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PubMed1996

Is skull sawing by autopsy assistants overlooked as a cause of vibration-induced white fingers?

BACKGROUND: Workers using vibrating tools have an increased prevalence of vibration-induced white fingers. One example of such workers is autopsy assistants, who use vibration for skull sawing. CASE HISTORY: A previously healthy 42-year-old Swedish male smoker had worked as an autopsy assistant at a forensic department between 1977 and 1991. He prepared corpses for autopsy, including sawing the skulls with an electric saw. Beginning in 1983, his right index finger blanched in cold. During subsequent years the blanching spread to the other fingers on the right hand, except for the thumb. The findings in the physical examination and the results of blood tests were normal. Digital blood pressure after cooling showed a severe vasospastic reaction in both middle fingers. Vibration measurements during skull sawing showed a frequency-weighted acceleration level of 8.9 m.s-2. QUESTIONNAIRE SURVEY: A questionnaire was mailed to all assistants (N = 17) preparing autopsies and to all medical examiners, as referents (N = 18), at the Swedish Institutes of Forensic Medicine. It was answered by 13 assistants (76%), 1 woman and 12 men, and 16 medical examiners (89%), 3 women and 13 men. Eleven of the assistants (85%), including one woman, and one of the physicians (6%), a men, reported a history of blanching fingers provoked by chill (difference 79%, P = 0.00003, Fisher's exact test). CONCLUSIONS: Autopsy assistants at forensic departments seem to have an increased prevalence of self-reported blanching fingers, which may be an effect of exposure to high levels of vibration.

Adult↗

PubMed1994

Impaired nerve conduction in the carpal tunnel of platers and truck assemblers exposed to hand-arm vibration.

OBJECTIVES: The goal of this study was to assess the relative risks of sustaining impaired nerve conduction in the hands among vibration-exposed persons as opposed to nonvibration-exposed referents. METHODS: In a cross-sectional study design platers and truck assembly workers were contrasted to office workers. The 4-h frequency-weighted vibration was 4.6 m.s-2 and 1.0 m.s-2 for the platers and assemblers, respectively. The ergonomic factors were measured as forced grip time. The conduction velocity, distal latency time, and amplitude of the median nerve were measured for both hands. RESULTS: The sensory nerve conduction velocity was slower in the right hand than in the left. An increased risk of prolonged latency time was found for the platers and assemblers when contrasted to the office workers. The relative risks (rate ratios) of impaired nerve conduction for the carpal tunnel segment varied between 1.4 and 2.0 for the distal latency and between 0.9 and 1.7 for the nerve conduction velocity. The rate ratios were generally higher for the left-hand side than for the right-hand side. The risks were not proportional to either the weighted or unweighted vibration exposure. CONCLUSIONS: The contributions from vibration and ergonomic factors to impaired nerve conduction velocity were inseparable in this study. Ergonomic factors such as forceful gripping and extreme positions, apart from vibration exposure, may be strong determinants of impaired nerve conduction in the carpal tunnel area.

Adult↗

PubMed1987

Peripheral neurological assessment methods for workers exposed to hand-arm vibration. An appraisal.

Peripheral neurological assessment methods for workers exposed to hand-arm vibration have included vibration perception and esthesiometric threshold testing, electroneurography, handgrip force, and manipulative dexterity. For epidemiologic investigations with the purpose of detecting vibration effects anticipated as moderate to large in size in occupational populations, these methods have demonstrated their usefulness. Concerning their value in the assessment of individual workers, there is little quantitative information, as there have been no studies which have conducted rigorous "gold standard" neurological evaluation with which the results of independently performed diagnostic tests can be compared. However, results from four papers which used depth-sense (or ridge) and two-point discrimination esthesiometry were available for an analysis of the sensitivity of these tests in the detection of Taylor-Pelmear stages 2 and 3 of the hand-arm vibration syndrome. With specificity set at 90%, sensitivity ranged from 45 to 96% for depth-sense esthesiometry and from 19 to 75% for two-point discrimination. In addition, likelihood ratios were determined, as a measure of the capacity of the tests to alter pretest probability of disease. Because of their direct clinical interpretation and application, the use of likelihood ratios is suggested for future research on diagnostic methods used for vibration-exposed workers.

Arm↗

PubMed1987

Physiological methods used in Japan for the diagnosis of suspected hand-arm vibration syndrome.

