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PubMed2004

Vibration with the canalith repositioning maneuver: a prospective randomized study to determine efficacy.

OBJECTIVES/HYPOTHESIS: The objective was to determine whether the inclusion of vibration and additional treatment cycles has an effect on short- and long-term success rates in the treatment of benign paroxysmal positional vertigo with the canalith repositioning maneuver. STUDY DESIGN: Prospective randomized study of patients treated at a tertiary vestibular rehabilitation center. METHODS: Variables identified for statistical analysis included patient age, gender, vibration used, and canalith repositioning cycles. Analysis using Student t test, chi2 test, Kaplan-Meier curves with log rank test, and Cox proportional hazards regression was performed. RESULTS: One hundred two patients with benign paroxysmal positional vertigo treated over a 1-year period (August 2001-August 2002) were randomly assigned to receive the canalith repositioning maneuver with or without vibration. Average duration of follow-up was 9.44 months. The single treatment success rate was 93.1%. To relieve symptoms, 29.4% of patients required more than one canalith repositioning cycle. The relapse rate was 30.5%. Thirty-nine patients were assigned to the canalith repositioning group with vibration, and 63 to the canalith repositioning group without vibration. There was no statistical difference in age, gender, initial success rates, or relapse rates between the canalith repositioning groups with and without vibration. On average, patients required 1.38 canalith repositioning cycles for successful treatment. Vibration did not affect the number of canalith repositioning cycles required to convert the Dix-Hallpike test result to normal. The need for additional canalith repositioning cycles had no statistical effect on initial treatment success or relapse rates. CONCLUSION: Vibration provided no additional benefit in initial treatment success or in reducing long-term relapse rates when included in the canalith repositioning maneuver. Many patients with benign paroxysmal positional vertigo require more than one canalith repositioning cycle at the time of initial treatment to relieve symptoms, but this does not indicate a higher likelihood for recurrence. No variable predicted a higher rate of recurrence.

Chi-Square Distribution↗

PubMed1988

Neuropharmacologic effects of vibration on the dorsal root ganglion. An animal model.

The neuropharmacologic effects of low frequency vibration on the dorsal root ganglion, a reported epidemiological cause of low-back pain, have only recently been described. This investigation was undertaken to validate the hypothesis that substance P and VIP, known to be produced in the dorsal root ganglion cell bodies, will be affected by low frequency vibration. Three New Zealand white rabbits were vibrated at discrete frequencies (2-10 Hz) to determine the resonant frequency of the rabbit spine. The resonating frequency was in the (3.5-5.0 Hz) range. The peak amplitude was at 4.5 Hz. Ten female New Zealand white rabbits were then paired into two groups of five. One group served as a control and had exactly the same procedures performed as the experimental group except for the vibration. The L4-5 and L5-6 dorsal root ganglia were removed bilaterally and prepared for substance P and VIP extraction by radioimmunoassay technique. The control rabbits mean immunoreactive substance P was 14.06 pg/ml tissue, whereas the experimental or vibrated rabbits had a mean of 8.40 pg/ml (P less than 0.003). The control rabbits mean immunoreactive vasoactive intestinal peptide was 9.58 pg/ml whereas the experimental or vibrated rabbits had a mean of 20.9 pg/ml, P less than 0.07. Substance P is only one of several dorsal root ganglion neuropeptides that may play a role in nociceptor transmission. VIP is a neuropeptide that plays a role in reorganization of the nervous system following injury. The effects of low frequency vibration on dorsal root ganglion transmitters are essential to the understanding of vibration as a cause of back pain.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Self-reported low back symptoms in urban bus drivers exposed to whole-body vibration.

