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At least 73 records · Page 4Linked to original sources
PubMed1993

Review: morphological changes associated with endolymphatic hydrops.

Endolymphatic hydrops of the inner ear is identified as a swelling of the endolymphatic spaces. This morphopathology in man can only be confirmed at post-mortem examination although it is believed to underlie the auditory dysfunction and vestibular disturbances associated with Menière's disease. This is an illusive inner ear disorder characterized typically by the fluctuant hearing loss, tinnitus and episodes of vertigo. Menière's disease remains a major problem in otorhinolaryngology since the cause of the disease is not known and various treatments are recommended, often with unsatisfactory results. Experimentally induced endolymphatic hydrops in the animal model has been developed in order to understand better the consequences of this morphopathology on inner ear structure and function. Further investigations on the model might, in the future, lead to a more efficient management of the disorder.

Animals↗
PubMed1979

Ocular tilt reaction with peripheral vestibular lesion.

Following inadvertent destruction of the left vestibular labyrinth during stapedectomy, a patient developed a transient abnormality of posture consisting of leftward ocular counterrolling, leftward had tilting, and a right-over-left skew deviation. This postural pattern, known as the "ocular tilt reaction," is the normal compensatory response of the dependent utricle to tilting. In this patient, the unopposed action of the intact right utricle was presumably responsible for the appearance of a normal leftward ocular tilt reaction.

Adult↗
PubMed1986

Abnormalities of the brainstem auditory response of the dog associated with equilibrium deficit and seizure.

The brainstem auditory evoked response (BAER) was recorded from 20 dogs, 10 exhibited vestibular deficit, and 10 presented with a history of seizures. Two dogs exhibited both types of signs. Abnormalities of the BAER, prolonged interwave latency, were seen in 8 of the 10 animals with vestibular problems, and in 7 of the 10 animals with seizure history. Several different diagnosis were associated with BAER abnormalities in both groups of animals. In 55.5% of the cases exhibiting abnormalities of the BAER, postmortem evidence of brainstem pathology was not detected. The electroencephalogram (EEG) was normal in three instances of abnormalities of the BAER. The BAER was normal in three dogs with abnormalities of the EEG. The BAER is presented as a useful diagnostic tool for brain lesions in animals with vestibular deficit and seizure history, but appears most useful when used in conjunction with the EEG. Correlations of abnormalities of the BAER and clinical course of disease are discussed.

Animals↗
PubMed1988

Disorders of the vestibular system.

Disorders of the vestibular system are common in veterinary practice and result in a clinical syndrome characterized by head tilt, asymmetric ataxia, and nystagmus. These signs may occur with lesions involving the peripheral or central vestibular structures. Careful neurologic evaluation of the animal and knowledge of surrounding neuroanatomic structures and their functions enable the clinician to differentiate between peripheral and central disorders. Conditions resulting in peripheral vestibular symptoms include idiopathic syndromes, otitis interna, trauma, neoplasia, drug-induced ototoxicity, and congenital disorders. Radiographs of the petrous temporal bone and tympanic bulla and examination of the tympanic membrane are useful in determining the specific etiology. Central vestibular dysfunction may result from inflammatory CNS diseases, neoplasia, trauma, thiamine deficiency, and storage diseases. Cerebrospinal fluid analysis, skull radiographs, and computed tomography are diagnostic tests useful in animals with central vestibular symptoms. Once the etiology is identified, specific therapy may be provided and a more accurate prognosis can be determined.

Animals↗
PubMedDate not supplied

Factors influencing collagen-induced autoimmune ear disease.

In 1981, the authors described a type II collagen-induced autoimmune ear disease (CIAED) model. The purpose of this study was to gather further evidence that this is a sound animal model to use in evaluating inner ear diseases. The temporal bone lesions of CIAED in Lewis and Wistar rats were characterized by the presence of sensorineural hearing loss with mild atrophy of the organ of Corti and spiral ganglion degeneration, vestibular dysfunction with vacuolar degeneration of the crista ampullaris, otospongiosis-like lesions in the tympanic annules, cochlear vasculitis, and eustachian tube disease. Both cellular and humoral immune responses to type II collagen were demonstrated. The induction of ear lesions depends on many factors. In general, animals immunized with antigens in complete Freund's adjuvant showed relatively more severe lesions than animals immunized with antigens in incomplete Freund's adjuvant, but the duration of the immunization seems to be a more important factor in reproducing severe lesions. The strain and the source of the animals are also important factors in autoimmune inner ear diseases, as is the condition of the host animals. Subclinical or clinical mycoplasma infection in the rat markedly reduced the incidence and severity of lesions in type II collagen-induced arthritis. Many researchers did not consider sialoductal adenovirus, widely present among laboratory rats, a lesion-producing factor in rats. Although many factors influence the induction and severity of CIAED, these animal models provide an excellent new avenue of inner ear research.

