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PubMed2001

Hand-arm vibration exposure influences performance of daily activities.

PURPOSE: Although much research has been performed on the effects of vibration on nerves, muscles and vascular structures, little is known of the effects that vibration exposure to handheld tools can give on the ability to perform activities of daily living. The objective of the present study was to analyse the consequences of vibration exposure on performance of daily activities. METHOD: In a total group of 105 exposed male workers, a standardized self-administered ADL questionnaire, the EDAQ including 102 activity items plus 22 diagnosis-specific activity items, was filled out. RESULTS: Forty-four workers (42%) expressed one or more difficulties in performing daily activities in the total study group. The data demonstrated that pain and reduced grip force showed a strong correlation with difficulties in performing daily activities. CONCLUSION: Working in a cold environment, using vibrating machines. handwriting, picking up small objects, opening lids, lifting and carrying were activities perceived as most difficult to accomplish.

Activities of Daily Living↗
PubMedDate not supplied

Task-based assessment of occupational vibration and noise exposures in forestry workers.

Forty-two noise exposures and 164 whole-body (WBV) and hand-arm (HAV) vibration exposures were collected from 43 forestry workers in six trades employed by two forestry companies. Data were collected on 10 days over 8 weeks during various felling, logging, and log handling operations. Up to 5 volunteers were monitored for noise and vibration daily using datalogging noise dosimeters, which provided daily time-weighted averages (TWAs) and 1-min averages; and a precision sound level meter equipped to measure human vibration, which provided triaxial HAV and WBV event-weighted averages (AEQS). Workers completed a short questionnaire throughout the workday detailing the timing and number of tasks performed and equipment used. Substantial overexposures to noise and vibration were seen; for example, 60% of Occupational Safety and Health Administration (OSHA) TWAs and 83% of National Institute for Occupational Safety and Health (NIOSH) noise TWAs exceeded 85 dBA, 33-53% of the axis-specific HAV AEQS exceeded the 8-hour American Conference of Governmental Industrial Hygienists' HAV threshold limit value, and 34% of all summary weighted WBV AEQS exceeded the Commission of the European Communities' 8-hour exposure limit. The mean for 99 WBV summary weighted AEQ was 3.53 +/- 7.12 m/sec2, whereas the mean for 65 HAV summary weighted AEQ was 5.45 +/- 5.25 m/sec2. The mean OSHA TWA was 86.1 +/- 6.2 dBA, whereas the mean NIOSH TWA was 90.2 +/- 5.1 dBA. The task and tool with the highest exposure levels were unbelling chokers on landings and chain saws (noise), log processing and frontend loaders (WBV), and notching stumps and chain saws (HAV). An internal validation substudy indicated excellent agreement between worker-reported and researcher-documented tasks and tools.

Adult↗
PubMed1980

Analysis of mitral and aortic valve vibrations and their role in the production of the first and second heart sounds.

Using a theoretical approach and stress and vibration analysis, formulae have been derived for the frequencies that would be generated by considering the mitral and aortic valve leaflets as vibrating membranes. In the analysis the physical characteristics of the valves, such as loading, valve geometry and valve tissue mechanical properties, were taken into consideration. The analysis showed that the fundamental frequencies for both the vibrating valves increase with the pressure difference across the valve membranes. This suggests that for a better understanding of the role played by the vibrating heart valves in the production of heart sounds, data are needed on the relation between these frequencies and the pressure difference across the valves. Unfortunately such data do not seem to be available.

Aortic Valve↗
PubMed1983

Sensory effects of pulling or vibrating exposed tendons in man.