The prevalence of self-reported low back symptoms was investigated by a postal questionnaire in a group of 234 urban bus drivers exposed to whole-body vibration and postural stress and in a control group of 125 maintenance workers employed at the same bus municipal company. The average vertical whole-body vibration magnitude measured on the seat pan of the buses was 0.4 m/s2. After controlling for potential confounders, the prevalence odds ratios for the bus drivers compared to the controls significantly exceeded 1 for several types of low back symptoms (leg pain, acute low back pain, low back pain). The occurrence of low back symptoms increased with increasing whole-body vibration exposure expressed in terms of total (lifetime) vibration dose (years m2/s4), equivalent vibration magnitude (m/s2), and duration of exposure (years of service). The highest prevalence of disc protrusion was found among the bus drivers with more severe whole-body vibration exposure. Frequent awkward postures at work were also related to some types of low back symptoms. It is concluded that bus driving is associated with an increased risk for low back troubles. This excess risk may be due to both whole-body vibration exposure and prolonged sitting in a constrained posture. The findings of this study also indicated that among the bus drivers low back symptoms occurred at whole-body vibration exposure levels that were lower than the health-based exposure limits proposed by the International Standard ISO 2631/1.

Adult↗

PubMed2000

The adaptive significance of host location by vibrational sounding in parasitoid wasps.

Vibrational sounding, which is a form of echolocation, is a means of host location by some parasitoid wasps. The wasp taps the substrate (wood, stem or soil) and detects the position of a potential host through the returning 'echoes'. The deployment of vibrational sounding is inferred through the form of the subgenual organ in the female tibia in combination with the presence of modifications to the female antenna used for tapping the substrate. Vibrational sounding and its associated modifications were found in two families. The use of vibrational sounding by parasitoid wasps was positively correlated with the depth of the host in the substrate relative to the size of the parasitoid. There were also significant correlations between the use of vibrational sounding and parasitism of immobile and concealed hosts and between vibrational sounding and idiobiosis. The data suggested that vibrational sounding evolved under a variety of ecological conditions, being employed in the location of wood-boring, stem-boring, soil-dwelling and cocooned hosts and stem-nesting aculeates, often in situations in which the host does not produce vibrations itself.

Acoustics↗

PubMed2005

Vastus lateralis oxygenation and blood volume measured by near-infrared spectroscopy during whole body vibration.

The purpose of this study was to investigate the effects of whole body vibration (WBV) on oxygenation of vastus lateralis muscle during squatting exercise. Eighteen male subjects [mean age, 27.3 +/- 6.0 (SD) years; mean height, 171.8 +/- 4.9 cm; mean weight, 64.4 +/- 6.1 kg] performed squatting exercise on a vibration platform for 3 min with and without vibration, and changes in oxygenation of the vastus lateralis muscle were determined by near-infrared spectroscopy. The muscle oxygenation levels and total haemoglobin and myoglobin levels (total Hb/Mb) decreased during squatting exercise with and without vibration. After exercise, the muscle oxygenation level and total Hb/Mb rapidly increased from the minimum value during exercise and remained constant for latter 10 min. The muscle oxygenation levels with vibration from 90 to 180 s after the start of squatting exercise were significantly lower than those without vibration. Total Hb/Mb with vibration from 90 s after the squatting exercise to 540 s were significantly higher than those without vibration. This study demonstrated that WBV exercise affects the oxygenation level of vastus lateralis muscle and reduces muscle oxygenation level compared to that with no WBV. Therefore, WBV exercise may be an efficient training stimulus for muscle deoxygenation.

Adult↗

PubMedDate not supplied

Mechanical vibration in ambulance transport.

OBJECTIVE: To study the effects of mechanical vibration on neonates during ambulance transport. DESIGN: Study used an infant mannequin in an isolette and measured the vibration levels experienced during controlled ambulance transports. PARTICIPANTS: Transport nurses and paramedics used a hospital-based mobile intensive care unit (MICU). MAIN OUTCOME MEASURE: Measured vibration levels at specific locations within the ambulance and isolette. Investigated nonstandard mattresses and additional modifications to the isolette that would dampen the vibration transferred to the neonate. RESULTS: The analysis of variance showed significant differences (p < .002) in the amount of vibration among the specific locations in the ambulance. A gel-filled mattress decreased the transfer of mechanical vibration to the infant mannequin. Additional modifications to the isolette tray decreased vibration. CONCLUSIONS: Relatively inexpensive modifications can be made to the isolette tray and mattress to decrease the vibration levels experienced in transport.