In the pathogenesis of hand-arm vibration syndrome, vibration affects the peripheral system, especially the circulatory, nervous, and musculoskeletal systems. Medical questionnaires, physical examinations, and laboratory tests are used to diagnose the hand-arm vibration syndrome. The laboratory tests are satisfactory diagnostic aids for detecting slight disorders of the peripheral circulatory, nervous, and musculoskeletal systems. Peripheral circulatory function tests include skin temperature measured by a thermistor under specific temperature conditions, the nail compression test, and the cold provocation test (10-min immersion in cold water at 5 or 10 degrees C). To assess peripheral nervous function, tests for the pain and vibration senses are included. Peripheral musculoskeletal function tests consist of grip strength, pinch strength and tapping counts. These physiological tests are applied in worker screening twice a year. These tests have been authorized by the Ministry of Labour since 1973. Several criteria for the tests, although not authorized, are widely used. The diagnostic implication of each separate test may be low. Consequently, some laboratory tests should be evaluated, along with medical questionnaires and physical examinations, in the diagnosis of suspected hand-arm vibration syndrome.

Arm↗

PubMed1987

Acute effects of whole-body vibration. Stabilography and electrogastrography.

The influence of whole-body vibration on postural control and stomach motility was investigated. Fifteen subjects were exposed to two vibration signals (3 and 6 Hz random) while sitting for 1 h on a vibration simulator. A control situation, ie, sitting for 1 h without vibration, was also included. Stabilographic recordings before and 1 and 15 min after the sitting showed that exposure to these frequencies had no effect on postural control. Electrogastrographic (EGG) measurements before and during the sitting showed that, for 3 Hz, there was an initial increase in activity which decreased towards normal values. For 6 Hz there was a significant increase in activity for EGG frequencies of 0.05 and 0.13 Hz. The results imply that stomach motility can be affected by whole-body vibration in certain frequency ranges.

Adult↗

PubMed1987

Noise-induced hearing loss in relation to vibration-induced white finger in chain-saw workers.

From the viewpoint of the etiologies of noise-induced permanent threshold shift (NIPTS) and vibration-induced white finger (VWF), the association between VWF and hearing loss was examined among 499 chain-saw workers who underwent a compulsory health examination for vibration syndrome. They were classified by age, duration of noise and vibration exposure, and the severity of VWF. The severity of VWF was evaluated according to the following criteria: no prior history; VWF history, but symptoms had disappeared; VWF present but appearing rarely; frequent appearance of VWF (more than 20 times per winter season). In three age groups (ie, 40-49, 50-59, 60-69 years) with 5-9 years of exposure, the chainsaw workers with VWF had a significantly greater hearing loss at higher frequencies than those without VWF. However, in the 10- to 14-year exposure groups, a significant difference was not found between the VWF and non-VWF groups, except that the 50- to 59-year age groups showed a significant difference in mean age. It was suggested that interindividual differences in susceptibility to noise and vibration may be the reason for the synergistic effects of noise and vibration.

Adult↗

PubMed1986

Cardiovascular responses of vibration-exposed workers to a cold provocation test.

Hemodynamic functions and changes in sympathetic nervous activity were assessed in 50 vibration-exposed workers without vibration-induced white finger (VWF), in 13 subjects with VWF, and in 41 referents. Indices of systolic time intervals such as the electromechanical systole index (QS2I) and the left ventricular ejection time index (LVETI) were found to be significantly shorter in the vibration workers than in the referents both at rest and during a cold provocation test. A significant inverse relationship between urinary levels of free catecholamines and the duration of the LVETI was observed under resting conditions. The recovery rate of the basal finger skin temperature after cold provocation was slower in the vibration-exposed workers than in the referents. The indices of platelet aggregation were about the same in all the groups studied. The results of this investigation suggest that cardiac sympathetic tone and digital vascular reactivity to cold are increased in vibration-exposed workers.

Catecholamines↗

PubMed1986

Physiological response of the rat to different vibration frequencies.

