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PubMed1998

Vibration sense in the upper limb in patients with repetitive strain injury and a group of at-risk office workers.

OBJECTIVES: To investigate in patients with repetitive strain injury (RSI) and in office workers using computer keyboard equipment (a) whether the vibration threshold in the hand was altered, (b) the immediate effects of keyboard use on vibration thresholds and (c) whether the tolerance of suprathreshold vibration was normal. METHOD: A vibrametre (Somedic Ab, Stockholm Sweden) was used to obtain threshold vibration measurements, by the method of limits, for all peripheral-nerve cutaneous distributions in the hand. Tolerance of suprathreshold stimulation was obtained by stimulation of the soft tissues of the forearm by increasing the amplitude of vibration. RESULTS: Thresholds for vibration were significantly raised for the median nerve in both the patient and office-worker groups. The patient group additionally had raised thresholds for the ulnar nerve. Following use of the keyboard, thresholds for the median nerve were further elevated in the patient group, but not in the other groups, demonstrating a work-related exacerbation. At suprathreshold stimulation. 14 members (82%) of the patient group experienced an allodynic response to vibration, indicating, possible changes in the central processing of non-noxious sensory information. This changed sensory response was not seen in either the office-worker or control groups. CONCLUSION: Patients may have a minor polyneuropathy, whereas the office workers demonstrate early signs of the condition. Quantitative measurement of vibration perception may prove useful in patient assessment and for detection of the early onset of RSI in the work environment.

Adult↗
PubMed2000

Effect of vibration magnitude and repetitive exposure on finger blood flow in healthy subjects.

In order to study the effect of the magnitude of vibrations and repetitive exposure on finger blood flow, we exposed ten healthy subjects to three experimental conditions: (1) vibration of 3.16 m/s2 at 60 Hz, (2) vibration of 31.6 m/s2 at 60 Hz, and (3) no vibration, as a control. Under the experimental conditions, the right hand was exposed to 5-min vibration three times, with intervening 5-min rests. Meanwhile, the blood flows of both middle fingers were continuously measured with a blood flow meter based on the thermal diffusion method. Finger blood flow was significantly decreased in both hands with exposure to vibrations of 3.16 m/s2 and 31.6 m/s2. Increased magnitude of vibration tended to enhance the decrease in finger blood flow in both hands, and repeated exposure to vibration had cumulative effects on the decrease in finger blood flow in the unexposed left hand.

Adult↗
PubMed1977

Reduction in inspiratory activity in response to sternal vibration.

It has been shown previously that there is a reduction in tidal volume in response to longitudinal sternal vibration at 100 Hz. In the present study it was shown that the effect of such vibration is to reduce tidal volume (VT) and prolong inspiratory time (ti) in such a way that points from vibrated and non-vibrated breaths fall on the same VT:ti curve. This indicates that the normal mechanisms which terminate inspiration are unaffected by vibration. The effect of vibration is simply to reduce the rate at which inspiration proceeds. This was illustrated here when vibration reduced the rate of fall of intrapleural pressure during inspiration, and also reduced the instantaneous ventilation at any level of chemical drive. Electrophysiological recordings made here from phrenic motoneurones support these findings. It is concluded that sensory nerves in the chest wall, which can be excited by vibration, can inhibit inspiration.

Animals↗
PubMed1980

Inspiratory inhibitory reflex caused by the chest wall vibration in man.

The effects of chest wall vibrations on tidal volume (VT), inspiratory time (TI) and expiratory time (TE) were measured in normal man during rebreathing. Two vibrators, frequency 100 HZ, were applied bilaterally over the 7th to 10th intercostal spaces anterior to the mid-axillary line. The vibrators were triggered by chest wall movement during the inspiratory phase once or twice, intermittently, every 4-10 breaths. The VT and TI of "vibrated" breaths were decreased compared with preceding control breaths. These effects were clearly paralleled by a reduction in averaged integrated EMG recordings from the diaphragm. The initial time course of the integrated EMG activities in vibrated and non-vibrated breaths were almost equal. However, the relationship between VT and TI of vibrated breaths was shifted downward from that of the non-vibrated (control) breaths. The depression of VT was augmented as the VT of control breath increased. The findings suggest that supraspinal intercostal inhibitory reflex normally contributes to the phase switching mechanism of respiration in man.

