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PubMedDate not supplied

Alternate and simultaneous binaural bithermal caloric testing: a comparison.

This study compares the results from simultaneous binaural bithermal and alternate binaural bithermal caloric testing of 652 patients with dizziness. Also compared are the abilities of these tests to distinguish between a population of healthy asymptomatic subjects and our patient population. Caloric testing used a closed-loop irrigation system. Eye movements were monitored with electro-oculography. The agreement between the results from the two tests was low. Also, while the simultaneous test was more sensitive, the alternate test was more specific. Using receiver-operator characteristic methodology, it was found that the ability of the alternate test to distinguish between a healthy population and a patient population was superior to that of the simultaneous test. There was no improvement in the ability to distinguish between a healthy population and a patient population when the results from the two tests were combined as compared to using the alternate caloric test alone.

Algorithms↗
PubMedDate not supplied

Waardenburg's syndrome: variations in expressivity.

Twenty-seven subjects with a family history of Waardenburg's syndrome were examined with respect to 18 specific characteristics of the syndrome, with particular emphasis in identifying the spectrum of the phenotypic expression of affected persons. Our results indicate that patients with the syndrome may have a variety of clinical signs, and an accurate diagnosis will therefore depend on a thorough and pertinent family history and physical examination.

Abnormalities, Multiple↗
PubMed1989

Dynamic posturography and caloric test results in patients with and without vertigo.

Patients with dizziness were evaluated with caloric stimulation and with dynamic platform posturography (Neurocom Equitest). The ability of these tests to detect abnormalities in patients with and without vertigo was assessed. In 159 patients, roughly a third had abnormal calorics while half experienced one or more "falls" during posturography. Calorics revealed proportionately more abnormalities in patients with vertigo, whereas posturography alone did not distinguish between patients with or without vertigo. Posturography did, however, identify abnormalities in a third of patients with normal calorics, regardless of their history of vertigo. Overall, more patients with vertigo had at least one abnormal test result (70%) compared with patients without vertigo (47%). We conclude that caloric abnormalities correlate with a history of vertigo, whereas posturographic deficits can be identified regardless of the presence of vertigo.

Adolescent↗
PubMed1979

Caloric pattern test with special reference to failure of fixation-suppression.

Fixation-suppression of caloric nystagmus was studied in 1230 consecutive cases. An analysis of caloric nystagmus with failure of fixation-suppression (FFS) made it possible to classify patterns of FFS into three types: Type I: FFS was observed bilaterally in caloric nystagmus; Type II: FFS was recognized unilaterally on either side; Type III: FFS was seen in either direction of nystagmus. On the basis of these three types, the underlying neuroanatomical substrate responsible for FFS is discussed.

Brain Diseases↗
PubMedDate not supplied

Caloric nystagmus decay during parabolic flight.

In human subjects the caloric test was conducted during parabolic flight. The slow-phase velocity (SPV) of the caloric nystagmus increased proportionally to the value of the g-force. The nystagmus disappeared in microgravity, after an exponential SPV decay that showed a specific time constant (Tc). The average Tc value of this SPV decay is on a lower level than the one found after a sudden stop-test in the laboratory in a 1-g condition. Because of the exponential characteristics of the SPV decays and their Tc values, evoked in both conditions, a common working mechanism of cupular stimulation is likely. Most probably a fluid movement, caused either by a sudden stop in a 1-g condition or by weightlessness after a calorization, provokes a cupula flexion followed by a reflexion. The results support the Bárány convection theory with regard to the endolymph movement following the caloric test.

Caloric Tests↗
PubMed1995

Influence of low dose alcohol on fixation suppression.

The decrease of fixation suppression after small doses of alcohol was studied in 40 healthy volunteers (20 male, 20 female) using rotatory stimulation. 0.5 g alcohol per kg body weight were given within 20 min. The maximum fixation suppression and blood alcohol concentrations (BAC) were measured before and at 15, 30, 45, 60, 120, 180 and 240 min after ingestion. We determined the maximum angular acceleration during which total suppression of the vestibulo-ocular-reflex (VOR) was still possible. Fixation suppression was successful up to mean values of 43.6 degrees/S2 before ingestion of alcohol (reference level). A first significant deterioration of fixation suppression was observed at BAC of 20 mg/100 ml decreasing constantly with increasing BAC. At the median maximum BAC of 65 mg/100 ml, fixation suppression was possible up to acceleration values of 20% compared with reference levels. Measuring of the maximum fixation suppression in rotational tests is a reproducible easy method to describe the central nervous system control of vestibular functions. This method shows impressingly the enormous effects of low doses of alcohol on equilibrium. It is concluded that at BAC of more than 50 mg/100 ml a remaining vestibular nystagmus might be observed when driving a bend.

