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PubMed1976

Computer processing of audiological and vestibular data. II. A further note.

This paper provides an addendum to an earlier paper describing the development of a computer record system for patient data. The specific problems addressed pertain to the storage and retrieval of historical information, physical signs and diagnosis. Some preliminary comparisons of audiological and vestibular test results are given for groups of patients with diagnoses of acoustic neuroma, Ménière's disease, temporal bone fracture and vestibular neuronitis.

Diagnosis, Computer-Assisted↗
PubMed1981

[The origin of efferent fibers to the inner ear on reptiles. A HRP study in Caiman crocodilus (author's transl)].

The origin of efferent fibers to the inner ear was studied in Caiman crocodilus. After injection of horseradish peroxidase into the basilar papilla or into the ampullae of the horizontal and anterior semicircular canals, neurons labeled by the granular reaction product of retrogradely transported HRP were found in the medulla oblongata bilaterally. Parent cells of the efferent cochlear bundle were found in the medial reticular nucleus and in the rostroventral division of the superior olive bilaterally. Efferent vestibular neurons were found in the medial reticular nucleus bilaterally with more neurons ipsilateral to the injection site.

Alligators and Crocodiles↗
PubMedDate not supplied

Scarpa's ganglion in the rat and guinea pig.

This study describes the location of the cell-bodies of the primary afferent vestibular neurons (Scarpa's ganglion) in relation to the internal auditory meatus of the temporal bone in rats and guinea pigs. In these species the internal auditory meatus consists of three distinct opening or pores (foramina) into the temporal bone. The superior division of the vestibular nerve emerges from the dorsal-most foramen and the pars superior of Scarpa's ganglion is visible as a ridge or 'frill' which occupies the foramen. The inferior division of the vestibular nerve emerges from the cochlear foramen and the cell-bodies of the pars inferior of Scarpa's ganglion lie in the dorsal and rostral area of this foramen. A thin layer of cell-bodies, the isthmus ganglionaris, stretches across the bony transverse crest separating these two foramen. In the newborn rat Scarpa's ganglion is an ovoid structure lying within the cranial cavity.

Animals↗
PubMed2000

Spatial distribution of semicircular canal nerve evoked monosynaptic response components in frog vestibular nuclei.

Most second-order vestibular neurons receive a canal-specific monosynaptic excitation, although the central projections of semicircular canal afferents overlap extensively. This remarkable canal specificity prompted us to study the spatial organization of evoked field potentials following selective stimulation of individual canal nerves. Electrically evoked responses in the vestibular nuclei were mapped systematically in vitro. Constructed activation maps were superimposed on a cytoarchitectonically defined anatomical map. The spatial activation maps for pre- and postsynaptic response components evoked by stimulation of a given canal nerve were similar. Activation maps for monosynaptic inputs from different canals tended to show a differential distribution of their peak amplitudes, although the overlap was considerable. Anterior vertical canal signals peaked in the superior vestibular nucleus, posterior vertical canal signals peaked in the descending and in the dorsal part of the lateral vestibular nucleus, whereas horizontal canal signals peaked in the descending and in the ventral part of the lateral vestibular nucleus. A similar, differential but overlapping, spatial organization of the canal inputs was described also for other vertebrates, suggesting a crude but rather conservative topographical organization of semicircular canal nerve projections within the vestibular nuclei. Differences in the precision of topological representations between vestibular and other sensory modalities are discussed.

Animals↗
PubMed1984

Disabling positional vertigo.

We have identified a group of patients with vestibular disorders whose symptoms are not consistent with the commonly recognized syndromes such as Meniere's disease, benign paroxysmal positional vertigo, and vestibular neuronitis. These patients have a constant positional vertigo and are often nauseated to an extent that makes them disabled. Their symptoms do not respond to conventional medical treatment or habituating therapy. We have found specific clinical-pathological signs in these patients that indicate that the vestibular nerve is compressed intracranially by blood vessels. Treatment of nine such patients by microvascular decompression of the eighth nerve brought total relief of symptoms in eight patients and improvement in one. We suggest that this syndrome be named disabling positional vertigo.

