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PubMed1988

Variability in vibration perception threshold among sites: a potential source of error in biothesiometry.

Vibration perception threshold was measured with a biothesiometer by a single observer at both medial malleoli and both big toes in 110 diabetic patients aged 15-65 selected at random and in 64 non-diabetic subjects aged 20-65. The vibration perception threshold showed appreciable individual variation both between contralateral sites and between ipsilateral sites, differing by at least 30% between the big toes in 26 (24%) of the diabetic patients and 16 (25%) of the non-diabetic group. Variability between sites was significantly greater in the diabetics than the normal subjects. The vibration perception threshold exceeded published normal values at one or more sites in 22 of the diabetic patients but at all four sites in only four. The wide variability in vibration perception threshold among sites may be due to the tissue characteristics locally and, in diabetic patients, possibly to asymmetric neuropathy. Biothesiometer readings at single or unilateral sites may be unrepresentative or misleading.

Adolescent↗
PubMed2005

Short latency responses in the averaged electro-oculogram elicited by vibrational impulse stimuli applied to the skull: could they reflect vestibulo-ocular reflex function?

OBJECTIVES: To investigate whether vibrational impulse stimuli applied to the skull can be used to evoke the vestibulo-ocular reflex (VOR) and detect vestibular lesions. METHODS: Twenty four patients with unilateral vestibular loss (UVD), five with bilateral vestibular loss, two with ocular palsies, and 10 healthy subjects participated. Vibrations of the skull were induced with head taps and with a single period of 160 Hz tone burst on the inion, vertex, and the mastoids while the patients viewed a distant target. Several patients were also examined while viewing a near target, with eccentric gaze and in tilted postures. Responses were recorded by EOG. RESULTS: Responses occurred between 5 ms and 20 ms and seemed to be compensatory to the second phase of the sine wave of vibration impulse and were greatly diminished/absent in patients with bilateral VD and ocular palsies. The patients with UVD had asymmetrical responses in the vertical EOG with stimuli applied on the inion and vertex, with enhancement of the response amplitude on the side of vestibular loss and/or diminution on the healthy side. The asymmetry ratios between the healthy subjects and patients with UVD, and among patients with UVD were statistically significant. Some gaze and positional influences could be demonstrated consistent with otolithic reflexes. CONCLUSION: If the asymmetric responses to skull vibration in UVD result from passive oscillatory movements of the orbital tissues they may reflect the otolith mediated sustained skew torsion. Conversely, if generated by active eye movements, their likely origin is a phasic VOR.

Electrooculography↗
PubMed1982

Contribution of tonic vibration reflex to the evaluation and diagnosis of cerebellar disorders.

Biceps brachii tonic vibration reflexes were elicited in patients with either focal or diffuse cerebellar damage and spino-cerebellar degenerations. As compared to normal controls, tonic vibration reflex amplitude was reduced in cerebellar patients, particularly in cases with unilateral hemispheric lesion, who exhibited a clear cut tonic vibration reflex asymmetry even when clinical symptoms were mild. These reflexes were absent or very weak in patients with spino-cerebellar degenerations. Muscle vibration induced in most of the patients an enhancement of mild or latent clinical symptoms such as intention tremor, difficulty in muscle relaxation or motor incoordination.

Adolescent↗
PubMed1978

Prevalence of vibration-induced white finger in fluorspar mines in Weardale.

A combined epidemiological and clinical study of vibration-induced white finger (VWF) was carried out involving 115 men in four fluorspar mines. The overall prevalence of VWF was found to be 50% among 42 vibration-exposed subjects, while that of constitutional white finger (CWF) was 5-6% in all men studied. The VWF latent interval was 1-19 years with a mean of 5-6 years. An association was observed between the exposure time and VWF stages which included 18 men in Stage 0, three in the intermediate Stage of 0T/0N, five in Stage 2 and 16 in Stage 3; no men were seen at Stage 1. Among those with VWF in Stage 3, the index, middle and ring fingers were affected in both hands and the little fingers and thumbs were last to be involved. Clinically, on general examination, apart from vibration-induced white finger, the men in the 'vibration' group were not as healthy as those in the 'control' group. The circumference of the index fingers was not significantly different for the different groups. Neurological tests showed that the ridge test and, to a lesser extent, the two-point discrimination and the light touch tests, could be regarded as useful for the diagnosis of VWF.

Adolescent↗
PubMed1987

Vibration white finger: a follow up study.

