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At least 73 records · Page 4Linked to original sources
PubMed1985

Aqueductal stenosis--results of vestibular function tests.

A case of aqueductal stenosis is reported. The patient was a 14-year-old Japanese girl who was suffering from bilateral tinnitus and unsteadiness of gait. A series of neuro-otological tests revealed prolonged acoustically evoked brain stem response (ABR) latency, disturbed standing reflex, inhibited optokinetic nystagmus (OKN) and ataxic eye tracking test (ETT). Marked distension of the lateral and third ventricles was noticed on CT examination of the brain. A positive contrast ventriculogram using iotalamic acid showed occlusion of the cerebral (Sylvian) aqueduct. All of these results are suggestive of benign, non-neoplastic aqueductal stenosis with associated hydrocephalus. The patient underwent ventriculo-peritoneal shunt and, following the surgery, the results of neuro-otological, including radiological, re-examination indicated a remarkable recovery.

Adolescent↗
PubMed1999

[Thermographic detection of heat radiation in caloric vestibular function tests].

BACKGROUND: Since Bárány; caloric irrigations in the external ear canal have been used for unilateral stimulation of the peripheral vestibular system. However, the mechanism of heat transfer from the auditory canal to the vestibular organ is not completely known. From the physical point of view, three mechanisms may be discussed: heat conduction via the bone, convection via the middle ear gas, or radiation. Feldmann et al. (1991) singled out radiation as a very important factor in this regard. Using high-resolution thermography, we were able to "see" radiation almost directly in temporal bone experiments. METHODS: Using the system of infrared thermovision specially adapted for close-up studies, the effect of calorization can be observed and documented in colored planar thermograms. Fresh temporal bone specimens had to be prepared so as to permit simultaneous observation of the tympanic membrane and the medial tympanic wall. RESULTS: Changes in temperature were readily visible during experimental caloric tests: turning blue indicated cooling and red indicated warming. In the caloric test with 44 degrees C or 30 degrees C water, changes in color of the eardrum appeared immediately. At the very same time, however, an area of the medial tympanic wall also changed color. This velocity of transfer cannot be attained by conduction or convection: heat radiation is the only possible explanation. This could only be demonstrated at the very onset of the reaction; subsequent thermograms became more and more diffuse. In this stage the heat transfer may also be effected by conduction and/or convection. CONCLUSIONS: Thermography demonstrates that radiation is a very important factor in heat transfer; at least in the initial phase of calorization.

Body Temperature↗
PubMed1987

[Current computerized support for vestibular function tests. II. An expert system for the classification of vertigo].

A computerized system (VERTIGO) aimed to the classification and diagnosis of different types of vertigo has been developed. It is based on the shell EXPERT (Weiss and Kulikowski, 1979). At present only the findings arising from patient history are considered as input data and the diagnostic possibilities of the system have been limited to the differential diagnosis of vertigo due to peripheral vestibular disorders. About thirty different forms of vertigo are taken into account. They are clustered in two groups, true vertigo and dizziness. Data are collected through a computer controlled questionnaire. Using the facilities offered by EXPERT, the sequence of the questions can be modified according to the flow of information in order to reproduce different diagnostic strategies. After history taking, the system presents a summary of the available findings followed by its diagnostic conclusions. Different conclusions can be proposed with different degrees of certainty. Conclusions can be justified by the system when required.

Adult↗
PubMed1996

Galvanic-induced postural movements as a test of vestibular function in humans.

Galvanic stimulation produces a postural sway and eye movements in humans. Since galvanic currents are thought to exert their effect at the trigger zone of the vestibular nerve, an intact vestibular nerve should be necessary to produce a response. We have used galvanic stimulation in humans to test the hypothesis that intact vestibular nerve fibers are required to obtain a postural away response. Experimental subjects included normal subjects, patients who had undergone resection of an acoustic neuroma, and patients who had undergone vestibular neurectomy and surgical labyrinthectomy. Our results support the hypothesis that an intact vestibular nerve is necessary to produce a response. Moreover, two patients with recurrent vertigo following vestibular neurectomy and labyrinthectomy, who had absent ice-water caloric test responses in the operated ears, were found to have a positive galvanic response. This result suggested that their recurrent vertigo was based on intact residual vestibular nerve fibers. Although previous research has not yielded a routine clinical use for galvanic stimulation, our results suggest that galvanic stimulation of the vestibular system can provide unique and valuable diagnostic information.

Aged↗
PubMed1994

New tests of vestibular function.

Three new, simple, clinically applicable tests of vestibular function are described. The first is a test of the response of the lateral semicircular canals to high accelerations. The test can even be done at the bedside where it can reveal severe unilateral or bilateral loss of lateral canal function. The test can also be recorded in a laboratory where it might show a less severe deficit of lateral canal function. The second is a simple, laboratory test of utricular function which depends on a subject's ability to align a bar with the subjective visual vertical. Patients with acute unilateral peripheral vestibular lesions invariably set the bar toward the side of the lesion. The third is a laboratory test of saccular function relying on a click-evoked inhibitory vestibulo-collic reflex recorded in the ipsilateral sternomastoid muscle. It can be done with equipment used for auditory evoked potentials.

Functional Laterality↗
PubMed1976

A quantitative rotational test of vestibular function.

