[Conditions of longitudinal vibration transmission in the arm].
Explore the source record for details and available documents.
Arm↗
Biomedical subjects
I Pyykkö
Publications and source records attributed to I Pyykkö.
[Studies on the etiologic mechanism of traumatic vasospasm].
Explore the source record for details and available documents.
Hand↗
Transmission of vibration in the hand-arm system with special reference to changes in compression force and acceleration.
The transmission of longitudinal vibration in the hand-arm system of five subjects was investigated. Altogether 405 individual tests were made. Vibration was measured with an accelerometer (weight 0.4 g) fixed in turn to the wrist, the elbow, and the upper arm by means of a supporting device (weight 34 g). A handle with strain gauges attached was used to study the effect of compression force (10, 20 and 40 N) and constant acceleration (1, 3 and 10 g) on the transmission of vibration at frequencies from 20 to 630 Hz. In the curves recorded, sharp dips appeared which were evidently caused by resonances from the soft tissues of the hand. However in the hand-arm system no common resonance frequency was observed that would harmfully affect the health of workers. Vibration in the hand-arm system was attenuated at an average of 3 dB per octave at the frequencies between 20 and 100 Hz. Between 100 and 630 Hz the attenuation was about 6 dB per octave in the wrist and 10 dB per octave in the elbow and upper arm. At the frequency of 630 Hz the attenuation was hence about 35 dB in the wrist and about 45 DB in the elbow. The attenuation of vibration in the elbow joint was 2 to 4 dB at all frequencies. The hand-arm system appears to be linear at the acceleration range considered; the increase in handle vibration by, e.g., 10 dB also increased vibration in the hand by 10 dB. When the grip strength was increased fourfold, i.e., 12 dB, vibration increased only 3 to 5 dB in the hand-arm system. Thus changing the weight of a vibrating tool does not reduce vibration enough. Therefore attempts to reduce vibration should concentrate on the mechanical parts of the engines.
Acceleration↗
Vibration induced changes of sympathetic vasomotor tone.
Explore the source record for details and available documents.
Adult↗
The prevalence and symptoms of traumatic vasospastic disease among lumberjacks in Finland. A field study.
Explore the source record for details and available documents.
Adult↗
Vibration frequencies and amplitudes in the aetiology of traumatic vasospastic disease.
Explore the source record for details and available documents.
Adult↗
Smoking habits and postural stability.
PURPOSE: It has been reported that tobacco smoking temporarily affects postural stability We have examined whether smoking habits have a long-term effect on the body balance control using computer-aided posturography. SUBJECTS AND METHODS: The postural stability of 80 male forest workers was measured with a force platform technique with eyes closed. Average body sway velocity (ASV [mm/s]) was determined and used as a stability index. Detailed interviews on tobacco smoking and otologic examinations were carried out. Smoking habits were classified into five categories: nonsmokers (53.8%), ex-smokers (17.5%) and current smokers, comprising light (3.8%), moderate (15%), and heavy (10%) smokers. RESULTS: The smoking habits of the subjects correlated significantly with ASV, but hours of the exposure to noise and hand-arm vibration from chain saws did not. The correlation of the smoking habits remained significant even after eliminating the effect of age and exposure by partialization. Age in itself had no effect on ASV but interacted with smoking to increase ASV. The group means of ASV increased with the increase in smoking. Significant differences in ASV were found in the moderate and heavy smokers compared with the nonsmokers. CONCLUSION: Smokers exhibited more unstable posturographic results than nonsmokers. Smoking habits were suggested to have a long-term effect on the posture control system.
Adult↗
Effects of pure-tone sound, impulse noise, and vibration on visual orientation.
Eye movements and the electroencephalogram (EEG) were recorded in intact rabbits during an optokinetic test when the animals were exposed to pure-tone sound (85 dB at 4,000 Hz), impulse noise (159 dB), and vibration directed to the abdomen (at an amplitude of 0.9 mm at frequencies of 40 to 140 Hz). The frequency and velocity of optokinetic nystagmus significantly increased in response to these stimuli. The increase seen with vibration was greater than that resulting from sound, and the response was strongest when sound and vibration were combined. The increase of optokinetic nystagmus seen with induced vibration was progressive and dependent on the frequency. The increase was weakest during vibration at 40 Hz and strongest during vibration at 140 Hz. Electroencephalograms (EEGs) of the amygdaloid complex, dorsal hippocampus, midbrain reticular formation, and frontal motor cortex all were activated during exposure to sound and vibration, but activation of the hippocampal EEG was most closely related to the increase of optokinetic nystagmus. During optokinetic tests, impulse noise regularly triggered nystagmic beats. When the rabbits were not in the test apparatus, nystagmus was produced in response to about 18 per cent of the presentations of impulse noise, while activation of the EEG was constant. Thus, vibration and noise, when excessive, may interfere with visual orientation and hence disturb equilibrium. These findings can be related to the nonspecific dizziness that occurs in aerospace or industrial workers exposed to excessive noise and vibration.
Acoustic Stimulation↗
Effect of alertness and visual attention on optokinetic nystagmus in humans.