To study the course of vibration white finger (VWF) 55 men were re-examined three and a half to six years after the first examination. The patients were interviewed and finger systolic pressure after general body and local finger cooling was measured. The test results at the two examinations were compared. At the follow up examination some patients experienced a subjective improvement of VWF symptoms but not until more than three years had passed after they had stopped working with vibrating tools. To study the effect of diminished cold exposure on subjective symptoms, vibration exposed outdoor workers who changed to unexposed indoor work were studied separately. In this subgroup also improvement was reported only when more than three years has passed after the change of work, indicating that diminished cold exposure is not the primary explanation for the improvement. The cold provocation test, however, showed no tendency towards a diminished reaction of the vessels to cooling. Patients who continue to work with vibrating tools report a subjective increase in symptoms. This subjective impairment was reflected in an increased reaction to cold as measured in the cold provocation test.

Adult↗
PubMed1988

Forestry workers exposed to vibration: a neurological study.

Neurological findings were examined in 186 forestry workers with a mean exposure to chain saw vibration of 16.6 hours. The prevalence of active vibration induced white fingers was 5%, parethaesias of the hands 53%, and muscle weakness 13%. Clinical polyneuropathy was observed in 16 forestry workers in the hands (7.5%) which did not correlate with alcohol consumption. Seventy nine forestry workers of the total population were selected for electromyographic examination. Generalised EMG based polyneuropathy in the hands was observed in only two of the 79 forestry workers (2.5%). The carpal tunnel syndrome was found in 20 of the 79 forestry workers (26%). Headache and vertigo were not linked with exposure to vibration in forestry and a significant part of the numbness reported may be due to the carpal tunnel syndrome. Sensorimotor polyneuropathy is rare among forestry workers. The rise in the vibration detection thresholds was linked to the carpal tunnel syndrome.

Adult↗
PubMed1990

Assessment of autonomic nervous function in patients with vibration syndrome using heart rate variation and plasma cyclic nucleotides.

A case-control study was performed to investigate the autonomic nervous function in vibration syndrome. The subjects were 20 patients with a history of Raynaud's phenomenon (vibration white finger (VWF) (+) group), 20 patients without such a history (VWF(-) group), and 20 healthy workers (control group). Their ages and years under medical treatment for vibration syndrome were matched individually among the groups. They were examined using the test of R-R interval variations in the electrocardiogram at rest and during deep breathing and the test of plasma cyclic nucleotide (cyclic AMP and cyclic GMP) responses to whole body exposure to cold. The heart rate variation resulting from respiratory arrhythmia reflects parasympathetic activity; the changes of plasma cyclic AMP and GMP levels reflect sympathetic and parasympathetic receptor functions. The reduced R-R interval variations were observed in the VWF(+) group. Although exposure to cold induced a significant increase of plasma cyclic AMP level, the percentage increase was almost the same among the three groups. The response of plasma cyclic GMP level to cold exposure was highly activated in the VWF(+) and the VWF(-) groups. On the basis of these results, it is considered that the parasympathetic function of patients with vibration syndrome is lower at rest, and that exposure to cold induces a hypperresponse of the parasympathetic nervous system and the alpha-2 adrenergic mechanism as a result of activation of the sympathetic nervous system. Moreover, in patients with VWF, the contribution of the alpha-2 adrenergic mechanism is presumably larger than that in the patients without VWF.

Autonomic Nervous System↗
PubMed1990

Carpal tunnel syndrome in vibration disease.

The presence of carpal tunnel syndrome (CTS) in 125 forestry workers with exposure to vibration was examined clinically by electromyography and by determining vibration detection thresholds. Numbness of the hands was present in 43%, history of diminished hand muscle force in 15%, and Raynaud's phenomenon in 27%. The muscle weakness correlated significantly with motor nerve conduction velocity in the median nerve in both hands. In 25 forestry workers CTS was diagnosed. The condition was bilateral in 48%; otherwise it was more common on the right side. Fifteen patients were referred for surgery but because of spontaneous recovery or refusal by the patients only five underwent surgery; of these four improved. The motor conduction velocity of the ulnar nerve was decreased among patients with CTS supporting the idea that entrapment neuropathies in the hands may be due to tissue swelling caused by vibration at work. Total exposure time to vibration correlated with the decrease in motor conduction velocity in the ulnar nerve.

Adult↗
PubMed1993

Temporary threshold shifts in fingertip vibratory sensation from hand-transmitted vibration and repetitive shock.

