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PubMed1977

[Acute isolated vestibular paralysis. A clinical and electronystagmographic follow-up study in 28 patients].

Twenty-eight patients with unilateral acute vestibular paralysis (vestibular neuronitis) were examined after a period of 4-140 months. Seventeen of these patients were examined by electronystagmography with caloric stimuli at 44 degrees, 30 degrees, 17 degrees and 0 degrees C. Most were free of subjective symptoms only one-third had slight unsteadiness after sudden head movement. Subjective symptoms were independent of the presence of permanent canal paralysis or partial recovery of caloric excitability. Spontaneous nystagmus of 3-6,6% intensities was found in 11 of 17 patients. The normal limit for physiological spontaneous nystagmus should therefore be below 3 degrees/s. The most reliable parameter was the maximum velocity of the slow phase, as a mean value of the 4 caloric responses (values corrected for spontaneous nystagmus). The results were: 6 patients with persistent canal paralysis; 4 patients with considerable hypoexcitability; and 7 patients with moderate hypoexcitability. In no patient complete restoration of normal caloric response was found. This is attributed to the described method of caloric testing, which permits exact measurement of small side differences in excitability.

Acute Disease↗
PubMed1993

Neuronal responses to vestibular and callosal stimulation in the anterior suprasylvian gyrus of the cat.

Neuronal responses to electrical stimulation at the horizontal ampulla (HA), vestibular nerve (at the windows) and corpus callosum (CC) were investigated in neurons in the anterior suprasylvian gyrus of the cat. The field potentials to HA stimulation had short latency: 2.9 +/- 0.3 (mean +/- SD) ms from the stimulus to the onset and 5.6 +/- 1.9 ms to the peak. The focus of the evoked potentials was located in the anterior suprasylvian (ASS) gyrus or near the ASS sulcus. HA stimulation activated 6 neurons out of 674 examined, with the mean latency of 4.3 +/- 1.1 ms. Of these 6, four neurons also responded to window stimulation. Fifty-six neurons responded to window stimulation with the mean latency of 6.1 +/- 2.4 ms. The mean latency for CC stimulation was 1.9 +/- 0.9 ms (n = 76). Four neurons responded to CC stimulation antidromically (mean = 0.9 +/- 0.3 ms) and one of them also responded orthodromically. The convergence of CC inputs in relation to HA or window stimulation was examined. One (17%) of the 6 HA-activated cells responded to CC stimulation, compared with 8 (14%) of the 56 neurons activated by window stimulation. The other 612 neurons did not respond to either HA or window stimulation, and 80 (13%) of the 612 responded to CC stimulation. Therefore, it is concluded that neurons in the ASS gyrus received callosal input equally irrespective of the presence or absence of responses to ampulla or window stimulation. WGA-HRP was injected in the ASS gyrus to identify the passing callosal fibers in the CC. Fibers from the ASS area passed at the rostral third of the CC. The present results indicate that the ASS area received vestibular projection with short latency, but responses of this projection did not seem to be very strong, at least from the present unit study, to HA stimulation. Discussion was made on the poor neuronal responses to electrical HA stimulation in comparison with previous studies. Also consideration was made on neuronal activity to CC stimulation.

Animals↗
PubMed1992

Noradrenergic and cholinergic modulations of corticocerebellar activity modify the gain of vestibulospinal reflexes.