Adult↗
PubMed1977

The brain as a dream state generator: an activation-synthesis hypothesis of the dream process.

Recent research in the neurobiology of dreaming sleep provides new evidence for possible structural and functional substrates of formal aspects of the dream process. The data suggest that dreaming sleep is physiologically determined and shaped by a brain stem neuronal mechanism that can be modeled physiologically and mathematically. Formal features of the generator processes with strong implications for dream theory include periodicity and automaticity of forebrain activation, suggesting a preprogrammed neural basis for dream mentation in sleep; intense and sporadic activation of brain stem sensorimotor circuits including reticular, oculomotor, and vestibular neurons, possibly determining spatiotemporal aspects of dream imagery; and shifts in transmitter ratios, possibly accounting for dream amnesia. The authors suggest that the automatically activated forebrain synthesizes the dream by comparing information generated in specific brain stem circuits with information stored in memory.

Animals↗
PubMed1970

A short-latency labyrinthine input to the vestibular nuclei in the pigeon.

Electrical stimulation of the pigeon labyrinth evokes responses in many second-order vestibular neurons with a latency shorter than the monosynaptic delay. These early responses are probably due to electrically mediated synaptic transmission, or perhaps to antidromic invasion of cells supplying efferent fibers to the labyrinth. In either case the results demonstrate a difference between cat and pigeon with respect to connections between labyrinth and vestibular nuclei.

Animals↗
PubMed2004

Islet-1 expression in the developing chicken inner ear.

The cell types of the inner ear originate from the otic placode, a thickened layer of ectoderm adjacent to the developing hindbrain. The placode invaginates and forms the otic pit, which pinches off as a small vesicle called the otocyst. Presumptive cochleovestibular neurons delaminate from the anterior ventral part of the otocyst and form the cochleovestibular ganglion of the inner ear. Here we show that the LIM/homeodomain protein islet-1 is expressed in cells of the ventral part of the otic placode and that this ventral expression is maintained at the otic pit and the otocyst stages. Auditory and vestibular neurons originate from this islet-1-positive zone of the otocyst, and these neurons maintain islet-1 expression until adulthood. We also demonstrate that islet-1 becomes up-regulated in the presumptive sensory epithelia of the inner ear in regions that are defined by the expression domains of BMP4. The up-regulation of islet-1 in developing inner ear hair and supporting cells is accompanied by down-regulation of Pax-2 in these cell types. Islet-1 expression in hair and supporting cells persists until early postnatal stages, when the transcriptional regulator is down-regulated in hair cells. Our data is consistent with a role for islet-1 in differentiating inner ear neurons and sensory epithelia cells, perhaps in the specification of cellular subtypes in conjunction with other LIM/homeodomain proteins.

Actins↗
PubMed1994

Effect of muscimol microinjections into the prepositus hypoglossi and the medial vestibular nuclei on cat eye movements.

1. For horizontal eye movements, previous observations led to the hypothesis that the legendary neural integrator necessary for correct gaze holding, adequate vestibuloocular reflex (VOR), and optokinetic nystagmus, was located in the region of the complex formed by the nucleus prepositus hypoglossi (NPH) and the medial vestibular nucleus (MVN). 2. The aim of the present study was to test the respective contributions of the NPH, of the rostral part of the MVN, which contains most second-order vestibular neurons, and of the central part of the MVN to the horizontal integrator. 3. An injection of muscimol was used to inactivate each of these three zones in the cat's brain. Muscimol is a gamma-aminobutyric acid (GABA) agonist. By binding to GABAA receptors, it induces a hyperpolarization of the neurons that nullifies their activity. Muscimol was injected into the brain stem of the alert cat through a micropipette by an air pressure system. 4. The search coil technique was used to record spontaneous eye movements and the VOR induced by rotating a turntable at a constant velocity. VOR was analyzed by a new method: transient analysis of vestibular nystagmus. 5. A unilateral injection of muscimol into the NPH induced a bilateral gaze-holding failure: saccades were followed by a centripetal postsaccadic drift. A vestibular imbalance was also present but it was moderate and variable. The VOR responses were distorted drastically. Through transient analysis of vestibular nystagmus, that distortion was revealed to be due more to a failure of the neural integrator than to an alteration of the vestibular input to the neural integrator. The responses to a rotation either toward the injected side or in the opposite direction were asymmetrical. The direction of that asymmetry was variable. 6. A unilateral injection of muscimol into the rostral part of the MVN caused a vestibular imbalance: in complete darkness, a nystagmus appeared, whose linear slow phases were directed toward the side of injection. 7. A unilateral injection of muscimol into the central part of the MVN induced a syndrome where a severe bilateral gaze-holding failure was combined with a vestibular imbalance. In the light, saccades were followed by a bilateral centripetal postsaccadic drift. In complete darkness, a nystagmus was observed, whose curved slow phases were directed towards the side of injection. The VOR responses were distorted drastically. Here again, that distortion was revealed by our analysis to be due more to a failure of the neural integrator than to an alteration of the vestibular input to the neural integrator.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1995