Adolescent↗
PubMed1991

Vibration arthrometry in assessment of knee disorders: the problem of angular velocity.

A knee joint that has sustained a painful injury will typically require skillful examination, by an orthopaedic surgeon, for signs of internal damage. These signs include characteristic sounds and vibrations, which are produced by the knee when it is stressed. The technique of vibration arthrometry is being developed to assist the clinical examiner in identifying these vibrations and to improve diagnostic accuracy. To detect and record the knee vibrations, small lightweight accelerometers are positioned on various bony prominences around the knee. These produce electronic signals which permit objective analysis of the vibration characteristics. It has been found that varying the investigative procedure can affect the magnitude of some parameters of the vibration signal. If these parameters are to be used in evidence of knee pathology, the effect of the investigative procedure must be normalized. The effect of speed of joint movement has been quantified in a pilot study involving 24 patients with internal knee damage. Custom-designed hardware was used to measure joint speed as the rate of change of joint angle, which was measured by an electrogoniometer. It was found that the energy content of the vibration, reflected by the peak amplitude and root mean square value was strongly affected by joint speed. However, the characteristic shape of the vibration, reflected by the peak frequency in the harmonic spectrum of the signal, remained similar for the range of joint speed in the investigation.

Adult↗
PubMed1991

Vibration disappearance threshold may be raised by measuring it.

The influence of duration and intensity of the initial level of vibration on vibration perception threshold was studied in 15 healthy young subjects (aged 27.9 +/- 7.6 years) with a Vibrameter (Somedic AB Sweden). The threshold for increasing vibration corresponded well to the normal values published by the manufacturer. The thresholds for decreasing vibration were measured with three different starting conditions: starting from a low level of vibration, a high level, and from a low level sustained for one minute. Higher intensity and longer duration of the initial vibration raised the disappearance threshold significantly. Vibration disappearance thresholds can be influenced by measuring them. As a result, the investigation of the vibration sense calls for strict control over intensity and duration of the stimuli.

Adult↗
PubMed1987

Evidence that adenosine mediates the depression of spinal dorsal horn neurons induced by peripheral vibration in the cat.

Nociceptive neurons in the dorsal horn of the cat spinal cord are depressed by vibration applied to the ipsilateral hind limb. The present study investigated the pharmacological properties of this depression because of the possibility that it represents the neural basis at the spinal level for the analgesic effects of vibration in humans. Experiments were done in cats anesthetized with sodium pentobarbital and acutely spinalized at the first lumbar level. Extracellular recordings were made from nociceptive neurons in the lower lumbar segments. The depression of these neurons induced by vibration to the hindlimb was attenuated by administration of the P1-purinergic (adenosine) receptor antagonist, caffeine (20-60 mg/kg i.v.); the maximum attenuation was 100%. Effects of caffeine began within 2 min after the start of injection (1-3 min injection period), were greatest in the 10 min period after the end of injection and lasted for up to 2 hr. Importantly, another P1-purinergic receptor antagonist, which does not cross the blood-brain barrier, 8-sulphophenyltheophylline (8-16 mg/kg), had no effect on the depression when given intravenously (n = 5); however, when administered by iontophoresis 8-sulphophenyltheophylline blocked the depression in 2 of 6 units. Dipyridamole (1.0-2.0 mg/kg i.v.), an inhibitor of adenosine uptake, potentiated the depression in 2 of 5 cases. These results prompt us to suggest that depression induced by vibration may be mediated by adenosine via the activation of P1-purinergic receptors. On the other hand, the GABAA antagonist, bicuculline, failed to attenuate vibration-induced depression when administered either intravenously (0.2-0.4 mg/kg; n = 5) or by iontophoresis (n = 10) and the glycine antagonist, strychnine (0.2-0.6 mg/kg; n = 3) and the opiate antagonist, naloxone (0.1-0.4 mg/kg; n = 4) were similarly ineffective. These findings suggest that vibration-induced depression of these units occurs without involvement of bicuculline-sensitive GABA receptors, strychnine-sensitive glycine receptors and naloxone-sensitive opiate receptors. In view of the fact that vibration-induced depression is evoked synaptically, this study is the first to demonstrate in the central nervous system a synaptic response which is mediated by adenosine. In addition, we suggest that the analgesic effects of vibration in humans may be mediated at the spinal level by activation of P1-purinergic receptors.

