The authors performed a case-control study to assess the usefulness of ultrasound in the diagnosis of carpal tunnel syndrome. Twenty-seven patients (40 wrists) with carpal tunnel syndrome and 15 controls (30 wrists) were examined. The cross-sectional area of the median nerve at the tunnel inlet was found to be the most useful diagnostic criterion: the cut-off value for the diagnosis of carpal tunnel syndrome was 6.5 square mm (sensitivity 89.5% and specificity of 93%).
The diagnosis of carpal tunnel syndrome is usually made on clinical grounds. Electrodiagnostic testing can be helpful in confirming the diagnosis, but with recognized limitations of false positive and negative study results. Previous studies have supported the role of advanced imaging (MRI and ultrasound) in the diagnosis of carpal tunnel syndrome. However, the available evidence to date does not support the routine use of advanced imaging in the diagnosis of this condition.