Animals↗
PubMed1987

Head tilt in horses.

Head tilt in the horse is commonly a sign of either central or peripheral vestibular disease. The confirmation of vestibular disease is based on physical findings, including results of cranial-nerve function evaluation and observation of stance, posture, and gait. Further localization is made by ancillary tests such as cerebral spinal fluid analysis, electrodiagnostic testing, and radiography. The normal anatomy and physiology of the vestibular system, the abnormal clinical signs demonstrated during physical examination, and the various etiologies are discussed.

Animals↗
PubMed1977

Vestibular disease, and its relationship to facial paralysis in the horse: a clinical study of 7 cases.

The signs observed in 6 cases of peripheral vestibular disease included incoordination, head tilt and nystagmus. The intensity of the signs varied greatly with duration of the disease, and in 3 cases facial paralysis was also present. Tympanosclerosis was demonstrable in all cases subject to radiology. Trauma was the causative factor in most cases. The causes of, and relationships between, vestibular dysfunction and concomitant facial paralysis are discussed. The exact etiology of the tympanosclerosis is unknown.

Animals↗
PubMed1979

Head-eye coordination in normals and in patients with vestibular disorders.

Oculomotor response in the absence of vision was examined in 8 normal subjects, 11 unilaterally labyrinthectomised patients and 2 patients with suspected bilateral canal paresis. The experiments involved (a) voluntary oscillation of the head, (b) whole body oscillation on a turntable and (c) stimulation of neck afferents by oscillation of the body with the head fixed. In the patients with unilateral lesions there was a directional preponderance of the slow phase eye velocity towards the side of the lesion which differed significantly from that of the normal population. In the patients with bilateral paresis the oculomotor response to whole body oscillation was negligible, whereas the response to voluntary head movement had a mean gain of 0.45 and at high frequency could not be suppressed when viewing a head-fixed image. The saccadic activity during voluntary head movement was similar in all subjects and was correlated with slow phase velocity.

Eye Movements↗
PubMed1984

Low and high frequency sinusoidal rotational testing in patients with peripheral vestibular lesions.

We found a consistent pattern of response to low and high frequency sinusoidal rotational testing in patients with chronic compensated unilateral and bilateral peripheral vestibular lesions. Gain (peak slow phase eye velocity/peak chair velocity) was decreased and phase lead increased at low frequencies but both measurements approached normal at high frequencies. Asymmetries in gain, when present, were approximately the same in the low and high frequency range. These changes can be explained by a simple first order linear model of the vestibulo-ocular reflex if one assumes that the goal of the compensation process is to maintain gain in the high frequency range.

Electrooculography↗
PubMedDate not supplied

Hearing thresholds of normal and fenestrated deaf pigeons. A behavioural study on hearing with the vestibular organ.

Hearing thresholds were measured for 5 normal pigeons with the heart-rate conditioning method. After extirpation of the membranous cochlea on both sides and fenestration of the lateral canals, hearing thresholds were measured again with the same method at 250, 750 and 1500 Hz. Hearing thresholds found in this way for deaf fenestrated pigeons correspond very well to threshold values for the "Tullio effect". Electrical activity in the vestibular nerve evoked by sound is thought to be the origin of these phenomena.

Animals↗
PubMedDate not supplied

Cochleo-vestibular disturbances in diving.

Insidious development of high-tone sensorineural hearing loss may be associated with diving, but the evidence is not certain and further research is needed. 'Internal ear barotrauma' can cause an acute or relatively acute onset of hearing loss and/or vertigo, and it may be that 'alternobaric vertigo' provides a link between the insidious and acute forms of labyrinthine injury in diving. With deep diving, decompression sickness and other syndromes can also affect the cochleo-vestibular system. These aetiologies and effects will be discussed, together with evidence from an audiometric survey of naval divers and of 5 experimental deep divers.

Cochlea↗