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PubMed1997

[Clinical study in vertiginuous patients suspected of having neurovascular compression syndrome of the eighth cranial nerve].

Neurovascular compression syndrome of the 5th and 7th cranial nerves has been recognized as the cause of trigeminal neuralgia and hemifacial spasm. On the other hand, it is still difficult to diagnose vertigo as neurovascular compression syndrome of the 8th cranial nerve. To detect some specific finding in this syndrome of the 8th cranial nerve, 5 patients with vertigo with hemifacial spasm were examined for the clinical course and neuro-otological features. In all patients MRI and/or angiography suggested vascular compression against the 8th cranial nerve. The clinical courses of these patients revealed various symptoms resembling benign paroxysmal positional vertigo, vestibular neuronitis and Meniere's disease. Audiograms showed two normal hearing patterns, bilateral high frequency hearing loss probably due to aging in one case, bilateral C5-dip in one and fluctuating unilateral hearing loss like Meniere's disease in one. The prolongation of IPL I-III on auditory brainstem response proposed as a criterion by Møller was detected in one case. No response in the caloric test was found in two cases. These abnormalities in the auditory brainstem response and caloric test appeared to be useful for diagnosis but were uncommon findings in all cases. Electronystagmographic examinations including the eye tracking test, optokinetic nystagmus and optokinetic pattern were all normal. We could not find any specific clinical findings valuable for diagnosis of neurovascular compression syndrome of the 8th cranial nerve. It is proposed that the indication of microvascular decompression should be decided carefully.

Cerebral Angiography↗
PubMed1995

[Multivariate analysis of everyday handicap of patients with dizziness].

A preliminary questionnaire consisting of 30 questions was developed to evaluate handicaps in everyday life for 105 patients with dizziness. Factor analysis divided the questions into 5 principal factors of handicap due to dizziness: 1) disturbance of social activity, 2) body motion precipitating dizziness, 3) limitation of physical activity, 4) emotional disturbance, and 5) disturbance of interpersonal communications. The score of each factor was calculated as the sum of the scores of three principal questions in the corresponding factor. There was no contribution of clinical diagnosis, patient's age or gender, or duration of the disease to the score of each factor. Thus, it is concluded that the reorganized questionnaire which consists of three principal questions in 5 factors can be used for evaluating dizziness handicaps in everyday life. The score of the emotional factor in patients with Meniere's disease was higher than that for other vestibular disease. The score of the body motion factor in patients with vestibular neuronitis was higher than that for vertebro-basilar artery insufficiency. Thus, the re-organized questionnaire can also be used for evaluating the contribution of each factor to dizziness handicaps in everyday life.

Activities of Daily Living↗
PubMed1999

The effect of head orientation on the vestibular evoked potentials to linear acceleration impulses in rats.

OBJECTIVE: To investigate the influence of linear acceleration impulses delivered when the head is held in different static head orientations, on the first wave of the short latency vestibular evoked potential (VsEP). The first wave is the compound action potential of the primary vestibular neurons synchronously activated. BACKGROUND: It has been shown previously that the VsEP elicited in response to linear acceleration is initiated mainly in the otolith organs. These organs are responsive to both dynamic and static linear forces, including gravity. METHODS: VsEPs to linear acceleration stimuli (4g) were recorded when the rats head was oriented so that a) the plane of the utricular macula was aligned with the plane of the stimulus, b) in supine position and c) with the head pitched up and down in various angles with respect to gravity (stimulus-head spatial relation remained constant) as compared to a reference position. RESULTS: With the stimulus aligned with the plane of the utricular macula, the amplitude of the first wave of the L-VsEPs was significantly larger than in the reference position. In the supine position, the amplitude of the first wave was significantly larger and the latency was significantly shorter. The amplitude of the first VsEP wave tended to be larger in the "head up" orientations as compared to the "head down" orientations (not statistically significant). CONCLUSIONS: These results demonstrate the influence of head position and gravity on the VsEPs to linear acceleration impulses, which is in accordance with their otolithic origin.

Acceleration↗
PubMed2002

[Changes in plasma inner ear hormones after endolymphatic sac drainage and steroid-instillation surgery (EDSS)].

