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At least 307 records · Page 17Linked to original sources
PubMed1980

Visual-vestibular convergence in the vestibular nuclei of the cat.

Responses from neurons of the vestibular nuclei were recorded in N2O-anaesthetized cats. Most neurons in the rostral parts of the nuclei responded to bimodal visual-vestibular stimulation, following a trapezoidal velocity profile. Both combinations of the two stimuli were tested: rotation of the animal with stationary visual field and rotation with overtaking visual field, i.e. the visual pattern running in the same direction as the turntable with twice the velocity. Some correlation of physiological data with results in corresponding psychophysical experiments were found. As a possible biological function of visual-vestibular convergence a phylogenetic solution for discrimination of body and outer world movement is discussed.

Animals↗
PubMed1984

Changes in the human vestibulo-ocular reflex after loss of peripheral sensitivity.

Quantitative rotational testing was used to study changes in the vestibulo-ocular reflex of patients with unilateral and bilateral peripheral vestibular lesions. Compared with normal subjects, the patients exhibited a characteristic pattern of decreased gain and increased phase lead at low frequencies of sinusoidal stimulation and decreased time constants on impulsive stimulation. By contrast, gain and phase measurements on high-frequency-low-amplitude sinusoidal stimulation were often normal. In the patients with bilateral lesions, the results of caloric testing correlated with the results of low-frequency rotational testing but not with the results of high-frequency testing. There are two main clinical implications of these findings. First, patients with absent response to caloric stimulation (unilateral or bilateral) may have a normal response to high-frequency sinusoidal rotation (i.e., the frequencies that constitute most natural head movements). This probably explains why such patients do not report oscillopsia. Second, low-frequency sinusoidal rotational testing and caloric testing are more sensitive than high-frequency sinusoidal or impulsive rotational testing for detecting early loss of vestibular sensitivity due, for example, to ototoxic drugs.

Adult↗
PubMed1977

[The diagnostic value of the Stepping Test of Unterberger (author's transl)].

Of the vestibulo-spinal reactions, the "stepping test" is considered to be the most important, especially for unilateral peripheral vestibular disturbances. Electronystagmography was performed on seven patients after transtemporal neurectomy of the vestibular nerve, 17 patients with a nearly compensated vesitbular defect after vestibular neuronitis, and seven patients after suboccipital removal of acoustic neuromas. These results were then compared to the spontaneous stepping test. The test could not be performed on six of the seven patients with the operated acoustic neuroma, and on three other patients. The test was positive in only ten of the other 22 patients. It was incorrect in five patients and equivocal in seven. A reliable spontaneous vestibulo-spinal reaction with nearly compensated peripheral vestibular defects could not be determined during the present study.

Adult↗
PubMed2003

Vestibular neuronitis in pilots: follow-up results and implications for flight safety.

OBJECTIVES To report our experience over the past 12 years with the evaluation and follow-up of pilots with vestibular neuronitis and to discuss points relevant to flight safety and the resumption of flying duties. STUDY DESIGN A retrospective, consecutive case series.METHODS Eighteen military pilots with vestibular neuronitis were examined and followed up. A complete otoneurological workup was performed, including both physical examination and laboratory evaluation. The latter included electro-oculography (EOG) and a rotatory chair test using the smooth harmonic acceleration protocol. RESULTS The mean patient age was 35 +/- 6 years (range, 23 to 42 y), and the average follow-up period was 20.5 +/- 12.8 months (mean +/- standard deviation [SD]; (range, 11 to 48 mo). Electro-oculography caloric test on presentation documented significant unilateral hypofunction in all patients. Thirteen of the 18 patients (72%) had abnormal smooth harmonic acceleration test results. None of the pilots reported any symptoms on follow-up. However, five (28%) had positive otoneurological examination findings, and eight (44%) still had significant caloric lateralization (>25%). The average caloric hypofunction was reduced from 67.8% +/- 29.3% at onset to 40% +/- 16% (mean +/- SD, <.05, paired test). Seven of the patients (39%) had additional electro-oculography findings beyond caloric hypofunction. These included spontaneous, positional, and positioning nystagmus. Smooth harmonic acceleration disease on follow-up was documented in eight patients (44%), five of whom had canal paresis. Eleven patients (61%) demonstrated residual vestibular damage on follow-up. In 6 of these 11 cases (55%), the laboratory evaluation revealed vestibular deficits otherwise undiagnosed by the bedside test battery. CONCLUSIONS The vestibular system plays a central role in orientation awareness and is often challenged by flying conditions. The finding that approximately 60% of pilots who have had vestibular neuronitis continue to show signs of vestibular malfunction, despite apparent clinical recovery, emphasizes the need for a complete vestibular evaluation, including specific bedside testing and laboratory examinations, before flying duties can be resumed.

