Background The most commonly used ultrasonographic measurements for the diagnosis of CTS are measurement of the median nerve cross-sectional area (m-CSA) at different levels of the carpal tunnel.1 The cross-sectional area of a nerve may differ according to biometric characteristics such as age, sex, height, weight and wrist thickness.2–4
Objectives The aim of this study was to assess the diagnostic utility of the ultrasonographic ratio of m-CSA to ulnar nerve cross-sectional area (u-CSA), the m-CSA/ u-CSA ratio, in carpal tunnel syndrome (CTS).
Methods Patients (n=50) with positive symptoms and electromyography results of CTS and control subjects (n=50) with negative electromyography results of CTS were evaluated. The most symptomatic hand of each participant were included in the assesment. Ultrasonographic m-CSA and u-CSA measurements were made at the level of the pisiform bone, and m-CSA/u-CSA ratio was calculated.
Results Using the m-CSA cut-off value of 9.95 mm2 showed a sensitivity of 92% and a specificity of 42%. Conversely, the cut-off value 13.90 mm2 showed a sensitivity of 56% and a specificity of 92%. Using the cut-off value 2.96 for the ratio of m-CSA/u-CSA showed a sensitivity of 86% and a specificity of 38% while using the cut-off value 3.71 showed a sensitivity of 52% and a specificity of 90% in the diagnosis of CTS.
Conclusions The ratio of m-CSA/u-CSA at the level of the pisiform bone did not provide an additional benefit for the diagnosis of CTS. Ultrasonographic m-CSA measured at the same level was found to be more sensitive and specific method.
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Disclosure of Interest None declared