Temporary threshold shifts (TTSs) in vibrotactile perception produced by continuous vibration and repetitive shock have been investigated. Subjects were exposed to vertical hand-transmitted 100 Hz continuous vibration and various repetitive shocks of equal energy content formed from one complete cycle of a 100 Hz sine wave. The repetition rate of the cycles was 5, 25, 50, or 100 s-1 while the root-mean-square (rms) acceleration measured over exposures of five minutes was held constant at 2.5, 5, or 10 ms-2 rms (weighted according to British Standard (BS) 6842 and International Standard (ISO) 5349). A control condition with no vibration was also included. Subjects held a handle with 10% of their maximum hand grip force. When exposed to five shocks per second at each of the three frequency-weighted acceleration magnitudes the subjects developed a small TTS. Exposure to 100 shocks per second (continuous vibration) at each of the three frequency-weighted acceleration magnitudes caused a large TTS, although the total frequency-weighted energy was the same as when exposed to five shocks per second. The relation between the TTS, the logarithm of the shock repetition rate, and the logarithm of the frequency-weighted rms acceleration was described by the relation TTS = -16.256 + 11.812 log10 R + 15.179 log10 ahw, where TTS is the temporary threshold shift, R is the shock repetition rate, and ahw is the frequency-weighted rms acceleration according to BS 6842 and ISO 5349. The results suggest that the equal energy hypothesis underlying BS 6842 and ISO 5349 is inappropriate for the prediction of the TTS produced by repetitive shocks.

Acceleration↗
PubMed2000

Vibration exposure, smoking, and vascular dysfunction.

OBJECTIVES: Vibration white finger (VWF), also known as "occupational Raynaud's phenomenon", is marked by arterial hyperresponsiveness and vasoconstriction during cold stimulation. The impact of tobacco use, and by extension stopping smoking, on the long term course of the disease has been inconclusively characterised. The objectives of this study included assessment of the impact of tobacco use on symptoms and on objective tests in shipyard workers exposed to vibration, and in gauging the natural history of the disorder after stopping exposure and changing smoking patterns. METHODS: In a cross sectional investigation, 601 current and former users of pneumatic tools were evaluated subjectively for cold related vascular symptoms, and tested by cold challenge plethysmography. There was follow up and subsequent testing of 199 members of the severely effected subgroup of smokers and non-smokers, many of whom had stopped smoking in the interval between tests. Effects of smoking and stopping smoking on symptoms and plethsymographic results were assessed. RESULTS: Symptoms and measured abnormal vascular responses related to cold were more severe in smokers than in non-smokers. Follow up of 199 severely effected members of the cohort, all removed from exposure for 2 years, indicated that smokers were almost twice as likely to have more severe vasospasm (test finger/control finger systolic blood pressure% (FSBP%) <30) than were non-smokers (-32.2% v 17.4%). 53 Subjects who stopped smoking during the interval between tests improved, and were indistinguishable from non-smokers similarly exposed to vibration. Additional physiological benefits of stopping smoking were still apparent at further follow up examination, 1 year later. Improvements evident on plethysmography were not accompanied by improvements in symptoms, which were unaffected by smoking. CONCLUSIONS: Smoking seems to delay physiological improvement in response to cold challenge in workers with VWF, after the end of exposure to vibration. Symptoms were less likely to improve over time than digital blood pressure, and were less affected by smoking.

Adult↗
PubMed2003

Hand-arm vibration syndrome in Swedish car mechanics.

AIMS: To assess the occurrence of hand-arm vibration syndrome (HAVS) in Swedish car mechanics, and the relation between HAVS and duration of exposure. METHODS: A total of 806 mechanics answered a questionnaire on vascular and neurological symptoms, and exposure to vibrations. Mechanics with symptoms, and some mechanics without symptoms, were invited to a clinical examination, including also a timed Allen test. Vascular and neurological symptoms were classified using the Stockholm Workshop scales. The mean daily exposure (mainly using nut-runners) was 14 minutes and the mean exposure duration, 12 years. Published data have shown vibration levels in nut-runners of about 3.5 m/s(2). RESULTS: In the questionnaire, 24% reported cold induced white finger (WF), 25% persistent numbness, and 13%, reduced grip force. The clinical examination showed a prevalence of vibration induced white finger (VWF) of about 15%, mainly in stage 2, and after 20 years, of 25%. A survival analysis showed similar results. We found that the International Organisation for Standardisation (ISO) model underestimates the risk of VWF. The incidence after 1975 was 19 cases per 1000 person-years. Slow refill times in the timed Allen test were common (15% had a refill time of >20 seconds), and associated with the presence of VWF. The clinical examination revealed neurological symptoms in the hands in about 25% of subjects, mainly at stage 2. After 20 years, the prevalence was 40%. The questionnaire items on WF and numbness both showed likelihood ratios of 13. CONCLUSION: HAVS is common among Swedish car mechanics in spite of short daily exposure times. This underlines the need for preventive measures.