Acceleration↗

PubMed1975

n the mechanism of inhibitory action of vibrations as studied in a molluscan catch muscle and in vertebrate vascular smooth muscle.

In previous studies longitudinal vibrations have been found to reduce active force development in smooth muscle, possibly due to a direct action on the contractile mechanism. In the present experiments the inhibitory effect of vibrations on isometric tension was studied in isolated preparations of the rat portal vein, the rabbit thoracic aorta and the anterior byssus retractor muscle (ABRM) of the Mytilus edulis. The results demonstrate that vibrations of appropriate frequency and amplitude caused prompt inhibition of contractile tension and that complete recovery of active force normally occurred after cessation of vibration in vertebrate smooth muscle as well as during the phasic contraction of ABRM. However, in the "catch" of the ABRM there was no regain in force following the vibration induced inhibition. The contractile proteins are considered to be a locked state during the catch situation. Thus, this contracted state seems to be released by vibrations. It is therefore concluded that vibrations do interfere with the interrelationship between the myofilaments. This conclusion supports the previously forwarded hypothesis that vibrations act by increasing the rate of detachment of actin-myosin crosslinks in vertebrate smooth muscle.

Acetylcholine↗

PubMed2006

In vivo lumbar erector spinae oxygenation and blood volume measurements in healthy men during seated whole-body vibration.

Exposure to whole-body vibration is implicated as one of the occupational risk factors for lower back disorders; however, its influence on the lumbar muscle physiology is still poorly understood. The objective of this study was to investigate the effects of backrest support and hand grip contractions on lumbar muscle oxygenation and blood volume responses during seated whole-body vibration using continuous dual-wave near-infrared spectroscopy. Thirteen healthy men were exposed to frequencies of 3, 4.5 and 6 Hz on a vibration simulator, in randomized order on separate days. Each day the duration of the protocol was 30 min. During the fifth minute of vibration 'with' and 'without' backrest support, participants performed maximal rhythmic hand grip contractions for 1 min. In general, erector spinae oxygenation and blood volume showed a trend to decrease with vibration exposure compared to the control condition. However, these responses were not influenced by the change in vibration frequency (P > 0.05). Sitting without backrest resulted in a greater decrease in oxygenation (by 27%, P = 0.02) and blood volume (by 11%, P = 0.05) than with backrest, implying a deficiency in oxygen supply owing to the sitting posture. Compared to the vibration-only condition, hand grip work decreased both oxygenation (by 22%, P = 0.003) and blood volume responses (by 13%, P = 0.04), suggesting that postural load due to prolonged sitting combined with physical activity during vibration might further burden paraspinal muscles. The influence of adipose tissue thickness of the lumbar muscle on optically derived oxygenation and blood volume changes was inconclusive.

Adipose Tissue↗

PubMed1981

Action of vibration on the response of cat muscle spindle Ia afferents to low frequency sinusoidal stretching.

1. A study has been made of the effect of continuous vibration, at 150 Hz, upon the response of muscle spindle afferents to low frequency sinusoidal stretching (1 and 8 Hz). Using the soleus muscle of the anaesthetized cat, with severed ventral roots, recordings were made of single Ia afferents and of the massed Ia afferent discharges in the main bulk of the cut L7 dorsal root. 2. When the amplitude of vibration was large (50 micrometers, short pulses) and that of the sinusoidal stretching was not too great (50-100 micrometers, peak-to-peak) the discharge of the afferents was largely locked 1:1 to the vibration and the response to the sinusoidal stretching was abolished. 3. When the amplitude of the vibration was reduced to below that eliciting continuous afferent driving, then the response to sinusoidal stretching of any amplitude was often markedly increased. This arose through the vibration having a much more powerful excitatory action during the rising phase of the sinusoidal stretch than it did during the falling phase. 4. Averaged over a full cycle, the phase of the response to the sinusoidal stretching tended to be delayed during the vibration in comparison with the normal. This was largely dependent upon the afferents continuing to respond maximally to the vibration around the peak of the sinusoidal stretch, at which stage their unvibrated response is declining, rather than to a phase lag of the whole pattern of response. 5. The results are discussed in relation to the effects of vibration on tremor and the human stretch reflex, and on the determination of the frequency-response of spindle afferents.