In addition to mossy fibers and climbing fibers, the cerebellar cortex receives noradrenergic and cholinergic afferents. Since the Purkinje (P) cells of the cerebellar vermis (culmen) respond to roll tilt of the animal with a discharge pattern that is out of phase with respect to that of the related lateral vestibular neurons, thus exerting a facilitatory influence on the gain of the vestibulospinal (VS) reflex, we tested the effects of local microinjection into the anterior vermis of noradrenergic and cholinergic agents on these reflexes. In decerebrate cats, unilateral microinjection in the paramedial zone B of the culmen of 0.25 microliters of small doses of alpha 1-, alpha 2-, and beta-noradrenergic agonists (i.e., metoxamine, clonidine, and isoproterenol, respectively) increased the response gain (in impulses/second per deg) of the EMG response of the ipsilateral and to some extent also of the contralateral triceps brachii to animal tilt (at 0.15 Hz, +/- 10 degrees). On the other hand local injection of the corresponding antagonists (i.e., prazosin, yohimbine, and propranolol) either decreased the gain of the ipsilateral triceps brachii to labyrinth stimulation or else prevented the occurrence of the effects induced by the corresponding agonists. An increase in gain of the VS reflexes was also elicited in other experiments by unilateral microinjection either of the nonselective cholinergic agonist carbachol or of the anticholinesterase eserine sulfate. Thus, the effects could be produced by increasing the naturally present amount of acetylcholine. Further experiments indicated that a bilateral increase in the response gain of the triceps brachii to labyrinth stimulation occurred after microinjection of a selective muscarinic (bethanechol) or nicotinic agonist (nicotine), while just the opposite result was obtained after microinjection of the corresponding muscarinic (scopolamine) and nicotinic (hexamethonium, D-tubocurarine) blockers. The effects of the noradrenergic and cholinergic agonists, which persisted for about two hours after the injection, were site specific and dose dependent. It appears, therefore, that the noradrenergic and cholinergic afferents to the cerebellar vermis intervene in the gain regulation of the VS reflexes, possibly by increasing the amplitude of modulation of the P cells to labyrinth stimulation.

Animals↗
PubMed2005

Vertigo and imbalance in children: a retrospective study in a Helsinki University otorhinolaryngology clinic.

OBJECTIVE: To determine medical characteristics of children with vertigo who visited an otorhinolaryngology (ENT) clinic during a 5-year period. DESIGN: A retrospective chart review carried out between 2000 and 2004. SETTING: Helsinki University Central Hospital tertiary referral center ENT clinic. SUBJECTS: A total of 119 children (63 girls and 56 boys), ranging in age from 7 months to 17 years (mean age, 10.9 years at examination). MAIN OUTCOME MEASURES: Patients were identified from the ENT clinic database based on hospital discharge codes, with data stored in the database and the SPSS program applied for statistical analysis. RESULTS: Only 0.7% of children visiting the hospital during the 5-year period had vertigo. Benign paroxysmal vertigo of childhood, migraine-associated dizziness, vestibular neuronitis, and otitis media-related dizziness accounted for vertigo in most of the children. CONCLUSIONS: Vertigo is a rare primary complaint of children in an ENT clinic. In achieving a diagnosis, the most valuable tools are medical history, an otoneurologic examination, electronystagmography, and audiography.

Adolescent↗
PubMed1986

Cytoarchitecture and saccular innervation of nucleus y in the mouse.

The cytoarchitecture and saccular innervation of the mouse nucleus y were investigated by using Golgi, Nissl, and myelin stains and anterograde axonal transport of horseradish peroxidase. Nucleus y was found to be a compact group of cells in a small fiber-free region dorsal to the restiform body. Qualitative and morphometric analyses showed that most (75%) of the nucleus y neurons could not be reliably subdivided into morphologic subgroups, but varied continuously in soma size (15-25 microns), shape (fusiform to stellate), and number of dendrites (two to four), and had sparsely branched dendrites with an average of 3 to 4 spines per 10 microns of length. Three groups of cells that were identified morphometrically accounted for 10% (type I: large stellate cells), 9% (type II: long-dendrite cells), and 6% (type III: elongated soma cells) of the y neurons. Vestibular nerve axons transporting horseradish peroxidase after injury at their origin in the saccular neuroepithelium were found to form a dense terminal meshwork that was virtually co-extensive with the cytoarchitectonic boundaries of nucleus y. Nucleus y was distinguished from the overlying infracerebellar nucleus on the basis of anatomical, cytoarchitectural, and hodological features.

Animals↗
PubMed1989

Afferent and efferent projections of the VIIIth cranial nerve in the lamprey Lampetra japonica.