We treated 33 cases of intractable Meniere's disease with endolymphatic sac drainage and steroid-instillation surgery (EDSS), attaining good long-term results in vertigo and hearing. To elucidate how EDSS affects the diseased inner ear, we examined changes in plasma inner ear hormones after EDSS. Among inner ear hormones, plasma vasopressin was significantly decreased after EDSS compared to after mastoidectomy. In cases with good long-term results in vertigo and hearing, postoperative plasma vasopressin remained lower over the long term than in cases with poor results. In cases with negative glycerol test results one year after surgery, postoperative plasma vasopressin also remained significantly lower over the long term than in cases with positive results. Previous studies reported that vestibular neurons projected into hypothalamic supraoptic and paraventricular nuclei and that changes in the inner ear pressure were related to plasma vasopressin. Taken together with present findings, this suggests that EDSS may reduce plasma vasopressin through modification of the diseased inner ear environment, resulting in improved inner ear function.

Aldosterone↗
PubMed1975

[Electron microscopic identification of spoon-like contacts in the oculomotor nerve of the trout].

In the nc. n. oculomotorii of the trout exist different types of axonal terminals of second order vestibular neurons. In semithin sections there are observed seldom very large end-knobs (calyciferous endings). Electron microscopic pictures of the same terminal show typical spoon-like endings. A random sample like analysis of the mitochondrial density refers to functional differences between the different types of endings. A intramitochondrial cristaline inclusion in the axoplasma of a neuron is shown.

Animals↗
PubMed2004

Bilateral latero-pontine infarction: a rare syndrome, an unusual imaging.

The authors present one case of bilateral infarction of the brain stem, in the territory of the antero-inferior cerebellar artery. Besides the fact that such bilateral ischaemic lesions are rare, the initial clinical presentation mimicking a vestibular neuronitis indicates that this latero-pontine syndrome may appear as a peripheral disorder. It also reminds clinicians that careful and repeated examinations should always be performed in all patients suffering from vertigo. An unusual iconography is also presented.

Cerebral Infarction↗
PubMed2006

Initial evaluation of vertigo.

Benign paroxysmal positional vertigo, acute vestibular neuronitis, and Meniere's disease cause most cases of vertigo; however, family physicians must consider other causes including cerebrovascular disease, migraine, psychological disease, perilymphatic fistulas, multiple sclerosis, and intracranial neoplasms. Once it is determined that a patient has vertigo, the next task is to determine whether the patient has a peripheral or central cause of vertigo. Knowing the typical clinical presentations of the various causes of vertigo aids in making this distinction. The history (i.e., timing and duration of symptoms, provoking factors, associated signs and symptoms) and physical examination (especially of the head and neck and neurologic systems, as well as special tests such as the Dix-Hallpike maneuver) provide important clues to the diagnosis. Associated neurologic signs and symptoms, such as nystagmus that does not lessen when the patient focuses, point to central (and often more serious) causes of vertigo, which require further work-up with selected laboratory and radiologic studies such as magnetic resonance imaging.

Algorithms↗
PubMed1987

The role of acute and latent virus infections in the pathogenesis of inner ear disturbances.

The possible role of herpesviral infections of the inner ear in suddenly appearing inner ear disturbances was investigated. Experimental pseudorabies virus (PRV, Herpes sui 1) infection of mice and swine was used as a model system. Infected mice represented the productive cycle of PRV infection (acute phase), whereas the latent phase of infection could be tested in swine. From the acutely infected mice the virus could be reisolated from perilymphatic fluid and various parts of the brain. Massive histopathologic alterations and signs of total cell damage to the organ of Corti and the vestibular organ were found. Accordingly, in all of the cells of the inner ear multiple copies of the PRV genome could be demonstrated. We therefore suggest that the disturbances of the inner ear were induced by the acute virus infection. In two latently infected swine (sixty weeks after infection), PRV could not be recovered either from the perilymphatic fluid or from a variety of different neural and extraneural tissues. However, histopathologic changes similar to those found in the acutely infected mice were observed. The presence of viral DNA could be demonstrated by in situ cytohybridization in both sensory and supportive cells of the inner ear and vestibular organ, but not in the corresponding nerve fibers, which is in contrast to the acutely infected mice. The distribution of the viral genome was further analyzed in adjacent areas of the central nervous system. An involvement of acute and latent herpes virus infection in inner ear dysfunction including sudden deafness and vestibular neuronitis in man, might be suggested from the results described. The presented animal model system, PRV-infected swine, should permit further studies on a possible role of herpetic recurrences, particularly with regard to inner ear disturbances.