The role of muscle receptors in proprioception has been demonstrated in a variety of ways (for review see McCloskey, 1978) but is still doubted by some. One simple but critical experiment has produced conflicting results: when a tendon of a conscious subject is exposed at operation under local anaesthesia, and pulled so as to stretch its muscle while the joint at which the muscle acts is held still, the subject is claimed by some to perceive nothing (Gelfan and Carter, 1967; Moberg, 1972), while others claim that the subject feels that the joint seems to move (Matthews and Simmonds, 1974). In the present study 4 patients were studied while undergoing surgery at the wrist or hand under local anaesthesia, and a more extensive study was carried out in the laboratory on the exposed, transected tendon of extensor hallucis longus of one of the authors (D.I.McC.). All 4 patients and the experimental subject detected stretches imposed on their muscles, and reported them as rotations of the joint or joints to which those muscles attach. In all cases the movements reported were in the direction of joint rotation that would normally stretch the muscle tested. In the experimental subject it was shown that stretches were detected with comparable acuity to that demonstrable for the detection of movements imposed on the intact toe. Also, the subject was able to detect, as joint movements, sinusoidal stretches of less than 1 mm imposed on the tendon at 1 or 5 Hz. The experimental subject experienced illusory movements of plantar flexion of the big toe when longitudinal vibration at 100 Hz, 20 to 100 microns amplitude was applied. These were sometimes partly masked by spread of the vibration through the foot. These vibration-induced illusions correspond to those reported by Goodwin et al. (1972) for transverse vibration applied through the skin. The subject could maintain a constant tension through the tendon in a contraction in which his effort was held constant. If, during such an effort, a downward movement was imposed on the toe to which the tendon normally connects, or the skin on the bottom of the toe was scratched, achieved tension fell.

Adult↗
PubMed1987

Stretch and vibration reflexes of wrist flexor muscles in spasticity.

The surface electromyographic (EMG) reflex responses of the voluntarily contracting flexor carpi radialis evoked by 'stretch' and by tendon vibration have been compared in patients with spasticity of the upper limb, arising from upper motor neuron lesions, and normal subjects. Reflex responses to 'stretch' comprised increases in EMG activity lasting up to 100 ms which were often divided into 'short' and 'long'-latency peaks. The short-latency responses of spastic patients were increased in size compared with those of normal subjects whereas later activity was commonly reduced or absent. In both groups vibration elicited short-latency, essentially phasic responses with activity falling back to or below the background level within 50 ms despite continuing stimulation. These initial reflex responses were exaggerated in the spastics as compared with the normals. In the relaxed state 'stretch' and vibration either failed to elicit reflex responses in normal subjects or reflexes were of small amplitude; in spastic patients both modes of stimulation regularly evoked well developed responses. These findings with 'stretch' and vibration, both of which forms of stimulation powerfully excite primary endings of muscle spindles, support the view that group Ia afferent-mediated reflex action is enhanced in spasticity. The observation that the normal long-latency responses evoked by stretch, which have been attributed to the action of spindle group II afferents (Matthews, 1984a) additionally excited with this stimulus, are depressed in many spastic patients is consistent with reduced group II effects. Observed abnormalities of stretch reflex behaviour did not readily explain the severity of accompanying spasticity of individual patients.

Adult↗
PubMed1993

Decrease of contralateral neglect by neck muscle vibration and spatial orientation of trunk midline.

Three patients with a right hemisphere lesion and marked left-sided neglect without visual field defects were asked to detect and identify stimuli which were tachistoscopically presented in the left or right visual half-field. Neglect of stimuli presented in the contralesional left visual field, which was observed when the patient's body was in a normal upright position with trunk, head and gaze oriented straight ahead to the middle of the projection screen, could be reduced by vibrating the left posterior neck muscles as well as by turning the trunk 15 degrees to the left. In contrast, unspecific stimulation on the left side of the patient's body, produced by vibrating the left hand muscles or the proprioceptive signal induced by turning the head 15 degrees to the left, had no compensatory effects. The results showed that the afferent information about real lengthening of the left posterior neck muscles (produced by turning the trunk) as apparent lengthening of these muscles (produced by their vibration), leads to a remission of contralateral neglect. Thus, the proprioceptive input from the neck muscles, i.e. the head-on-trunk signal, appears to influence the extension of the neglected part of space in patients with neglect. The signal seems to contribute substantially to the neural generation of the egocentric frame of reference that allows the determination of body position with respect to visual space. We hypothesize that the reduction of neglect by vibration of the contralateral posterior neck muscles is based on a shift of the subjective spatial localization of the sagittal midplane in the contralesional direction and a corresponding alteration of the egocentric coordinate system necessary for visuomotor coordination and exploration of space.