Action Potentials↗

PubMed1984

Evidence from the use of vibration that the human long-latency stretch reflex depends upon spindle secondary afferents.

The electromyographic activity of flexor pollicis longus has been recorded in normal human subjects on moving the tip of the thumb with the proximal phalanx clamped. Ramp and hold displacements (stretches) were compared with high-frequency sinusoidal movement (vibration). The subject exerted a constant flexor force between stimuli and made no voluntary response to them. On stretching the muscle by forcibly extending the thumb at various constant velocities the usual combination of short-latency (ca. 25-30 ms) and long-latency (ca. 40 ms) components of response were observed. The short-latency response progressively predominated as the velocity was increased (60-900 deg s-1, 9 deg joint displacement). One subject still showed only a long-latency response with the fastest stretch, arguing that it is a distinct reflex entity. On commencing vibration (143 Hz, 3 deg movement peak-to-peak) a short-latency response was regularly obtained, but any long-latency response was always small in relation to that elicited by stretch. This was equally so when the short-latency responses to the two types of stimulation were matched by using appropriate parameters of stimulation. The time course of the vibration response did not change appreciably with change of amplitude of vibration, so that its temporal profile was always quite different from that of the stretch response. The observed differences are in accordance with the hypothesis that the spindle group II afferents produce the long-latency excitation, with the time lost peripherally in afferent conduction rather than centrally. In relation to the strength of their Ia excitatory actions, stretch is known to excite secondary afferents more powerfully than does vibration. The findings are not readily accommodated on the hypothesis that the long-latency response is a transcortical reflex elicited by the initial Ia input, since vibration should then also have had a powerful long-latency action. Similar responses to vibration were obtained when it was applied percutaneously to the tendon of flexor pollicis longus 6 cm above the wrist. Also, those elicited by thumb vibration persisted largely unchanged when the thumb was anaesthetized. This confirms that they were dependent upon the excitation of receptors in flexor pollicis longus, presumably the Ia afferents, rather than upon cutaneous or joint receptors in the thumb. The stretch responses also depended upon muscle receptors, since they too survived anaesthesia.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed1991

Differential activation of motor units in the wrist extensor muscles during the tonic vibration reflex in man.

