Relations between ultrasonographic, elastographic and electromyoneurographic parameters in patients with carpal tunnel syndrome

Introduction: To test the new proposed ultrasonographic (US) diagnostic algorithm for carpal tunnel syndrome (CTS) (Goldberg G, 2016), to compare cross-sectional area (CSA), wrist-to-forearm CSA ratio (WFR) and the elasticity of the median nerve (MN) between 2 groups: healthy volunteers and patients with electrodiagnostically proven CTS.

Methods: 10 patients with CTS (20 hands) and 12 healthy volunteers (24 hands) underwent US of the MN. The CSA and MN strain was measured (MN strain was measured three times) by a radiologist (with 30 years of experience) and by medical resident. Examiners were blinded to the diagnosis of CTS and US measurements made by each other. The mean value was used for the analysis. Patients having had a prior wrist trauma, operation or rheumatic diseases were excluded.

Results: Both hands in 10 patients diagnosed with CTS at the EMG service (9 women and 1 men, mean ± SD age 62.3 ± 5.3 years, range 56 – 72 years, 15 hands with mild, 2 moderate, 2 severe CTS) and in 12 healthy volunteers (8 women and 4 men, mean ± SD age 60.6 ± 8.7 years, range 51 – 82 years) were studied. CSA and WFR in the patients with CTS were significantly higher than those in the healthy volunteers (p < 0.05) according to both examiners. The MN strain in the patients with CTS were not significantly higher than those in the healthy volunteers (p > 0.05) according to both examiners. Sensitivity of the algorithm was 89%, specificity 24%.

Conclusion:

US can provide improvement in patients' selection for the EMG examination. Yet our study suggests that selection criteria (CSA and WFR values) should be reconsidered separately by each clinic performing the examination. Elastography may not be helpful for diagnosing mild CTS.