Acute Disease↗
PubMed1985

[Effects of changes in K+ in the perilymphatic fluid on the activity of vestibular receptors in the frog].

The effect of rapid changes in K+ concentration (from 0 up to 5 mM) in the perilymphatic fluid was tested on ampullar receptor activity in isolated semicircular canals of the frog. The effects of the different K-concentrations were evaluated by recording both the transepithelium potentials (Adc) and the postsynaptic potentials (EPSPs and spikes discharge) led off from the ampullar nerve. The results have clearly demonstrated that crista ampullaris sensory cells are extremely sensitive to K-changes (+/- 0.25 mM). In fact both transepithelial potentials and discharge activity (EPSPs and propagated spikes) of first order vestibular neurones may be decreased or increased by decreasing or increasing the K-concentration in the outer fluid. The possible mechanism of action of K+ on ampullar receptors is discussed.

Animals↗
PubMed1983

[Effects of temperature on postsynaptic potentials at the cyto-neural junctions of the frog semicircular canal].

An analysis of the EPSPs recorded intracellularly from single fibres of the VIII nerve revealed that the resting release of chemical transmitter at the cyto-neural junctions in the sensory organ of frog semicircular canals displays a rather low temperature dependence. This provides evidence that, in labyrinthine receptors, the resting activity is actually "evoked" in nature. A comparison between the discharge of EPSPs and propagated spikes in the VIII nerve fibres has shown that the "encoders" of primary vestibular neurones are highly sensitive to temperature changes and irreversibly damaged at temperatures exceeding 28 degrees C.

Animals↗
PubMed1981

[Vestibular Responses of neurons of the anterior suprasylvian region of the cat cortex and their interaction with responses to acoustic stimulation and stimulation of the facial nerve].

Neuronal responses to stimulation of the vestibular, acoustic and facial nerves were studied in the cat anterior suprasylvian gyrus cortex under chloralose (70 m/kg). The vestibular projection field was found to be adjacent to and partly overlapped with the acoustic and facial projections. The focus of maximum vestibular-evoked activity was located rostrally to the anterior suprasylvian gyrus and was clearly distinct from that evoked by acoustic auditory and facial stimuli. In the focus of maximal activity of the vestibular projection the vestibular afferent input was predominant.

Afferent Pathways↗
PubMed1994

Central projections of the octaval nerve in larval lamprey: an HRP study.

HRP tracing techniques and silver staining methods were used to investigate the central projections of the octaval nerve of the larval sea lamprey (Petromyzon marinus). We compare our findings with those reported for the adult and for other anamniotes. The general pattern of afferent projections (to the ventral octavolateral area of the medulla oblongata and to the cerebellar plate) is similar to that in the adult, although we did not observe projections to the trigeminal, reticular or contralateral medullary areas. We describe the pattern of connections of the octaval afferents with the different octaval nuclei (i.e. subdivisions of the ventral octavolateral area), and report the presence of a small number of efferent vestibular neurons.

Aging↗
PubMed1994

[The interaction of vestibular inputs with differing orientations of the otoliths in a gravitational field].

In alert pigeons Columba livia effects of static tilts about fore-aft and binaural axes (angles of tilts: 30-40 deg) on neck and ocular nystagmus elicited by monaural galvanic stimulation of the lateral semicircular canals with sinusoidal currents (peak amplitudes: 20-100 microA; period: 35 sec) were investigated. It was shown that the same angles of the tilts elicited different changes of horizontal nystagmus parameters in different animals. In some of them changes of quantitative characteristics of opposite-directed nystagmus differed with signs. Data support the correctness of recently (Stolbkov, 1989) proposed scheme of forming vestibulomotor reactions, according to which signals from heterolateral vestibular nuclei, during nystagmus, which are integrated, contain both canal and otolith components independent of stimulus mode addressed to canals or otoliths (separately or jointly). Results suggest also that caloric test may be a source of incorrect conclusions concerning state of vestibular system during static tilts the responses of functionally asymmetric semicircular canals may be symmetric ones. Moreover data suggest that sensitivity of convergent vestibular neurons to the canal signals is different depending on separated or combined canal and otolith stimulations.