Adenosine↗
PubMed1993

Occupational exposure to hand vibration in northern Ontario gold miners.

Nineteen underground gold mine drillers who operate vibration equipment and a control group of 16 gold mill workers without vibration exposure were evaluated. Assessment included static two-point discrimination, moving two-point discrimination, vibration threshold, and cutaneous pressure threshold. Provocative tests, including Tinel, pressure, and Phalen signs, were performed at the carpal and cubital tunnels. Mean age of the miners was 35 years, and the mean age of the control group was 31 years. The mean time of vibration exposure was 14 years. Numbness, pain, and weakness was reported in 12 miners and 1 control subject. Symptoms of vibration white finger were found in 16 miners and 3 control subjects. The miners had a higher incidence of positive provocative tests at the carpal and cubital tunnels and higher cutaneous pressure thresholds than the control group. Significantly higher vibration thresholds were found in the miners versus the control subjects. A correlation between years of vibration exposure and vibration threshold was found.

Adult↗
PubMed1994

A method for determining three-dimensional vibration in the ear.

In the classical concept of the middle ear function the malleus rotates around a fixed axis which implies that at small amplitudes of vibration its displacement is essentially one dimensional. As a consequence malleus vibrations have been measured previously along a single viewing axis. As a first step in the study of the complete malleus motion we determined the three dimensional components at a single point (umbo) of the manubrium. To define 3-D motion it is in principle necessary to measure the vibrations from widely different observation angles. The viewing angles are limited however in our case by the ear canal geometry to about +/-15 degrees. In order to resolve the 3-D components under these conditions it is necessary to measure the vibration components with high accuracy. Amplitude and phase of the umbo vibrations were measured with a heterodyne interferometer over a wide frequency range (100 Hz to 20 kHz). The system included a two axis goniometer with the axes of rotation positioned at the focal plane of the interferometer objective lens. It was therefore possible to change the viewing angle in small increments around two orthogonal axes while keeping the same point in focus. From a redundant set of measurements the three orthogonal components of vibration were calculated by least squares fitting. The vector sum of the three components gives the three dimensional motion of the observed point. The vibration of the point on the umbo was found not to follow a straight line but an elliptical path instead. The shape of the ellipse and the inclination of the plane of the ellipse with respect to the stationary malleus position changed with frequency. These observations are consistent with our earlier findings that the mode of malleus vibration changes with frequency [Decraemer et al. (1991) Hear. Res. 54, 305-318].

Acoustic Stimulation↗
PubMed2006

Modification of human postural responses to soleus muscle vibration by rotation of visual scene.

Sensory interaction in posture control in 20 healthy subjects was investigated by postural responses to differently timed proprioceptive and visual stimulation. As proprioceptive stimulation was used both soleus muscles vibration. Visual stimulation was rotating disc moving in forward and backward direction. Centre of foot pressure (CoP) and trunk tilts in antero-posterior (AP) direction were measured during stance by two accelerometers on the upper and the lower trunk level. Subjects performed four series of eight trials lasted 20s: vibration with eyes open and closed, visual scene motion forward or backward, vibration together with scene motion forward or backward, scene motion forward or backward 3s before vibration. The results showed that early velocities and final angles of body tilt induced by soleus muscle vibration were modified by motion of visual scene. Early part of postural responses was changed slightly if sensory stimulation starts together. When visual stimulation started 3s before muscle vibration, the induced early CoP and trunk tilt records of postural response to vibration occurred with the faster slope similar for both directions of scene motion and for condition of vibration alone with eyes closed. Significantly different final CoP shifts and trunk angles were measured between condition with visual scene motion forward and backward. The effect of visual input on posture control was two times enhanced in paired sensory stimulation. The results indicated an important influence of unstable visual field on posture response to somatosensory stimulation where the early part of postural reaction indicated absence of visual influence.

