Medizinische Universität Graz - Research portal
Selected Publication:
Klammer, A.
Ultrasound for the diagnosis of carpal tunnel syndrome
[ Diplomarbeit ] Medical University of Graz; 2013. pp. 58
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- Authors Med Uni Graz:
- Advisor:
- Dejaco Christian
- Quasthoff Stefan
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- Abstract:
- Objective: Carpal Tunnel Syndrome (CTS) is the most common entrapment syndrome of peripheral nerves. In addition to clinical assessments and nerve conduction studies, high-resolution ultrasound is more and more used for diagnosis of CTS investigating morphologic changes of the median nerve. The determination of the nerve cross-sectional-area (CSA¿s) is promising; however, no thresholds for an abnormal CSA have been established so far. The aim of this study was the comparison of sonographically determined median nerve CSA¿s at different anatomical landmarks for diagnosis of CTS. In addition, the value of power Doppler (PD)-signals within the median nerve was investigated. Methods: Prospective study on 135 consecutive patients with suspected CTS undergoing two visits within three months. Final diagnosis of CTS was established by clinical and electrophysiological findings. CSA was sonographically measured at 5 different levels at forearm and wrist; and CSA wrist to forearm ratios or differences were calculated. Intra-neural PD-signals were semiquantitatively graded. Diagnostic values of different ultrasound methods were compared by receiving operating characteristic (ROC) curves using SPSS. Results: CTS was diagnosed in 111 (45.5%) wrists; 84 (34.4%) had no CTS and 49 (20.1%) were possible CTS cases. Diagnostic values were comparable for all sonographic methods to determine median nerve swelling with AUCs ranging from 0.75 to 0.85. Thresholds of 9.8 and 13.8 mm2 for the largest CSA of the median nerve yielded a sensitivity of 92% and a specificity of 92%, respectively. A PD-score ¿2 had a specificity of 90% for the diagnosis of CTS. Sonographic median nerve volumetry revealed a good reliability with an intra-class correlation coefficient of 0.90 (95% CI: 0.79-0.95). Conclusion: Sonographic assessment of median nerve swelling and vascularity allows for a reliable diagnosis of CTS. Determination of CSA at its maximal shape offers an easily reproducible tool for CTS classification in daily clinical practice.