Animals↗
PubMed1994

Electro-oculographic findings pre- and post-cochlear implantation.

Vestibular symptoms following cochlear implantation are relatively rare, in spite of well-documented evidence of a significant surviving vestibular neuron population in profoundly deaf individuals. This report details the electro-oculographic (EOG) findings before and after insertion of the Nucleus 22-channel cochlear implant in 25 adults. These findings are correlated to the clinical course of these patients.

Adolescent↗
PubMed1997

[Acute vertigo caused by ischemia of the postero-inferior cerebellar artery or PICA. Apropos of 2 cases].

Based on two cases and a review of the recent literature, we would like to draw attention to the fact that a cerebellar infarction, localised to the territory of the PICA, can present with just a single clinical feature-acute rotary vertigo. Cerebellar vascular accidents remain a little known cause of acute vertigo, often masquerading as a peripheral vestibular disturbance. The main differential diagnosis is vestibular neuronitis. The prognosis is usually good, but the risk of a late recurrence or of a further cerebro-vascular episode is difficult to predict. This uncommon aetiology should not be ignored because of the risk of progression towards a sort of pseudo-tumoral infarct, in which the risk of a fatal outcome remains ever present. In most cases, however, sequelae are few or absent.

Acute Disease↗
PubMed2000

Convergent properties of vestibular-related brain stem neurons in the gerbil.

Three classes of vestibular-related neurons were found in and near the prepositus and medial vestibular nuclei of alert or decerebrate gerbils, those responding to: horizontal translational motion, horizontal head rotation, or both. Their distribution ratios were 1:2:2, respectively. Many cells responsive to translational motion exhibited spatiotemporal characteristics with both response gain and phase varying as a function of the stimulus vector angle. Rotationally sensitive neurons were distributed as Type I, II, or III responses (sensitive to ipsilateral, contralateral, or both directions, respectively) in the ratios of 4:6:1. Four tested factors shaped the response dynamics of the sampled neurons: canal-otolith convergence, oculomotor-related activity, rotational Type (I or II), and the phase of the maximum response. Type I nonconvergent cells displayed increasing gains with increasing rotational stimulus frequency (0.1-2.0 Hz, 60 degrees /s), whereas Type II neurons with convergent inputs had response gains that markedly decreased with increasing translational stimulus frequency (0.25-2.0 Hz, +/-0.1 g). Type I convergent and Type II nonconvergent neurons exhibited essentially flat gains across the stimulus frequency range. Oculomotor-related activity was noted in 30% of the cells across all functional types, appearing as burst/pause discharge patterns related to the fast phase of nystagmus during head rotation. Oculomotor-related activity was correlated with enhanced dynamic range compared with the same category that had no oculomotor-related response. Finally, responses that were in-phase with head velocity during rotation exhibited greater gains with stimulus frequency increments than neurons with out-of-phase responses. In contrast, for translational motion, neurons out of phase with head acceleration exhibited low-pass characteristics, whereas in-phase neurons did not. Data from decerebrate preparations revealed that although similar response types could be detected, the sampled cells generally had lower background discharge rates, on average one-third lower response gains, and convergent properties that differed from those found in the alert animals. On the basis of the dynamic response of identified cell types, we propose a pair of models in which inhibitory input from vestibular-related neurons converges on oculomotor neurons with excitatory inputs from the vestibular nuclei. Simple signal convergence and combinations of different types of vestibular labyrinth information can enrich the dynamic characteristics of the rotational and translational vestibuloocular responses.

Acceleration↗
PubMed1987

[Corticofugal effects on the neuronal activity of the vestibular nuclei in the cat].

Neuronal responses to stimulation of vestibular (V1), motor and orbital brain cortex were recorded extracellularly in lateral and medial vestibular nuclei of bulbar complex in experiments carried on nonanesthetized immobilized cats. Both phasic and (more often) tonic responses mainly of inhibitory type were observed. In morphological experiments the horseradish peroxidase was injected into the above nuclei. Marked neurons were found in the anterior supra- and ectosylvian brain gyri, in the region of cruciform sulcus and orbital cerebral cortex. The obtained data are discussed in the aspect of corticovestibular interaction.

Animals↗