1. Single motor unit activity was recorded in the extensor carpi radialis longus and extensor carpi radialis brevis muscles of five healthy human subjects, using metal microelectrodes. 2. Motor units were characterized on the basis of their twitch contraction times and their force recruitment thresholds during voluntary imposed-ramp contractions. 3. The discharge patterns of forty-three motor units were studied during tonic vibration reflex elicited by prolonged (150 s) trains of vibration (30 Hz) applied to the distal tendons of the muscles. The temporal relationships between the individual small tendon taps of the vibratory stimulus and the motor unit impulses were analysed on dot raster displays and post-stimulus time histograms. 4. After tendon taps, the impulses of motor units with long twitch contraction times (mean +/- S.D., 47.2 +/- 10.7 ms) and low recruitment thresholds (0.88 +/- 0.6 N) formed a single narrow peak (P1) with a latency (22.7 +/- 1.4 ms) which was comparable to that of the tendon jerk in the extensor carpi radialis muscles. These motor units were named 'P1 units'. On the other hand, the response of motor units with shorter twitch contraction times (31.1 +/- 3.3 ms) and higher recruitment thresholds (3.21 +/- 1.3 N) showed two peaks: a short latency (23.4 +/- 1.3 ms) P1 peak similar to the previous one and a P2 peak occurring 9.4 +/- 1.2 ms later. These motor units were named 'P1-P2 units'. 5. When the reflex contraction increased slowly, the P1 peaks of 'P1-P2 units' were clearly predominant at the beginning of the contraction, during the rising phase of the motor unit discharge frequency, while the P2 peaks became predominant when the units had reached their maximal discharge frequency. 6. Increasing the tendon vibration frequency (35, 55, 75, 95 Hz) did not modify the 'P1 unit' discharge pattern. Due to interference between vibration period and peak latencies, increasing the vibration frequency caused the P1 and P2 peaks of 'P1-P2 units' to overlap. 7. Superficial cutaneous stimulation of the dorsal side of the forearm during tendon vibration noticeably decreased the P1 peaks in both types of motor units. In the P2 peaks it could result in either a decrease or an increase but the average effect was a slight increase. 8. When applied 10 s before tendon vibration, cutaneous stimulation considerably suppressed the tonic vibration reflex.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed2004

Extracellular signal-regulated kinase activation and endothelin-1 production in human endothelial cells exposed to vibration.

Hand-arm vibration syndrome is a vascular disease of occupational origin and a form of secondary Raynaud's phenomenon. Chronic exposure to hand-held vibrating tools may cause endothelial injury. This study investigates the biomechanical forces involved in the transduction of fluid vibration in the endothelium. Human endothelial cells were exposed to direct vibration and rapid low-volume fluid oscillation. Rapid low-volume fluid oscillation was used to simulate the effects of vibration by generating defined temporal gradients in fluid shear stress across an endothelial monolayer. Extracellular signal-regulated kinase (ERK1/2) phosphorylation and endothelin-1 (ET-1) release were monitored as specific biochemical markers for temporal gradients and endothelial response, respectively. Both vibrational methods were found to phosphorylate ERK1/2 in a similar pattern. At a fixed frequency of fluid oscillation where the duration of each pulse cycle remained constant, ERK1/2 phosphorylation increased with the increasing magnitude of the applied temporal gradient. However, when the frequency of flow oscillation was increased (thus decreasing the duration of each pulse cycle), ERK1/2 phosphorylation was attenuated across all temporal gradient flow profiles. Fluid oscillation significantly stimulated ET-1 release compared to steady flow, and endothelin-1 was also attenuated with the increase in oscillation frequency. Taken together, these results show that both the absolute magnitude of the temporal gradient and the frequency/duration of each pulse cycle play a role in the biomechanical transduction of fluid vibrational forces in endothelial cells. Furthermore, this study reports for the first time a link between the ERK1/2 signal transduction pathway and transmission of vibrational forces in the endothelium.

Blotting, Western↗

PubMedDate not supplied

Analysis of skin deformation profiles during sinusoidal vibration of fingerpad.

Vibrotactile perception threshold measurement has been widely used to diagnose the severity of peripheral neuropathy associated with hand-arm vibration syndrome and sensory losses in stroke and diabetic patients. The vibration perception threshold is believed to be influenced by many factors, such as contact force and vibration frequency. The present study is intended to analyze, theoretically, the time-dependent deformation profile of skin surface, strain distributions within soft tissue, and response force of a fingertip when it is stimulated by a probe vibrating with a sinusoidal movement. A two-dimensional finite element model, which incorporates the essential anatomical structures of a finger: skin, subcutaneous tissue, bone, and nail, has been proposed to analyze the effects of vibration amplitude, frequency, and preindentation on the dynamic interaction between the fingerpad and vibrating probe. The simulation results suggest that the fraction of time over which the skin separates from the probe during vibration increases with increasing vibration frequency and amplitude, and decreases with increased preindentation of the probe. The preindentation of the probe has been found to significantly reduce the trend of skin/probe decoupling. The simulation results show reasonably consistent trends with the reported experimental data.

