Carpal tunnel syndrome: elastosonographic strain ratio and cross-sectional area evaluation for the diagnosis and disease severity.

Abstract

To evaluate the role of gray scale ultrasonography (US) and real time elastosonography (RTE) in carpal tunnel syndrome (CTS). Both wrists of 18 healthy volunteers (n=36) formed the control group (Group 1) and 19 symptomatic outpatients of the neurology clinic constituted the patient group. According to nerve conduction study results, cases with mild CTS (n=15) formed Group 2; cases with moderate to severe CTS (n=20) formed Group 3. Cross sectional area (CSA) and strain ratio (SR) were measured at carpal tunnel inlet (CTI) and 4 cm proximal to the distal end of the radius (P). CSA and SR change score (CSACTI-CSAP; SRCTI-SRP), CSA and SR ratio score (CSACTI / CSAP; SRCTI / SRP) were calculated. The median nerve was significantly stiffer in Group 2 compared to Group 1; also in Group 3 compared to Group 1 (p=0.000). For CSACTI, the difference was significant between Group 1 and Group 3 (p=0.000), also between Group 2 and Group 3 (p=0.001). For CSA change scores the difference was only significant between Group 1 and Group 3 (p=0.015). In the diagnosis of CTS the best cut-off value for CSACTI was 10.8 (p=0.001), 2.3 for SRCTI (p=0.000), 4.9 for the CSA change score (p=0.005), 0.05 for the SR change score (p=0.000), 1.3 for the the CSA ratio score (p=0.015) and 1.1 for the SR ratio score (p=0.000). SR measurements do not exclude patients even with mild CTS but cannot categorize disease severity. CSA measurements on the other hand can categorize disease severity. Therefore, the combined use of US and RTE is suggested.