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At least 1,351 records · Page 75Linked to original sources
PubMed1994

Effect of hand-arm vibration on inner ear and cardiac functions in man.

To evaluate distant effects of hand-arm vibration we studied Finnish forestry workers using chain saw during the years 1972 through 1990. The hearing was tested annually and individual regression curves for sensorineural hearing loss (SHL) were calculated. Robinson's model was used in prediction of SHL. The heart rate variation (HRV) indexes at rest and during deep breathing test were analyzed to measure autonomic nervous function. In Robinson's model the measured SHL (17.8 dB) respected the predicted SHL (17.2 dB). The subjects with VWF had on average, 10 dB greater hearing loss than those who did not have VWF. The regression model based increase of hearing loss during follow up correlated with ageing, not to VWF. The intercept differed significantly in those with VWF from those without VWF. We found a significant difference between HRV indexes during deep breathing test in those with the shortest and those with the longest vibration exposure. The HRV decreased with age, but multiple regression analysis showed that the total exposure time to vibration had an independent negative association with HRV indexes. Our results suggest that prolonged exposure to vibration caused by chain saw has negative effects an autonomic functions. The aggravated hearing loss in subjects with VWF may be due to vibration induced changes in the autonomic nervous system or internal factors of the blood vessels.

Arm↗
PubMed1994

Raynaud's phenomenon of fingers and toes among vibration-exposed patients.

Eleven patients with Raynaud's phenomenon of the toes as well as the fingers were encountered among about 1,000 vibration-exposed patients. They consisted composed of four chain-saw operators, five rock drillers, a stone quarrier and a welder in a shipyard. All the cases were examined carefully for differential diagnosis, but there were no particular abnormalities in hematological, immunological and homodynamic examinations. The rock drillers, quarrier and welder had direct vibration exposure of the foot, which was considered to be responsible for their Raynaud's phenomenon of the toe. Four chain-saw operators, who had been little exposed to vibration of the foot directly, were examined further on skin temperature of fingers and toes every three hours except at night and in a 30-min cold provocation test at 5 degrees C. The skin temperature of both their fingers and toes was lower than in age-matched healthy controls. The chain-saw operators started to work in the 1960's and early in the 1970's, when the chain saw vibration level was high. It is, hence, considered that they were exposed to strong vibration of the hand from chain saws, and then suffered severe Raynaud's phenomenon of both fingers and toes.

Aged↗
PubMed1994

Pathological changes of finger and toe in patients with vibration syndrome.

Pathological findings of the fingers and toes were studied in finger and toe skin specimens from 21 male patients with vibration syndrome and 13 referent male cadavers. Thickening of the medial muscle layer of small arteries or arterioles, and increase of collagen fibers in the connective tissues, especially in perivascular regions, were noted in not only the finger but also the toe in patients with vibration syndrome. The ratio of the media/external diameter in the finger and toe was significantly greater in the patients than in the referents, even in the patients who had operated chain saws, bush cutters or grinders and had not been exposed to vibration of the foot directly. And the ratio in the finger was approximately parallel with that in the toe in the same subject. The present findings pathohistologically confirmed the existence of circulatory disturbances in the feet as well as the hands. The medial thickening of arteries and perivascular fibrosis in the toe can result from not only direct vibration exposure of the foot, but also long-term repeated vasoconstriction and circulatory disturbances in the foot through the activation of the sympathetic nerve system caused by hand-arm vibration.

Aged↗
PubMed1994

Vibration exposure and prevention in Japan.

Working conditions of vibration exposure have generally improved, but many difficult problems must be solved such as (1) hygienic improvements in a variety of vibrating tools; (2) improving working conditions, for example, by limiting the time of operation in spite of economic difficulties such as those faced by those who work on a piece rate basis; (3) gathering more complete information about the risk population because of the large number of self-employed in informal employment sectors; and (4) finding work places after rehabilitation for patients, particularly in mountainous rural areas or in small scale industries. Historical observation of vibration and preventive measures in Japanese national forests was presented on the basis of the results of a retrospective cohort study in Kyushu, Japan. Prevalence rate of VWF remarkably changed from 58.4% in the groups that began to operate chain saws in 1960 to only a few cases in the groups who started the operation after 1971. When we compare the relationships between the results of long term cohort study and the consequences of preventive measures of vibration syndrome, the most important factor is the decrease of vibration exposure (improvement in chain saws plus the time restriction system). The comprehensive prevention system used in Japanese national forests consists of the following: (1) Health care system; (2) Work regulation system; (3) System for improving mechanized tools; (4) Warming system to protect against cold conditions; and (5) Education and training system.

Humans↗
PubMed1994

Correlations among examination findings, subjective symptoms and classification of stages in vibration syndrome.

