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By dint of prolonged or repeated or frequent use of hand-held power tools like power drills, saws, pneumatic drills, and jackhammers, the constellation of vascular, neurological and musculoskeletal signs and symptoms that may occur in workers (farmers, forestry workers, stone drillers, stone cutters and chippers, quarry drillers, aircraft engine workers, sheet metal workers, polishers, grinders, molders, forklift drivers, riveters, dental technicians, orthopedists, sewing machine operators, etc). which is called as Hand-Arm Vibration Syndrome (HAVS). This is due to slight but repeated injury to the small nerves and blood vessels in the fingers.

Risk Factors

Use of vibrating tools, beta-blockers (medications used to manage cardiac arrhythmias, migraines, anxiety and high blood pressure), cigarette smoking and exposure to cold.

Symptoms and Diagnosis

Nerves are affected initially, leading to changes in sensation (numbness, tingling) which will be followed by Reynaud’s phenomenon (disease of arteries comes in bouts or attacks that are triggered by cold weather or touching a cold object) resulting from changes in the blood vessels and resulting in a white finger. These changes also lead to muscular aches and pains. As the condition develops, numbness becomes permanent. This leads to muscle weakness and wasting. There may be other manifestations from damage to bone and muscle reported and includes exostoses and cysts in carpal bones, carpal tunnel syndrome and osteoarthritis. For diagnosis, evidence of long-term exposure to vibration, episodes of sensorineural effects, calluses on the hand, loss of sensation in the digits affected and muscle weakness are required.

Number of standardized investigations such as,

The Vibrotactile Threshold Test (testing the mechanoreceptors),
The Thermal Aesthesiometry Test (assessment of thermal receptor’s threshold),
The Purdue Pegboard Test (Measuring the dexterity and detecting the loss of fine movement to both hands),
The Grip Force Measurement Test (measuring the grip strength of both hands), and
The Cold Provocation Test (visual evidence of blanching) are done on the diagnosis of the HAVs.

Prevention and Control

The Control of Vibration at Work regulations 2005, which came into force in July 2005, placing a legal obligation on employers to assess and identify measures to eliminate or reduce risks from exposure to hand-arm vibration, ensure that control measures to reduce vibration are properly applied and that information, training and health surveillance are provided. As it is not clear whether nerve symptoms can improve once they have developed, so, easing off using vibrating tools if possible is the recommended action. Smoking may make symptoms worse; chemicals in tobacco can cause the small blood vessels to narrow, so stop smoking. Medications include beta-blockers, and anti-migraine, decongestants should be avoided. Cutting out caffeine, amphetamines and cocaine also recommended. Keeping the hands warm with proper battery-heated gloves, wrap up the whole body warm by wearing heat-pack jackets, hats and scarves, and giving frequent exercise to the hands are ideal advices of prevention. While using the vibrating tools in unavoidable situations, the vibration reducing material of a VR glove plays an important role in the attenuation of vibration transmitted to the palm and fingers. VR gloves (the air glove) amplify vibration at the palm in the 125-200 Hz frequency range, and to frequencies above 200 Hz with the gel, hybrid and leather gloves (ISO 10819-2013).

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Know safety! No injury!
No safety! Know Injury!

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Article written by:
Ananth Tamilmaniarasu
HSE Trainer,
Green World Group,
Dubai

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