Adult↗
PubMed2000

[Physiological evaluation of vestibular training load].

Objective. To evaluate the effects of vestibular training by observing the variations of the physiological indices. It is helpful in grasping the training load, setting down and implementing the training plan. Method. 10 healthy subjects received linear acceleration, continuous Coriolis acceleration and discontinuous Coriolis acceleration stimuli on different dates. The stimulus was stopped when there were slight autonomic nervous symptoms, ECG, EGG and BP were recorded before during and after the stimuli. Computerized Dynamic Posturography (correction of Postrograph) (CDP) was tested before and after experiment. Result. One subject finished the training of the three stimuli with only slight autonomic nervous symptoms. The CDP tests pre- and post-experiment indicated that for most subjects the contribution of vestibular function in maintaining dynamic posture equilibrium increased after the linear acceleration stimuli, but decreased after continuous Coriolis acceleration stimuli, and there was great individual difference after discontinuous Coriolis acceleration stimuli because the stimulation was relatively heavy. The equilibrium score in SOT2 decreased significantly after linear acceleration stimuli, and increased significantly after discontinuous Coriolis acceleration stimuli. Conclusion. The training methods we designed and used in this experiment are feasible, and the required training load can be reached. EGG, BP and the percentage of LF (low frequency) in ECG R-R power spectrum can reflect the subject's condition when the period stimuli stopped. It provided important reference in the determination of training stimulation load.

Acceleration↗
PubMed1989

[The effect of nystagmus of labyrinth origin on the eye movement curve and optokinetic nystagmus].

The authors evaluated the interaction of follow-up eye movements, of the optokinetic nystagmus with the nystagmus of labyrinthine origin. In 15 subjects without data on an impaired vestibular system they observed during a calorically induced nystagmus follow-up eye movements and the optokinetic nystagmus. They confirmed changes of these curves which were closely associated with the direction of the nystagmus. The above changes can be used as one of the criteria for the differentiation of a spontaneous nystagmus of peripheral origin from central nystagmus.

Adolescent↗
PubMed1987

[Balloon method and water irrigation in thermal vestibular assessment. Electronystagmographic comparison of both methods].

In cases of large central perforation of the eardrum, caloric test of the vestibular organ cannot be carried out by irrigation of the external auditory canal with water but must be done with a balloon instilled in the external auditory canal perfused with water. Caloric responses were registered by using water irrigation and balloon irrigation in 40 healthy persons. Nystagmographic registrations were analysed. Frequency, slow phase velocity and amplitude of nystagmus were measured. Cumulative percentage curves of the four caloric responses are drawn to compare the distribution of data in balloon and water irrigation (Figures 2-5). In addition, mean values and standard deviations of data and of difference in excitability related to the total excitability are recorded in table 1. Statistics (Wilcoxon test for matched pairs) reveals no significant differences in nystagmographic pattern of caloric reactions between water and balloon stimulation. It is concluded that in the caloric test of the vestibular organ balloon irrigation is equivalent to water irrigation. Balloon irrigation is more comfortable for the patient and easier to handle.

Caloric Tests↗
PubMed1985

[Biophysical aspects on the result of the Spacelab experiment and consequences for Bárány's theory].

On testing the peripheral vestibular apparatus of astronauts with healthy labyrinths, nystagmus was observed when flushing the ears with hot or cold water even in the absence of gravitation. In the opinion of some scientists, this seems to refute Bárány's theory. They attempt to explain nystagmus as a result of compression. The hypothesis of Bárány, basing on terrestrial conditions, explains the peripheral impulse as the result of a convective flow caused by heating or cooling within the horizontal semicircular canal. However, if gravitation is absent any such circulation is excluded, because buoyancy is impossible without gravitation. The article shows, on the one hand, that the compression hypothesis cannot be correct, where as on the other Bárány's theory needs completion. For, in addition to the convective flow, the expansion of the endolymph resulting from heat must be considered. This effect occurs even in the absence of gravitation.

Aerospace Medicine↗