Occupational vibration syndrome

1. Occupational vibration syndrome Department of Occupational Medicine Finnish Institute of Occupational Health Markku Sainio Markku Vanhanen

2. Definitions • Vibration • Hand-arm vibration (HAV) • Whole-body vibration (WBV) • Vibration white finger (VWF) • Hand-arm vibration syndrome (HAVS) • Raynaud's phenomenon • Electroneuromyograpy (ENMG)

3. Vibration • Periodic motion of a body in alternate opposite directions from a position of rest • Mathematical "vector quantity"= described by both a direction and a magnitude • directions of vibration • acceleration • Present in most work settings where mechanical equipment is used

4. Measurements and standards • ACGIH TLVs 1984 • 4 m/s2 < 8 hours a day • 6 m/s2 < 6 hours a day • 8 m/s2 < 2 hours a day • 12 m/s2 < 1 hour a day • ISO 5349 (1986) • Standard for measurements over frequencies from 5 to 1500 Hz • Mitä laatua käytetään, millaiset tasot aih tautia, impact vibration (high impulsiveness) important!

5. Dose-response curves and threshold limits • are not applicable to all tools • are derived from chain-saw data • do not take into account impulsiveness and high frequency of many tools

6. Directive 2002/44/EC… .. on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (vibration)... • daily (8 h) exp. limit value 5 m/s2 • daily exp. action limit value 2,5 m/s2

7. HAV as occupational disease in Finland 1990-2001 RODFIOH • 2001-4/2002 10 • 1999-2000 32 16 • 1997-98 38 17 • 1995-96 37 7 • 1993-94 44 18 • 1990-92 (3 yrs) 92 37

8. Chain saw work 22 Construction worker 15 Miners+ drillers 15 Machine work,-repair, tool makers 9 Welders 5 Pipework 4 Railroad or road work 3 Stonework 3 1-2 : dental technician, teacher, painter, manufacture of diff. devices, plastics worker etc. Occupations (FIOH 1990-2001)

9. Exposure • Vibration level, acceleration, frequency, angles, impulses • Duration, continuity, radiation of the vibration (tool weight, grip strength, hand position, exposure area) • Smoking increases VWF prevalence, if > 20 cigarettes/d > 20 years • Temperature

10. Hand-arm vibration syndrome (HAVS) • Disease entity with separate components, all of which may not be recognized at the same time: • Circulatory disturbances • secondary Raynaud: vasospasm with local finger blanching • Sensory and secondary motor disturbances • local polyneuropathy: numbness, clumsiness • Musculoskeletal disturbances (?) • HAVS may lead to severe disease causing permanent working disability

11. Hand-arm vibration syndrome (HAVS) • White finger symptoms are essential • however, not always present • Dose-related (quantity and quality of exposure) • May be reversible, but usually irreversible and progressive if exposure continues • Smoking and cold exposure predisposing risk factors • Individual differences in susceptibility (other causes of Raynaud???)

12. Symptoms • Cold/damp (sometimes vibration) induced white fingers • However, also peripheral sensory reduction and slight clumsiness without white fingers • More proximal bone and joint symptoms occur occasionally (may be due to ergonomic factors) • Carpal tunnel syndrome and epicondylitis coexist often

13. PATOPHYSIOLOGY • Local oedema in nerve and perineural tissue • Local damage in non-myelinated nerve fibers  changes in blood vessels vasoconstriction in cold • mechanism: adrenergic reseptor damage in vessel wallsalfa-2-reseptor predominance

14. Objective findings • Vibration detection levels increase (damaged thick myelin fibers) • Temperature detection levels increase (damaged thin myelin fibers) • Two-point differentiation ability reduced • Grip strength reduced • Finger pletysmography: blood pressure of the affected finger drops in cold exposure • ENMG: sensory conduction velocities reduced before motor velocities

15. Diagnosis I • Exposure sufficient • Exp. in Occupational med+neurology+fysiatry • Clinical status: Sensory testing, grip strength, fine motor testing • Finger pletysmography (sensitive, not all mild cases detected, replicability ok) • Lab: La, CRP, PVK, tromb, CDT, GT, TSH, kryoglobulins, RF, nucleus-ab, B-gluc, Pt-Gluc-R1, S-B12-vit, fE-folaat

16. Diagnosis II • ENMG, possible carpal tunnel syndrome and excludes other PNS disease • Vibration and cold/hot perception threshold • Neurologist: PNP exclusion • Fysiatrist: exclusion of TOS or over extremity/cervical disease • Angiography not rutinely used

17. VWF ”clinical problems" • No white finger findings, only sensory findings • White finger findings, but also • generalized polyneuropathy • cervical radiculopathy • blood vessel changes mimicing vasculitis • Primary Raynaud´s disease in the history or symptoms/findings suggesting it (prevalence 5-6% in males) • Occupational rehabilitation is often difficult (progressed HAVS or wide accompanied musculoskeletal symptoms)

18. Whole body vibration • May increase the rsik of low back pain, disc protrusion and joint arthritis • May increase the risk of spontaneous abortions and premature births • Difficult to diagnose at indivudual level • Directive 2002/44/EC • 8 hour limit 1,15 m/s2 • 8 hour action limit 0,5 m/s2

19. Treatment and prevention • Calcium antagonists may help • Carpal tunnel operation may help, but may also worsen symptoms • Stop smoking, reduce risk factors of polyneuropathy • Stop or decrease exposure to minimum • technical improvements of tools • minimum exposure time • gloves etc. • Increase temperature • Periodic health examinations

20. Literature • Hannu Vironkannas: ”Peripheral vascular and nerve disorders in workers exposed to hand-arm vibration with special reference to snowmobile drivers”, 1992. (Thesis) • Pelmear PL, Leong D. Review of occupational standards and guidelines for hand-arm (segmental) vibration syndrome (HAVS). Applied Occupational and Environmental Hygiene. Vol 15(3):291-302, 2000.