Acute Disease↗
PubMed1978

Criteria for the evaluation of nystagmus.

Suitable criteria are reported for the analysis and evaluation of the caloric nystagmus as well as for the differentiation of the pathological from the physiological spontaneous nystagmus. Relative values for the difference and the directional preponderance, related to the intensity of the total reaction, seem to be the most appropriate criteria for the evaluation of the caloric test. The values obtained in patients should be compared with interquantile areas of healthy subjects. The parameters 'maximum slow phase velocity' and 'maximum frequency' seem most suitable for the assessment of the reaction intensity in the ENG. At present, the examination with Frenzel's glasses represents the best possibility for differentiation between physiological and pathological spontaneous nystagmus.

Adolescent↗
PubMed1981

Diagnostic advantages of the Torok monothermal differential caloric test.

In the Torok monothermal differential caloric test, each ear is irrigated with 10 ml and 100 ml of water at 20 degrees C in 5 and 20 sec., respectively. The intensity of the induced nystagmus is expressed in terms of frequency at culmination. The ratio between the weak and strong caloric responses may be normal of disproportionately large or small. When large, the ratio exceeds 3.5 and is called vestibular decruitment, a sign of labyrinthine disease. A ratio of 1.1 or less is called vestibular decruitment, a sign indicative of posterior fossa abnormality. Of 54 patients showing decruitment, a central lesion was confirmed in 51, an identification rate of 94%. The test is thus valuable in differentiating labyrinthine from retrolabyrinthine lesions.

Adult↗
PubMed2001

Head tilt suppression test as a differential diagnostic tool in vertiginous patients.

The head tilt suppression test has been known to be a diagnostic tool to distinguish between centrally originating dizziness and peripheral vertigo, as the latter enhances the natural spontaneous firing rate of the velocity storage system and decreases the time constant; however, the otolith organ is now considered to be a cause of head tilting effect. Therefore we questioned whether the head tilt suppression test is still worth differential diagnostic tool. We measured the time constant and initial eye velocity of pre- and post-rotatory nystagmus in a velocity step test in nine healthy adults. The time constant was significantly affected by head tilting (p = 0.001), pre- and post-rotatory nystagmus (p = 0.020) and the compounding interaction between them (p < 0.000). The initial eye velocity was also significantly affected by pre- and post-rotatory nystagmus (p = 0.016) and the compounding interaction (p < 0.000), but not by head tilting (Wilks' Lambda = 0.054). The head tilt suppression test is a useful method for the differential diagnosis of vertiginous patients. It is affected by pre- and post-rotatory nystagmus and their interaction, however, other central parameters in vestibular function testing should also be considered in order to obtain an exact differential diagnosis.

Adult↗
PubMed1981

[Pseudocaloric nystagmus (author's transl)].

The effect of bithermal caloric tests on the velocity of spontaneous nystagmus was retrospectively studied in 107 patients with unilateral vestibular areflexia. In 35 out of 107 patients, the velocity or pre-test nystagmus was not lower than 15 jerks in 30 seconds. In our series, spontaneous nystagmus before the caloric test was mostly seen in patients with neuritis or sudden deafness, and as a rule, the tests had little effect on the velocity of the nystagmus. In 7 out of 10 cases of areflexic Mènière's disease spontaneous nystagmus was revealed by caloric tests. Spontaneous pre-test nystagmus was present in 6 out of 29 cases of neurinoma; its velocity was always reduced during the caloric tests. In 14 out of 25 cases of head injury, areflexia was usually compensated. Vestibular compensation can now be defined as the absence of vertigo, of spontaneous nystagmus before and after caloric tests and directional predominance.