Aged↗
PubMed1998

Perceptual and oculomotor effects of neck muscle vibration in vestibular neuritis. Ipsilateral somatosensory substitution of vestibular function.

Afferent cervical somatosensory input may substitute for absent vestibular information as part of central vestibular compensation after unilateral peripheral vestibular deficit. In order to determine the particular contribution of neck muscle spindles to the perception of body orientation and to the oculomotor system, we measured (i) the subjective visual straight ahead (SVA) by psychophysical tests and (ii) the changes in eye position by video-nystagmography during unilateral stimulation of the posterior neck muscles by vibration (100 Hz). Twenty-five patients with subacute unilateral vestibular lesion (vestibular neuritis) and 25 controls participated in the study. Vibration elicited a horizontal displacement of SVA towards the side of stimulation in all subjects. Mean displacement (+/- SD) was 3.28 +/- 2.96 degrees for right-side and 3.45 +/- 2.93 degrees for left-side stimulation in controls. Muscle stimulation on the patients' lesion side induced a significantly higher displacement (11.51 +/- 6.63 degrees) than contralateral stimulation (3.04 +/- 2.95 degrees, P < 0.01, paired Student's t test). The mean difference during stimulation between the two sides in the patients was 8.02 +/- 5.52 degrees; in the controls, however, it was only 0.74 +/- 0.47 degree (P < 0.001, Student's t test). This asymmetry increased gradually in patients over a period of weeks, reaching a maximum at days 60-80 and declining thereafter. Videonystagmography revealed that ipsilateral stimulation in patients induced large horizontal eye deviations of up to 25 degrees towards the side of the lesion (9.1 +/- 7.6 degrees, n = 18). Contralateral stimulation induced only small shifts, which were within the range of controls. The correlation coefficient between displacement of the SVA and change in eye position was high (r = 0.94, P < 0.0001), indicating that the shift of SVA is the perceptual correlate of the directional change of gaze in space. This interpretation was supported by two control experiments in which the subject was required to (i) indicate the subjective straight ahead by finger-pointing with the eyes closed and (ii) adjust SVA when looking through horizontally reversing prisms. Vibration of neck muscles caused almost no displacement of the SVA when it was indicated by pointing with the eyes closed, but reversed the direction of the displacement if the subject wore reversing prisms. In summary, our data showed: (i) an increase in muscle spindle input following unilateral vestibular lesion; (ii) this increase is asymmetrical, restricted to the affected side, and gradually builds up over weeks; and (iii) the perceived effects during vibration are secondary to changes in eye position rather than changes in cortical representation of body orientation. This is the first study to demonstrate a unilateral increase in somatosensory weight, which substitutes for missing vestibular input.

Adolescent↗
PubMed1995

Age effects on reflex and postural responses to propriomuscular inputs generated by tendon vibration.

The effects of aging on two sensorimotor levels of propriomuscular function were investigated in a young (20- to 44-year-old) and an elderly (60- to 86-year-old) population by eliciting segmental reflex and postural responses via the same muscle spindle inflow generated by applying the same pattern of tendon vibration. The latency and amplitude of the reflex responses to vibration (tonic vibration reflex) of the biceps and triceps brachii did not depend on the subjects' age. No major age-related changes were observed in the deep reflexes of the lower limbs. The postural responses to the same vibratory stimulation applied to both the soleus or the tibialis anterior muscles (vibration-induced falling) did not show any changes in latency depending on either age or the visual conditions, whereas the intensity of these responses decreased both with age and when the use of vision was possible. Our results suggest that the two levels at which the same propriomuscular messages were processed are differentially affected by aging. The lower reflex level does not undergo any noticeable impairment, whereas the higher postural control level deteriorates in the elderly, which might be partly responsible for the balance problems which tend to occur more frequently with advancing age.

