Diagnosis of Carpal Tunnel Syndrome in Patients Without Diabetes With Hemodialysis Using Ultrasonography: Is It a Useful Adjunctive Tool?

Objective: (1) To examine the ultrasonography (US) characteristics in patients with hemodialysis-related carpal tunnel syndrome (H-CTS) and (2) to evaluate the accuracy of a proposed US parameter-dynamic ratio of median nerve-to-hamate hook distance (RMHD) in diagnosis of H-CTS. Design: A case-control study. Setting: A tertiary medical center and a secondary hospital from November 2017 to March 2021. Participants: Consecutive patients (N=207) without diabetes under hemodialysis were recruited and divided into a hemodialysis without carpel tunnel syndrome (CTS) (H-Control) group and an H-CTS group. Age-matched volunteers (N=89) without diabetes or upper extremity disorders were enrolled as the control group. Intervention: US examinations by 2 operators blinded to the patient's clinical information. Main Outcome Measures: US parameters including cross-sectional area of the median nerve at the carpal tunnel inlet (CSA-I) and outlet (CSA-O), the flattening ratio of the median nerve at the inlet (FR-I) and outlet (FR-O), and RMHD. Results: Handedness and arteriovenous fistula showed no associations with CSA-I/O and FR-I/O. Compared with the control group (n=69), the CSA-I was significantly larger in the H-Control group (n=63) and H-CTS group (n=76) (P<.001, both). There were no significant differences in the FR-I/-O among the 3 groups. For the second aim, in the H-CTS group (n=38), there was a significantly lower RMHD compared with both the control (n=20) and H-Control groups (n=30) (0.1%±2.2% vs 3.5±2.3% and 3.8±1.7%, P<.001, both). An RMHD cutoff value of <2.7% yielded a specificity of 80.0%, a sensitivity of 94.7%, and an overall accuracy of 88.2% in the diagnosis of H-CTS. Conclusions: Neither CSA-I/-O or FR-I/-O have a role in the diagnosis of H-CTS. RMHD might be a useful US parameter in the diagnosis of CTS in patients without diabetes undergoing hemodialysis.