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Re: Raynaud's phenomenon in vibration exposed workers

Editor

Chronic hand vibration exposure is now a well-described cause of Raynaud's phenomenon. According to Palmer et al, it is estimated that 220,000 cases of Raynaud's phenomenon are attributable to vibration exposure in Great Britain.[1] These epidemiological data, based on a questionnaire, are considered reasonably accurate.[2] About 4.2 million workers are exposed to hand transmitted vibration but the real health and economic impact is unknown.[3] More precise clinical data are therefore necessary before implementing a large preventive program. The hand-arm vibration syndrome encompass a wide range of disorders being responsible for digital blanching and paresthesias.[4] Different vascular problems such as a pure vasospastic phenomenon, a digital organic microangiopathy or an occlusive arterial thrombosis can be observed. A diffuse vibration neuropathy with mechanical skin receptors involvement or a carpal tunnel syndrome are also often associated.[5] The relationship between these neurovascular disorders is not clear but autonomic dysfunction in carpal tunnel syndrome can induce a Raynaud's phenomenon which is curable with surgery.[6] The prognosis of these neurovascular troubles is dependant on the underlying trouble and cannot be evaluated with a simple questionnaire. As no single test can reliably stage the vascular and neurological component, the use of a battery of tests is necessary. Digital capillaroscopy and plethysmography with nerve conduction studies are recommended as the basic tests. Cold provocation tests are effective for grading a pure vasospastic Raynaud's phenomenon but is less reliable in other forms of vibration-induced white finger explaining why this test is not always well correlated with the vascular symptoms.[7][8] Doppler and duplex studies are useful to assess the severity of an occlusive arterial disease. Workers using hand-held vibrating tools are also exposed to diverse environmental and occupational factors accounting for the wide clinical spectra of the disease. Epidemiological studies have pointed out that the prevalence of vibration-induced white finger is very wide, ranging from 0- 5% in warm climate to 80-100% in northern climate.[9] In the pure vasospastic Raynaud's phenomenon, cold exposure is probably the most important triggering factor and cold protection the most effective preventive measure. In the case of digital blanching associated with carpal tunnel syndrome, other ergonomic factors such as repetitive forceful use of the hands are likely to play a dominant role and a workplace ergonomic modification is indicated.[10] Hypothenar hammer syndrome is a another frequent cause of digital blanching in mechanics and carpenters requiring prevention of repetitive hand trauma.[11][12] For the digital organic microangiopathy and the diffuse vibration neuropathy, vibration exposure is the only identified factor and suppression of the exposition is essential. In consequences, a detailed and precise clinical diagnosis with objective tests is important to determine the real cause of the vascular symptoms. The impact of vibration exposure on health will be more precisely evaluated and prevention will be more effective.

1. Palmer KT, Griffin MJ, Syddall H, et al. Prevalence of Raynaud's phenomenon in Great Britain and its relation to hand transmitted vibration: a national postal survey. Occup Environ Med 2000;57:448-52.

2. Palmer KT, Haward B, Griffin MJ, et al. Validity of self reported occupational exposures to hand transmitted and whole body vibration. Occup Environ Med 2000;57:237-41.

3. Palmer KT, Griffin MJ, Bendall H, et al. Prevalence and pattern of occupational exposure to hand transmitted vibration in Great Britain: findings from a national survey. Occup Environ Med 2000;57:218-28.

4. Noel B. Pathophysiology and classification of the vibration white finger. Int Arch Occup Environ Health 2000;73:150-5.

5. Stromberg T, Dahlin LB, Rosen I, et al. Neurophysiological findings in vibration-exposed male workers. J Hand Surg [Br] 1999;24:203-9.

6. Verghese J, Galanopoulou AS, Herskovitz S. Autonomic dysfunction in idiopathic carpal tunnel syndrome. Muscle Nerve 2000;23:1209-13.

7. McLafferty RB, Edwards JM, Ferris BL, et al. Raynaud's syndrome in workers who use vibrating pneumatic air knives. J Vasc Surg 1999;30:1-7.

8. McGeoch KL, Gilmour WH. Cross sectional study of a workforce exposed to hand-arm vibration: with objective tests and the Stockholm workshop scales. Occup Environ Med 2000;57:35-42.

9. Bovenzi M. Exposure-response relationship in the hand-arm vibration syndrome: an overview of current epidemiology research. Int Arch Occup Environ Health 1998;71:509-19.

10. Gemne G. Diagnostics of hand-arm system disorders in workers who use vibrating tools. Occup Environ Med 1997;54:90-5.

11. Little JM, Ferguson DA. The incidence of the hypothenar hammer syndrome. Arch Surg 1972;105:684-5.