Adult↗
PubMed1996

Effects of vibration on the hand-arm system of miners in India.

Sixty-six Jackhammer drillers and 35 blasters from two mines were clinically screened for hand-arm vibration syndrome (HAVS). The screening consisted of questionnaire-based information, clinical examination including measurement of phalangeal circumferences of fingers (FCT) and motor nerve conduction (MCV) studies. In a warm environment, the prevalence of symptom complexes suggested the existence of peripheral neuropathy and musculoskeletal abnormalities rather than any peripheral circulatory disorders. Clinical examination revealed soft tissue wasting in the hands (26 cases), ulnar nerve impairment (23 cases), median nerve impairment (16 cases) and Dupuytren's contracture (4 cases). Mean motor nerve conduction velocities of 59 out of 66 drillers who volunteered for this assessment were not significantly different from those of the 35 blasters. The results of their correlation coefficients varied considerably for MCVs when age and years of vibration exposure underwent regression analysis. However, comparison of MCV and FCT of 30 drillers with 30 matched blasters revealed that the mean MCV of the right median nerve in the vibration exposed group was significantly decreased (p < 0.01) and for the mean FCT, the proximal phalanxes of the right index finger, left thumb and left ring fingers were thinner in the vibration exposed group (p < 0.05).

Adult↗
PubMed2001

Exposure to hand-transmitted vibration and pain in the neck and upper limbs.

Workers exposed to hand-transmitted vibration (HTV) often experience aches and pains in the upper limbs, but there have been few studies of the pattern and severity of symptoms, or their relationship to the estimated dose of vibration. As part of a wider survey of vibration, we mailed a questionnaire about exposures to HTV and pain in the neck and upper limbs to a sample of men selected at random from the registration lists of 34 British general practices and the pay records of the armed services. Analysis was confined to the 1856 male respondents who had been employed in manual occupations for a year or more and who reported the last week as being representative of their job. Inquiry was made about pain in the neck, shoulder, elbow and wrist/hand over the past week and past year (including pains that limited normal activity). Subjects were classed according to their lifetime exposure to HTV and their estimated average daily vibration dose [A(8) r.m.s.] in the previous week. A total of 283 men had a minimum estimated A(8) greater than a proposed action level of 2.8 m/s(2), and in this group symptoms were about twice as prevalent as in manual workers who had never used vibratory tools. The excess risk was somewhat higher for distal sites than for proximal ones (e.g. the prevalence ratio for hand/wrist pain in the past week was 2.7 versus 1.8 for neck pain). This accords with the pattern of transmission of HTV to the upper limb, although a confounding effect from other ergonomic risk factors cannot be discounted.

Adolescent↗
PubMed2003

Hypothenar hammer syndrome: a discrete syndrome to be distinguished from hand-arm vibration syndrome.

BACKGROUND: Hypothenar hammer syndrome (HHS) is a cause of vascular insufficiency to the hand and may be manifest as Raynaud's phenomenon. The cause is trauma to the vulnerable portion of the ulnar artery as it passes over the hamate bone, which may result in thrombosis, irregularity or aneurysm formation. AIM: This review was undertaken in order to clarify the features of HHS that may differentiate it from hand-arm vibration syndrome. METHODS: A tiered review of world literature was undertaken using Medline and EMBase as the primary search engines. Fifty-two relevant articles were critically reviewed. CONCLUSION: Colour and temperature changes occur more diffusely in HHS than in classical Raynaud's phenomenon and the absence of the triphasic colour change may alert clinicians to the diagnosis, which may be confirmed by Allen's test. Doppler or arteriographic studies are required for confirmation. It is important to recognize the possibility of HHS in the occupational setting as a potentially curable cause of Raynaud's phenomenon, distinct from hand-arm vibration syndrome. The possibility exists of HHS occurring as a result of repeated hypothenar trauma from vibrating tools, in which case the nature and magnitude of the individual episode of trauma may be more important than the weighted acceleration level of vibration exposure.

