No abstract

ABSTRACI The current status of subjects with vibration induced white finger (VWF) was observed in order to follow up the natural course of VWF after the use of chain saws had ceased. The prevalence rate of VWF after the use of chain saws had ceased in all time periods fell to 50-2% after more than 12 years' observation. There was a pronounced tendency for the percentage prevalence to rise as the vibration exposure periods after VWF occurred increased, and a similar pattern was observed concerning the exposure periods before VWF occurred. Numbness of hands and arms takes longer to recover than VWF.

Habitual use of many vibrating tools has been found to be connected with the appearance of various disorders affecting the blood vessels, nerves, bones, joints, muscles or connective tissues of the hand and forearm. The vibration exposures required to cause these diseases are not known exactly, either with respect to vibration intensity and the vibration frequency spectrum, or with respect to daily exposure time and total exposure period. The purpose of this study is to investigate available data on the physical conditions in Japan that have caused vibration induced white finger (VWF) and attempt to establish approximate relationships between vibration conditions and prevalence of VWF. The vibration conditions were evaluated using the method of vibration assessment recommended by the International Standardized Organization, which uses the weighted vibration level of the frequency weighted, dominant, single axis component of vibration directed into the hand. A clear correlation between level, prevalence of VWF and exposure period can be found. The results also suggest the relationship between the weighted levels and latent intervals. These dose-effect relationships enable the prediction of the average latent interval for a population group and the range of progression of the disorders--all from a measurement of the vibration entering the hands. In Japanese cases, 4, 8, and 15% of VWF prevalence correspond with 10, 20, and 40% of VWF prevalence in the Draft International Standard ISO/DIS 5349 (1982) within the weighted vibration level range of 2 to 50m X s-2.

A case-control study was undertaken to evaluate some factors affecting the prognosis of vibration-induced white finger (VWF), 286 workers, who had used a chain saw in forests and had showed some symptoms and signs that were suspected to be vibration syndrome during some of the years from 1956 to 1980, were selected by medical examinations from a total of 612 forestry workers, and were divided into four groups according to the prognosis of the VWF based on a twenty-year follow-up. The study shows an association between the prognosis of VWF and vibration components, particularly vibration levels, severity of the syndromes not only in peripheral circulation but also in peripheral neuropathy before exposure to vibration ceased. There are also significant associations between the prognosis of peripheral neuromuscular symptoms and the factors of aging and duration of exposure. The study suggests that smoking habits and history of heart failure and diabetes had no effect on the prognosis of VWF.

Body reactions during chain saw work were studied in 14 subjects. The subjects divided into three groups (control, sulpiride, and propranolol) possibility of vibration disease and cardiovascular diseases. None complained of Raynaud's phenomenon in the fingers, but some had slight numbness in the fingers and arms, palmar hyperhydrosis, or shoulder stiffness. The cumulative operation time was from 0920 to 1690.The subjects were divided into three groups: group I consisted of six control subjects, group 2 of four men with intramuscular premedication of 100 mg sulpiride, one of the benzamide derivatives, and group 3 of four men who received 20 mg propranolol administered by mouth. No significant differences were noted between these three groups.As shown in fig 1, the experimental procedures are as follows. Firstly, after explaining the experimental purposes and procedures to all the subjects, laboratory examinations were performed: electrocardiograms (12 limb and precordial leads), blood pressure, digital plethysmography with auditory stimuli for detecting the sympathetic nervous tones,67 and blood sampling. Blood chemistry included estimations of adrenocorticotropic hormone (ACTH), cortisol, adrenaline, noradrenaline, and dopamine concentrations. A second examination was then made after the administration of sulpiride or propranolol. After these procedures, the subjects operated chain saws for seven minutes. Electrocardiographic recordings with a bipolar lead on the chest and the electroencephalographic recordings with two monopolar leads from left and right frontal poles were made during the successive cutting of logs with a chain saw. 667