Anterograde and retrograde transport of horseradish peroxidase was used to examine the afferent and efferent projections of the VIIIth cranial nerve in the lamprey Lampetra japonica. Ganglion cells of the VIIIth nerve are classified into three types on the basis of their morphology. The central processes of these ganglion cells enter the medulla in two groups: the anterior group (mostly thick fibers) and the posterior group (mostly thin fibers). Afferent fibers mainly terminate within the ipsilateral ventral and octavomotor nuclei of the octavolateralis area and within the granular and molecular layer of the cerebellum. Some fibers terminate in the contralateral cerebellum, the medial and dorsal nuclei of the octavolateralis area, the descending nucleus of the trigeminal nerve, some cranial motor nuclei, and the lateral octavus nucleus, which has not been described previously. This small nucleus is located beneath the descending nucleus of the trigeminal nerve near the obex. Within the ventral nucleus, thin fibers occupy the dorsal part and thick fibers occupy the ventral part. The basic projection pattern of the primary afferents of the VIIIth nerve in the lampreys was similar to that of gnathostome fishes that have been studied to date. Cell bodies of the efferent vestibular neurons are located between the ipsilateral trigeminal motor nucleus and the facial motor nucleus. The lateral location of these cell bodies differs from that of all other fish species that have been studied.

Animals↗
PubMed1977

Semicircular canal radii of curvature (R) in cat, guinea pig and man.

The radii of curvature (R) of the horizontal (Rh), anterior (Ra) and posterior (Rp) semicircular canals were measured by a new technique (called ROTA) for cat, guinea pig and man. For each canal, data points from the osseous canal were rotated and plotted by computer such that the plane of the sheet of computer plot corresponded to the plane best fitting that canal. The radius of each osseous canal was determined and where necessary, the radius of the arc of data points was corrected for thickness of the absent tissue. For cat, guinea pig and man there are differences in R between canals within a labyrinth suggesting that if other things are equal there could be differences in the average mechanical sensitivity of the canals, which is consistent with physiological recordings from primary vestibular neurons in the cat. The Rs determined by ROTA are compared with Rs determined by conventional histological means.

Action Potentials↗
PubMed1998

Developmental changes in growth factors released by the embryonic inner ear.

Recent studies have demonstrated a role for neurotrophins in regulating the survival of developing auditory and vestibular neurons. However, the developmental time-course for neurotrophin production and release by inner ear tissues has not been defined. In the present study, neurotrophin-like activity was evaluated from culture medium conditioned by early- or midembryonic stage inner ears. Examination of the proteinaceous properties of conditioned medium revealed a developmental change in growth factor release by the inner ear. Neurotrophin-like molecules were not detected in medium conditioned by early stage otocysts. In contrast, neurotrophin-like bioactivity was detected in medium conditioned by middevelopmental stage inner ears. Western blot analysis revealed that NT-3 was released by the rat inner ear at midstages of inner ear development. ELISA measurements revealed that both NT-3 and BDNF are produced by the middevelopmental stage inner ear, and that NT-3 protein levels are higher than BDNF levels. These results suggest that there are developmental changes in the release of growth factors by the inner ear.

Animals↗
PubMed1991

Medial vestibular nucleus in the guinea-pig. I. Intrinsic membrane properties in brainstem slices.

Intracellular recordings were obtained from medial vestibular nuclei neurones (MVNn) in guinea-pig brainstem slices. Two main distinct neuronal classes were encountered. Type A MVNn (32.3%) were characterized by a broad action potential followed by a deep single afterhyperpolarization, a transient A-like rectification, and a single range of firing in response to current injection. Type B MVNn (47.1%), in contrast, were distinguished by the presence of a thin action potential followed first by a fast and then by a delayed and slower afterhyperpolarization. In addition, they displayed a secondary range of firing in their response to current injection. A majority of B MVNn also had either sub-threshold plateau potentials or low threshold spike bursts or a combination thereof. A third, non-homogeneous class of cells, could not be fitted into either one of the two main classes (20.6%, type C MVNn).

Action Potentials↗
PubMed1978

Response characteristics of semicircular canal and otolith systems in cat. I. Dynamic responses of primary vestibular fibers.

