Carpal tunnel syndrome (CTS) is among the most common disorders of the upper extremity. At the moment electrodiagnostic testing (EDX) is often identified as a gold standard for CTS diagnosis. Recent studies show that ultrasonographic testing may become an alternative confirmatory tool for the disorder.
To compare the cross sectional area (CSA), wrist-to-forearm ratio (WFR) and the elasticity of the median nerve (MN) between patients with CTS and healthy subjects and to evaluate diagnostic usefulness of these measurements in diagnosis of CTS.
Materials and Methods:
Patients diagnosed with CTS as well as healthy volunteers were examined by two observers, experienced radiologist and medical resident with 1 year of experience. Both were blinded to the diagnosis. Standard measurements of CSA of the MN were performed. Elasticity of the nerve was measured using strain ratio elastography. In order to evaluate the diagnostic utility of ultrasound, recently proposed diagnostic algorithm was tested (Goldberg G, 2016). QuickDASH questionnaire was used to evaluate the ability of ultrasound and EDX to assess symptom severity of CTS patients.
27 wrists with CTS and 25 healthy wrists were analyzed. CSA and WFR were significantly higher in CTS patients than in healthy volunteers. However, there was no significant difference in elasticity of the MN in our sample. There was no correlation between the MN conduction velocity, clinical symptoms and ultrasound measurements. Logistic regression revealed that ultrasound measurements had weak relationship between prediction and grouping. Diagnostic algorithm had specificity of 81.5% and sensitivity of 24%.
Currently there is no reliable ultrasonographic diagnostic algorithm. Further ultrasound studies are needed for the development of better diagnostic tools combining various diagnostic techniques.
Keywords: carpal tunnel syndrome, cross sectional area, elastosonography, strain ratio, quickDASH.