Effects of prolonged wrist flexion on transmission of sensory information in carpal tunnel syndrome

A Novel Device to Evaluate the Vibrotactile Threshold

This paper presents the initial prototype design of a vibrotactile threshold evaluator for the workplace (VTEW), which is portable and configurable in terms of the probe diameter (2–10 mm), applied frequency (1–500 Hz), angle of probe (0–120 deg), and displacement of probe (1–1500 μm), and is operated with a customizable LABVIEW interface. The vibrotactile threshold is the minimum amplitude of vibration that is perceived at a particular frequency by a subject and is analogous to a hearing test. It can be used to evaluate neuropathy, for instance due to carpal tunnel syndrome or peripheral neuropathy secondary to diabetes. The vibrotactile threshold (VT) at 50 Hz was evaluated using VTEW and an established device, the Vibrotactile Tester (VTT). These results were compared for validation of VTEW. Each subject underwent Phalen’s and Tinel’s test, and the results of these clinical evaluations for carpal tunnel syndrome were used to classify subjects as symptomatic and asymptomatic. The results of the VTEW and the VTT were statistically similar and the age correction developed for both devices from this study were similar to the previously conducted studies. The mean VT values from the VTEW showed an increased VT for symptomatic subjects. The low frequency range of the VTEW was used to evaluate the VT at 4 Hz, and a comparison of VT at 4 Hz and 50 Hz showed a higher sensitivity of subjects to 50 Hz as compared to 4 Hz. The gender effect on VT was also studied and discussed, along with recommendation for further investigation. A novel and highly customizable device for testing the vibrotactile threshold is presented, with results demonstrating identification of symptomatic subjects. This device could be used to regularly test workers at risk for developing carpal tunnel syndrome (e.g. assembly line workers) to monitor for elevations in VT. Other applications include using the low frequency to evaluate peripheral neuropathy.

Progress in vibrotactile threshold evaluation techniques: a review

Vibrotactile threshold (VT) testing has been used for nearly a century to investigate activation of human somatosensory pathways. This use of vibrotactile stimuli provides a versatile tool for detecting peripheral neuropathies, and has been broadly used for investigation of carpal tunnel syndrome. New applications include investigation of drug-induced neuropathies and diabetes-related neuropathies. As a feedback device, the vibrotactile stimuli could be used as an information delivery system for rehabilitative feedback devices for upper limb musculoskeletal disorders or as information channels for the visually impaired. This review provides a comprehensive review of the advancement in VT measurement techniques over time and a comparison of these techniques in terms of various hardware features used and the testing protocols implemented. The advantages and limitations of these methods have been discussed along with specific recommendations for their implementation and suggestions for incorporation into clinical practice.