A vibration injury can include sensory, vascular and muscular problems. Often there is a very troublesome cold-intolerance, which not necessarily must be associated with white fingers. There may also be an influence on life quality and capacity to perform activities of daily living.
 

Neurological problems
Impaired sensory-motor functions of the hand may have a number of various reasons. It is important to perform relevant clinical tests and laboratory investigations to clarify the underlying reasons for an impaired hand function. A vibrametry test can verify if the hands capacity to perceive vibrations is impaired, but this test is not enough to identify a firm diagnosis and to identify the true reason for a sensory impairment.

Sensory problems in the hand can be based on, e.g., a cervical rizopathy or entrapment of nerve trunks in the arm or hand, for instance a carpal tunnel syndrome or an ulnar nerve entrapment. A polyneuropathy, for instance diabetes, can be an alternative explanation. If a patient has been subjected to vibrations via hand-held vibrating tools, the vibrations may certainly offer a plausible explanation.

 The patients own story is very important for the diagnosis. When was the debut of the symptoms? Do the symptoms vary over 24 hours? Which fingers and which parts of the hand feel numb? Is his numbness combined with pain? Is there some harmful influence, such as vibrations, at work or during leisure? These are examples of question of importance for the diagnosis.

 A clinical investigation can usually confirm or exclude a carpal tunnel syndrome or an ulnar nerve entrapment at elbow or wrist level, but sometimes a neurophysiologic investigation is necessary to confirm the diagnosis.

  When there is a vibration injury, perception of touch applied to the finger pulp is often impaired at an early stage. To assess the capacity to perceive pressure Semmes-Weinstein’s monofilaments of various thicknesses should be used.  Another important test is the two-point (2 PD) discrimination test, i.e. the capacity to differentiate between two close pressure points, applied to the skin. Normally, the two-point discrimination capacity in the finger pulp is 4-5 mm. In a vibration injury, the two-point discrimination capacity is not impaired as early as the capacity to perceive pressure.

 The fine motor capacity is tested by the Purdue Pegboard test, which is based on an assessment of the hands capacity to manipulate and move small items.

 A neurophysiologic investigation can sometimes be needed to confirm or exclude a vibration injury. A sensory nerve conduction test implies assessment of the conduction velocity of sensory impulses in the nerve. Assessment of sensory conduction velocity over the carpal tunnel segment can sometimes be necessary to confirm a carpal tunnel syndrome. 

An important component of a vibration injury is usually damage to the thin nerve fibres transmitting temperature stimuli. There are various tests to assess the capacity to perceive heat and cold stimuli respectively and to feel changes in temperature of a test element applied to the fingers.

Vascular symptoms
The patents own story is important for a judgement of vasospastic problems in the fingers ( ”white fingers”). Various laboratory tests can be performed at clinical physiological laboratories at larger hospitals. Among such tests are assessment of finger systolic blood pressure (FSBP) and critical opening pressure (COP) after cold provocation.

Muscular symptoms
Sometimes there is impairment of the handgrip force as well as the power in the pinch grip and key grip. The handgrip force should be assessed using a JAMAR-dynamometer. The force in the pinch grip and key grip should be assessed using a standardized instrument, a so-called pinch gauge.