CUTOFF VALUE OF TWO-POINT DISCRIMINATION DISTANCES IN CARPAL TUNNEL SYNDROME

Abstract

Background: Two-point discrimination test (2PD) represents large sensor fiber, which is more sensitive than smaller fiber to detect abnormality in carpal tunnel syndrome (CTS). Few studies have focused in 2PD to diagnose CTS. Objective: The study aimed to establish the cutoff value of 2PD to determine CTS. Methods: A descriptive diagnostic study was conducted at the Outpatient Department of Rehabilitation Medicine, Phramongkutklao Hospital. Participants who were suspected of having CTS were included in the study. All participants performed the 2PD test at the thumb, index finger and middle finger. The nerve conduction studies were performed and definitive diagnosis of CTS was based on the results. Data were analyzed using the receiver operation coefficient curve. Results: Of 48 participants (total of 95 hands), CTS was diagnosed in 85 hands (89.5%). Additionally, of all CTS hands, severity was mild degree in 17 hands (28.4%), moderate degree in 31 hands (32.6%) and severe degree in 37 hands (39%). The optimum cutoff values were >4 mm having the sensitivities of 75.3, 68.2 and 68.2% while the specificities were 80, 90 and 90%, respectively, for the thumb, index finger and middle finger. The areas under curve were 0.826, 0.833 and 0.823, respectively. Conclusion: The participants with more than 4 mm of 2PD at the thumb, index finger and middle finger had high probability of having CTS.