Hyperreactivity of the central sympathetic nervous system in vibration-induced white finger.

Vibration exposed workers with and without vibration-induced white finger (VWF), subjects with primary Raynaud's phenomenon and non-exposed controls were investigated in the present studies. The applied stimuli comprised cold stimuli, vibration exposure, and postural stimuli. The digital vasomotor responses to these stimuli were objectively quantified by measurements of finger systolic blood pressure and relative capillary blood flow rate in the skin of the finger. The results indicate that hyperreactivity of the central sympathetic nervous system may function as an/the abnormal element of the reflex mechanisms triggering the predominant portion of the vasoconstriction in episodic arterial closure of VWF. The hyperreactivity of the central sympathetic nervous system may be induced by prolonged exposure to hand-arm vibration, possibly by activation of the vibration elicited central sympathetic vasoconstrictor reflex mechanisms.