Carpal tunnel sonography by the rheumatologist versus nerve conduction study by the neurologist

Objective. To determine the value of sonogaphy (SG) performed by the rheuma tologist to diagnose carpal tunnel syndrome (CTS). Methods. Sixty-three patients with clinical signs of CTS according to the n eurologist. based on patient history and clinical examination, were studied . In the 6 weeks prior to surgery, SG was performed by a rheumatologist and nerve conduction study (NCS) was assessed. Improvement of initial complain ts of 90% or more 3 months after surgery was considered to be the post-hoc gold standard for the diagnosis of CTS. Results. After surgery, 47 patients (75%) experienced greater than or equal to 90% relief of complaints. Mean cross sectional area of the median nerve for patients with CTS was 11.3 mm(2) compared to 6.1 mm(2) in the control group. The sensitivity to detect CTS was 0.70 for SG and 0.98 for NCS, and specificity was 0.63 for SG and 0.19 for NCS. Positive predictive value was 0.85 for SG and 0.78 for NCS; negative predictive value was 0.42 for SG an d 0.75 for NCS. Accuracy was 0.68 for SG and 0.78 for NCS. Conclusion. CTS can be identified by SG less sensitively but more specifica lly than by NCS.