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At least 1,297 records · Page 72Linked to original sources
PubMed1993

Disequilibrium of unknown cause in older people.

Many older people complain of a sense of unsteadiness when standing or walking and many are fearful of falling. The cause of this disequilibrium is often difficult to determine even after thorough clinical evaluation. To better understand the pathogenesis of this symptom in a community-dwelling population, we studied 26 patients > 75 years old who complained of disequilibrium in whom no cause was evident after clinical evaluation. Each patient and each of 26 age-matched controls underwent a comprehensive evaluation that included a history and examination, a questionnaire, functional scales, a gait and balance scale, mini-mental state testing, audiometry, visual acuity, visual tracking, rotational vestibular testing, and quantitative posturography. Although none had Romberg's sign, patients tended to sway more and do poorer on semiquantitative gait and balance testing than did controls. Patients showed few differences from controls for most other measurements. However, 7 patients, designated Group V, had profoundly reduced vestibular function. In the remaining 19 patients (Group D), the average vestibular function was still significantly lower than controls. Sway velocity measured with posturography was increased in the patients compared with controls, particularly in Group V patients. Measures of vestibular function correlated with increased sway velocity both in Group D alone and among all study participants. Quantitative measurement of vestibular function should be considered in older people complaining of disequilibrium, particularly if the cause is not apparent after the initial evaluation.

Activities of Daily Living↗
PubMed2005

A report of two cases of unilateral vestibulopathie after systemic ototoxic treatment.

PURPOSE OF THE STUDY: To present the cases of two patients that developed unilateral vestibular hypofunction after systemic treatment with ototoxic agents, although they manifested symptoms more typical of bilateral vestibular hypofunction. MATERIAL AND METHODS: The patients were seen after having recovered from their initial illnesses, and both of them denied suffering any spells of vertigo, loss of hearing during the treatment or tinnitus. RESULTS: In both patients, oscillopsia and vestibular ataxia were of varying intensity. Bedside vestibular examination, caloric and rotatory chair testing, and vestibular evoked myogenic potentials were congruent with a complete unilateral loss of vestibular function. Audiometry was normal in one case whereas in the other, there was a moderate bilateral sensorineural loss of hearing that was present before treatment and that did not change during the course of the treatment. CONCLUSION: The existence of unilateral vestibular loss was an unsuspected finding but after careful bedside examination, it was confirmed through extensive vestibular testing. However, this infrequent finding responded very well to vestibular rehabilitation. Different mechanisms are proposed to explain this phenomenon, although there is still no clear evidence of which may account for the responses observed.

Adult↗
PubMedDate not supplied

Visual suppression of caloric nystagmus in cats.

A newly devised animal box with which caloric tests can be easily performed in the awake cat is presented. This device is also useful for position and optokinetic tests. Visual suppression of caloric nystagmus was investigated in such vertebrates as monkeys, cats and rabbits. There was a definite species difference in the rate of visual suppression of caloric nystagmus. It may be that the difference among species is due to a difference in fixation function among animal species.

Animals↗
PubMed2004

Motion sickness: its pathophysiology and treatment.

The pathogenesis of motion sickness includes both inner-ear stimulation by body movement, especially a Coriolis-type stimulus, and optokinetic stimulation due to the shift of the surrounding visual fields. According to Kornhuber, Sakata and others, the vestibular cerebellum also participates in an important way. We conducted this study to elucidate the influence of the vestibular cerebellum on the development of motion sickness. We initially focused attention on the visual suppression test of Takemori et al. as a test for vestibular cerebellar function. We reported a modification of this test, described as postrotatoric nystagmus. We employed this test as a rotatoric visual suppression test using milder stimulus for patients complaining of motion sickness. The pathogenesis and treatment of motion sickness are also discussed.

Adolescent↗
PubMed1988

Caloric stimulation during short episodes of microgravity.

Caloric testing was performed during parabolic flight at the NASA Reduced Gravity Facility in Houston, Texas. Six test subjects were stimulated with continuous unilateral air insufflation (25 degrees R), in a manner similar to the experiments performed in the extended weightlessness of orbital flight during the SL1 and D1 Spacelab missions. Nystagmus response was recorded by electro-oculography and eye video image. It was the purpose of the experiments to re-examine the apparent discrepancy between the disappearance of caloric nystagmus during short episodes of weightlessness and the finding that caloric responses can be elicited during periods of extended weightlessness. The present results agree with those of earlier experiments in that a prompt reduction of caloric nystagmus occurs on transition from hypergravity (1.8 G) to weightlessness. The time constant of nystagmus decay was estimated to be approximately 2-3s, a value which cannot be explained by cupular mechanics. A central gating mechanism involving the labyrinthine canal and otolithic afferents is proposed for the observed modulation of caloric nystagmus.

Caloric Tests↗
PubMed1988

Chronic labyrinthine ischemia.

