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Background and Aim: Carpal tunnel syndrome (CTS) is the most common form of peripheral entrapment neuropathy. The use of sonography for investigation and diagnosis of musculoskeletal conditions has been rapidly increasing over the past few decades. The purpose of this study was to determine whether sonography can be an alternative method to nerve conduction study (NCS) in the diagnosis of CTS. Material and Methods: This prospective cross-sectional descriptive study included patients with electrodiagnostically proven CTS and healthy control subjects. Anthropometric and demographic data included age, height, body mass index (BMI), sex, occupation, medication history, hand dominance, and underlying disorders associated with CTS. Median nerve Cross-Sectional Area (CSA), Flattening Ratio (FR), and flexor retinaculum thickness were measured. Then, we compared the results between ultrasonography and nerve conduction study. Results: In this study, we assessed 120 wrists with CTS (cases) in 90 patients and 60 healthy wrists in 30 patients (control group). CTS was mild in 57, moderate in 29, and severe in 34 wrists. Post hoc comparisons between the patients with CTS and controls demonstrated that the cross sectional areas at various levels of the median nerve were significantly greater in the CTS group compared to the control group. CSA at the tunnel inlet with a threshold higher than 9.15 mm2 showed the best diagnostic accuracy with a sensitivity and specificity of 99.2% and 88.3% respectively. Cross-sectional areas of the median nerve in mild, moderate and severe carpal tunnel syndrome showed statistically significant differences. Conclusion: Ultrasonographic measurement of the cross-sectional area of median nerve is useful for the diagnosis and grading of CTS. Use of sonography as the first-line measure may effectively reduce the number of nerve conduction studies in the diagnosis of CTS. Key words: Carpal tunnel syndrome, Ultrasonography, Nerve conduction velocity. Received: Jan 7, 2013 Accepted: Jul 23, 2014

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Background and Aim: 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.

Materials and Methods: 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.
Results: 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%.
Conclusion: 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.