This paper describes a quantitative vestibular test in which the stimulus is a constant angular acceleration of 3 degrees/sec2 for 80 sec. The nystagmus output is plotted as cumulative slow phase eye displacement against time and is displayed on an oscilloscope screen along with the output from a mathematical model describing vestibulo-oculomotor function. External dials allow one to change the equation constants thereby altering the shape of the model output. Values for equation constants which match the model output to the patient can be read directly from the dials, thus providing a description of the vestibular system under test. Results indicate that vestibular asymmetry (manifest by spontaneous nystagmus is not uncommon in normals, and only when spontaneous nystagmus is coupled with vestibular gain does one get a measure of abnormality. The significance of altered vestibular parameters in certain pathological states is discussed.

Acceleration↗
PubMed1989

On the search for markers of poor vestibular compensation.

The effectiveness of pursuit gain, cancellation of the vestibulo-ocular reflex, and a clinical oscillopsia test were assessed as vestibular function tests and tests that may allow prediction of which patients would compensate poorly after vestibular surgery. Cancellation of the vestibulo-ocular reflex in 17 patients and 17 control subjects was compared. Pursuit gain for 17 patients was determined for three frequencies at peak velocities of 25 and 50 degrees/sec. The oscillopsia test was administered to seven patients during at least the first 6 postoperative months. We are unable to state that any of these parameters were effective "markers" of impaired compensation, but the oscillopsia test appears to be a useful clinical tool for vestibular examination.

Ear, Inner↗
PubMed1969

Modern tests of vestibular function, with special reference to their value in clinical practice.

The many vestibular tests now available provide the means of accurate localization of lesions at all levels of the vestibular pathways. The value of the test procedures described has been well established in the examination of very many patients over the past twenty years, and though other forms of tests are available only those have been included which have proved to give consistently useful information.Most of these tests can be undertaken by the clinician without the use of any costly equipment, and together with a careful history and examination the diagnosis can in most cases be arrived at. Recognition of the highly important role of optic fixation and ocular deviations on vestibular nystagmus, together with recent facilities to demonstrate this electronystagmographically, may provide additional valuable and more precise information.

Adult↗
PubMed1986

Relative frequency of inferior vestibular schwannoma.

Until quite recently, acoustic tumors were not diagnosed until they had reached relatively large size. Vestibular function tests were positive in a large percentage of these cases. Since vestibular function tests are limited to lesions of the superior branch of the vestibular nerve, it was thought that 90% of vestibular schwannomas arose from the superior vestibular nerve. Recently, as the diagnostic efficiency of auditory tests has improved, many small tumors are being detected. As the size of the tumors decreases, the efficiency of vestibular function testing has also decreased. A review of histologic and surgical literature demonstrates that the earlier estimate is inaccurate, and that only 50% of vestibular schwannomas originate on the superior branch of the vestibular nerve. This warrants a critical review of the value of vestibular function tests in the evaluation of suspected vestibular schwannomas.

Cranial Nerve Neoplasms↗
PubMed1995

Evaluation of the human vestibulo-ocular reflex at high frequencies with a helmet, driven by reactive torque.

A new technique was developed to test the VOR in humans. A tightly but comfortably fitting helmet was provided with an electronically controlled torque motor that rotated a mass around a vertical axis. Acceleration of the motor caused reactive torque of the helmet in the opposite direction which was transmitted to the (freely movable) head. Sinusoidal head oscillations in the frequency range 2-20 Hz (peak-to-peak amplitudes about 10 degrees and 0.1 degrees respectively) were easily achieved, as well as step displacements of the head with accelerations on the order of 1000 degrees/s2. Limitation of the maximum torque and lack of any rigid attachment of the head to a fixed structure made the technique safe and comfortable. Eye and head rotations were recorded, independently of head translations, with eye and head search coils in a homogeneous a.c. magnetic field. In normal subjects, gain was near unity at 2 Hz: above 8 Hz, gain increased progressively toward 1.1-1.3 at 20 Hz. Phase lag increased from a few degrees at 2 Hz to about 45 degrees at 20 Hz. Above 2 Hz, these results were unaffected by visual conditions; lower gains and increased phase lags were found in subjects with bilateral or unilateral vestibular loss. For step displacements, gain (measured in the first 100 ms) was near unity for normals, near zero after bilateral vestibular loss and strongly asymmetrical after unilateral vestibular loss. Thus, the technique seems highly effective in testing vestibular function with minimal contamination by other systems.

Acceleration↗
PubMed2000

[Effects on vestibular function by irradiation in the patients with nasopharyngeal carcinoma].

OBJECTIVE: To investigate effects on vestibular function by irradiation in the patients with nasopharyngeal carcinoma. METHOD: Twenty patients with nasopharyngeal carcinoma were routinely irradiated with dose of 70 Gy (3 cases > 70 Gy). RESULT: Nine cases (45%) were abnormal in vestibular function test after radical irradiation in 20 cases (spontaneous nystagmus n = 3; unlateral canal paresis n = 4; bilateral canal paresis n = 2; bilateral vestibular function absent n = 2). The other 11 cases(55%) were normal in vestibular function test. CONCLUSION: Vestibular function may be damaged after radical irradiation in patients with nasopharyngeal carcinoma. During professional identification, this factor must be respected and vestibular function, cochlear function and tubal function must be separately evaluated.

Adult↗