Adaptation, Physiological↗

PubMed2005

Estimation of vibration power absorption density in human fingers.

The absorption of hand-transmitted vibration energy may be an etiological factor in vibration-induced disorders. The vibration power absorption density (VPAD) may be a better measure of energy than the total power absorption of the hand-arm system. The objectives of the present study are to develop a method to estimate the average absorption density in the fingers and to investigate its basic characteristics. Ten healthy male subjects were used in this study. The biodynamic response of the fingers in a power grip subjected to a broad-band random excitation was measured under three grip forces (15, 30, 50 N) and three push forces (35, 45, 50 N). The response was used to estimate the total finger energy absorption. The response, together with the finger volume, was also used to estimate the amount of tissue effectively involved in the absorption. Then, the average VPAD under constant-acceleration, constant-power density, constant-velocity vibration spectra, and 20 tool vibration spectra were calculated. The correlations between the VPAD and the unweighted and weighted accelerations (ISO 5349-1, 2001) were also examined. The VPAD depends on both the characteristics of the vibration spectrum and the biodynamic response of the finger-hand-arm system. The biodynamic response generally plays a more important role in determining the VPAD in the middle frequency range (31.5-400 Hz) than those at the low and high ends. The applied force significantly affected the VPAD. The finger VPAD was highly correlated to the unweighted acceleration. The average VPAD can be determined using the proposed experimental method. It can serve as an alternative tool to quantify the severity of the vibration exposure for studying vibration-induced finger disorders.

Absorption↗

PubMed2002

Effect of phase on discomfort caused by vertical whole-body vibration and shock--experimental investigation.

An experimental study has investigated the effect of "phase" on the subjective responses of human subjects exposed to vertical whole-body vibration and shock. The stimuli were formed from two frequency components: 3 and 9 Hz for continuous vibrations and 3 and 12 Hz for shocks. The two frequency components, each having 1.0 ms(-2) peak acceleration, were combined to form various waveforms. The effects of the vibration magnitude on the discomfort caused by the input stimuli were also investigated with both the continuous vibrations and the shocks. Various objective measurements of acceleration and force at the seat surface, the effects of different frequency weightings and second and fourth power evaluations were compared with judgments of the discomfort of the stimuli. It was found that a 6% to 12% increase in magnitude produced a statistically significant increase in discomfort with both the continuous vibrations and the shocks. Judgments of discomfort caused by changes in vibration magnitude were highly correlated with all of the objective measurements used in the study. The effects on discomfort of the phase between components in the continuous vibrations were not statistically significant, as predicted using evaluation methods with a power of 2. However, small changes in discomfort were correlated with the vibration dose value (VDV) of the Wb frequency-weighted acceleration. The effect of phase between frequency components within the shocks was statistically significant, although no objective measurement method used in the study was correlated with the subjective judgments.

Acceleration↗

PubMed2002

Chaotic vibration induced by turbulent noise in a two-mass model of vocal folds.

The contribution of turbulent noise was modeled in symmetric vocal folds. A two-mass model was used to simulate irregular vocal fold vibrations. The threshold values of system parameters to produce irregular vibrations were decreased as a result of turbulent airflow. Periodic vibrations were then driven into the regions of irregular vibrations. Using nonlinear dynamics including Poincaré map and Lyapunov exponents, irregular vibrations were demonstrated as chaos. For the deterministic vocal-fold model with noise free and steady airflow, a fine period-doubling bifurcation cascade was shown in a bifurcation diagram. However, turbulent noise added to the vocal-fold model would induce chaotic vibrations, broaden the regions of irregular vocal fold vibrations, and inhibit the fine period-doubling bifurcations in the bifurcation diagrams. The perturbations from neurological and biomechanical effects were simulated as a random variation of the vocal fold stiffness. Turbulent noise as an external random source, as well as random stiffness perturbation as an internal random source, played important roles in the presence of irregular vocal fold vibrations.