From data collected in 1966, 1973, 1986 and 1989, we analyzed the correlations among examination findings, subjective symptoms, stages in the disorder of vibration syndrome and vibration exposure. As vibration syndrome progressed and vibration exposure accumulated, abnormality of examination findings, the prevalence of vibration induced white finger (VWF), numbness (N) and other subjective symptoms increased. Abnormality of examination findings and prevalence of subjective symptoms in the VWF(+) N(+) group were greatly different from those in the VWF(-) N(-) group. Both findings and symptoms showed closer correlations with VWF(+) than with N(+). Stages in the disorder traced the progression from VWF(-)N(-) to VWF(-)N(+), then to VWF(+)N(+/-), and finally to VWF(+/++)N(+/++). Pathophysiologically, it seems that VWF(+) and N(+) relayed many more cold and pain signals from the hand to the central nervous system. Such signals may activate autonomic nervous activity. In the recovery, subjective symptoms correlated more closely with N(+) than with VWF(+). This is because VWF involves the autonomic nervous system's hyperactivity and hypersensitivity to cold, both of which subside gradually in the recovery; N, however, involves pathological changes in nerve tissue which are irreversible.

Adult↗
PubMed1994

Autonomic nervous function of hand-arm vibration syndrome patients.

We have investigated the autonomic nervous function of hand-arm vibration syndrome patients using blood chemical analyses and electrophysiological methods. When exposed to whole body cooling, hand-arm vibration syndrome patients showed a significantly greater increase of plasma norepinephrine than the age-matched healthy controls. The patients also exhibited reduced variation of R-R intervals in electrocardiogram during deep breathing. When classifying the subjects according to the Stockholm Workshop scale of VWF, the subjects of stage 3 showed the most remarkable findings followed by the subjects of stage 2. The findings of the stage 3 subjects were also greater than those of diabetes patients. The excess secretion of norepinephrine in blood reveals that the responsiveness of the sympathetic nervous system to cold exposure is enhanced in hand-arm vibration syndrome patients. The R-R interval variation suggests that the basal activity of the parasympathetic nervous system is reduced. We observed that plasma norepinephrine also increased during short-term exposure of hand-arm to vibration and noise exposure potentiated the effect. It seems likely that repeated vibration exposures of the hand-arm system develop the hyperactivity of the sympathetic nervous system.

Arm↗
PubMed1994

Pathophysiology of white fingers in workers using hand-held vibrating tools.

The pathogenic events and the localization of the primary lesion in white fingers among persons using hand-held vibrating tools are still unclarified. A "vibration disease" has been proposed to be due to damage to the limbic system and other brain structures which causes autonomic dysfunction. Current common opinion regards the pathogenesis of white fingers to be a result of longterm exposure to various physical and psychological environmental stressors, but the relative importance of one stressor or other is unknown. Observations indicating a chronic autonomic disturbance include changes in cardiac functions, excessive hearing loss in persons with VWF, and reduced toe skin temperature also in the absence of acute cold or vibration exposure. Sympathetic hyperactivity alone has long been postulated to account for vibration-induced white fingers, but damage to vaso-regulatory structures and functions in the finger skin now also seems to be involved. An abnormal level of sympathetic efferents is likely to be important for producing the symptoms in white fingers. Recent findings, however, indicate that the pathogenesis also involves changes in alpha-adrenergic receptor mechanisms as well as endothelial damage with deficient function of endothelial-derived relaxing factor. The role of vessel lumen reduction due to organic changes and an increase in whole blood viscosity remains unclarified. The understanding of the influence of confounders such as cold exposure, smoking habits and variations in individual susceptibility is also lacking. In particular, the physiological complexity of the response to cold is so great and the interaction between various vaso-regulatory mechanisms so intricate that only a multifactorial etiology and pathogenesis is likely for Raynaud's phenomenon in persons using hand-held vibrating tools. A model is suggested for the manifestation of abnormally strong vasoconstriction and white fingers as a result of a narrowing of the gap between the individual symptom threshold and the level of sympathetic activity.

Fingers↗
PubMed1994

Hand-arm vibration in snowmobile drivers.

Hand-arm vibration was measured on the handlebars of snowmobiles (N = 29) and a postal inquiry was made among reindeer herders, N = 2,705. Since many subjects had used also other vibrating tools a snowmobile group proper (N = 334) was established, and in this group 18% of the subjects reported that they had experienced white finger attacks and 48% numbness of the hands. The age-adjusted prevalence of the white finger syndrome was more than three times higher in the snowmobile group than in the controls. The frequency-weighted acceleration of snowmobile vibration was 3.5 m/s2, and risk evaluation based on the annex of the ISO 5349 standard predicted the prevalence of the white finger syndrome well in the snowmobile group. The most critical points for damping the vibration were the motor mounting and resonance in the steering yoke. There is a need for health care, technical improvements, changes in working habits and other protection means to reduce the symptoms of vibration associated with driving terrain vehicles.

