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PubMedDate not supplied

Quantification of slow compensatory eye movements in patients with bilateral vestibular loss. A study with a broad frequency-band rotatory test.

Seven patients with bilateral vestibular dysfunction were investigated with a new broad frequency oscillatory test. The vestibular stimulation was of two types: a pseudo-random oscillation in the frequency range 0.5-4 Hz and a sinusoidal frequency sweep from 0.5 to 3.5 Hz. Compensatory eye movements were recorded by EOG. Gain and phase values between eye and head movements were extracted using power spectral analysis technique. Two different visual conditions were used: 1) fixating a stationary target and /) fixating a moving target (visual suppression test). At high frequencies all patients showed a reduced VOR gain compared to normal subjects. At low frequencies gain values were close to normal when using a predictable (sinusoidal) stimulation. With a non-predictable (pseudo-random) stimulation gain values were significantly reduced even at low frequencies. The patients with the most severe loss showed a phase lag at higher frequencies (condition 1). The results in the oscillatory test were compared to subjective symptoms and caloric responses. The new test appears to be better suited to assess the vestibular function in patients with suspected bilateral vestibular loss than the caloric test or other traditional procedures.

Adult↗
PubMedDate not supplied

Long-term deficits of goal-directed vestibulo-ocular function following total unilateral loss of peripheral vestibular function.

Brief whole-body movements (+/- 5 to 170 degrees/s peak velocity; approximately equal to 0.5 s duration), applied during 1.44-s intervals of total darkness while subjects "looked" at a just-viewed target, were used to examine vestibulo-ocular function in 3 patients who had compensated to total unilateral loss of peripheral vestibular function. We found that the combined effects of slow-phase and saccadic eye movements both tended to keep the eyes stabilized on the unseen target. Compensatory slow-phases elicited during rapid head movements ipsilateral to (i.e., towards) the lesion were only about 60% as effective as those elicited during rapid contralateral movements. Compensatory gaze-correcting saccades tended to supplement deficient slow-phase movements, especially during rapid ipsilateral head movement. However, the gaze-correcting effect of saccades was only about half of the required for perfect stabilization. Thus, two functional vestibular deficits were observed during rapid ipsilateral head movements: (1) reduced slow-phase stabilization, and (2) reduced saccadic ability to adequately supplement the deficient slow phases. However, overall vestibular functional capability, as assessed by observation of the net effect of both slow phases and saccades, was much better than would be indicated by conventional observation of slow-phase movements alone.

Adult↗
PubMed2000

[Expression of heat shock protein 70 in immune response of the guinea pig inner ear].

OBJECTIVE: To explore whether the immune response of the inner ear could induce heat shock protein (hsp) 70 in guinea pig cochlea. METHODS: A model of autoimmune inner ear disease (AIED) was established by systemically immunizing the guinea pig with the homologous crude inner ear antigen (CIEAg). The immunized cochleae and normal control cochleae were examined for the expression of hsp70 with techniques of immunohistochemistry and in situ hybridization. RESULTS: In the control animals, the expression of the hsp70-like protein appeared only in the spiral ganglion, whereas in the cochleae with CIEAg immunization, strong expression of the hsp70-like protein and its mRNA appeared in the spiral ganglion as well as in the stria vascularis and the spiral ligament. The hearing thresholds were significantly increased in 10 out of 28 cochleae (35.7%) with CIEAg immunization. CONCLUSION: The results suggest that the immune response of the inner ear can induce the expression of hsp70 in the guinea pig cochlea.

Animals↗
PubMed2000

[The role of heat shock protein 70 and its autoantibody in experimental autoimmune inner ear disease].