Adolescent↗
PubMed1992

Effect of acupuncture at right Hoku point on the bilateral vibration-induced finger flexion reflex in man.

Vibration applied to the volar side of the finger tip has been reported to induce finger flexion reflex. Acupuncture is reported to inhibit this vibration-induced finger flexion reflex (VFR) in the ipsilateral hand. The purpose of this study was to investigate the effect of unilateral acupuncture in the hand on VFR in both hands. As no systematic study on the relationship between VFR and the force of voluntary contraction with no vibration (Initial Force: IF) has been reported, this relationship was studied prior to the present study on acupuncture. VFR was induced by mechanical vibration on the volar side of the middle finger tip with 10 g to 500 g IF. With approximately 300 g IF, VFR was consistent. Therefore, approximately 300 g IF was applied for VFR induction to study the effect of acupuncture on VFR. A stainless steel needle was inserted into the right Hoku point and remained inserted (in-situ technique) for 10 minutes. VFR in both hands was significantly decreased by acupuncture at the right Hoku point (% control force of VFR: right, 67.8%; left, 74.6%). The present results suggest that acupuncture in the unilateral hand influences the bilateral reflex arc of VFR.

Acupuncture Points↗
PubMed2005

Vibrational autoionization in polyatomic molecules.

The vibrationally autoionizing Rydberg states of small polyatomic molecules provide a fascinating laboratory in which to study fundamental nonadiabatic processes. In this review, recent results on the vibrational mode dependence of vibrational autoionization are discussed. In general, autoionization rates depend strongly on the character of the normal mode driving the process and on the electronic character of the Rydberg electron. Although quantitative calculations based on multichannel quantum defect theory are available for some polyatomic molecules, including H3, only qualitative information exists for most molecules. This review shows how qualitative information, such as Walsh diagrams along different normal coordinates of the molecule, can provide insight into the vibrational autoionization rates.

Electrons↗
PubMed2005

Ultrafast chemistry: using time-resolved vibrational spectroscopy for interrogation of structural dynamics.

Time-resolved infrared (IR) and Raman spectroscopy elucidates molecular structure evolution during ultrafast chemical reactions. Following vibrational marker modes in real time provides direct insight into the structural dynamics, as is evidenced in studies on intramolecular hydrogen transfer, bimolecular proton transfer, electron transfer, hydrogen bonding during solvation dynamics, bond fission in organometallic compounds and heme proteins, cis-trans isomerization in retinal proteins, and transformations in photochromic switch pairs. Femtosecond IR spectroscopy monitors the site-specific interactions in hydrogen bonds. Conversion between excited electronic states can be followed for intramolecular electron transfer by inspection of the fingerprint IR- or Raman-active vibrations in conjunction with quantum chemical calculations. Excess internal vibrational energy, generated either by optical excitation or by internal conversion from the electronic excited state to the ground state, is observable through transient frequency shifts of IR-active vibrations and through nonequilibrium populations as deduced by Raman resonances.

Electron Transport↗
PubMed1989

Frequency and amplitude effects during high-frequency vibration ventilation in dogs.

High-frequency external body vibration, combined with constant gas flow at the tracheal carina, was previously shown to be an effective method of ventilation in normal dogs. The effects of frequency (f) and amplitude of the vibration were investigated in the present study. Eleven anesthetized and paralyzed dogs were placed on a vibrating table (4-32 Hz). O2 was delivered near the tracheal carina at 0.51.kg-1.min-1, while mean airway pressure was kept at 2.4 +/- 0.9 cmH2O. Table vertical displacement (D) and acceleration (a), esophageal (Pes), and tracheal (Ptr) peak-to-peak pressures, and tidal volume (VT) were measured as estimates of the input amplitude applied to the animal. Steady-state arterial PCO2 (PaCO2) and arterial PO2 (PaO2) values were used to monitor overall gas exchange. Typically, eucapnia was achieved with f greater than 16 Hz, D = 1 mm, a = 1 G, Pes = Ptr = 4 +/- 2 cmH2O, and VT less than 2 ml. Inverse exponential relationships were found between PaCO2 and f, a, Pes, and Ptr (exponents: -0.69, -0.38, -0.48, and -0.54, respectively); PaCO2 decreased linearly with increased displacement or VT at a fixed frequency (17 +/- 1 Hz). PaO2 was independent of both f and D (393 +/- 78 Torr, mean +/- SD). These data demonstrate the very small VT, Ptr, and Pes associated with vibration ventilation. It is clear, however, that mechanisms other then those described for conventional ventilation and high-frequency ventilation must be evoked to explain our data. One such possible mechanism is forcing of flow oscillation between lung regions (i.e., forced pendelluft).