Vibration (acceleration of 50 m/s2 and frequencies from 30 to 960 Hz) was applied to the tail and hind legs of rats for a 4-h period. The responses of the peripheral circulatory and peripheral nervous systems, muscle function, and the central nervous system were examined. When a tail was exposed to the vibration stimulus, the skin temperature dropped significantly at 30 and 240 Hz; the blood flow decreased significantly at 30, 60, and 480 Hz; and the peripheral nerve conduction velocity was significantly slower at 30, 60, and 120 Hz. After vibration of the hind legs the activity of plasma creatine phosphokinase (CPK) showed significantly high values at 30, 60, 120, and 480 Hz and was especially high at 30 Hz; the content of brain norepinephrine was significantly decreased at 120 Hz in the hypothalamus; dopamine was significantly increased at 60 Hz in the medulla oblongata and pons; and serotonin was significantly increased at 120 Hz in the hypothalamus. Thus the physiological responses of the rat to local vibration depend on, among other variables, the vibration frequency. In the case of the response of plasma CPK it would appear to depend on the amplitude (displacement) of this stimulus.

Animals↗

PubMed1986

Digital high-speed sampling of combined exposure to noise and vibration.

The digital high-speed sampling technique was applied to simultaneous measurements of exposure to noise and vibration among workers who used hand-held power tools in a shipyard. The transducers were two accelerometers and two microphones which measured the transmission of vibration acceleration from the handle of the tool to the wrist and the attenuation of noise by the earmuffs. The measurements were taken by a microcomputer-controlled digital multichannel sampling unit. An analogue-digital converter was used with a 100-kHz scanner for multichannel signal acquisition in the 10 kHz bandwidth. The sound pressure was A-weighted, and the vibration acceleration was both unweighted and weighted according to the guidelines of the International Organization for Standardization. Impulsiveness was determined as the difference between the peak and root-mean-square levels. The noise exposure was 81 dB during grinding and 85 dB during hammering. The earmuffs provided protection against impulse noise at least when the impulses contained high frequencies. The transmission loss of vibration acceleration between the tool handle and wrist was 45 dB for grinding and 29 dB for hammering. The transmission of noise and vibration was affected by the frequency content and impulsiveness of the signals.

Fingers↗

PubMed1986

Vibration syndrome among Finnish forest workers, a follow-up from 1972 to 1983.

A longitudinal survey on the prevalence of vibration syndrome among professional forest workers was conducted from 1972 (118 workers) to 1983 (206 workers). The prevalence of vibration-induced white finger (VWF) was 40% among the workers in 1972; it gradually declined to 5% in 1983. Three new workers developed VWF symptoms during the follow-up period. They had only used saws equipped with antivibration handles. The prevalence of VWF has decreased mainly due to the reduction of chain-saw vibration. The prevalence of paresthesias of the hands and arms declined from 78% in 1972 to 37% in 1976, and then increased to 51% in 1983. The recent increase was thought to be due to static muscle load and the ageing of the workers. No correlation was found between the severity of VWF and peripheral nerve symptoms. No significant changes in muscle fatigue occurred during the follow-up period; it was present in about 10-15% of the workers. The forest workers subjectively assessed musculoskeletal load and strain as being more harmful than the symptoms of vibration syndrome. The preventive measures aimed at reducing chain-saw vibration, implemented since 1970, have been beneficial and explain the decreased prevalence of VWF.

Cross-Sectional Studies↗

PubMed1984

High impulse acceleration levels in hand-held vibratory tools. An additional factor in the hazards associated with the hand-arm vibration syndrome.

The measurement of the root-mean-square (rms) acceleration of vibration does does not take into consideration the short high peak values of the vibratory signal, which may be a hazard contributing to the development of vibration-induced disease. A method for evaluating the impulse character of vibratory signals is given, and impulsiveness is defined as the difference between the peak and rms signals. Measurements were taken during pedestal grinding, during chain sawing with three different generations of saws, and during chiseling with a pneumatic hammer. The measurements comprised (i) analyses done according to the International Organization for Standardization (ISO) draft, (ii) an evaluation of impulsiveness, and (iii) an analysis of the short-time history transient. The risk of vibration-induced white fingers was estimated by the ISO method, and the results were compared with those observed. It was found that the analysis of impulsiveness provided additional data and partly explained the observed symptoms of vibration-induced white fingers. The parameters for the impulsiveness of the vibration signal agreed with the short-time history analysis.

Humans↗

PubMed1998

Vibrotactile sense in the hand-arm vibration syndrome.