1. The activity of cat semicircular canal and otolith afferents was studied during yaw and roll rotations, respectively, to examine their dynamic behavior. 2. A sinusoidal analysis of the canal afferent activities showed that their dynamic characteristics are similar to those of second order vestibular neurons, except for a two to three-fold lower absolute gain. This agrees with earlier studies using angular acceleration steps. 3. Both divisions of the eighth nerve were sampled so as to examine afferents from both the utriculus and sacculus. Within the range of inputs used (+/- 25 degrees lateral tilt), the presumed sacular afferents (inferior division) showed either a gamma- or beta-response. However, the gain of their response was generally much less than for the afferents of the superior division (mostly utricular). This behavior is to be expected on the basis of receptor orientations and the components of gravity acting upon the macular receptors. 4. In response to ramp changes in angular position, some otolith units showed a phasic-tonic response pattern, i.e., an overshoot followed by an adaptation to a new steady state level of activity. The majority of units showed predominantly tonic responses proportional to displacement. 5. During sinusoidal rotations the predominantly tonic units showed small phase leads of 0 to 15 degrees at 0.025 Hz which remained constant or decreased to 0 to -15 degrees at 1.0 Hz. The gains were flat or increased by up to 2 fold. The phasic-tonic units showed greater phase leads, 10 to 50 degrees, and gains which increased from 2 to 8 fold. 6. This behavior of otolith afferents suggests that they can provide information about both the magnitude and the rate of change of linear acceleration stimuli.

Acoustic Maculae↗
PubMed1982

The use of matrices in analyzing the three-dimensional behavior of the vestibulo-ocular reflex.

The vestibulo-ocular reflex rotates the eye about the axis of a head rotation at the same speed but in the opposite direction to make the visual axes in space independent of head motion. This reflex works in all three degrees of freedom: roll, pitch, and yaw. The rotations may be described by vectors and the reflex by a transformation in the form of a matrix. The reflex consists of three parts: sensory, central, and motor. The transduction of head rotation into three neural signals, which may also be described by a vector, is described by a canal matrix. The neural, motor-command vector is transformed to an eye rotation by a muscle matrix. Since these two matrices are known, one can solve for the central matrix which gives the strength of the connections between all the vestibular neurons and all the eye-muscle motoneurons. The role of the metric tensor in these transformations is described. This method of analysis is used in three applications. A lesion may be simulated by altering the elements in any or all of the three component matrices. By matrix multiplication, the resulting abnormal behavior of the reflex can be described quantitatively in all degrees of freedom. The method is also used to directly compare the differences in brain-stem connections between humans and rabbits that accommodate the altered actions of the muscles of the two species. Finally the method allows a quantitative assessment of the changes that take place in the brain-stem connections when plastic changes are induced by artificially dissociating head movements from apparent motion of the visual environment.

Animals↗
PubMed1994

One-year outcome for patients with a chief complaint of dizziness.

UNLABELLED: OBJECTIVE. To determine the one-year outcome for patients with a chief complaint of dizziness that had persisted at least two weeks. DESIGN: Prospective cohort study. SETTING: Federal teaching hospital. PATIENTS: 100 dizzy patients and 25 control subjects. MEASUREMENTS: The primary outcome was dizziness status (improved or not improved); the secondary outcomes were morbidity and health care utilization. RESULTS: The dizziness resolved for 18 patients, whereas the status improved for 37, stayed the same for 32, and worsened for 11, with two patients lost to follow-up. Thus, 55% of patients whose dizziness had not resolved two weeks after their initial visits improved over the subsequent 12 months. Logistic regression revealed four independent predictors of persistent dizziness at one-year follow-up: dizziness due to psychiatric causes, dysequilibrium, vertigo other than benign positional vertigo, vestibular neuronitis, or migraine (odds ratio, 6.3; 95% CI, 2.1-18.6); daily dizziness (odds ratio, 6.4; 95% CI, 2.0-21.0); dizziness worse with walking (odds ratio, 3.0; 95% CI, 1.1-9.0); and patient had initially feared a serious illness (odds ratio, 0.25; 95% CI, 0.10-0.74). These four factors could be used to classify patients as having either a high (82%), medium (47%), or low (0%) likelihood of improvement at one-year follow-up. One patient died from heart failure, and none developed a serious disease for which dizziness had been a harbinger. Dizziness was not associated with an increased number of clinic visits. CONCLUSIONS: Among patients with a chief complaint of dizziness who are still symptomatic at two-week follow-up, more than half improve within a year. Clinical factors identify patients at higher risk for persistent dizziness.

