Ultrasonography for the diagnosis of carpal tunnel syndrome: correlation of clinical symptoms, cross-sectional areas and electroneuromyography.

Maire Ratasvuori,Markus Sormaala,Antti Kinnunen,Nina Lindfors

doi:10.1177/17531934211059808

Abstract

This study evaluates the usefulness of ultrasonography in diagnosing carpal tunnel syndrome (CTS). The cross-sectional area of the median nerve was measured at the forearm and its entry into the carpal tunnel and compared with clinical symptoms and electroneuromyography. A total of 124 patients were examined, 77 patients with clinically confirmed CTS and 47 controls. A significant correlation was found between the ultrasonography cross-sectional area values at entry points into the carpal tunnel and electroneuromyography. The highest sensitivity (87%) and specificity (91%) for different cut-off values (8.5-12.5 mm2) of the cross-sectional area was for 11.5 mm2. The use of ultrasonography may provide a quick and reliable differential diagnostic tool for the primary diagnosis of CTS in patients with classical symptoms.Level of evidence: II.

Highlights

The lack of a gold standard remains problematic for the diagnosis of carpal tunnel syndrome (CTS)
The mean cross-sectional area in clinically confirmed CTS patients was significantly higher as compared with the control group (Table 2)
In receiver operating characteristic (ROC) analysis, a cross-sectional area cut-off value of 11.5 mm yielded a sensitivity of 87% and a specificity of 91% (Figure 2)

Summary

Introduction

The lack of a gold standard remains problematic for the diagnosis of carpal tunnel syndrome (CTS). CTS is diagnosed by nerve-conduction studies (Sonoo et al, 2018; Torres-Costoso et al, 2018); there are variations in the cut-off points used for determining what constitutes abnormalities. The American Association of Surgery has recommended a validated diagnostic tool for CTS known as CTS-6, including numbness and tingling in the median nerve distribution, nocturnal numbness, weakness, atrophy of the thenar musculature, positive Tinel’s sign, positive Phalen’s test and loss of 2-point discrimination (Surgeons, 2016). On the basis of recent studies, physical tests alone cannot be regarded as reliable screening methods for CTS (Dale et al, 2011; Izadi et al, 2018) even with the CTS-6 criteria, as clinical accuracy is not always 100% and additional diagnostic criteria are recommended (Surgeons, 2016)

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