OBJECTIVES: The purpose of this study was to investigate disturbances of the vibrotactile sense and their relation to clinical symptoms and findings among male symptomatic workers suffering from the hand-arm vibration syndrome. METHODS: Ninety-six such patients were interviewed and given a clinical and tactilometric examination. The symptoms were classified according to the Stockholm Workshop Scale. A sensibility index was used to quantify vibrotactile sense in the tactilogram. RESULTS: An abnormal sensibility index (<0.8) was recorded for 57.3% of the patients (mean of 4 fingers), at least 1 finger being abnormal in 72.9% of the patients. The sensibility index did not statistically differ between the patients suffering from sensorineural symptoms and those with vibration white finger. The stages of sensorineural symptoms, according to the Stockholm Workshop Scale, corresponded with the sensibility index, whereas the stages of vibration white finger did not. There were significant differences in the sensibility index between the fingers, between the right and left hands, and between the fingers innervated by the ulnar and median nerves. Bilateral symptoms and cold intolerance were associated with considerable impairment of the vibrotactile sense. Clinical median nerve involvement in the carpal tunnel was not reflected by the sensibility index. CONCLUSIONS: There is a considerable degree of neural involvement in all symptomatic vibration-exposed patients irrespective of symptoms. As symptoms progress, the severity of sensorineural symptoms, but not of vibration white finger, is reflected by the sensibility index. Cold intolerance is strongly related to nervous involvement and should be noted in the patient history. Tactilometry should be performed on 1 median and 1 ulnar nerve-innervated finger of both hands, as an examination of 1 finger alone may be misleading.

Adult↗

PubMed2000

Relationship between vibration dose and the absorption of mechanical power in the hand.

OBJECTIVES: The aim of this study was to examine the relationship between calculated vibration dose and the measured absorption of vibration power in the human hand, as well as the measured grip and feed forces applied by the subjects. METHODS: The study was carried out with 10 healthy subjects. A special handle was used during the measurements. The influence of 4 different vibration levels with different durations during a test period of 5 minutes was investigated. The number of exposure intervals varied between 1 and 5. The same overall equivalent acceleration was used in all the experiments. RESULTS: There is a significant difference between the calculated vibration dose and the amount of measured absorption of power. A higher acceleration level leads to significantly higher absorption. Furthermore, the outcome shows that rest periods contribute to a lower absorption of power in the hand and also lower feed forces. Conclusions This study supports the hypothesis that vibration-free rest periods give the human organism an opportunity to recover.

Adult↗

PubMed1988

[Cutaneous vibration and thermal-cooling threshold in control subjects].

The cutaneous vibration and thermal-cooling thresholds were evaluated on the palmar side of the distal phalanx of the right index finger and on the plantar side of the distal phalanx of the right great toe in 70 control subjects without sensory symptoms and signs, aged from 13 to 83 years, by using a Vibration Sensitivity Tester and a Thermal Sensitivity Tester (Sensortek, N. J., USA). Both vibration and thermal-cooling thresholds of the index finger, and vibration threshold of the great toe were statistically significantly increased with age. Based on the data obtained from these subjects, the lower and upper limits of 95% confidence limit of the predicted value of each of the thresholds for each decade were calculated. These values are useful for the detection of the abnormal cutaneous vibration and thermal-cooling thresholds not only in general neurology, but also in occupational neurology.

Adolescent↗

PubMed1998

Osteometric dimensions of metacarpal bones with respect to the professional exposure to vibration.

The comparative analysis of the osteometric dimensions of metacarpal bones in three groups of males (aged from 23 to 63 years) differing with respect to the presence of the professionally connected long-term exposure to the vibration is performed. The sample encompasses forest workers employed in wood industry (exposed to heavy physical work and to the daily use of hand-held vibrating tools) from two regions of Croatia: Podravina (n = 192) and Gorski Kotar (n = 115). The control group is formed using the random sample (selected according to age criterion) of phenotypically healthy male inhabitants of rural communities of Eastern Adriatic islands and peninsula (n = 200). Additionally, the influence of the level of calcium in diet, as a regional nutritional characteristic of particular regions of Croatia, is also considered. The regression of the percent cortical area (PCA) of the second left metacarpal bone and age showed that significant decrease of PCA in older age can be observed only in males from Eastern Adriatic (the control group), while that is not so in either group of males professionally exposed to vibration. Authors conclude that the analysis of the osteometric dimensions performed on males professionally daily exposed to vibration missed to provide evidence to support the hypothesis of long-term exposure to vibration as a risk for accelerated osteoporosis of metacarpal bones.