The effect of alertness and visual attention on optokinetic nystagmus (OKN) and optokinetic after-nystagmus (OKAN) was studied in 20 volunteers. Electroencephalographic (EEG) activity was recorded over the occipital lobe. Exposure to sound and vibration caused a significant increase in the mean slow-phase velocity of OKN, whereas its maximum slow-phase velocity remained unaffected. Vibration tended to increase the mean slow-phase velocity of OKN more than sound did, though the difference was not statistically significant. Vibration also significantly increased the OKAN. When alpha rhythm appeared in the occipital EEG during OKN, the velocity of concurrent slow phases was reduced. However, the periods of alpha rhythm did not differ between the different stimulus conditions. The findings suggest that sound and vibration activate the subcortical optokinetic mechanism, thus causing an increase in the mean velocity of OKN. Abatement of visual attention is reflected in temporary reduction of OKN in conjunction with the appearance of alpha waves and is to be interpreted as transient quiescence of the cortical optokinetic mechanism.
Acoustic Stimulation↗
Further evidence of a relation between noise-induced permanent threshold shift and vibration-induced digital vasospasms.
The relation between noise-induced permanent threshold shift (NIPTS) and vibration-induced dysfunction in the digital circulation was examined in a longitudinal survey among forest workers. The survey was based on annual examinations done between 1972 and 1983. Thirty-two forest workers with digital vasospasms were compared with referents matched for age, exposure, and use of ear protectors. No significant differences between the groups were observed at 1,000 or 2,000 Hz. The forest workers with digital vasospasms had significantly greater NIPTS at 4,000 and 8,000 Hz than the symptom-free referents. During the follow-up period, the gap in NIPTS between the two groups did not increase. Vibration measurements from chain saws manufactured in different years indicated that chain saws manufactured after 1970 had a tenfold reduction in vibration, whereas the reduction in noise levels was only slight. The results suggest that vibration-induced activation of the autonomic nervous system, which is thought to elicit digital vasospasms, may also contribute to the development of NIPTS.
Adult↗
Decision tree induction in the diagnosis of otoneurological diseases.
Expert systems have been applied in medicine as diagnostic aids and education tools. The construction of a knowledge base for an expert system may be a difficult task; to automate this task several machine learning methods have been developed. These methods can be also used in the refinement of knowledge bases for removing inconsistencies and redundancies, and for simplifying decision rules. In this study, decision tree induction was employed to acquire diagnostic knowledge for otoneurological diseases and to extract relevant parameters from the database of an otoneurological expert system ONE. The records of patients with benign positional vertigo, Meniere's disease, sudden deafness, traumatic vertigo, vestibular neuritis and vestibular schwannoma were retrieved from the database of ONE, and for each disease, decision trees were constructed. The study shows that decision tree induction is a useful technique for acquiring diagnostic knowledge for otoneurological diseases and for extracting relevant parameters from a large set of parameters.
Algorithms↗
Role of transtympanic endoscopy of the middle ear in the diagnosis of perilymphatic fistula in patients with sensorineural hearing loss or vertigo.
BACKGROUND: The diagnosis of perilymphatic fistula (PLF) is often difficult, and therefore the condition can be overlooked. Tympanoscopy presents an alternative procedure for visualising the middle ear anatomy, and it may help to diagnose PLF. AIM: The aim of this study was to evaluate the use of middle ear endoscopy in establishing the diagnosis of PLF and in defining its incidence in patients with sensorineural hearing loss and/or vertigo and tinnitus. SUBJECTS AND METHODS: Two hundred and sixty-five patients (22-80 years of age, mean 48 years) were prospectively and consecutively referred for middle ear examination with tympanoscopy. Tympanoscopy was performed using endoscopes with visual angles of 5 and 25 degrees and an outer diameter of 1.7 mm. The round window niche (with its secondary membrane), the oval window with a stapes superstructure, a part of the facial recess and the area in the fissula ante fenestram were examined and video-recorded. RESULTS: For 1 patient, tympanoscopy revealed fistula in the round window membrane that was covered with a fibrinous layer. In 4 cases abnormal mucosal shining appeared in the round window, but no PLF was present. In 7 cases the tympanic cavity could not be visualised because of the adhesive tympanic membrane, abnormal anatomy or the prominent exostoses of the external ear canal. In 6 cases a postendoscopic middle ear infection was found. No permanent tympanic membrane perforation occurred in any of the patients in this study. CONCLUSIONS: Tympanoscopy is a rapid examination tool with which to verify certain areas of the middle ear anatomy, but it is of limited value for ruling out the presence of PLF.
Adult↗
Velocity of rapid eye movements and vertigo of central origin.
