[Studies of peripheral nerve conduction velocities in vibrating tool operators].
Vibrating tools such as chain-saws, rock-drills, grinders and tie-tampers have been widely used in many kinds of industries in Japan, causing vibration syndrome among the operators. As is well-known, the syndrome includes disorders of the peripheral circulation in the hands, e.g. Raynaud's phenomenon, and of the peripheral and central nervous systems. As the result of preventive countermeasures to the syndrome during the last decade, the picture of the syndrome has been partly changing especially for the patients among the state forestry workers; for example, the prevalence of the peripheral nerve disorders has been relatively increasing compared with that of Raynaud's phenomenon. Peripheral nerve disorders such as numbness, paresthesia and hypesthesia in the upper limbs tend to be usually cumulative and irreversible. The disorders are very important problem of vibration syndrome from the standpoint of treatment and prevention, though there are only a few reports of the study on the disorders using electrophysiological methods. In order to make objectively clear the peripheral nerve disorders, 236 male vibrating tool operators (= Group V) were examined. The following nerve conduction velocities were measured: (1) Maximal motor nerve conduction velocities (MCV) of the median and ulnar nerves in the forearm. (2) Sensory nerve conduction velocities (SCV) of the median and ulnar nerves in the forearm and palm. (3) Residual latency (RL) of the median and ulnar nerves. Besides, working conditions and complaints relevant to vibration syndrome were examined by using questionnaires. MCVs, SCVs and RLs that were outside of mean +/- 2 S.D. of the control group (= Group C), consisting of 30 healthy men, were evaluated as abnormal. The obtained results led to the following conclusions: (1) All MCVs, SCVs and RLs of Group V were significantly less than those of the control group. In Group V, prevalence of the abnormality in each of forearm SCVs was higher than that in each of MCVs of the corresponding nerves. (2) The difference between the median and ulnar SCV in the palm and the respective SCV in the forearm of each subject was significantly greater for Group V than Group C. (Palm-forearm difference) (3) The difference between the forearm and palmar SCV of the ulnar nerve and the respective velocities of the median nerve was statistically greater for Group V than for Group C. (Ulnar-median difference) (4) Ulnar SCV in the palm of Group V was significantly related to the total operating hours of vibrating tools. (5) There was no significant relation between all the nerve conduction velocities and the white finger attack. But a significant relation was noticed between the prevalence of the abnormal values of ulnar SCV in the palm and the peripheral circulatory function score computed from the data of nail press test and cold immersion test.
D000328:Adult; D006801:Humans; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction; D009784:Occupational Diseases / Q000503:physiopathology*; D010525:Peripheral Nerves / Q000503:physiopathology*; D010523:Peripheral Nervous System Diseases / Q000209:etiology / Q000503:physiopathology*; D011928:Raynaud Disease / Q000503:physiopathology; D013997:Time Factors; D014732:Vibration / Q000009:adverse effects*