Adult↗

PubMed2000

Rhythmic sensitization of nematocyst discharge in response to vibrational stimuli.

Sea anemones capture prey by discharging nematocysts and other cnidae. Discharge of microbasic p-mastigophore (mpm) nematocysts is regulated in part by hair bundle mechanoreceptors on tentacles arising from multicellular complexes consisting of supporting cells and a sensory neuron. Anemone hair bundles detect movements of prey and then sensitize cnidocytes (cnida-containing cells) to discharge mpm nematocysts in response to contact between the prey and tentacle. Data from a simple bioassay based on counting nematocysts discharged into test probes, indicate that approximately twice as many nematocysts discharge into test probes touched to tentacles after sensitization than before sensitization. We here report that sub-second bursts of vibrational stimuli at key frequencies (51, 55, 65, or 74 Hz; Watson GM, Mire P, Hudson RR. 1998. J Exp Zool 281:582-593) sensitize discharge for at least 90 sec. Very few complete cycles of vibration are sufficient to sensitize discharge. However, as the number of cycles of vibration is increased, discharge is sensitized in rhythmic patterns. Computer analysis of the data by fast Fourier transforms indicates discharge to vibrations at 65 Hz is sensitized every 6.75 cycles. At 51 Hz discharge is sensitized every 2.00 cycles. At 74 Hz, discharge is sensitized in a polyrhythm occurring every 4.26, 3.76, 2.46, and 2. 10 cycles, respectively. At 55 Hz, discharge is sensitized in a polyrhythm occurring every 6.09, 3.20, 2.91, and 2.0 cycles, respectively. Apparently, cells in the neuronal pathway interconnecting anemone hair bundles with cnidocytes count cycles of vibration and then sensitize discharge or not according to the tally. J. Exp. Zool. 286:262-269, 2000.

Animals↗

PubMed2001

Effect of vibrational stress and spaceflight on regulation of heat shock proteins hsp70 and hsp27 in human lymphocytes (Jurkat).

Heat shock protein levels are increased in cells as a result of exposure to stress. To determine whether heat shock protein regulation could be used to evaluate stress in cells during spaceflight, the response of Jurkat cells to spaceflight and simulated space shuttle launch vibration was investigated by evaluating hsp70 and hsp27 gene expression. Gene expression was assessed by reverse transcription-polymerase chain reaction using mRNA extracted from vibrated, nonvibrated, space-flown, and ground control cells. Results indicate that mechanical stresses of vibration and low gravity do not up-regulate the mRNA for hsp70, although the gene encoding hsp27 is up-regulated by spaceflight but not by vibration. In ground controls, the mRNA for hsp70 and hsp27 increased with time in culture. We conclude that hsp70 gene expression is a useful indicator of stress related to culture density but is not an indicator of the stresses of launch vibration or microgravity. Up-regulation of hsp27 gene expression in microgravity is a new finding.

Cell Division↗

PubMed2001

[Aspects of diastolic function of the heart in vibration disease].

AIM: To study effects of occupational vibrations on the myocardium, to elucidate early alterations in cardiac performance and to introduce approaches to their correction. MATERIALS AND METHODS: Doppler echocardiography was made to evaluate diastolic function of the heart ventricles in 54 men with vibration disease. Mean exposure to local vibration was 22.4 years. The examinees were divided into two groups: 42 men (mean age 46.8 years) with vibration disease of the first degree--group 1; 12 men (mean age 51.2 years) of the first-second and second degree--group 2. RESULTS: In group 2 compared to group 1 there was a decrease of maximal velocity of early filling (MVEF) by 24.2%, early filling phase (EFP) by 27%, ratio MVEF/MVLF 1.17-fold, increase of isometric relation phase by 15.9%. For the right ventricle there was a decrease in MVEF by 15.4%, MVEF/MVLF 1.51-fold, prolongation of EFP by 20%. By these indices, the groups differed significantly in the diseases severity. Trimetasidine had a corrective effect on diastolic function of both left and right ventricles of the heart. CONCLUSION: Patients with vibration disease were diagnosed to have left and right ventricular diastolic dysfunction.

Data Interpretation, Statistical↗