Pathogenic and clinical aspects of polyneuropathies, with reference to the hand-arm vibration syndrome

Along with attacks of white finger, symptoms suggesting peripheral sensorimotor neuropathy, ie, polyneuropathy or entrapment neuropathy, are very important in the hand-arm vibration syndrome. Peripheral neuropathies are probably associated with the occurrence of the syndrome because of a selection mechanism. Polyneuropathy may be a contributing factor in the development of entrapment neuropathies in the upper extremities. It has multiple pathogenic mechanisms and numerous causative factors. However, peripheral nerves can react to pathological stimuli in a limited number of ways. Wallerian degeneration, segmental demyelination, and axonal degeneration are the classical neuropathological types of peripheral neuropathies, of which the first two are possible direct consequences of vibration exposure. The clinical manifestations of polyneuropathy range from sensory to motor types, sometimes with autonomic involvement. Whenever polyneuropathy is encountered in the hand-arm vibration syndrome, its etiologic possibilities should be considered. Regardless of the variable criteria used by different authors, individual diagnosis of the syndrome is always a probability diagnosis, and adequate neurological differential diagnostics have to be employed.