Carpal tunnel syndrome: clinical and sonographic follow-up after surgery.

High-resolution sonography has the same accuracy as electrophysiological studies in confirming the diagnosis in carpal tunnel syndrome (CTS), but the value of sonographic follow-up after surgery requires prospective examination. The aims of the present study were to assess: (1) change in the size of the median nerve at the proximal carpal tunnel after surgery compared to conservative treatment, and (2) the correlation between sonographic characteristics and clinical outcome after surgery. Seventy-nine patients undergoing surgery for CTS were assessed at least 6 months after surgery. The patients completed questionnaires and underwent sonography. Postoperative improvement was scored by the patient on a 6-point ordinal transition scale ranging from "completely recovered" to "much worse." The median cross-sectional area of the median nerve at the proximal carpal tunnel decreased after surgery from 14 mm2 [interquartile range (IQR) 12-16 mm2] to 11.5 mm2 (IQR 11-13.5 mm2) (P < 0.0001); no significant changes in the cross-sectional area occurred in symptomatic hands treated conservatively or in asymptomatic hands. Sonography at the time of diagnosis was not a predictor of postoperative outcome, but in this study only a relatively small number of patients had a poor postoperative outcome.