessels, the surface of the lumen of the vessels, the total vascular surface, the thickness of the wall of vessels in each selected image were measured with an Autocad software. The results per specimen were averaged for statistical analysis.

Results: Six months after surgery the SF-36 mental and physical summary scores (P< 0.001 and P=0.001, respectively), the Symptom severity score (P< 0.001) and the HI-Ob (P< 0.001) improved. In comparison with cadavers, the typical pathologic findings of SSCT of patients with CTS were vascular hypertrophy and vessel’s wall thickening. At multivariate linear regression analyses greater histopathological changes were important predictor of lower SF-36 scores following surgery. As for the electromyographic parameters, higher preoperative values of 3M SCV and MCV were positively associated with SF-36 BP and SF scores. The greater neurophysiological impairment of the median nerve was predictive of lower SF-36 VT at follow up. Older patients, females and patients who had had the higher number or severity of comorbidities preoperatively achieved the lower SF-36 scores following surgery.

Conclusions: We demonstrated many variables to be associated with the CTS and its surgical treatments thus confirming data from previous reports and suggesting new important associations that have not been described previously. Physicians should consider these results when discussing with patients on the likely outcomes of carpal tunnel surgery.