Reliability of Ulnar Nerve Sensation Tests in Patients with Cubital Tunnel Syndrome and Healthy Subjects

Static two-point discrimination (2PD) and Semmes-Weinstein monofilament (SWM) tests are commonly used to evaluate sensory disorders in the hand. The aim of this study was to evaluate the reliability of 2PD and SWM tests in the ulnar nerve innervation area in patients with cubital tunnel syndrome (CuTS) and healthy individuals. This was a two-group repeated-measures inter-rater and intra-rater reliability study. Twenty-one patients with CuTS and 30 healthy adults participated. The static 2PD test was performed using a standardized Dellon discriminator, whereas the SWM test was conducted using TOUCH TEST monofilaments. Two examiners performed both tests at the hypothenar eminence and the fourth and fifth digits (ulnar nerve innervation hand territory). First, examiner A conducted three series of 2PD and SWM tests twice with a 15-min rest period (within-day intra-rater reliability). Next, examiner B repeated the same examination 5 min after (inter-rater reliability). Examiner A conducted the same examination 7 days after (between-day intra-rater reliability). For single measurements, the inter-rater reliability and within-day intra-rater reliability in the 2PD was at least 0.81 in patients with CuTS or healthy subjects. The between-days intra-rater reliability for a single measurement varied from 0.56 to 0.95 in CuTS patients and healthy subjects. The between-days intra-rater reliability for mean value from three measurements was above 0.80. The kappa for SWM was above 0.8 and the percentage of agreement was at least 90% for all sessions and trials. In conclusion, the 2PD and SWM tests are reliable for assessing sensation in the ulnar nerve innervation area of the hand in patients with CuTS and healthy subjects.