Search results for "Vestibular function tests"
showing 10 items of 17 documents
Vestibular Function after Acoustic Neuroma Removal with Preservation of One Branch of the Vestibular Nerve
2002
Background Vestibular compensation after acoustic neuroma surgery is affected by many parameters. Apart from surgical approach, age of the patient, and comorbidity, the use of rehabilitative vestibular training and the degree of preoperative vestibular compensation play their respective roles. Objective To examine whether and how surgical preservation of one branch of the vestibular nerve affects the compensation process in patients after acoustic neuroma removal. Study design Prospective study involving 29 patients with acoustic neuromas. In 15 patients operated on by the middle fossa or retrosigmoid approach, one branch of the vestibular nerve could be preserved intraoperatively, and the …
Transition from self tilt to object tilt during maintained lateral tilt in parabolic flight.
1991
Abstract 19 young healthy subjects were subjected to parabolic rollercoaster flight. A horizontal luminous line was seen by the subjects in a headfixed goggle device. During the hypergravic phases of parabolic flight the luminous line seemed to rotate into and during the hypogravic phase against the direction of static head tilt. Ocular counter rotation and activity of the neck position receptors cannot explain these subjective rotations. We conclude that information from the otolith system, converging with visual information within the brain, dislocated the headfixed visual target line. While the retinal image of the luminous line remains unchanged, loading and unloading the otoliths in pa…
Vestibular Decruitment
1993
Torok studied the ratio obtained between the responses to two different heat stimulation intensities of the same temperature. A decrease in response to the strong stimulus (i.e., a diminished ratio) was called "vestibular decruitment," and was regarded as a topodiagnostic indicator of central vestibular lesion, reflecting "adaptation" or "fatigue." The authors studied the reliability of vestibular decruitment obtained by Torok's technique in the indication of central vestibular pathology. Twenty-eight normal individuals and 30 patients previously diagnosed by other methods with diffuse pathology of the central nervous system were evaluated. The results obtained show that the two stimuli use…
Static posturography with dynamic tests. Usefulness of biomechanical parameters in assessing vestibular patients.
2012
Abstract Introduction and objective Posturography allows us in evaluating postural control. This study showed the posturographic parameters that were useful for assessing the functional ability to maintain balance in our sample of vestibular patients. Material and methods Of a total of 89 patients, 59 were healthy subjects and 30 had a peripheral vestibular disorder. The subjects were studied using the posturographic NedSVE/IBV system, combining static (Romberg) and dynamic (stability limits and rhythmic weight shifts) tests. We then compared the measurements found in the groups. Results Normal subjects showed significantly lower oscillations than our patients in all of the posturographic p…
Comparative study of the effect of gentamicin on the vestibulo-ocular and visual vestibulo-ocular reflexes in the cat.
1991
The ototoxic effect of an aminoglycoside, gentamicin, on the vestibular system was investigated in cats given daily doses of 40 mg/kg i.m. for 14 days. Periodically, measurements were made of the vestibulo-ocular reflex (VOR) and visual vestibulo-ocular reflex (ViVOR) responses induced by rotatory stimuli at various frequencies from 0.0125 Hz to 0.8 Hz. After the cessation of drug administration, a progressively declining response to VOR stimuli continued, manifested by gain (ratio of peak response to peak stimulus amplitude) and phase relationships. The ViVOR was affected only in the gain measurements. The changes in the response amplitude (gain) were greater for the VOR than for the ViVOR…
Evidence of unilateral isolated utricular hypofunction
2010
The findings demonstrate that an enduring unilateral utricular dysfunction, possibly together with canal hypofunction, can occur after labyrinthine disease or injury. They also suggest that unilateral, isolated utricular dysfunction - or utricle paresis - can occur, representing a novel entity in the differential diagnosis of peripheral vestibular function. The occurrence of subjective visual vertical (SVV) asymmetry in the presence of symmetric vestibular evoked myogenic potentials (VEMPs) also confirms that the information from the utricles, rather than the saccules, dominates SVV estimation.To determine the incidence of unilateral utricular hypofunction.The retrospective clinical study d…
Ocular counterrolling. Some practical considerations of a new evaluation method for diagnostic purposes.
1986
Ocular counterrolling (OCR) data taken from the literature (12 publications) were used to test the best fit (least-square fit) of these measurements with respect to three mathematical models: a sine relation between OCR and the lateral tilt stimulus, a complex cosine-square relation, and a logarithmic relation between OCR gain and tilt. The latter proved to be the best fitting function. On the basis of this model, we attempted to define a physiological transfer function between OCR gain and tilt, which could serve as a reference of normal population, assuming healthy subjects for the investigations applied. Comparison of this physiological range with pathological data demonstrated marked di…
Clinical verification of a unilateral otolith test.
1992
Abstract In a previous study13 we reported promising results for a new test to differentiate in vivo unilateral otolith functions. That study pointed to a need for further validation on known pathological cases. In this presentation we will detail the results gathered on a group of clinically verified vestibular defectives (verum) and a normal (control) group. The subjects in the verum group were former patients of the ENT clinic of the university hospital. These subjects had usually suffered from neurinoma of the VIIth cranial nerve or inner ear infections. All had required surgical intervention including removal of the vestibular system. The patients were contacted usually two or more yea…
Vestibular compensation in cerebellar stroke patients.
2014
Background and purpose There is little evidence about the site where compensatory vestibular mechanisms in patients with cerebellar strokes take place. Methods To determine whether the location of a cerebellar lesion might be a crucial variable in vestibular compensation a sample of 22 patients with cerebellar stroke were tested for graviceptive function in the acute and chronic stage. Results Our statistical anatomical lesion analysis indicated that mainly lesions of the cerebellar hemispheres (lobule V, VI, VIIa) hinder vestibular compensation and might lead to an overcompensation. Conclusions Overcompensation-induced dysfunction can be explained by the absence of cerebellar inhibitory si…
Testing utricular function by means of on-axis rotation
2005
Subjective visual vertical (SVV) estimation during on-axis rotation provides an efficient screening test of utricle function. The survey demonstrates that isolated disorders of peripheral utricular function can occur while SCC function appears normal.The present study aimed to investigate estimation of SVV during constant velocity yaw rotation (with the head held on-axis--to enhance any asymmetry between right and left utricular responses), as a useful screening test.In all, 230 patients were recruited from the dizziness clinic. For each patient, the SVV was estimated (a) while held stationary, and (b) during constant angular velocity (240 degrees/s), with the head centred on-axis. Bitherma…