Three-Dimensional Magnetic Resonance Imaging of Median Nerve Volume for Assessing Carpal Tunnel Syndrome Severity

Introduction/Aims: 3D magnetic resonance imaging (MRI) is a tool for visualizing and quantifying the volume of the median nerve; however, the diagnostic value of the volume of the median nerve for assessing CTS severity is unclear. This study aimed to evaluate the utility of 3T MRI combined with three-dimensional (3D) imaging to assess the cross-sectional volume (CSV) of the median nerve for diagnosing carpal tunnel syndrome (CTS) and determining its severity. Methods: We used MRI to measure the CSV of the median nerve in 95 patients with CTS and 26 healthy controls. CTS severity was graded according to the Padua classification, and differences in CSV according to severity were analyzed. Results: The mean CSVs for the severity groups were as follows: control, 22.4 mm³; minimal, 28.8 mm³; moderate, 34.4 mm³; severe, 53.6 mm³; and extreme, 48.3 mm³. CSV increased with CTS severity, with significantly higher values in the severe and extreme groups compared with the moderate, minimal, and control groups. Discussion: This study showed that the CSV of the median nerve increased with disease severity, both visually and in three dimensions. This helps to visually understand the severity of CTS, and the association between morphology and disease severity may contribute to a better understanding of the pathophysiology of CTS.