Cohort Studies↗
PubMed1998

[Characteristics of the innervation of the head and neck].

Innervation of the head and neck differs from other regions of the body in certain respects. In particular, besides the external cuneate nucleus, thick-calibre neck muscle afferents project directly, to the vestibular nuclear complex. This projection is most prominent in segments C2 and 3 and is sparse or absent in more caudal segments. Thus, proprioceptive neck muscle afferents gain direct access to vestibulospinal, vestibulooculomotor and other secondary or even higher order vestibular neurons that receive labyrinthine input. Proprioceptive input via indirect spinovestibular pathways is also most prominent from C2 and 3 compared to more caudal levels. Likewise, thin calibre, mainly nociceptive afferents from cervical segments are channelled via the parabrachial nuclei in the rostral pons to limbic structures different from the targets of thoracolumbar afferents. It is tempting to consider these neuroantomical peculiarities relevant for the pathogenesis of the puzzling symptoms after whiplash injury.

Brain Stem↗
PubMed2000

Afferent diversity and the organization of central vestibular pathways.

This review considers whether the vestibular system includes separate populations of sensory axons innervating individual organs and giving rise to distinct central pathways. There is a variability in the discharge properties of afferents supplying each organ. Discharge regularity provides a marker for this diversity since fibers which differ in this way also differ in many other properties. Postspike recovery of excitability determines the discharge regularity of an afferent and its sensitivity to depolarizing inputs. Sensitivity is small in regularly discharging afferents and large in irregularly discharging afferents. The enhanced sensitivity of irregular fibers explains their larger responses to sensory inputs, to efferent activation, and to externally applied galvanic currents, but not their distinctive response dynamics. Morphophysiological studies show that regular and irregular afferents innervate overlapping regions of the vestibular nuclei. Intracellular recordings of EPSPs reveal that some secondary vestibular neurons receive a restricted input from regular or irregular afferents, but that most such neurons receive a mixed input from both kinds of afferents. Anodal currents delivered to the labyrinth can result in a selective and reversible silencing of irregular afferents. Such a functional ablation can provide estimates of the relative contributions of regular and irregular inputs to a central neuron's discharge. From such estimates it is concluded that secondary neurons need not resemble their afferent inputs in discharge regularity or response dynamics. Several suggestions are made as to the potentially distinctive contributions made by regular and irregular afferents: (1) Reflecting their response dynamics, regular and irregular afferents could compensate for differences in the dynamic loads of various reflexes or of individual reflexes in different parts of their frequency range; (2) The gating of irregular inputs to secondary VOR neurons could modify the operation of reflexes under varying behavioral circumstances; (3) Two-dimensional sensitivity can arise from the convergence onto secondary neurons of otolith inputs differing in their directional properties and response dynamics; (4) Calyx afferents have relatively low gains when compared with irregular dimorphic afferents. This could serve to expand the stimulus range over which the response of calyx afferents remains linear, while at the same time preserving the other features peculiar to irregular afferents. Among those features are phasic response dynamics and large responses to efferent activation; (5) Because of the convergence of several afferents onto each secondary neuron, information transmission to the latter depends on the gain of individual afferents, but not on their discharge regularity.

Animals↗
PubMed1987

The neural generators of the vestibular evoked response.

A new method for the induction and recording of a short-latency vestibular evoked response (VsER) to intense acceleration impulses with skin electrodes was studied in cats. The first two waves, P1 and P2, had latencies of 2.5 and 3.5 ms, respectively, and coincided with the recorded gross neural activity in the vestibular nerve and nuclei, respectively. Single second-order vestibular neurons with low and irregular activity responded to the same acceleration impulses with a latency as short as 3.5 ms.

