Sympathetic responses to hand-arm vibration and symptoms of the foot.

Vibration syndrome is generally considered to consist of disorders in the upper extremities which are directly exposed to vibration. However, it has been shown that vibration syndrome patients have circulatory disturbances in the foot as well: several chain-saw operators, who were little exposed to vibration of the foot, had Raynaud's phenomenon of the toes, and those with frequent attacks of vibration-induced white finger (VWF) had a higher prevalence of coldness felt in both the hands and the feet, and the patients with VWF had lower skin temperature of the toes as well as the fingers. Moreover, arterial pathological changes like medial muscular hypertrophy have been observed in both the fingers and the toes of the patients. Hand-arm vibration elicits a sympathetic nervous reflex, leading to vasoconstriction of the four extremities. Long-term repeated vasoconstriction may result in such arterial changes and then circulatory disturbances of the feet.