Indicators of upper extremity musculoskeletal disorders: Digital vibration threshold testing and infrared thermography

Upper extremity musculoskeletal disorders (UEMSDs) such as carpal tunnel syndrome and tendinitis comprise a large percentage of workplace illnesses. However, options for screening, surveillance and diagnosis of UEMSDs are limited. Detection of UEMSDs other than nerve compression syndromes has depended on symptoms and on various clinical signs of undocumented validity and reliability. Other modalities including medical imaging and quantitative sensory testing (QST) are less well developed.; The objective of this thesis was to examine two potential indicators of UEMSDs—digital vibration threshold testing (VTT) and infrared thermographic imaging. Thermography detects cutaneous temperature, a blood flow surrogate. VTT reflects nerve functionality.; UEMSD signs and symptoms in automobile manufacturing workers (n = 1187) were examined for their association with vibration thresholds (VTs) in cross-sectional analysis, and one year following such testing. Associations with workers' estimates of ergonomic stressors were also examined.; Three groups of office workers (n = 29) underwent dorsal hand thermographic imaging before and after typing for nine minutes. Changes in mean dorsum temperature through several imaging periods were determined for controls and for subjects with distal UEMSDs, with and without subjectively cold hands exacerbated by keyboard usage.; VTs were associated with greater hand/arm numbness frequency in cross-sectional analysis, and also with its persistence one year after VTT. VTs were also associated with de Quervain's disease and extensor and flexor compartment disorders, in cross-sectional analysis and in follow-up incident cases. Associations were found with hand force, vibration intensity as felt through the floor, and a sum of exposures.; Three distinct blood flow patterns in response to a typing challenge were seen in the three office worker groups. Warm cases and controls both increased mean dorsum temperature after typing, while cold cases decreased. An ambient temperature effect was seen in both cold cases and controls.; VTT may be useful in early detection of UEMSD signs and symptoms. Further studies are necessary to assess its validity and feasibility for the conditions where associations were found. Longitudinal studies in larger case groups with detailed symptom characterization would clarify the utility of thermography in such early detection. Validity and feasibility measurements could then follow.