Adult↗
PubMed2006

Soft tissue vibrations within one soft tissue compartment.

The concept of muscle tuning suggests that vibrations of the soft tissue compartments of the leg initiated by impacts are minimized by muscular activity prior to heel-strike of heel-toe running. For the quantification of muscle tuning it has been assumed (1) that the soft tissue compartment acts as one lumped mass and (2) that vibration energy dissipation does occur within one muscle. The purpose of this study was to test these two assumptions. It was hypothesized that (H1) the movement of the soft tissue compartment is not homogeneous, (H2) the vibration frequencies for different muscles within one soft tissue compartment are different and (3) attenuation of vibration movement within one muscle does occur. Soft tissue vibrations were measured using accelerometers on four locations on the quadriceps soft tissue compartment during heel-toe running. There were differences in the peak soft tissue acceleration and time of peak acceleration between accelerometer locations. The dominant frequency was similar throughout the soft tissue compartment, however; there was an attenuation of high-frequency vibration energy between distal and proximal points overlying one muscle. This evidence suggests that accelerometer placement is important when quantifying the acceleration magnitude and timing of peak soft tissue compartment but not when estimating the resonant vibration characteristics of a soft tissue compartment. It also provides initial evidence to support the idea that vibration control through muscle tuning may be achieved through changes in energy dissipating properties within the soft tissue compartment.

Acceleration↗
PubMed2004

Ab initio and DFT studies of the vibrational spectra of hydrogen-bonded PhOH...(H2O)4 complexes.

The vibrational characteristics (vibrational frequencies and infrared intensities) for the hydrogen-bonded complex of phenol with four water molecules PhOH...(H2O)4 (structure 4A) have been predicted using ab initio and DFT (B3LYP) calculations with 6-31G(d,p) basis set. The changes in the vibrational characteristics from free monomers to a complex have been calculated. The ab initio and B3LYP calculations show that the observed four intense bands at 3299, 3341, 3386 and 3430 cm(-1) can be assigned to the hydrogen-bonded OH stretching vibrations in the complex PhOH...(H2O)4 (4A). The complexation leads to very large red shifts of these vibrations and very strong increase in their IR intensity. The predicted red shifts for these vibrations with B3LYP/6-31G(d,p) calculations are in very good agreement with the experimentally observed. It was established that the phenolic OH stretching vibration is the most sensitive to the hydrogen bonding. The predicted red-shift with the B3LYP/6-31G(d,p) calculations for the most stable ring structure 4A (-590 cm(-1)) is in better agreement with the experimentally observed than the red-shift, predicted with SCF/6-31G(d,p) calculations. The magnitude of the wavenumber shift is indicative of relatively strong OH...H hydrogen-bonded interaction. The complexation between phenol and four water molecules leads to strong increase of the IR intensity of the phenolic OH stretching vibration (up to 38 times).

Hydrogen↗
PubMed2006

Ultrasonic interrogation of tissue vibrations in arterial and organ injuries: preliminary in vivo results.

Soft tissues surrounding vascular injuries are known to vibrate at audible and palpable frequencies, producing bruits and thrills. We report the results of a feasibility study where Doppler ultrasound (US) was used to quantitatively estimate the tissue vibrations after induced trauma in an animal model. A software-programmable US system was used to acquire quadrature-demodulated ensembles of received US echoes bypassing clutter filtering and other conventional Doppler processing stages. The waveforms of tissue velocity surrounding the injury site were then estimated from the clutter data using autocorrelation and analyzed to determine vibration characteristics. Six New Zealand white rabbits and two juvenile pigs were used for the study. The femoral artery of the anesthetized animal was punctured with an 18-gauge needle to model a peripheral arterial trauma, and the liver was surgically exposed and incised to model organ trauma. Two types of oscillatory tissue motion were observed: "vibrations" with high frequency (>50 Hz) and low peak-peak amplitude (<1 microm) and "flutter" with low frequency (<50 Hz) and high peak-peak amplitude (>1 microm). Active bleeding in femoral artery punctures produced tissue vibrations at the frequency of 323 +/- 214 Hz (mean +/- standard deviation, pooled for both rabbits and pigs) and the amplitude of 0.24 +/- 0.15 microm. Active bleeding in liver incisions produced vibrations at the frequency of 120 +/- 47 Hz and the amplitude of 0.33 +/- 0.25 microm. Flutter was observed in punctured arteries at the frequency of 28 +/- 13 Hz the amplitude of 2.92 +/- 1.75 microm, and in incised livers at the frequency of 26 +/- 6 Hz and the amplitude of 1.53 +/- 0.76 microm. In a punctured artery, the vibration frequency and phase of tissue surrounding the artery were highly correlated between neighboring locations in tissue (correlation coefficient = 0.98), and with the flow oscillations in the lumen (correlation coefficient = 0.96). This preliminary study indicates that tissue vibrations could provide additional physiologic information for detecting, localizing and monitoring internal bleeding using US.