The role of GABA in NMDA-dependent long term depression (LTD) of rat medial vestibular nuclei.

The role of GABA in NMDA-dependent long term depression (LTD) in the medial vestibular nuclei (MVN) was studied on rat brainstem slices. High frequency stimulation (HFS) of the primary vestibular afferents induces a long lasting reduction of the polysynaptic (N2) component of the field potentials recorded in the dorsal portion of the MVN. The induction but not the maintenance of this depression was abolished by AP5, a specific blocking agent for glutamate NMDA receptors. The involvement of GABA in mediating the depression was checked by applying the GABAA and GABAB receptor antagonists, bicuculline and saclofen, before and after HFS. Under bicuculline and saclofen perfusion, HFS provoked a slight potentiation of the N2 wave, while the N2 depression clearly emerged after drug wash-out. This indicates that GABA is not involved in inducing the long term effect, but it is necessary for its expression. Similarly, the LTD reversed and a slight potentiation appeared when both drugs were administered after its induction. Most of these effects were due to the bicuculline, suggesting that GABAA receptors contribute to LTD more than GABAB do. According to our results, it is unlikely that the long lasting vestibular depression is the result of a homosynaptic LTD. On the contrary, our findings suggest that the depression is due to an enhancement of the GABA inhibitory effect, caused by an HFS dependent increase in gabaergic interneuron activity, which resets vestibular neuron excitability at a lower level.

2-Amino-5-phosphonovalerate↗
PubMedDate not supplied

Comparative aspects of the hodological organization of the vestibular nuclear complex and related neuron populations.

In recent years, axonal tracing and fate mapping studies in avian embryos have revealed a mosaic pattern of hodologically defined neuron groups within the vestibular nuclear complex and related nuclei. Specific vestibular neuron clusters projecting to different targets (spinal, oculomotor, cerebellar) reside within largely segregated neuroepithelial domains. The close relationship between this pattern and the neuromeric organization of the hindbrain suggests a strong link between the expression of specific developmental patterning genes (such as Hox and Pax genes) and the specification of the individual neuron groups. Earlier tracing studies in mammals and more recent tracing studies in anamniote species performed by other workers indicate that many of the hodological features seen in avians are highly conserved in the vertebrate line. Here, we compare and contrast hodological patterns in birds and other vertebrate classes in an attempt to elucidate common denominators that may represent an evolutionary bauplan for vestibular connectivity.

Animals↗
PubMed1981

Vestibular vertigo. A form of polyneuritis?

Vestibular vertigo traditionally has been considered to be of viral origin and some forms (acute vestibular neuronitis, acute labyrinthitis, acute vertigo) may be manifestations of a viral cranial polyneuritis. To test this hypothesis, otoneurologic signs and serum complement-fixation titers to herpes simplex and herpes zoster were determined in 16 patients with acute vertigo during their attack and several weeks later. One hundred unselected patients seen for nonotoneurologic problems served as control subjects. In addition to vestibular nerve abnormality, all patients with vertigo had some form of cranial nerve abnormality that cleared within four weeks of onset. These transient acute cranial nerve findings in patients with vestibular vertigo support the concept of inflammatory polyneuritis, and preliminary studies indicate that an anti-inflammatory agent such as prednisone may be the preferred treatment.

