Diagnostic value of median nerve shear wave ultrasound elastography in diagnosis and differentiation of carpal tunnel syndrome severity

Heba Refaat Ibrahim

doi:10.1186/s43055-021-00573-3

Abstract

BackgroundCarpal tunnel syndrome (CTS) is the commonest type of peripheral nerve entrapment syndromes. The study aimed at evaluation of diagnostic value of median nerve stiffness measured by shear wave ultrasound elastography for diagnosis and differentiation of CTS severity, correlated to electrophysiological studies. This case–control study involved 40 patients (56 wrists) with CTS of different severity and 40 controls (40 wrists). All participants underwent electrophysiological study to assess the CTS severity, high-resolution conventional B-mode ultrasound to assess cross-sectional area “CSA” of median nerve at carpal tunnel, ratio of median nerve CSA at carpal tunnel and forearm, and shear wave ultrasound elastography with measurement of median nerve mean stiffness and correlation to electrophysiological results as the reference standard.ResultsMean median nerve stiffness by shear wave US elastography was increased in patients with CTS compared to controls and across the different CTS severity groups (P value < 0.001 & 0.001, respectively). The cutoff value by ROC curve analysis for median nerve stiffness to differentiate between patients with CTS and control group was 65.4 kPa (P value < 0.001, 94.6% sensitivity, 97.3% specificity). Higher diagnostic accuracy was noted with the combination of shear wave elastography and conventional B-mode US with improved AUC (B-mode + shear wave; 0.962, P value < 0.001).ConclusionsShear wave ultrasound elastography of median nerve was able to discriminate different severity subgroups of CTS with high sensitivity, while conventional US couldn’t. The diagnostic accuracy of CTS was improved when combined high-resolution conventional B-mode US and complementary shear wave ultrasound elastography.

Highlights

Carpal tunnel syndrome (CTS) is the commonest type of peripheral nerve entrapment syndromes
Receiver operating characteristic curve analysis revealed that the optimal cutoff values for median nerve stiffness, median nerve Cross-sectional area (CSA), and wrist/forearm median nerve CSA ratio were (65.4 kPa, 8.5 mm2, and 1.3, respectively) to differentiate between patients with carpal tunnel syndrome (CTS) and control group with sensitivity and specificity for median nerve stiffness of 94.6% and 97.3%, respectively (Table 1; Fig. 7)
The median nerve CSA and wrist/forearm median nerve CSA ratio were found to be larger in patients with CTS compared to control group

Summary

Introduction

Carpal tunnel syndrome (CTS) is the commonest type of peripheral nerve entrapment syndromes. The study aimed at evaluation of diagnostic value of median nerve stiffness measured by shear wave ultrasound elastography for diagnosis and differentiation of CTS severity, correlated to electrophysiological studies. This case– control study involved 40 patients (56 wrists) with CTS of different severity and 40 controls (40 wrists). All participants underwent electrophysiological study to assess the CTS severity, high-resolution conventional B-mode ultrasound to assess cross-sectional area “CSA” of median nerve at carpal tunnel, ratio of median nerve CSA at carpal tunnel and forearm, and shear wave ultrasound elastography with measurement of median nerve mean stiffness and correlation to electrophysiological results as the reference standard. B-mode ultrasound and Doppler examination are used traditionally to examine peripheral nerves to gain information about nerve structure, cross-sectional area, echogenicity, vascularity and any anomalous anatomical structure [10, 11]

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