Animals↗
PubMed2004

[Vibration-induced nystagmus: mechanism and clinical interest].

UNLABELLED: In 1973 Lücke described nystagmus induced by application of a vibrator on the mastoid process. Since that time, several Authors have applied the vibrator test in normal subjects or patients suffering from various well-characterized conditions. OBJECTIVE: Recognizing that results obtained with the vibrator test are sometimes in contradiction with those of other vestibular tests, our aim was to formulate an assumption regarding the genesis of induced nystagmus in an attempt to explain such contradictions. MATERIAL AND METHODS: We considered seven very different clinical situations. Each patient underwent a standard protocol including pendular and caloric tests as well as the vibrator test. We sought an assumption allowing, i) an interpretation of the characteristic features of nystagmus induced by the vibrator in any situation, ii) an understanding of the reasons why some vibrator test results do not correlate with those of other vestibular tests. RESULTS AND CONCLUSION: We assume that the vibrator stimulates phasic cells of the cupula and the vestibular maculae preferentially, if not exclusively. This assumption allows us to retain a very simple protocol for the vibrator test useful for routine clinical practice.

Caloric Tests↗
PubMed2006

Manual vibration increases expiratory flow rate via increased intrapleural pressure in healthy adults: an experimental study.

QUESTION: What is the relationship between vibration of the chest wall and the resulting chest wall force, chest wall circumference,intrapleural pressure, and expiratory flow rate? Is the change in intrapleural pressure during vibration the sum of the intrapleural pressure due to recoil of the lung, chest wall compression, and chest wall oscillation? DESIGN: Randomised, within-subject,experimental study. PARTICIPANTS: Seven experienced cardiopulmonary physiotherapists and three healthy adults. INTERVENTION: Vibration (compression + oscillation), compression alone, and oscillation alone were applied manually to the chest walls of healthy participants during passive exertion and compared with passive expiration alone. OUTCOME MEASURES: Chest wall force, chest wall circumference, intrapleural pressure, and expiratory flow rate. RESULTS: During vibration, coherence was high(r2 > 0.97) between external chest wall force, chest wall circumference, intrapleural pressure, and expiratory flow. The mean change in intrapleural pressure during vibration was 9.55 cmH2O (SD 1.66), during chest compression alone was 8.06 cmH2O(SD 1.65), during oscillation alone was 7.93 cmH2O (SD 1.57), and during passive expiration alone was 6.82 cmH2O (SD 1.51). During vibration, compression contributed 13% of the change in intrapleural pressure, oscillation contributed 12%, and lung recoil contributed the remaining 75%. CONCLUSIONS: During vibration the chest behaves as a highly linear system. Changes in intrapleural pressure occurring during vibration appear to be the sum of changes in pressure due to lung recoil and the compressive and oscillatory components of the technique, which suggests that all three components are required to optimise expiratory flow.

Adult↗
PubMed2001

Oscillation of the lung by chest-wall vibration.