Animals↗
PubMedDate not supplied

A retrograde double-labeling technique for light microscopy. A combination of axonal transport of cholera toxin B-subunit and a gold-lectin conjugate.

A light microscopical, non-fluorescent, retrograde double-labeling technique is described. Cholera toxin B-subunit (CTb) and a conjugate of wheatgerm agglutinin and bovine serum albumin coupled to 10 nm gold particles (gold-lectin) are both excellent retrograde tracers and, when visualized by means of immunohistochemistry and silver intensification, respectively, may be readily identified within the same cell. This light microscopical retrograde double-labeling technique is illustrated in rat with experiments designed to investigate the collateralisation (1) of vestibular neurons to the spinal cord and oculomotor complex, (2) of spinal neurons to the left and right lateral reticular nucleus, and (3) of inferior olivary neurons to the uvula of the cerebellum. Advantages over fluorescent double-labeling experiments are found in the fact that the diaminobenzidine reaction product as well as the silver/gold deposits do not fade and can be examined in counterstained sections. Moreover, the injection sites can be kept quite small and may be guided by electrophysiological recording through the injection pipette.

Animals↗
PubMed1994

Neurotrophin and neurotrophin receptor mRNA expression in developing inner ear.

Receptors which bind the neurotrophins NGF, BDNF, NT-3 and NT-4/5 were shown to be present in cochlear and vestibular ganglion cells during development, implying a neurotrophic role for these molecules in the inner ear. We have found by in situ hybridization that cochlear and vestibular sensory epithelial cells express BDNF and NT-3 mRNAs, but neither NGF or NT-4 mRNAs, in mouse embryos from embryonic day (E)11.5 through postnatal day (P)1. NT-3 mRNA was expressed throughout the sensory epithelium whereas BDNF mRNA appeared to be localized in hair cells (vestibular) and epithelial precursors of hair cells (cochlea). BDNF mRNA was also expressed in a subpopulation of cells in the cochleovestibular ganglion at E11.5 and E12.5. Additionally, cochlear and vestibular neurons contained mRNAs encoding the neurotrophin receptors p75 and trkB. TrkA mRNA was transiently expressed in cochleovestibular ganglion cells at E12.5. These data suggest that BDNF and NT-3 play a role in cochleovestibular neuron survival and neurite outgrowth during development in the inner ear.

Animals↗
PubMed1991

Role of the visual input in recovery of function following unilateral vestibular lesion in the goldfish. I. Short-term behavioural changes.

Vestibular compensation, i.e. the partial or complete recovery of function following lesion of a labyrinth, has been suggested to be based on a multisensory substitution process involving vestibular, visual and somatosensory information. Teleost fish would seem ideal subjects for testing this proposal, because equilibrium orientation in the intact animal is largely under the bimodal control of the vestibular and visual systems. The role of the visual input in the compensation of behavioural deficits elicited by hemilabyrinthectomy (HL) was studied in goldfish maintained over the first two postoperative hours under different lighting conditions. HL caused severe postural and locomotory symptoms, which were the same or similar under all lighting conditions. The rate at which the various deficits disappeared, however, was dependent not only on the presence of light but also on its direction of incidence. Animals maintained under overhead illumination reached the criterion of successful compensation (completion of 5-min continuous and unimpaired swimming) within 10 min, whilst under unilateral illumination (90 degrees to the vertical) the time to criterion was significantly increased; animals exposed to illumination from below or infra-red illumination showed little or no signs of compensation up to 2 h after HL. It is concluded (1) that the immediately postoperative stage of vestibular compensation in the goldfish represents an integral part of the recovery process, within which all observable deficits can be compensated with remarkable rapidity; and (2) that the visual input is both necessary and sufficient for the compensation of the immediately postoperative deficits. We term this early stage of recovery the 'acute' phase and consider it to be based on a visual substitution process, whereby the missing labyrinthine input to the (partially) deafferented vestibular neurons is functionally replaced by visual afferents.

Animals↗