Acute Disease↗
PubMed2004

FGF22 and its close relatives are presynaptic organizing molecules in the mammalian brain.

Target-derived cues promote local differentiation of axons into nerve terminals at sites of synaptic contact. Using clustering of synaptic vesicles in cultured neurons as an assay, we purified putative target-derived presynaptic organizing molecules from mouse brain and identified FGF22 as a major active species. FGF7 and FGF10, the closest relatives of FGF22, share this activity; other FGFs have distinct effects. FGF22 is expressed by cerebellar granule cells during the period when they receive synapses. Its receptor, FGFR2, is expressed by pontine and vestibular neurons when their axons (mossy fibers) are making synapses on granule cells. Neutralization of FGF7, -10, and -22 inhibits presynaptic differentiation of mossy fibers at sites of contact with granule cells in vivo. Inactivation of FGFR2 has similar effects. These results indicate that FGF22 and its relatives are presynaptic organizing molecules in the mammalian brain and suggest new functions for this family of signaling molecules.

Animals↗
PubMed1992

[Automatic analysis by computer of the visual suppression test of pendular rotatory vestibular nystagmus].

This study presents an automatic computerized analysis of the visual suppression test of vestibular nystagmus. Visual suppression is measured during rotatory nystagmus examination. The amplitude variations and the frequency of the nystagmus are computed in the dark and in the light. This allows the computer to furnish with the help of an algorithm the percentage of nystagmus suppressed by ocular fixation. The results of the computerized analysis are compared to a qualitative evaluation. A percentage of 70% and more indicates a normal suppression reflex and corresponds qualitatively to a total or subtotal visual suppression. A percentage smaller than 70% indicates a pathological reflex corresponding qualitatively to a partial, weak or absent visual suppression. The study is based on 149 examinations realised in 12 healthy subjects and 137 patients. The patients are classified into 4 groups: a) 59 patients with peripheral vestibular lesions (Ménière's diseases 21, vestibular neuronitis 15, cupulolithiasis 16, ototoxicity 7), b) 67 patients with central lesions of the cerebellum and the brainstem (multiple sclerosis 23, infratentorial tumors 14, vascular brainstem lesions 14, degenerative diseases of the central nervous system 16), c) 6 patients with supratentorial central lesions (hemispheric vascular lesions 4, supratentorial tumors 2), d) 5 patients with congenital nystagmus. All healthy subjects and all patients with peripheral vestibular lesions have a total or subtotal visual suppression corresponding to computed rates greater than 70% (mean: 86.7% and 83.1%). In cerebellar and brainstem lesions about half the patients (56.8%) present a partial, weak or absent visual suppression corresponding to computed rates inferior to 70% (mean: 52.7%). In supratentorial disorders the visual suppression is total or subtotal with computed rates superior to 70% (mean: 79.2%). By patients with congenital nystagmus the visual suppression is uniformly pathological with computed rates inferior to 70% (mean: 19.2%). The results of the visual suppression test are concordant with those of smooth pursuit in 92.6% of cases and with those of optokinetic nystagmus in 89.3% of cases. This study confirms that the visual suppression test is a useful examination to detect disorders of the cerebellum and brainstem.

Adolescent↗
PubMed1983

[Vertigo--their typical clinical pictures from neurosurgical standpoints].

