Association between electrodiagnosis and neuromuscular ultrasound in the diagnosis and assessment of severity of carpal tunnel syndrome

Abstract

BackgroundNeuromuscular ultrasound plays an increasing role in diagnosing carpal tunnel syndrome (CTS). There are limited data supporting the correlation between the electrodiagnostic studies and ultrasound measurements in CTS.ObjectiveTo assess the association between different electrodiagnostic severities and ultrasound measurements of the median nerve in CTS.DesignA retrospective cohort study.SettingAn academic tertiary care center.PatientsPatients 18 years or older evaluated with upper limb electrodiagnostic studies and neuromuscular ultrasound.Main outcome measurementUltrasound measurements of the median nerve cross‐sectional area (CSA) at the wrist and the calculated wrist‐to‐forearm ratio (WFR) were compared with the electrodiagnostic severity (normal, mild, moderate, and severe). Mean analysis and analysis of variance test (α = 0.05) were performed to assess the association.ResultsA total of 1359 limbs were identified. There was a statistically significant association between electrodiagnostic severity of CTS and median nerve CSA at the wrist (p < .001), as well as the WFR (p < .001). The mean median nerve CSA at the wrist and WFR were 7.01 ± 2.06 mm2 (95% CI: 6.80–7.20) and 1.24 ± 0.36 (95% CI: 1.16–1.24) in electrodiagnostically normal median nerves, 10.47 ± 2.82 mm2 (95% CI: 10.25–10.75) and 2.06 ± 0.67 (95% CI: 2.04–2.16) in electrodiagnostically mild CTS, 12.95 ± 4.74 mm2 (95% CI: 12.41–13.59) and 2.49 ± 1.04 (95% CI: 2.37, 2.63) in electrodiagnostically moderate CTS, and 14.69 ± 5.38 mm2 (95% CI: 13.95–15.44) and 2.71 ± 1.02 (95% CI: 2.56–2.84) in electrodiagnostically severe CTS, respectively.ConclusionThis study suggests a direct association between electrodiagnostic severity and ultrasound measurements of the median nerve in patients with suspected CTS.