OBJECTIVE: To examine the effect of antigen stimulation on induction of the heat shock protein 70(HSP70) in the guinea pig cochlea and to explore the role of HSP70 and its autoantibody in the pathogenesis and diagnosis of autoimmunize inner ear disease (AIED). METHODS: To establish the animal model of AIED, homologous crude inner ear antigen was used to immunize the guinea pig. The expression of HSP70 was detected by immunocytochemistry and the relative staining densities were quantified with a light microscope image analysis system. The autoantibodies against HSP71 in the plasma of animals were tested by Western blot using purified recombinant human HSP71 as antigen. RESULTS: HSP70 presented in the normal guinea pig cochlea at a lower level. After immunological challenge, the levels of HSP70 immunoreactivity in the immunized animals were significantly increased as compared with control animals. Optical densities of cochleae of immunized animals were significantly greater than those of animals in the control group (P < 0.01). Most of the immunized animals had developed autoantibodies against HSP71. The incidence of autoantibody in the experimental group was significantly different (P < 0.01) from the control group. CONCLUSION: Antigen stimulation could lead to an increase in the synthesis of HSP70 in the guinea pig cochlea. The detection of autoantibody against HSP71 might have significance in the diagnosis of AIED.

Animals↗
PubMed1978

Galvanic disruption of vestibulospinal postural control by cochlear implant devices.

All subjects with implanted cochlear stimulators demonstrated evidence of abnormal postural stability without their stimulators activated. Instability increased when they were tested with cochlear stimulation units turned on, and additional instability was demonstrated in four of these subjects when tested in noise. These findings suggest that the electrical stimulation delivered by the cochlear prosthesis is not limited to the auditory system. The precise characteristics of electrical stimulation devices designed for stimulations limited to the cochlea and their spurious effects upon motor performance should be investigated. The design of future intralabyrinthine auditory electrical prostheses must include hardware designs and stimulus paradigms that avoid undesirable vestibular system stimulation.

Adult↗
PubMed1988

Motor proficiency associated with vestibular deficits in children with hearing impairments.

The purpose of this study was to investigate the relationship of vestibular function to motor proficiency, including balance, in children with hearing impairments. Thirteen children with normal hearing and 29 children with hearing impairments, ranging in age from 7 to 13 years, were classified into categories based on vestibular function using neuro-otologic measures (ie, vestibulo-ocular reflex function and posturography). Children in each category were tested for motor proficiency using clinical assessment measures (eg, balance, muscle tone, and coordination). The test results indicated that the children with hearing impairments and normal peripheral vestibular function (n = 7) exhibited normal motor proficiency, including balance. The children with hearing impairments and loss of peripheral vestibular sensitivity (n = 19) also demonstrated normal motor proficiency, except for balance ability. The children with hearing impairments and sensory organization deficits (n = 3), however, exhibited motor deficits in many areas. The results of this study indicate that motor proficiency in children with hearing impairments depends on vestibular function. Interventions for motor deficits in children with hearing impairments, therefore, must consider vestibular function as well as motor performance.

Adolescent↗
PubMed1986

[Significance of postrotatorius II within the scope of the rotatory test].

In 68 patients suffering from acute unilateral vestibular disorders 168 electronystagmograms could be analysed paying special attention to the nystagmographic reactions in the second postrotatory period. When the postrotatorius II was directed to the affected side (in 25% of our cases) this was an indication for an advanced extent of central compensation in the electronystagmogram. There was a good correlation between the postrotatorius II and the other nystagmographic reactions in the per- and postrotatory periods. However, the occurrence of the postrotatorius II agreed neither with the results of the vestibulo-spinal tests (Romberg, Unterberger) nor with the nystagmus findings observed with Frenzel's glasses. In many cases a latent spontaneous nystagmus could be detected with the postrotatorius II. Including the second postrotatory period in the evaluation of the electronystagmograms provides additional information permitting a much better assessment of the extent of central compensation.

Electronystagmography↗
PubMed1987

[Optimization of the immunofluorescence test for antibodies in the serum of patients with inner ear diseases].

Antibodies in the serum of patients with inner ear diseases can be demonstrated immunohistochemically with human kidney tissue. In this study a patient's serum with the typical positive reaction against proximal tubuli (antibodies against microsomes) and a serum with antibodies against mitochondria was tested with different dilutions of the fluorescein marked antiserum (FITC conjugate). For both sera a dilution of 1:160 showed positive reaction. The fluorescence of the control incubation was negligible. Employing the given technical details the immunohistochemical assay of antibodies with human kidney tissue has become a simple and reliable test for the most frequently found antibodies in patients with inner ear diseases.

Autoantibodies↗