Ultrasonography before and after surgery in carpal tunnel syndrome and relationship with clinical and electrophysiological findings. A new outcome predictor?

OBJECTIVE: To measure the cross-sectional area (CSA) of the median nerve by ultrasonography (US) before and after surgery in subjects with carpal tunnel syndrome (CTS), and to verify whether the normalization of presurgical parameters can be predicted by presurgical CSA values. PATIENTS AND METHODS: Sixty-seven consecutive cases, mean age 60.5 years, underwent surgical decompression. Before surgery, clinical and electrophysiological severity and self-assessment of symptoms (using the Boston questionnaire, BQ) were recorded. CSAs were measured proximal to the carpal tunnel inlet (CSA-I), at mid-tunnel (CSA-M), and at the tunnel outlet (CSA-O). Follow-ups were performed 1 and 6 months after surgery. Logistic regressions were performed with normalization of CSA, clinical and electrophysiological parameters as independent variables, and presurgical findings as dependent variables. RESULTS: Before and after surgery there were correlations between CSA-I and clinical and electrophysiological severity scales. After 1 and 6 months, the clinical, electrophysiological, and BQ findings improved. CSA-I reduced at the 1-month follow-up and CSA-O increased between the first and second follow-up. Presurgical values of CSA-I could predict the normalization of its postsurgical value, normalization of the clinical severity scale, BQ, and full patient satisfaction postsurgery. CONCLUSIONS: CSA-I is the most sensitive US measurement before surgery. The presurgical value of CSA-I is a predictor of postsurgical normalization of clinical parameters and of its own value.