Arm Injuries↗
PubMed2004

Effectiveness of therapy with iloprost in hand-arm vibration syndrome.

AIM: To evaluate the efficacy and tolerance of therapy with iloprost in hand-arm vibration syndrome. METHODS: We describe a clinical case of a male aged 53 years, who was a heavy smoker for 30 years and a mason working with vibrating tools since 1962. He presented with a history of 10 years of attacks of vasospasm, functional impairment and digital ulceration. He was diagnosed as having hand-arm vibration syndrome vascular stage 4 on the Stockholm Workshop 1986 Scale. Besides suspension from work and abstention from smoking, we began intravenous infusion of iloprost for 6 h in cycles of 3-6 consecutive days, arriving at a dose of 1.5-2.0 ng/kg/min. RESULTS: After eight cycles, he reported significant symptomatic and functional improvement. Iloprost was seen to be efficacious: the trophic skin lesions disappeared and his microcirculatory perfusion tests improved. There were no significant side effects. CONCLUSIONS: We suggest that the use of iloprost in the treatment of the most advanced stages of vascular hand-arm vibration syndrome warrants further study

Arm↗
PubMed2006

Vibration exposure and myocardial infarction incidence: the VHEEP case-control study.

OBJECTIVES: The main objectives of this study were to assess the risk of contracting first episode of myocardial infarction (MI) subsequent to vibration exposure and to assess a possible exposure-response relationship. METHODS: The Västernorrland heart epidemiology programme (VHEEP, a part of the Stockholm heart epidemiology programme study) was the source of the data. VHEEP is a population-based case-control study of risk factors for acute MI. Exposure information was collected by questionnaire and vibration exposure was assessed in 218 cases and 257 controls. Relative risks were estimated using odds ratios (ORs) from binary logistic regression. RESULTS: The results show that the OR of acute MI when exposed to vibration was 1.6 (95% CI: 1.1-2.4). It was not possible, however, to determine whether an exposure-response relationship was present. CONCLUSIONS: Working entailing vibrating machines is associated with an increased risk for acute MI.

Aged↗
PubMed2006

Bone cell responses to high-frequency vibration stress: does the nucleus oscillate within the cytoplasm?

Mechanosensing by cells directs changes in bone mass and structure in response to the challenges of mechanical loading. Low-amplitude, high-frequency loading stimulates bone growth by enhancing bone formation and inhibiting disuse osteoporosis. However, how bone cells sense vibration stress is unknown. Hence, we investigated bone cell responses to vibration stress at a wide frequency range (5-100 Hz). We used NO and prostaglandin E2 (PGE2) release, and COX-2 mRNA expression as parameters for bone cell response since these molecules regulate bone adaptation to mechanical loading. NO release positively correlated whereas PGE2 release negatively correlated to the maximum acceleration rate of the vibration stress. COX-2 mRNA expression increased in a frequency-dependent manner, which relates to increased NO release at high frequencies, confirming our previous results. The negatively correlated release of NO and PGE2 suggests that these signaling molecules play different roles in bone adaptation to high-frequency loading. The maximum acceleration rate is proportional to omega3 (frequency=omega/2pi), which is commensurate with the Stokes-Einstein relation for modeling cell nucleus motion within the cytoplasm due to vibration stress. Correlations of NO and PGE2 with the maximum acceleration rate then relate to nucleus oscillations, providing a physical basis for cellular mechanosensing of high-frequency loading.

3T3 Cells↗
PubMed1986

Acoustic radiation produced by B-71, B-72, and KH 70 bone vibrators.

