Objective: To use anatomic measurements on magnetic resonance imaging (MRI) and ultrasonography (USG) in diagnosing and grading carpal tunnel syndrome (CTS) using nerve conduction studies (NCS) as the gold standard.
Material and methods: In this prospective study, 26 patients with CTS (45 wrists; 22 female and 4 male patients; mean ± SD age of 49.42 + 14.47 years) and 19 age and sex matched healthy volunteers (32 wrists; 15 female and 4 male volunteers, mean ± SD age of 42.52 + 10.85 years) underwent MRI and USG. Cross-sectional area (CA) of median nerve was measured using free hand ROI at four levels: hamate hook (H0), pisiform bone (PI0), 1 cm proximal (PI1) and 2 cm proximal to PI0 (PI2). Relative median nerve signal intensity (MNSI) was calculated as ratio of median nerve signal intensity with hypothenar muscle signal intensity. Flexor retinacular bowing was calculated at hamate hook level. Echogenicity and Power Doppler vascularity of median nerve were assessed on USG. Independent t-test, chi square test and receiver operating characteristic curve analysis were used as appropriate.
Results: On USG, CA measured at PI0 (95% confidence interval of 0.872-0.987) and retinacular bowing (0.816-0.912), while, on MRI, CA at PI1 (0.874-0.997) were most useful in diagnosing CTS based on the ROC and Zombie plot analysis. Area under curves for CA measurements on USG and MRI were not significantly different. CA at PI1 on MRI (0.752-0.965) was significantly different between minimal to moderate CTS and severe to extreme CTS groups (on NCS).
Conclusion: CA of median nerve is the most useful parameter to diagnose and grade CTS and USG and MRI are comparable for measurements. Increased retinacular bowing on USG and hypoechogenicity of median nerve increase the diagnostic confidence while MRI helps in picking up important associated conditions.
Copyright © 2019. Published by Elsevier Inc.
Median Nerve Compression Can Be Detected by Magnetic Resonance Imaging of the Carpal TunnelRE Horch et al. Neurosurgery 41 (1), 76-82; discussion 82-3. PMID 9218298.The carpal tunnel was smaller in CTS patients than in healthy volunteers. During flexion and extension, the space available for the median nerve narrows. This may lead to …
The Pressure Angle of the Median Nerve as a New Magnetic Resonance Imaging Parameter for the Evaluation of Carpal TunnelG Somay et al. Clin Neurol Neurosurg 111 (1), 28-33. PMID 18848388.The pressure angle of the median nerve may prove useful in the assessment of idiopathic CTS, both before and after surgery.
A Comparison of the Performance of Anatomical MRI and DTI in Diagnosing Carpal Tunnel SyndromeSH Koh et al. Eur J Radiol 83 (11), 2065-73. PMID 25193779.The individual performances of both scans were not significantly different in diagnosing CTS. Measuring both CSA and FA at P1 may be useful and efficient to utilize the m …
Carpal Tunnel Syndrome: Usefulness of SonographyL Sarría et al. Eur Radiol 10 (12), 1920-5. PMID 11305571. - ReviewThe aim of this study was to evaluate sonographic signs described for carpal tunnel syndrome (CTS). Sixty-four wrists from 40 patients with CTS confirmed by electromyogra …
Ultrasonography for Diagnosing Carpal Tunnel Syndrome: A Meta-Analysis of Diagnostic Test AccuracyTW Tai et al. Ultrasound Med Biol 38 (7), 1121-8. PMID 22542258. - ReviewUltrasonography is widely used to diagnose carpal tunnel syndrome (CTS), a common peripheral neuropathy, but the reported diagnostic accuracy varies. This meta-analysis f …
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The Prognostic Value of Median Nerve Thickness in Diagnosing Carpal Tunnel Syndrome Using Magnetic Resonance Imaging: A Pilot StudyS Lee et al. Korean J Pain 33 (1), 54-59. PMID 31888318.Even though both MNCSA and MNT were significantly associated with CTS, MNT was identified as a more suitable measurement parameter.