Adult↗
PubMed1993

Audiovestibular findings in patients with vestibular neuritis: a long-term follow-up study.

During the years 1980-1981, 19 patients with a mean age of 39 years, given the diagnosis vestibular neuritis were subjected to a caloric bithermal test, a pure tone audiogram and stapedius reflex measurements within 1 week, 3 weeks, 9 weeks and 1 year after the onset of symptoms, respectively. In a majority of the patients the feeling of dysequilibrium and vertigo diminished within the first 3 weeks and the difference in caloric reaction between the two sides also diminished during this period. In 9 of the patients, a uni- or bilaterally elevated stapedius reflex threshold was found. The return of the caloric response was somewhat slower in this group of patients.

Adult↗
PubMed2003

A short latency vestibular evoked potential (VsEP) produced by bone-conducted acoustic stimulation.

In this paper data are presented from an experiment which provides evidence for the existence of a short latency, acoustically evoked potential of probable vestibular origin. The experiment was conducted in two phases using bone-conducted acoustic stimulation. In the first phase subjects were stimulated with 6-ms, 500-Hz tone bursts in order to obtain the threshold V(T) for vestibular evoked myogenic potentials (VEMP). It was confirmed that the difference between bone-conducted auditory and acoustic vestibular thresholds was slightly over 30 dB. The estimated threshold was then used as a reference value in the second part of the experiment to stimulate subjects over a range of intensities from -6 to +18 dB (re: V(T)). Averaged EEG recordings were made with eight Ag/AgCl electrodes placed on the scalp at Fpz, F3, F4, F7, F8, Cz, T3, and T4 according to the 10-20 system. Below V(T) auditory midlatency responses (MLRs) were observed. Above V(T) two additional potentials appeared: a positivity at about 10 ms (P10) which was maximal at Cz, and a negativity at about 15 ms (N15) which was maximal at Fpz. Extrapolation of the growth functions for the P10 and N15 indicated a threshold close to V(T), consistent with a vestibular origin of these potentials. Given the low threshold of vestibular acoustic sensitivity it is possible that this mode may make a contribution to the detection of and affective responses to loud low frequency sounds. The evoked potentials may also have application as a noninvasive and nontraumatic test of vestibular projections to the cortex.

Acoustic Stimulation↗
PubMed2003

Neurotologic issues.

Progress has been made in the diagnosis and treatment of inner ear disorders. Autoimmune inner ear disorders and Ménière's disease (MD), the prototype inner ear disease, are highlighted in this review of current knowledge and contemporary dietary, medical, surgical, and vestibular rehabilitation therapy. A number of other peripheral vestibular disorders are presented and contrasted with MD.

Adult↗
PubMed1990

Results of microvascular decompression of the eighth nerve as treatment for disabling positional vertigo.

A total of 41 patients who underwent microvascular decompression to relieve disabling positional vertigo in one 12-month period were studied. At follow-up examinations 2 1/2 to 3 1/2 years after the operation, 30 patients had total relief of their symptoms or were considerably improved, to the point that they could resume normal work or other activities in which they were not able to engage before the operation. Two of the 41 patients had mild improvement, and the final 9 patients had no change in their symptoms. One patient, who had had a previous vestibular nerve section without improvement, underwent microvascular decompression of the stump as well as decompression of the opposite side with no relief: 3 of these 9 patients had clear signs of bilateral vestibular nerve compression, but elected not to undergo a second procedure at that time. One patient lost hearing as a result of the operation, and 1 who had a second operation suffered a hearing loss and subsequently underwent vestibular nerve section with improvement of the symptoms. Two patients had transient deficits related to cranial nerves IV and X. The remaining patients had no complications from the operation.

Acoustic Impedance Tests↗