Animals↗
PubMed1996

Alteration of human cutaneous afferent discharges as the result of long-lasting vibration.

The unitary activities of slowly (15 SAI) and fast-adapting type I (12 FAI) skin mechanoreceptive afferent units innervating the anterior part of the human leg and foot were recorded by using the microneurographic method. The recordings were performed both at rest and on application of cutaneous stimuli of various intensities before and after exposure of the corresponding receptive fields to vibration (0.5 mm peak to peak, 100 pulses/s, 10 min). The results show that 11% of the units tested, which were previously silent, developed a bursting pattern of postvibratory activity, which lasted 12 min on average. This induced resting activity may account for the tingling sensations usually perceived after exposure to vibration. Furthermore, application of vibration to the cutaneous receptive fields impaired the response properties of the corresponding cutaneous fibers much more markedly in the case of the SAI than in the FAI units. More specifically, less than one-half of the FAI fibers tested showed a postvibratory depressed sensitivity to skin stroking applied at various velocities that persisted for only a few minutes, whereas the responses of all the SAI units to suprathreshold maintained skin indentations applied with increasing amplitudes decreased significantly for 20 min. These fairly durable changes in the transductive properties of the mechanoreceptive afferent units probably lead to an impairment of perceptual and sensorimotor processes and consequently may at least partly account for the alterations in sensorimotor performance that have been reported to occur in humans after exposure to vibration.

Adult↗
PubMed1999

Influence of brief daily tendon vibration on rat soleus muscle in non-weight-bearing situation.

The purpose of this study was to investigate whether tendon vibration could prevent soleus muscle atrophy during hindlimb unloading (HU). Mechanical vibrations with a constant low amplitude (0.3 mm) were applied (192 s/day) with constant frequency (120 Hz) to the Achilles tendon of the unloaded muscle during the 14-day HU period. Significant reductions in muscle mass (-41%), fiber size, maximal twitch (-54%), and tetanic tensions (-73%) as well as changes in fiber type and electrophoretic profiles and twitch-time parameters (-31% in the contraction time and -30% in the half relaxation time) were found after 14 days of HU when compared with the control soleus. Tendon vibration applied during HU significantly attenuated, but did not prevent, 1) the loss of muscle mass (17 vs. 41%); 2) the decrease in the fiber cross-sectional area of type IIA (-28 vs. -50%) and type IIC (-29 vs. -56%) fibers; and 3) the decrease in maximal twitch (-3 vs. -54%) and maximal tetanic tensions (-29 vs. -73%) and the half relaxation time (1 vs. -30%). Changes in the contraction time and in histological and electrophoretical parameters associated with HU were not counteracted. These findings suggest that tendon vibration can be used as a paradigm to counteract the atrophic process observed after HU.

Animals↗
PubMed2005

High-frequency, low-magnitude vibrations suppress the number of blood vessels per muscle fiber in mouse soleus muscle.

Extremely low-magnitude (0.3 g), high-frequency (30-90 Hz), whole body vibrations can stimulate bone formation and are hypothesized to provide a surrogate for the oscillations of muscle during contraction. Little is known, however, about the potential of these mechanical signals to stimulate adaptive responses in other tissues. The objective of this study was to determine whether low-level mechanical signals produce structural adaptations in the vasculature of skeletal muscle. Eight-week-old male BALB/cByJ (BALB) mice were divided into two experimental groups: mice subjected to low-level, whole body vibrations (45 Hz, 0.3 g) superimposed on normal cage activities for 15 min/day (n = 6), and age-matched controls (n = 7). After the 6-wk experimental protocol, sections from end and mid regions of the soleus muscles were stained with lectin from Bandeiraea Simplicifolia, an endothelial cell marker, and smooth muscle (SM) alpha-actin, a perivascular cell marker. Six weeks of this low-level vibration caused a 29% decrease in the number of lectin-positive vessels per muscle fiber in the end region of the soleus muscle, indicating a significant reduction in the number of capillaries per muscle fibers. Similarly, these vibrations caused a 36% reduction in SM alpha-actin-positive vessels per muscle fiber, indicating a reduction in the number of arterioles and venules. The decreases in lectin- and SM alpha-actin-positive vessels per muscle fiber ratios were not significant in the mid muscle sections. These results demonstrate the sensitivity of the vasculature in mouse skeletal muscle to whole body, low-level mechanical signals.

Adaptation, Physiological↗