The purpose of the present study was to describe the audiological and vestibular deficit in patients presumed to suffer from chronic impairment of the blood supply to the labyrinth. Thirty-nine subjects affected by various pathologies often impairing systemic blood circulation, which also presented labyrinthine damage of unclear origin, were evaluated for a possible relationship between these two conditions. At the time of this study 80 per cent of the subjects showed also a certain degree of increased blood viscosity. The most common finding in the group was slow and progressive bilateral sensorineural loss of hearing. In most of the subjects the labyrinthine damage began with high-tone loss which, in time, became a flat curve. Less common, but still found in many patients, was a fluctuation in threshold. Short periods of spontaneous subjective improvement in hearing were accompanied by a better result in the Pure Tone Audiogram and Speech Reception Threshold. The discrimination scores remained generally lower than expected. Vestibular examination revealed pathological results for all the subjects in at least some of the tests. The mild subjective complaints concerning equilibrium could be explained by a central nervous system compensation.

Aged↗
PubMed1987

Screening methods for caloric testing.

In order to evaluate the screening capacity and the reliability of monothermal caloric stimulation, the caloric results obtained in 272 patients have been reviewed. The results of a complete bithermal 4-test-set are compared with the results of the hot and cold stimulation considered separately. The supposition that a complete 4-test set is necessary only if the monothermal reaction shows significant asymmetry, is tested by determining how far this would lead to a correct evaluation compared with the final results obtained by the bithermal testing. The study shows that hot as well as cold monothermal screening would result in too many false positive as well as false negative findings. A test procedure consisting of an alternating bithermal stimulation is proposed as a technique for shortening the examination time. This technique has proven to be reliable and it is also more comfortable for the patient.

Caloric Tests↗
PubMedDate not supplied

Air calorics: a technique and results.

A major problem with air calorics appears to be one of technique. A pilot study led to the design of irrigating tips which allow consistant air presentation and simultaneous measurements of irrigating temperature at the delivery orifice (adding a second sensor). Preset temperatures of 24 C and 50 C in our system yielded air equilibration mean temperatures of 27.4 C and 45 C at the delivery orifice during testing. A normal study was carried out at these temperatures with an air flow of six liters per minute for 60 seconds. The range of caloric responses, mean maximum speed, and standard deviation are comparable to values previously reported with water stimulations. Statistical testing indicated no difference between ears for either warm or cold. Also, there was no significant difference for warm versus cold responses. We have performed over 2000 clinical examinations that incorporate this technique with satisfactory results and remarkable acceptance by the patients. The normal or "standard" probe size has been found to be adequate for the majority of the clinic population.

Air↗
PubMedDate not supplied

Results of new air caloric testing method among normal subjects. I. Biphasic testing.

A new air caloric testing method is described in which the temperature of a continuous aural irrigation is switched hot and cold values at times calculated to control the intensity of the resulting vestibular stimulation. Applications of low or high caloric stimulus intensities to normal subjects were well tolerated and reliably produced appropriate low or high intensity nystagmic responses. Nystagmus intensity values obtained from this study were compared with predicted intensity values from a computerized simulation of the actual test conditions, and also with values obtained when using biphasic water irrigations. As a result, further improvements in our methodology have been effected.

Air↗
PubMedDate not supplied

Caloric vestibular test with the use of air.

In a group of 28 test subjects the vestibular caloric test was performed with the aid of two different methods. In the first method the ears were irrigated for 30 sec with water with a temperature of 30 C and 44 C and later on with airstream with a temperature of 20 C and 50 C. The wet method proved to be a significant stronger stimulus than the dry method. The authors conclude that the water irrigation is the method of choice for the caloric test. The dry method is only useful when the wet method is undesirable.

Adolescent↗
PubMed1977

Air caloric test: irrigation technique.

The technique of using air to perform the caloric test is discussed. Greater temperature differences and larger volumes of air are needed to achieve stimulations equal to those caused by water irrigations. Special consideration must be given to the design and operation of air irrigation equipment. The effects of irrigating a wet canal and of misdirecting the air jet are discussed. A new air irrigation apparatus is described.

Air↗
PubMed1977

Comparison of caloric and sinusoidal tests in the vestibulotoxic cat.

In order to evaluate the relative sensitivity of caloric and sinusoidal angular acceleration tests, thermal and rotational stimuli were administered to cats rendered vestibulotoxic with streptomycin sulfate. Three groups of six cats each, receiving daily subcutaneous injections of saline, 100 mg/kg streptomycin or 200 mg/kg streptomycin, were administered optokinetic, caloric and sinusoidal stimuli. Vestibular responses were evaluated by changes in the total slow phase displacement of the eyes and frequency of nystagmic beats. The results demonstrated that the saline treated animals had a decrease in response consistent with habituation; whereas, experimental animals showed a marked, rapid abolition of eye movement. The decrease in response was greater for the larger dose of streptomycin. Caloric or sinusoidal acceleration tests were equally sensitive in monitoring the degree of nystagmic depression. The data suggested that sinusoidal acceleration tests could be easily applied to the clinical vestibular assessment of ototoxicity.

Animals↗