Vibration of the thoracic surface has been shown to modify the drive to breathe and the sensation of dyspnea. It has been suggested that respiratory muscle afferents generate these effects. The possibility that the consequences of chest-wall vibration also involve intra-pulmonary afferents led us to investigate whether such vibration reaches the airways. Two vibratory stimuli were independently applied to four chest-wall sites and two control sites on eight healthy subjects. During separate breath holds, the vibrator was held on each site while subjects periodically opened and closed the pharynx. Airway pressure (P(AW)) was measured at the mouth. Spectral analysis of P(AW) showed pressure oscillations occurred at the same frequency as that of the vibrators when the pharynx was open; oscillation amplitude was vastly reduced when the pharynx was closed. Oscillation amplitude was also significantly larger during vibration at greater amplitude. These data demonstrate that vibration over the chest-wall vibrates the lung and could potentially excite intrapulmonary receptors.

Adult↗
PubMed2003

Effects of local pressure and vibration on muscle pain from eccentric exercise and hypertonic saline.

In human subjects the triceps surae of one leg was exercised eccentrically by asking subjects to walk backwards on an inclined treadmill. Before the exercise controlled local pressure, applied to the muscle with an electromagnet, produced mild soreness, which was reduced when the pressure was combined with vibration. When delayed-onset muscle soreness (DOMS) had set in, 24-48 h after the exercise, vibration increased pain from local pressure. Vibrating at different frequencies suggested 80 Hz as the optimal frequency. During 2-h testing post-exercise, evidence of a change in character of the effects of vibration was first detected at 6 h. It persisted up to 72 h post-exercise. When muscle pain was generated in an unexercised triceps by injection of hypertonic (5%) saline, controlled local pressure applied to the sore area increased pain levels by 32% while pressure plus vibration reduced this to 11%. In a subject with DOMS, local pressure again increased pain from saline by 32% but combining it with vibration increased pain further by an additional 20%. The effect of vibration on DOMS could be abolished with a large nerve fibre block applied to the sciatic nerve. It is concluded that the vibration effects are the result of stimulation of large-diameter mechanoreceptive afferents in the muscle which, it is speculated, play a role in generating DOMS.

Analysis of Variance↗
PubMed1998

Phasic and tonic reflexes evoked in human antagonistic wrist muscles by tendon vibration.

The electromyographic reflex responses of the voluntarily contracting wrist flexor and extensor muscles to periods of vibration-evoked enhanced, Ia-dominated afferent discharge from flexor carpi radialis (FCR) were studied in normal human subjects. Three main response phases were characterised, namely, (i) phasic 'on' responses elicited at the commencement of stimulation, (ii) tonic response levels occurring during prolonged stimulation and (iii) phasic 'off' responses elicited at the termination of stimulation. The phasic 'on' reflex responses of FCR and extensor carpi radialis (ECR) comprised, respectively, a peak of autogenetic excitation of group mean latency 18.8 ms and a trough of reciprocal inhibition of group mean latency 38.0 ms. Prolonged (2 s) trains of FCR (agonist) vibration evoked a phase of tonic reflex excitation in FCR whose mean level was significantly increased, by 20%, above pre-stimulus activity and which did not change over the 0.5-2.0 s vibration period. Progressive reduction of the duration (from 2000 ms to 100 ms) of vibration trains demonstrated that phasic disfacilitatory 'off' troughs regularly occurred, with a consistent latency (mean 24.2 ms), on withdrawal of each period of enhanced Ia-input. This indicates that the responsible excitatory reflex mechanism was operational for the entire duration of each of the vibration periods tested. The extra latency (on average 5.4 ms) of phasic 'off' relative to 'on' responses may be attributed to factors (e.g. 5-10 ms duration of unitary muscle action potentials and afterdischarge in reflex pathways) which inevitably delay the appearance of overt disfacilitatory reductions in EMG rather than the involvement of different reflex pathways. Thus, short-latency, possibly monosynaptic, reflex excitation contributed throughout the entire tonic excitatory response. Sustained FCR (antagonist) vibration produced a significant tonic reciprocal inhibitory reflex depression, by 7% pre-stimulus EMG, of ECR activity which remained steady during the 0.5-2.0 s vibration period. The absence of well-defined phasic disinhibitory 'off' responses in ECR suggests that the contribution of oligosynaptic reflex inhibitory mechanisms to the tonic suppression of activity occurring during continuing vibration is relatively small.

Adult↗