Restricted blood flow

Microscopic analysis reveals that blood vessel walls thicken and narrow in regions of repetitive strain injury.
 
An interruption to the blood flow can also result from compression of a nerve due to swollen tissues. The blood vessels constrict and dilate inappropriately which can eventually lead to tingling, pain or even a complete loss of sensation. The hands become clumsy, especially in cold weather, and in extreme cases the fingers turn blue and white or simply white.
 
These latter symptoms are characteristic of Raynaud's disease, which has a variety of possible causes. The use of hand-held percussive or vibrating tools is a recognised risk factor in Vibration White Finger, for which many thousands of gas workers and miners received compensation in the late 1990s.