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PubMed1972

Otoneurology.

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Animals↗
PubMedDate not supplied

Response of single Purkinje neurons in the flocculus of albino rabbits to caloric stimulation.

The response of Purkinje neurons of the flocculus to caloric stimulation was investigated in the Urethane-chlorarose anesthetized rabbit. Twenty-five of 37 flocculus neurons which responded to ipsilateral caloric stimulation showed an increase in firing response, while 12 neurons showed a decrease. Fifteen of 28 flocculus neurons which responded to contralateral caloric stimulation showed an increase, while the firing of 13 neurons was decreased. Forty-one percent of flocculus neurons responded to ipsilateral caloric stimulation, and 41% responded to caloric stimulation of both sides. Eighteen percent of flocculus neurons responded only to contralateral stimulation. The ipsilateral flocculus may thus be responsible for the major control of the primary vestibular signal flow in the cerebellum.

Animals↗
PubMedDate not supplied

Evidence of direct thermal action upon the vestibular receptors in the caloric test. A re-interpretation of the data of Coats and Smith.

Although Bárány's convection theory has gained wide acceptance, there is strong evidence that the caloric response may include a component resulting from direct thermal stimulation of the vestibular end organs. It is argued on theoretical grounds that important new information could be obtained from a precise determination of the neutral head positions at which caloric irrigation fails to elicit a response. Although experimental studies using a bracketing procedure proved unsuccessful for this purpose, a re-examination of the extensive studies of Coats and Smith revealed that this information was already available. Reinterpreted in this way, their data clearly indicate that the hot and cold components resulting from direct thermal action equate to 42% and 34% respectively of the responses obtained in the planes of maximum reactivity. This is of sufficient magnitude to account for the anomalous findings in Spacelab I. Because of non-linearity in the relationship between neural discharge evoked by caloric irrigation and nystagmus magnitude, this component may be significantly less in the conventional caloric position. For this and other reasons there would seem to be no good reason to re-evaluate the clinical reliability of the caloric test.

Caloric Tests↗
PubMed2001

Vestibular system: anatomy and functional magnetic resonance imaging.

In this article, the authors present evidence that the multisensory parietoinsular cortex in humans is involved in perceiving both verticality and self-motion. This evidence is based on (a) lesional studies in patients who have acute unilateral infarctions and (b) positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) evidence of cerebral activation by use of vestibular caloric stimulation, galvanic stimulation, and optokinetic stimulation.

Animals↗
PubMed1993

A case of Bickerstaff's encephalitis. With special reference to neurotological findings.

The case of a 60-year old male with prodromal common cold symptoms and progression of brain stem involvement with no cardiac or respiratory complications is described. This conformed to the criteria of Bickerstaff's encephalitis. Neurotological examinations, including the OKN test, the caloric test, and the GBST were performed from onset to recovery of the disease. The results of these tests closely reflected the central nervous system disorders each time, but there was a discrepancy in the results of the two test batteries of equilibrium function, the caloric test and the GBST. The caloric test showed bilateral canal paresis while the GBST showed normal responses. These results suggested that the involved area of the vestibular nucleus was localized to the superior portions. Form our clinical observations, we can conclude that neurotological examinations provide more vital information for localized diagnosis and follow-up of the brain stem lesion in Bickerstaff's encephalitis.

Brain Stem↗
PubMed2003

Torsional eye movement responses to monaural and binaural galvanic vestibular stimulation: side-to-side asymmetries.

Vestibular stimulation by head accelerations always involves multisensory activation of the vestibular, somatosensory, and visual systems. Over the past few years, galvanic vestibular stimulation (GVS) has become increasingly popular for testing vestibular function for clinical and research purposes. Although GVS provides a nonphysiological stimulation, it is more selective than natural head accelerations and is thus an attractive tool for such tests. Eye movement responses elicited by GVS mainly consist of torsional and horizontal components, as first described by Hitzig in 1871. Animal experiments have shown that GVS increases the vestibular afferent spike frequency at the cathodal site and decreases it at the anodal site of stimulation. As a continuation of a study on age-dependency of eye movement responses to GVS, we analyzed side-to-side asymmetries in healthy subjects. It is necessary to know the normal range of asymmetry between left- and right-sided stimulation to interpret GVS responses in patients with vestibular diseases.

Adult↗
PubMed1978

Muscle responses and monosynaptic reflexes in falling monkey. Role of the vestibular system.

The free fall has been used in our laboratory as a way to test vestibular function in baboons in order to quantify vestibular compensation in the hemilabyrinthectomized animal. This study presents only those results that concern the contribution of the vestibular system to muscle responses due to sudden fall. EMG activity was recorded from the fully conscious animal using chronic electrodes implanted in various muscles. Spinal monosynaptic reflexes (Hoffmann's and tendon reflexes) were studied in the soleus muscle. Baboons were seated in a special chair suspended from an electromagnet and unexpectedly dropped 90 cm. Experiments were performed in normal, unilateral and bilateral vestibular neurectomized baboons. 1. In normal baboons, results showed a first short-latency response in all tested muscles, followed by a second peak of EMG activity in these muscles. Comparison with data from bilateral vestibular neurectomized baboons demonstrates that normal vestibular function is essential for the appearance of the first peak; the second peak rapidly disappears in our experimental situation where the animal's fall is mechanically braked and interrupted, so the animal does not have to make the postural adjustments necessary for landing, It is suggested that the first peak is concerned with the automatic and reflex control of landing, the second with the voluntary breaking of landing. 2. The modulation of monosynaptic spinal reflexes is closely related to the EMG response in soleus muscle. Facilitation of the H-reflex begins just prior to the onset of the EMG activity and continues as long as the baboon is falling. The T-reflex modulation presents a similar time course except in its early phase where it is depressed. Decrease in T and increase in H-reflexes suggest that the EMG response is most likely due to direct activation of alpha-motoneurons and not by means of the gamma-loop. 3. In unilateral vestibular neurectomized baboons, EMG and reflexological data show the classical asymmetry characterized by a strong decrease of the responses on the side of the lesion, and by a pronounced increase on the contralateral side. It is concluded that this represents the imbalance between the resting discharge of the vestibular neurons, and discloses the influence of labyrinthine afferences at the spinal level. We suggest consequently the use of EMG responses and modulation of spinal reflexes to fall in order to quantify vestibular compensation.

