| 1. |
- Dahlin, Lars, et al.
(författare)
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Low myelinated nerve-fibre density may lead to symptoms associated with nerve entrapment in vibration-induced neuropathy.
- 2014
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Ingår i: Journal of Occupational Medicine and Toxicology. - : Springer Science and Business Media LLC. - 1745-6673. ; 9:1
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Forskningsöversikt (refereegranskat)abstract
- Prolonged exposure to hand-held vibrating tools may cause a hand-arm vibration syndrome (HAVS), sometimes with individual susceptibility. The neurological symptoms seen in HAVS are similar to symptoms seen in patients with carpal tunnel syndrome (CTS) and there is a strong relationship between CTS and the use of vibrating tools. Vibration exposure to the hand is known to induce demyelination of nerve fibres and to reduce the density of myelinated nerve fibres in the nerve trunks. In view of current knowledge regarding the clinical effects of low nerve-fibre density in patients with neuropathies of varying aetiologies, such as diabetes, and that such a low density may lead to nerve entrapment symptoms, a reduction in myelinated nerve fibres may be a key factor behind the symptoms also seen in patients with HAVS and CTS. Furthermore, a reduced nerve-fibre density may result in a changed afferent signal pattern, resulting in turn in alterations in the brain, further prompting the symptoms seen in patients with HAVS and CTS. We conclude that a low nerve-fibre density lead to symptoms associated with nerve entrapment, such as CTS, in some patients with HAVS.
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| 2. |
- Edlund, Maria, 1972, et al.
(författare)
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A prospective cohort study investigating an exposure-response relationship among vibration-exposed male workers with numbness of the hands
- 2014
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Ingår i: Scandinavian Journal of Work Environment & Health. - : Scandinavian Journal of Work, Environment and Health. - 0355-3140 .- 1795-990X. ; 40:2, s. 203-209
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Tidskriftsartikel (refereegranskat)abstract
- Objective The aim of this study was to investigate the exposure response relationship of hand-arm vibration (HAY) exposure to neurological symptoms (numbness) of the hand in a cohort of vibration-exposed workers. Methods The baseline cohort comprised 241 office and manual workers with and without exposure to HAY. Numbness (the symptom or event) in the hand was assessed for all subjects at baseline and follow-ups after 5, 10, and 16 years. The workers were stratified into quartiles with no exposure in the first quartile and increasing intensity of exposure in quartiles 2-4 (groups 1-3). Data analysis was performed using survival analysis (time-to-event). Information on cumulative exposure and years of exposure to event was collected via questionnaires. Measurements were performed in accordance with the International Organization for Standardization (ISO) 5349-1. Results The hazard ratio (HR) of risk of event (numbness) differed statistically significantly between the non-exposed group (group 0) and the two higher exposure groups (groups 2 and 3). There was also a significant ratio difference between the lowest exposure group (group 1) and the two higher groups. The ratio for group 1 was 1.77 [95% confidence interval (95% CI) 0.96-3.26] compared with 3.78 (95% CI 2.15-6.62) and 5.31(95% CI 3.06-9.20) for groups 2 and 3, respectively. Conclusion The results suggest a dose response relationship between vibration exposure and numbness of the hands. This underlines the importance of keeping vibration levels low to prevent neurological injury to the hands.
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| 3. |
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| 4. |
- Sandén, Helena
(författare)
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Nerve conduction and vibrotactile perception thresholds in female computer workers and hand-arm vibration-exposed male manual workers
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Upper limb pain and disability are common problems, especially among working populations. The overall aim of this thesis was to investigate peripheral nerve function in the upper limb by nerve conduction test and vibration threshold test in working populations including female computer users (n = 82), hand-arm vibration-exposed male manual workers (n = 116), and female workers with chronic diffuse upper limb pain (n = 35). The studies have a cross-sectional design regarding peripheral nerve function measurements. Exposure assessments regarding computer work were made using questionnaires, and the cumulative hand-arm vibration dose in manual workers was calculated as the product of self-reported occupational exposure, as collected by questionnaire and interviews, and the measured or estimated hand-arm vibration exposure in 1987, 1992, 1997, 2002, and 2008. In contrast to nerve conduction measurements, the vibration threshold test is a psychophysical test. To investigate whether mood influences the measurements, perceived stress and energy were assessed using a two-dimensional mood adjective checklist, before the vibration threshold test. Adequate control of tissue temperature is a crucial factor in nerve conduction studies, and a bicycle ergometer test proved to be a simple and effective method of raising hand temperature. Nerve conduction measurements revealed no signs of early neural deficits of large myelinated nerve fibres measured in the upper limbs of either women who intensively use computer keyboard equipment or hand-arm vibration-exposed male manual workers, or female workers with chronic diffuse upper limb pain. In the present studies, the majority of the subjects did not have severe neurological symptoms and most subjects had not been referred to a clinic. Vibration threshold test revealed no signs of early nerve affliction in the upper limbs in women who intensively used computer keyboard equipment. Women with chronic pain had a small elevation of vibrotactile perception thresholds in the territories of the ulnar and radial nerves. Perceived stress and energy before the vibration threshold testing did not influence the thresholds. Although a peripheral mechanism cannot be excluded, the findings support the idea that increased vibration perception thresholds in chronic diffuse upper limb pain may be secondary to pain.
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| 5. |
- Sandén, Helena, et al.
(författare)
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Nerve conduction in relation to vibration exposure - a non-positive cohort study.
- 2010
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Ingår i: Journal of occupational medicine and toxicology. - : Springer Science and Business Media LLC. - 1745-6673. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- ABSTRACT:Background Peripheral neuropathy is one of the principal clinical disorders in workers with hand-arm vibration syndrome. Electrophysiological studies aimed at defining the nature of the injury have provided conflicting results. One reason for this lack of consistency might be the sparsity of published longitudinal etiological studies with both good assessment of exposure and a well-defined measure of disease. Against this background we measured conduction velocities in the hand after having assessed vibration exposure over 21 years in a cohort of manual workers. Methods The study group consisted of 155 male office and manual workers at an engineering plant that manufactured pulp and paper machinery. The study has a longitudinal design regarding exposure assessment and a cross-sectional design regarding the outcome of nerve conduction. Hand-arm vibration dose was calculated as the product of self-reported occupational exposure, collected by questionnaire and interviews, and the measured or estimated hand-arm vibration exposure in 1987, 1992, 1997, 2002, and 2008. Distal motor latencies in median and ulnar nerves and sensory nerve conduction over the carpal tunnel and the finger-palm segments in the median nerve were measured in 2008. Before the nerve conduction measurement, the subjects were systemically warmed by a bicycle ergometer test. Results There were no differences in distal latencies between subjects exposed to hand-arm vibration and unexposed subjects, neither in the sensory conduction latencies of the median nerve, nor in the motor conduction latencies of the median and ulnar nerves. Seven subjects (9%) in the exposed group and three subjects (12%) in the unexposed group had both pathological sensory nerve conduction at the wrist and symptoms suggestive of carpal tunnel syndrome. Conclusion Nerve conduction measurements of peripheral hand nerves revealed no exposure-response association between hand-arm vibration exposure and distal neuropathy of the large myelinated fibers in a cohort of male office and manual workers.
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