Although vertigo is commonly encountered in many clinical disciplines, meticulous analysis of the onset and nature of the vertigo is essential not to overlook the vertigo of brainstem or cerebral origin without any other neurological signs and symptoms. Three central vestibular projection pathways and their possible functional roles in relation to vertigo were briefly discussed. To illustrate the characteristic clinical features of vertigo of various origins, 16 typical cases were presented and discussed. Their etiology include Ménière's disease, vertigo of neurovascular compression, sudden deafness, acoustic neurinoma, Rumsay-Hunt's syndrome, BPPN (benign paroxysmal positioning nystagmus), vestibular neuronitis, brainstem infarct, MPPN (malignant persistent positional nystagmus) with brainstem midline hemorrhage, cerebellar hemorrhage followed by orthostatic hypotension, vertiginous epilepsy, TIA from MCA stenosis, intracerebral hemorrhage from a mycotic aneurysm, falx meningioma, subclavian steal phenomenon, and cervical spondylosis. It is wrong and quite dangerous to believe that vertigo of CNS origin should be associated with some definite neurological signs and symptoms and to diagnose the vertigo to be of peripheral origin merely based on normal findings of CT scan and angiography. Recently advanced detailed neurootological investigations are quite helpful in differentiating vertigo of various origins, but may totally overlook the vertigo of serious CNS pathology. For "solo vertigo," the key point is first differentiate BPPN and vertibular neuronitis from others after which careful neurosurgical and neurootological evaluation should be pursued regardless of presence or absence of concomitant neurological findings.

Adult↗
PubMed1998

[The phenomenon of the fixation suppression of caloric nystagmus in the diagnosis of vestibular disorders].

Fixation nystagmus suppression in caloric tests was used in examination of 56 patients suffering from chronic remittent labyrinthopathy, acute labyrinthopathy, vestibular neuronitis, otosclerosis, adhesive otitis media, vertebrobasilar insufficiency, motor disease, chronic remittent vestibulopathy and neurinoma of the VIII nerve. The bithermal test (BT) with electronystagmography was made to calculate the fixation suppression index (FSI). Complete suppression of the caloric nystagmus in at least one BT test appeared to be the most frequent variant of the response (24 cases). This was not dependent on the severity of the vestibular analyzer lesion. In 3 cases FSI of the caloric nystagmus was rather high (> 0.50). Introduction of the period of glance fixation in performance of all the 4 BT tests may serve an additional method in differential diagnosis of the vestibular disorders. The fixation test results should be compared to findings obtained in the other vestibulometric tests.

Acute Disease↗
PubMed1995

Gaba mediated long-term depression (LTD) in the rat medial vestibular nuclei.

As previously demonstrated, high frequency stimulation (HFS) of the primary vestibular afferents always induces a clear, long lasting depression of the polysynaptic (N2) component of the field potentials recorded in the dorsal portion of the medial vestibular nuclei (MVN). The induction of the HFS effect was mediated by the activation of glutamate NMDA receptors, since it was blocked by AP5. The mechanisms at the basis of such a depression were studied. Our results demonstrate that Gaba, acting on both GabaA and GabaB receptors, is involved in mediating this phenomenon. In fact, HFS applied during Bicuculline and Saclofen perfusion, was no longer able to induce an N2 depression, but provoked a slight potentiation. However, the N2 depression clearly emerged after drug wash-out. Furthermore, Bicuculline and Saclofen fully abolished the N2 depression and highlighted the potentiation, when administered after HFS. The possibility that the N2 depression is the result of a homosynaptic LTD can be excluded on the basis of our results. On the contrary, our findings suggest that the depression is due to an enhancement of the Gaba inhibitory effect due to an HFS dependent increase in gabaergic interneuron activity, which resets vestibular neuron excitability at a lower level.

Afferent Pathways↗
PubMed1992

[Immunohistochemistry of the Scarpa's ganglion and the crista ampullaris of patients with Menière disease].

In certain long-lasting cases of Menière's disease with recurrent attacks, despite of saccotomy, the removal of the vestibular ganglion is the only procedure that relieves vertigo. During ganglionectomy of this group of patients all fresh tissues gotten and gathered from operation are frozen immediately and preserved for immunohistochemical assay with direct and indirect incubations. The positive findings such as ASMA+, AEA+ and ANA+ in tissues of patient's own as well as in control tissues further confirmed the results previously reported by us. The immune-complex mediated arteriolar and capillary vasculitis on the basis of an autoimmune disorder as a secondary autoimmune marker might play a dominant role in this patients group. The demyelination of vestibular neurons in the Ganglion Scarpae might be the cause of the Menière symptoms. To confirming the hypothesis, the research plan must be continuously carried out.

Antibodies, Antinuclear↗