Animals↗
PubMed1984

Retrolabyrinthine vestibular nerve section: a viable alternative to the middle fossa approach.

Vestibular nerve section, whether by the middle fossa or retrolabyrinthine approach, is effective in relieving intractable vertigo while preserving hearing. However, the potential morbidity and technical difficulty of the middle fossa approach have limited its usefulness. In an attempt to determine if the two approaches produce comparable results, we evaluated 52 patients who underwent retrolabyrinthine vestibular neurectomy between April 1981 and March 1983 at the Otologic Medical Group. We compared their audiometric data and questionnaire responses with published data on patients who had a middle fossa vestibular neurectomy. Although differences between the two procedures do exist, the retrolabyrinthine method, with its 93% success rate in improving or resolving vertigo and its zero incidence of total sensorineural hearing loss, offers the surgeon a strong alternative to the middle fossa approach.

Adult↗
PubMed1996

Vestibular dysfunction in chronic inflammatory demyelinating polyneuropathy.

Chronic inflammatory demyelinating polyneuropathy (CIDP) has occasionally been associated with clinical or laboratory evidence (magnetic resonance imaging,[MRI], visual evoked response, and brainstem auditory evoked response [BAER] of cranial neuropathy. In most cases, the relationship of cranial nerve involvement to CIDP remains unclear. A 45-year-old woman noted foot numbness, limb weakness, gait and postural instability, and oscillopsia. An IgG kappa monoclonal gammopathy of undetermined significance was found. Bilateral vestibulopathy was documented by clinical examination, bithermal calorics, rotary chair testing, BAERs, and dynamic posturography. MRI with gadolinium demonstrated enhancement of cranial nerve VIII bilaterally. Over the next 6 years, the patients's relapsing and remitting course of CIDP and vestibulopathy was assessed by quantitative muscle and vestibular function testing (clinically and neurophysiologically), and dynamic visual acuity. There was a striking synchronization between her CIDP and vestibulopathy with respect to clinical course including relapses and responses to immune therapy. The response to therapy, and evidence derived from clinical and laboratory investigations, suggest that the vestibular dysfunction was immune mediated.

Chronic Disease↗
PubMed1993

Recovery of the vestibular function after vestibular neuronitis.

We performed steroid therapy on 34 cases with vestibular neuronitis and compared them with 77 patients not subjected to this therapy to examine the role of recovery of their vestibular function. Since no relation was noted between use of steroid and changes in subjective symptom of dizziness, the use of steroid is likely to facilitate the disappearance of spontaneous nystagmus in the early recovery stage. Canal paralysis recovered significantly by steroid and in cases of slight and moderate paralysis at the onset, recovery was more significant. Steroid therapy is argued to be effective for the recovery of vestibular function in cases of vestibular neuronitis.

Administration, Oral↗
PubMed1985

A new theory for thermal influences on endolymphatic flow.

We applied thermal stimuli to the partly isolated posterior canal of the bullfrog half-head preparation. Warming or cooling stimuli to the canal side changed the activity of the semicircular nerve. Our results suggest that changes in the endolymphatic density might be responsible for convection flow in the semicircular canal as well as calorically induced nystagmus.

Animals↗
PubMed2004

A case of Cronkhite-Canada syndrome with vestibular disturbances.

A 66-year-old Japanese man with Cronkhite-Canada syndrome (CCS) presented with complaints of long-lasting dysequilibrium. On neuro-otological examination, he showed gaze-evoked nystagmus at the rightward and leftward gaze, and saccadic pursuit. On the caloric test, he showed no response in either side, and on the head-impulse test he showed bilateral loss of vestibule-ocular reflexes around the yaw axis, while he had bilateral normal responses on the vestibular-evoked myogenic potential testing. Neuro-otological findings suggested that he had lesions in the peripheral vestibular system as well as the central nervous system. Neurological disorders such as sensory neuropathy have been reported in patients with CCS. This patient's balance problems could be due to CCS itself.

Aged↗
PubMed1983

Otoneurological test results analyzed by means of a quantitative statistical method.

This report is a presentation of an approach to the prediction of cerebellar-pontine (C-P) angle tumors and four peripheral vestibular diseases from a mathematical statistical point of view. The present study was performed in an attempt to quantify multidimensional, quantitative data. The data analyzed were from a total of 143 patients with C-P angle tumors, Menière's disease, sudden deafness, vestibular neuronitis, and benign paroxysmal positional vertigo (BPPV). Tests were carried out mainly on otoneurological parameters. By means of discriminant analysis as employed in the quantification method, the patients were classified in the 4-dimensional space.

Adult↗