Comparing the efficacy of multiple quantitative and qualitative ultrasound parameters for the diagnosis of carpal tunnel syndrome.

Purpose: Carpal tunnel syndrome (CTS) is a compression neuropathy causing significant morbidity. Over the years, ultrasound has been evaluated as an alternative to nerve conduction study (NCS) for diagnosing CTS, however, there is no consensus as to which ultrasound parameter is the best. Our study aimed to determine and compare the efficacy of various ultrasound-based variables for diagnosis of CTS.

Methods: 80 patients with clinical suspicion of CTS underwent ultrasound examination with calculation of cross-sectional area (CSA), delta CSA, wrist forearm ratio (WFR), palmer bowing (PB), flattening ratio (FR), flexor retinaculum thickness (FT), and evaluation of echogenicity and vascularity of median nerve. NCS was taken as the gold standard and the diagnostic efficacy of all these variables was compared, followed by receiver operator curve (ROC) analysis.

Results: Delta CSA had the highest accuracy (91.25%), followed by CSAc (80%), WFR (78.75%), and PB (73.75%). Youden's index and sensitivity were highest for delta CSA (0.783 and 96.15% respectively), while specificity was highest for FT (89.29%). The highest area under the curve was noted for delta CSA (97.1%), followed by WFR (AUC = 87.4%) and CSAc (AUC = 86.0%).

Conclusion: Delta CSA was found to be the best ultrasound parameter for diagnosis of CTS, followed by CSAc, WFR, and PB, and can be used as an alternative to NCS. Using ROC analysis this study also predicted the best cut-off values for these parameters which could improve their diagnostic accuracy and further research is needed to confirm these findings.