Ultrasonographic assessment of longitudinal median nerve and hand flexor tendon dynamics in carpal tunnel syndrome

Introduction: Changes in subsynovial connective tissue (SSCT) in carpal tunnel syndrome (CTS) patients may result in altered dynamics; consequently, quantification of these dynamics might support objective diagnosis of CTS. Methods: We measured and compared longitudinal excursion of the flexor digitorum superficialis and profundus tendons, the median nerve, and the SSCT between the most and least affected hands of 51 CTS patients during extension-to-fist motion. Results: Median nerve and flexor digitorum superficialis tendon excursions in the most affected hands were smaller than in the least affected hands of the same patients, whereas the excursions of the flexor digitorum profundus were larger. Based on these excursions, logistic regression models classified between 67% and 86% of the hands correctly as having CTS. Conclusions: The altered hand dynamics in CTS patients may have implications for the pathophysiology and clinical evaluation of CTS, and ultrasound-based classification models may further support the diagnosis of CTS.