Hand-Arm Vibration Syndrome (HAVS) is the medical term for symptoms caused by vibration damages that may occur in the fingers, hands and arms when working with vibrating tools or machinery. Vibration injuries are divided into three subgroups: neurological disorders, vascular and musculoskeletal.
Early symptoms are usually tingling and/or numbness in the hands and fingers. After a while, this turns to impaired sensibility and limited dexterity. Fully developed neurological vibration damage is irreversible, causing a high level of disability and work impairment. At this stage, hand function is severely reduced; the patient might drop things easily or have problems with tasks such as pouring water into a glass or inserting a key into a lock
Carpal tunnel syndrome is another common neurological vibration injury. If detected in time, most patients are expected to make a full recovery.
These injuries affect the capillaries (small blood vessels) in the hand and fingers, causing these to constrict (vasospasm). This causes blanching (episodes of whiteness), ususally triggered by exposure to cold. Other terms are "Vibration induced White Fingers" (VWF) or "secondary Raynaud's disease".
During the episodes of blanching, caused by a temporary ristriction of blood circulation to parts of the fingers or the hand, the person experiences numbness in the areas that have turned white. When the blood then returns, i.e. during the release of the vasospasm, the person is often experiencing a major discomfort such as tingling and pain.
Musculoskeletal injuries may take the form of arthritis, tendonitis and changes in muscle fibres, and can result in impaired grip force, reduced mobility and pain in the hand and arm.
Is is not clear why this is associated with reduced grip strength, but it might be due to damage to nerves and muscle structures. Many of those suffering from musculoskeletal vibration injuries are not diagnosed since many routine clinical tests often show normal results.
It is noteworthy that the muscle mass is often intact, but microscope studies of muscle biopsies have shown that there may be significant changes in the fibres.
It is well known that exposure to prolonged (i.e. for several years) exposure to vibration is harmful, and can cause various types of hand dysfunctions. Most common are loss of sensibility, blanching, and decreased grip force in the hands—that is, Hand-Arm Vibration Syndrome (HAVS).
The tendency to develop vibration injuries in the hands varies significantly between individuals; some get these symptoms after a few years of vibration exposure, while others can work for decades without problems.
When a vibration injury is fully developed, it is irreversible. The affected person will, in other words, not recover even if the vibration exposure ceases. At this point it cannot be cured by medical or surgical means.
Therefore, it is extremely important to detect incipient vibration damage while prophylactic measures are still effective. It might, for example, be possible to change tools or methods in order to prevent irreversible vibration injury.
Vibration injuries are common in many industries with vibration exposure, such as construction, cutting and sheet metal work, auto repair, welding and electrical work. The problems are also common occupations where the hands are exposed to very high-frequency vibrations, such as dental technicians and dentists.
The injuries often impact the working-age population (young or middle-aged men) and the consequences can be very serious. Damage to the nerves of the hand leads to reduced dexterity and impaired fine-motor skills (“clumsiness”), and, in some cases, severe pain and cramps.
Finger blanching is usually triggered by exposure to a humid or cold environment and can be extremely painful.