The Impact of Wrist Extension Provocation on Current Perception Thresholds in Patients with Carpal Tunnel Syndrome: A Pilot Study

Abstract

Purpose To determine whether current perception threshold (CPT) varied between subjects with and without carpal tunnel syndrome (CTS) and whether positioning in wrist extension (reversed Phalen's test) was provocative. Method Subjects ( n = 30) were tested using the Neurometer (Neutron, Inc., Baltimore, MD) at 5, 250, and 2,000 Hz in a rest and reverse Phalen's position. Group and positional differences were analyzed using analysis of variance. Results Higher CPT occurred at 2,000 Hz in both rest (p = 0.02) and reverse Phalen's position (p = 0.01) in CTS subjects. There was also a significant change in CPT in the CTS group following wrist extension, particularly at 2,000 Hz (p < 0.05). Conclusion A positional effect on sensibility was noted at 2,000 Hz in subjects with CTS. Further evaluation is required to determine the role and optimal test protocols for provocative-sensory testing in diagnosis and outcome assessment of CTS. For CPT these should focus on using the 2,000 Hz frequency.