Browsing by Author "Nilsson, T"

Filter results by typing the first few letters
Now showing 1 - 1 of 1
  • No Thumbnail Available
    Item
    Neurosensory function and white finger symptoms in relation to work and hand-transmitted vibration
    (Arbetslivsinstitutet, 1998) Nilsson, T
    The present thesis, which is based on six studies, focuses on the vascular and the neurological outcomes in relation to work and hand-transmitted vibration. The overall aim was to assess the quantitative relation between cumulative vibration exposure and self-reported signs of "white fingers", nerve conduction, nerve provocation test, and quantitative sensory testing of vibrotactile and thermal perception. Vibration exposure data was characterised from "ever employed" in a job involving use of vibrating tools to quantitative, individual estimates of cumulative frequency-weighted vibration exposure for each hand. The manual load aspect of the exposure was measured as time with a forced grip. The cross-sectional study on the vascular component of the hand-arm vibration syndrome revealed a high prevalence of white fingers in the plater group together with high risk estimates. Hand circulation was assessed by a symptom questionnaire and a timed Allen's test. The odds ratio for a positive Allen's test was higher for the vibration-exposed category than for the non-exposed. The neurological outcome was assessed in a cross-sectional and a follow-up study. In the cross-sectional study, a lower nerve velocity was found in the right hand than in the left. An increased risk of prolonged latency time was found for the vibration exposed plater group when contrasted to the office workers. The follow-up study, focusing on the change in nerve conduction during the five-year follow-up period, did not support the findings from the cross-sectional study. This indicates that vibration exposure per se, at the intensity level that we investigated was not a major specific risk factor over a five-year interval time span. In contrast an exposure-effect relation was indicated when ergonomic exposure was individually assessed. The prospective cohort study on nerve provocation revealed that work factors, including vibration exposure, were associated with AER signs. Subjects with AER signs showed lower nerve conduction velocities in the wrist. The study on vibrotactile function demonstrated elevated thresholds -primarily for the Pacinian mediated sensation : related to vibration. In the study on thermal perception the risk for the vibration exposed group of having contracted reduced thermal sensibility was found to be increased at all test sites. The risk was higher for the thenar measurements than the finger measurements. Application of the risk prediction model for white fingers in Annex A of ISO 5349 rather underestimated the VWF risk among the currently exposed platers. The results indicate a relation between sensory impairment and cumulative vibration exposure. This effect appeared at vibration levels below the limits suggested in the current standard.