Comparison of the diagnostic values of clinical examination, sonography and electrodiagnosis in the diagnosis of carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is the most common peripheral mononeuropathy which is caused by nerve compression, in the wrist area (carpal tunnel). The use of ultrasound for the examination and diagnosis of musculoskeletal diseases has been increasing over the last few decades. The aim of this study was to compare the diagnostic values of clinical examination, sonography, and electrodiagnosis in the diagnosis of carpal tunnel syndrome.

In this cross-sectional study (descriptive-analytic) we examined 70 wrists with symptoms consistent with CTS. Sonography and neural conduction studies were performed. Demographic data included age, height, gender, dominant hand, and underlying diseases associated with CTS. Clinical examination was performed and median nerve cross-section and thickness were measured by ultrasound. Then, the results of clinical examination, sonography, and neural conduction study were compared with one another.

We examined 70 wrists with symptoms consistent with CTS. Among 70 symptomatic wrists, 91.4% belonged to the women (mostly housewives) and the rest belonged to the men. The mean age of the patients was 49.56 ± 11.63 years. The results of NCV, clinical examination, distal flexor retinaculum sonography, and proximal sonography were positive in 82.9%,67.1%, 45.7%, and 32.9% of the patients respectively.  The results of this study showed that sonography of the entrance of the carpal tunnel with a cut-off point of 8.5 mm2 had the highest diagnostic value with a sensitivity of 27% and a specificity of 42%.

Measuring the median nerve surface area with ultrasound is useful for detecting and grading the severity of CTS, but it cannot replace neural conduction studies. The use of ultrasound as the first-line measure can be effective in decreasing the number of neurotransmission studies.