Peak velocities of voluntary saccades and fast phases of different qualities of nystagmus were studied in 20 normal subjects, 5 patients with pontine lesions and 5 patients with lesions in the frontal cortex. The peak velocity of saccades was related to the amplitude of the eye movement, the alertness of the subject and whether the subject could see the target or not. The effect of the age was not significant. The quick phases of caloric, optokinetic and angular acceleration induced nystagmus were equally rapid but somewhat slower than that of vestibular nystagmus recorded in standardized visual surrounding. In the same visual condition saccades were always faster than quick phases of nystagmus. Patients with cortical lesions had normal velocities in saccades and quick phases of nystagmus. Patients with pontine disorders had significantly reduced saccadic and quick phase velocity, and some of the patients exhibited dissociations between velocity mechanisms while the somewhat higher velocity in quick phase of vestibular nystagmus recorded in light is probably related to higher attention evoked by vestibular-visual interaction.
Adolescent↗
Eye movements in cerebellar and combined cerebellobrainstem diseases.
We report a quantitative analysis of eye movement disturbances in patients with isolated cerebellar disorders and patients with cerebellar disorders and concomitant brainstem involvement. The most characteristic abnormalities in the exclusively cerebellar patients were increased velocities of the slow phases of vestibular nystagmus induced by rotation in the dark and increased peak velocities of the fast phases of optokinetic nystagmus induced by full-field optokinetic stimuli. Dysmetria of saccades was found in three of six cerebellar patients and gaze nystagmus in all six patients. The typical findings in the combined cerebellobrainstem group were reduced peak velocities of voluntary saccades, defective smooth pursuit and reduced peak velocities of the fast component of nystagmus during rotation in both the dark and light. All patients with combined cerebellobrainstem disorder had dysmetric voluntary saccades and gaze nystagmus. The numbers of superimposed saccades during smooth pursuit were uniformly increased. Release of inhibition in cerebellar disorders may explain the hyperresponsiveness and inaccuracy of eye movements found in this study. In addition, when lesions also involve the brainstem, however, integrative centers coding eye velocity are affected, leading to slow and inaccurate eye movements. These features elicited clinically may be useful in the diagnosis of cerebellar and brainstem disorders.
Adult↗
Enhancement of eye motor response and electrical brain activity during noise and vibration in rabbits.
The relationship between electroencephalogram (EEG) and eye movements was studied in rabbits during optokinetic, vestibular, and optovestibular tests. EEG was recorded through permanently implanted electrodes. Exposure to noise and vibration increased the frequency and the velocity of optokinetic nystagmus (OKN). The increase was greater during vibration but greatest during combined noise and vibration. EEG activity was closely linked to changes in OKN and was particularly evident with the appearance of theta waves in the dorsal hippocampus. Also, rotation of the rabbit produced considerable activation in the EEG.
Animals↗
Dyspraxia of speech and of eye motility.
Five patients with a disturbance of their preprogramming of speech (dyspraxia of speech) were exposed to a comprehensive eye-motor test-battery. The saccades were found hypometric and inaccurate with irregular intervening pauses. The finding was interpreted as due to an extension of lesions from frontal cortical speech areas into visual motor cortex disturbing the normal preprogramming of voluntary saccades. The results were interpreted as supporting the assumption that voluntary saccades are initiated in the frontal cortex. An increase of vestibular nystagmus in these cases was related to a release of vestibular nystagmus due to the disappearance of cortical inhibition on brain stem acitivty.
Adult↗
Velocity patterns of rapid eye movements.
The peak velocities of saccades and fast phases of nystagmus were examined and compared in 20 healthy subjects. The peak velocities of both types of eye movements increased with increase of amplitudes. The saccades were found to be fastest in light, slower in darkness and slowest behind closed eyelids. The peak velocities of the quick phases of optokinetic and of vestibular nystagmus were found to be the same. Fast phases of optovestibular (optic as well as vestibular stimulation) nystagmus produced significantly higher peak velocities than the two others. At the same amplitude and during the same visual conditions the saccades were significantly faster than any type of fast components of nystagmus. The difference in velocity between voluntary and reflexive eye movements is possibly related to differences in antagonistic activity during these eye movements, but also to specific synaptic events during the voluntary action.
Adult↗
Quantification of tracking eye movements in patients with neurological disorders.
Tracking eye movements were studied in 20 healthy subjects and in 24 patients with vestibular neuronitis, disorders within the frontal cortex, the cerebellum or the brain stem. The tracking tests were performed at six different target velocities between 10-60 degrees s-1 and different parameters were evaluated. The maximum velocity gain of smooth pursuit as normal in the group with vestibular neuronitis but reduced in the groups with disorders within the frontal cortex, cerebellum and the brain stem. The total amplitude of tracking and amplitude of smooth pursuit were normal in the groups with vestibular neuronitis and frontal cortical disorders, while in the groups with cerebellar and brain stem disorders it was reduced. The frequency of superimposed saccades with amplitude range of 3-10 degrees was significantly increased in all groups; however, in the group with vestibular neuronitis the increase was significant only during tracking in the direction of spontaneous nystagmus. The number of superimposed saccades with amplitude range of 11-20 degrees was significantly increased only in the group with cerebellar disorders. The frequency of square waves was not significantly increased in any group. Quantitative analysis of tracking eye movements seems to be a valuable aid for evaluation of site of lesions in the central nervus system.
Adolescent↗