The amount of acoustic radiation produced by two samples of a Radioear B-71, B-72, and Pracitronic KH 70 bone vibrator was determined for 30 normal-hearing subjects at 4000 Hz. The mean amount of acoustic radiation was very similar for both samples of each vibrator type but significantly (p less than 0.05) different between the bone vibrator types. The mean amount of acoustic radiation averaged over both samples was 8.3 dB for the B-72, 4.3 dB for the B-71, and -0.3 dB for the KH 70. Individual subject data indicated that the B-72 produced excessive acoustic radiation (greater than 5 dB) for 80% of the subjects, the B-71 for 38% of the subjects, and the KH 70 for 8% of the subjects which could cause an invalid high-frequency air-bone gap. Precautions should be taken during bone conduction audiometry to eliminate the possibility of acoustic radiation produced by bone vibrators. A need for additional standards in this area is stressed.

Acoustics↗
PubMed2001

Removal of fractured posts using ultrasonic vibration: an in vivo study.

The purpose of this study was to determine the effectiveness of ultrasonic vibration in the removal of fractured posts from teeth under true clinical conditions. Thirty patients (16 men and 14 women with a mean age of 51 yr, SD 13.13) had ultrasonic vibration applied to the side of a fractured post fragment after creation of a small gutter around the fragment. A piezoelectric ultrasonic scaler was used to apply the vibration for two 15-s periods and then 30-s periods until the post fragment became loose. There was a significant correlation (r = 0.52, p = 0.003) between the cemented length of post fragment (mean length 3.8 mm, SD 1.39) and the time of ultrasonic vibration application (mean time 2.05 min, SD 1.62), but the correlation between post diameter and ultrasonic time did not reach statistical significance (r = 0.35, p = 0.059). The mean ultrasonic time was approximately 25% of that found in previous studies on post removal from extracted teeth probably because of suboptimal cementation of posts in the clinical situation.

Adult↗
PubMed2000

Effects of thyroplasty type I on vocal fold vibration.

OBJECTIVE: To ascertain effects of medialization thyroplasty on vocal fold vibration in glottic incompetence dysphonia. STUDY DESIGN: Quantitative videostroboscopic glottic measurements and vocal function study were perioperatively undertaken in 20 patients undergoing Isshiki's thyroplasty type I. METHODS: In digitized images, the glottal area, glottal width, posterior glottal width, and amplitude over an entire glottal cycle were measured and normalized by membranous vocal fold length. The ratio of closed phase to total phase of vibratory cycle was calculated from the data of the glottal area and the glottal width at the middle point of the membranous vocal fold. Well-accepted acoustic, aerodynamic, and perceptual measures analyzed vocal function. RESULTS: Glottal area and glottal width were reduced after surgery. While preoperative closure of glottal area was incomplete in all 20 patients, incomplete closure was obtained in 16 patients after surgery. In these 16 patients, closure of glottal width at the middle point of the membranous vocal fold was complete, whereas a posterior glottal gap remained in 14 patients. Closed phase over one cycle of glottal width waveform and amplitude of vocal fold vibration were increased after surgery. Glottal area, glottal width, posterior glottal width, and closed phase over one cycle of glottal width waveform correlated with vocal function measures. CONCLUSIONS: Thyroplasty type I reduces a glottal gap and increases closed phase over one cycle and amplitude of vocal fold vibration, although a posterior glottal gap remains. With the improved glottic vibration, thyroplasty type I provides more efficient phonation in patients with glottic incompetence dysphonia.

Adolescent↗
PubMedDate not supplied

Body height changes from vibration.

A device for measuring body height is reported (SD, 1 mm). The change in body height before and after vibration and quiet sitting respectively was studied in eight men aged 22-44 years who were free of back pain. The vibration frequency was set at 5 Hz and the acceleration at 2 msec-2. Subjects were asked to report for testing within 2 hours after arising from bed. Body height was measured before and immediately after vibration or sitting exposure and the measurements were repeated at different intervals up to 2 hours after the experiment. Results show that exposure to vibration increases the overall creep response in most subjects. There is a great deal of variability in response between subjects, but most of them show a recovery to the average creep response within a 2-hour time interval.

Adult↗