Humans↗

PubMed1976

TVR and vibration-induced timing of motor impulses in the human jaw elevator muscles.

In order to investigate myotatic reflex involvement in jaw muscle control, an analysis was made of the motor responses induced by mechanical vibration (120-160 Hz) of the jaw elevator muscles in healthy subjects. As seen in torque measurements and mean-voltage electromyographic (EMG) recordings, the vibration caused involuntary reciprocal changes in jaw muscle tone, the contraction force increasing in jaw elevators and decreasing in antagonistic jaw opening muscles. This tonic vibration reflex (TVR) elicited from the jaw elevators exhibited many characteristics similar to those previously described for limb muscle tonic vibration reflexes: it varied in strength from one subject to the next independently of the briskness of the jaw elevator tendon jerks; it had a gradual onset with successive recruitment of jaw elevator motor units firing largely out of phase with one another and at rates much lower than the vibration frequency; it was susceptible to voluntary control--when allowed visual feed-back from the torque meter all subjects were able to suppress the TVR and keep mean contraction force constant. The results indicate that with respect to the tonic motor response to sustained inflow in the Ia afferent nerve fibres, the jaw elevators do not differ markedly from other skeletal muscles. Independently of whether a TVR was present or not, the vibration caused a timing of the motor unit discharges in the jaw elevators that could not be controlled voluntarily and that showed up in gross EMG recordings as a marked grouping of discharges synchronous with each wave of vibration. A similar but less distinct grouping of the gross EMG pattern was seen in limb muscles exposed to vibration, the dispersion increasing with the peripheral conduction distances of the reflex arcs. It is suggested that contrary to the TVR, which depends on the sustained mean level of the Ia afferent input, the timing phenomenon depends, like the tendon jerk, on the degree of synchrony in the afferent Ia volleys. Monosynaptic projections may well be involved in the dynamic timing of motor discharges during tonic firing, but this does not imply that the TVR or the tonic stretch reflex is dependent upon such projections.

Action Potentials↗

PubMed1999

Proprioceptive regulation of voluntary ankle movements, demonstrated using muscle vibration, is impaired by Parkinson's disease.

OBJECTIVE: To test the hypothesis that the proprioceptive regulation of voluntary movement is disturbed by Parkinson's disease, the effects of experimental stimulation of proprioceptors, using muscle vibration, on the trajectories of voluntary dorsiflexion movements of the ankle joint were compared between parkinsonian and control subjects. METHODS: Twenty one patients with Parkinson's disease, on routine medication (levodopa in all but one), and an equal number of age matched, neurologically intact controls, were trained initially to make reproducible ankle dorsiflexion movements (20 degrees amplitude with a velocity of 9.7 degrees /s) following a visual "go" cue while movement trajectories were recorded goniometrically. During 50% of the experimental trials, vibration (105 Hz; 0.7 mm peak to peak) was applied to the Achilles tendon during the ankle movement to stimulate antagonist muscle spindles; vibrated and non-vibrated trials were interspersed randomly. Subjects' performance was assessed by measuring end point position-that is, the ankle angle attained 2 seconds after the visual "go" cue, from averaged (20 trials) trajectories. RESULTS: Statistical analysis of the end point amplitudes of movement showed that, whereas the amplitudes of non-vibrated movements did not differ significantly between patients with Parkinson's disease and controls, antagonist muscle vibration produced a highly significant reduction in the amplitudes of ankle dorsiflexion movements in both the patient and control groups. However, the extent of vibration induced undershooting produced in the patients with Parkinson's disease was significantly less than that in the controls; the mean vibrated/non-vibrated ratios were 0.86 and 0.54 for, respectively, the patient and control groups. CONCLUSIONS: The present finding of a reduction of vibration induced ankle movement errors in parkinsonian patients resembles qualitatively previous observations of wrist movements, and suggests that Parkinson's disease may produce a general impairment of proprioceptive guidance.

Aged↗