Adult↗
PubMed1994

Combined effects of cold, vibration and smoking, particularly in snowmobile users.

In a living and working environment more than one factor is usually important for physiological and psychological responses in the body. In this report the effects and combined effects of hand-arm vibration and cold, in particular their effect on frostbite, has been reviewed. As a second example is given the combined effect of vibration and smoking on vibration-induced white finger. In both cases our previous work among reindeer herders frequently using snowmobiles has been utilised as an example. Descriptive terms for combined effects have varied in previous multi-exposure studies. Here, the terminology recommended in the Saariselkä agreement has been applied, and according to that the combined effect between cold and vibration on frostbite was called synergism and between vibration and smoking on white finger Bliss synergism.

Adult↗
PubMedDate not supplied

Vibration in metal and non-metal incubators.

The purpose of this study was to determine the amount of vibration transmitted to the surface of an incubator mattress. Empty incubators with metal (n = 12) and non-metal (n = 12) bases were monitored for vibration levels when the incubators were turned "off" and when they were turned "on." High levels of low-frequency vibration were detected in both types of incubators in both conditions. The metal incubators transmitted significantly less vibration to the mattress than did the non-metal incubators at several frequencies in the "off," the "on," and the "adjusted" conditions. These results suggest that infants experience significant whole-body vibration while lying in incubators.

Acceleration↗
PubMed1993

Prevention, clinical, and pathophysiological research on vibration syndrome.

In the 1950s, introduction of portable power tools into the production process of many industries began on a large scale around the world and resulted in many cases of occupational vibration syndrome after the 1960s. There was an urgent need to undertake preventive steps, medical assessment and therapy throughout the world. At the end of 1964, our investigation began in Japanese national forests, and then in mining and stone quarries. Our research and efforts resulted in a comprehensive system for prevention of vibration syndrome in the Japanese national forest industry. It has presented a good model of prevention for other industries in Japan. Clinical and pathophysiological research on vibration syndrome in the 1960s and 1970s clarified disturbances of the peripheral circulatory, nervous, and musculoskeletal systems. From the mid-1970s, neurophysiological, neurochemical, and clinical research on vibration syndrome in relation to the autonomic nervous system developed. Our studies contributed to the advancement of research in this field. More in-depth study is needed to determine the role of the autonomic nervous system in vibration syndrome.

Humans↗
PubMed1994

Hand-arm vibration syndrome.

The hand-arm vibration syndrome affects workers who perform tasks that generate vibration. Raynaud's phenomenon and sensory impairment of the fingers are the predominant effects. A history of hand-arm vibration (HAV) exposure in a patient with these symptoms should alert the physician to the diagnosis. Referral to a special clinic or hospital department for multiple clinical tests is required to confirm the diagnosis and, using the Stockholm classification, to grade the severity in each hand. The assessment permits the patient to be monitored either for progression of or recovery from the syndrome. Avoidance of further vibration exposure is recommended, together with the prescription of a slow-release calcium channel blocker to improve peripheral circulation. Hand-arm vibration syndrome should be distinguished from carpal tunnel syndrome (CTS), which may have similar symptomatology but requires different treatments. Surgery is contraindicated in the former and should be the last resort for carpal tunnel syndrome in a worker requiring good grip-strength in future employment.

Arm Injuries↗
PubMed1993

[Measuring vibration sense in childhood. Normal values and initial experiences in polyneuropathies].

BACKGROUND: We have attempted to obtain normal values for vibration thresholds in children and to evaluate their application in polyneuropathies. METHODS: Vibration thresholds determinations were made by means of a handheld vibrameter (Fa Somedic AB Sweden): Within a constant frequency (100 Hz) and a calibrated pressure (450 g) the amplitude ranged variably from 0.01 to 399 microns. Measurements were made at three sites (carpal, tibial and tarsal). Vibration threshold (VT) was determined by the average of Vibration Perception Threshold (VPT) and Vibration Disappearance Threshold (VDT). RESULTS: Reference values obtained from 106 children and adolescents (control group), 5.5 to 19 years of age, correlated with age but not with sex. The amplitude of VT-values ranged from 0.4 microns (carpal at 6 years), to 1.10 microns (tarsal at 18 years). Patients with Friedreich's ataxia (n = 7) or hereditary motosensory neuropathy (n = 11) showed strongly increased thresholds at all sites up to a factor of 100. CONCLUSIONS: The examination by means of a vibrameter took at least 10 min, the shorter examination by tuning fork however showed to be less sensitive and rather inexact. An examination with a vibrameter is, as rule, reliably possible in children older than 5 years.

