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

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

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

Measurements and standards ACGIH TLVs 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!

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

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

HAV as occupational disease in Finland RODFIOH / (3 yrs)9237

Occupations (FIOH ) 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 : dental technician, teacher, painter, manufacture of diff. devices, plastics worker etc.

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

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

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???)

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

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

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

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

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

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)

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

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

Literature Hannu Vironkannas: ”Peripheral vascular and nerve disorders in workers exposed to hand-arm vibration with special reference to snowmobile drivers”, (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): , 2000.