Adolescent↗
PubMed1995

[Development of a piezo-electrical vibrator for middle ear implant. State of research].

Authors develop a piezoelectric vibrator for middle ear implant. Animal experimentation, on guinea pigs, demonstrated the efficiency and good tolerance of this vibrators. A study on human temporal bones led them to design a vibrator implantable on the stapes for humans. The in vitro study of the performances of this vibrators showed an excellent frequency fidelity between 0.5 and 8 kHz, and output levels over 110 dB SPL. A vibrator for humans, implantable on the head of the stapes, without interruption of the ossicular chain was realized. Its study on human temporal bones in implantation position, has begun, in parallel with a theoretical study with a mathematical model.

Animals↗
PubMed1996

The influence of individual factors on the absorption of vibration energy in the hand and arm.

The detrimental effects of vibrating hand-held tools upon humans have been known for a long time, and determination of the absorption of vibration energy into the operator's hand and arm could be an alternative method of risk assessment. The energy absorption in the hand and arm during exposure to random vibration has been measured in 84 subjects, 40 males and 44 females. A special handle was used during the measurements. The influence of various experimental conditions, such as vibration level (3-12m/s2), vibration direction (Xh, Yh, Zh), and grip force (25-75 N) were studied. Furthermore, the influence on the absorption of different individual biological factors, such as age, weight, height, hand and arm dimensions as well as blood pressure were also investigated. The subject also provided demographic data through a questionnaire covering work, symptoms of finger blanching and numbness as well as current use of nicotine (snuff of tobacco). The results show that energy absorption is influenced by exposure directions and levels as well as grip forces. Furthermore, the results show that individual biological differences between subjects, for instance age, hand volume and hand thickness, have a significant influence on the amount of absorbed energy. Blood pressure had no influence on the absorption. The same was also found for the subjective reported symptoms of finger blanching or numbness as well as for use of nicotine.

Adult↗
PubMed1995

High level of plasma thrombomodulin (TM) concentration and correlation with endothelin (ET)-1 in vibration-exposed patients.

We measured plasma level of TM and ET-1 in vibration exposed patients. The results showed the plasma level of TM in vibration exposed patients was significantly higher than in normal controls. The present findings showed relatively wide damage of endothelial cells in the vascular bed of vibration-exposed patients. On the other hand, the mean level of ET-1 in these patients tended to be higher than in normal controls, though there was no difference. Further studies are necessary about the mechanism of endothelial damage in vibration syndrome patients and its contribution to peripheral circulatory disturbance of vibration syndrome including the role of ET-1.

Case-Control Studies↗
PubMed1995

PIMEX--an instructive way to study vibration exposure and work posture.

The PIMEX-method (PIcture-Mix-EXposure) involves measurement of exposure with a direct-reading instrument. The signal from the instrument is superimposed to the recording from a video camera to produce a video film which continuously shows the subject at work and how exposure varies. Application can be a physical factor such as vibration. We used this new method to study vibrations from hand held grinders. Using Brüel and Kjaer miniaturized accelerometer 4374 and vibration meter 2513 we measured vibrations at the grinders main and support handles. We studied different grinders at work on the metal surface as well as at idle speed. Workers posture such as arms in under-up position was evaluated. The PIMEX-method has been encouraging to show correlation between vibration exposure, work technique and different grinders.

Cumulative Trauma Disorders↗
PubMed1997

High performance seizure-monitoring system using a vibration sensor and videotape recording: behavioral analysis of genetically epileptic rats.

A new seizure-monitoring apparatus containing a piezoceramic vibration sensor combined with videotape recording was developed. Behavioral analysis of Ihara's genetically epileptic rat (IGER), which is a recently developed novel mutant with spontaneously limbic-like seizures, was performed using this new device. Twenty 8-month-old male IGERs were monitored continuously for 72 h. Abnormal behaviors were detected by use of a vibration recorder, and epileptic seizures were confirmed by videotape recordings taken synchronously with vibration recording. Representative forms of seizures were generalized convulsions and circling seizures. Generalized convulsions were found in 13 rats, and circling seizures in 7 of 20 animals. Two rats had generalized and circling seizures, and two rats did not have seizures. Although there was no apparent circadian rhythm to the generalized seizures, circling seizures occurred mostly between 1800 and 0800 h. A correlation between the sleep-wake cycle and the occurrence of circling seizures seems likely. Without exception, all the seizure actions were recorded by the vibration recorder and the videotape recorder. To eliminate the risk of a false-negative result, investigators scrutinized the information obtained from the vibration sensor and the videotape recorder. The newly developed seizure-monitoring system was found to facilitate detailed analysis of epileptic seizures in rats.

Animals↗