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At least 19 recordsLinked to original sources
PubMedDate not supplied

Influence of age on results of vestibular function tests. Review of literature and presentation of caloric test results.

Following a bibliographic review of currently known, age-dependent morphological and functional changes of the vestibular and auditory system, results are presented of our investigations concerning the influence of age on the outcome of the caloric test on 102 healthy subjects from six age groups ranging between the ages of 11 and 70 years. They prove, without any doubt, that the absolute values of nystagmic parameters in the caloric test are dependent upon age; but not in such a way that the intensity of reaction decreases with advancing age. On the contrary, they indicate that in awake, healthy subjects of middle and late middle-age, the most intensive reactions occur (maximum slow phase velocity, maximum amplitude, maximum frequency, total number of beats). In addition, based on the statistical analysis, it seems probable that the extent of the side difference of excitability depends upon age. Individuals in their middle years show side differences to a considerably lesser degree than children and elderly subjects. These represent findings which, to our knowledge, are reported here for the first time. Provided our results gain further substantiation, standard values for a true quantitative evaluation of the caloric test could only be determined as in the audiometric functional tests on the basis of larger test series of healthy subjects belonging to different age groups.

Adolescent↗
PubMed1978

[Unilateral deafness (author's transl)].

Unilateral conductive deafness has a readily determined aetiology in most cases. In contrast, unilateral sensorineural hearing loss requires more refined and extensive investigation. The most frequent causes of unilateral sensorineural hearing loss in our patients were sudden deafness, Menière's disease, cranio-vertebral dysplasia and cerebellopontine angle tumors. Early diagnosis of acoustic neuroma or other lesions of the internal auditory meatus or cerebellopontine angle requires special attention. The definitive diagnosis of these tumors often demands intensive clinical investigation but a high degree of suspicion may be entertained following modern routine audiometry, vestibular function testing and radiological examination. The importance of early diagnosis of these lesions is stressed with regard to the mortality rate for larger tumors and to the preservation of facial nerve function. The reliability of different diagnostic investigations is documented.

Brain Diseases↗
PubMed1978

The effect of the endolymphatic subarachnoid shunt operation on vestibular function.

Preoperative vestibular function was studied in 56 patients undergoing the endolymphatic subarachnoid shunt procedure for Ménière's disease by electronystagmographic recording of bithermal air caloric stimulation. Fifty-two percent had normal vestibular function while 48% had a reduced vestibular response on the affected side using 20% difference as being significant. Best results of surgery with relief of vertigo were found in the group of patients with normal preoperative vestibular function (82%) while the group with reduced vestibular response preoperatively showed 63% with a good result. Postoperatively, 81% had a reduced vestibular response in the operated-on ear with 62% obtaining relief of vertigo. In patients with normal vestibular function postoperatively excellent relief of vertigo was obtained. Of patients with normal vestibular function preoperatively, 69% developed a reduced vestibular response postoperatively with only 55% having relief of vertigo. The results of surgery could be predicted more accurately using the results of vestibular function tests than audiometric data. It appears that for best results the endolymphatic subarachnoid shunt procedure should be performed early in the course of Ménière's disease when hearing is fluctuating and vestibular function is normal.

Adolescent↗
PubMed1979

Central vestibular involvement in peroneal muscle atrophy: a preliminary report.

A family is presented in which 6 out of 8 members were found to have peroneal muscle atrophy. Neurophysiological and histopathological evidence for the hypertrophic form of this disease was obtained in 3 patients. Three patients with peroneal muscle atrophy and 1 unaffected family member had abnormal differential caloric tests. This is the first report of an apparently hereditary dysfunction of the central vestibular system associated with a hereditary neuropathy.

Caloric Tests↗
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↗
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↗
PubMed1976

[Pseudocaloric nystagmus (author's transl)].

A pseudocaloric nystagmus is, in its strict sense, a spontaneous nystagmus activated by the unspecific stimulus of syringing the auditory canal. 40 patients with a unilateral, peripheral-vestibular defect were examined electronystagmographically. With most patients the 30 degrees caloric stimulation gave an incorrect result of the degree of hypoexcitability with all parameters (duration, maximum frequency and maximum intensity). This incorrect result was most pronounced with patients after neurectomy of the vestibular nerve, who frequently had a heavily reduced reaction of the healthy ear. For quantitative measurement of genuine pseudocaloric effects, by a special method of examination (as for instance by consideration of the "maximum spontaneous nystagmus"), the "real" vestibular excitability was calculated. Data exceeding this value were regarded as genuine pseudocaloric nystagmus. At stimulation temperatures of 44 degrees to 17 degrees C they were so low as to be negligible. They were only found with 5 of the 40 patients and amounted to only 10-20% of the reaction of the healthy ear. However, with ice water there frequently were considerable pseudocaloric reactions. So testing with ice water is not appropriate.

Caloric Tests↗
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↗
PubMed1979

The accuracy of the simultaneous binaural bithermal test in the diagnosis of acoustic neuroma.

Forty-three patients with a surgically confirmed unilateral acoustic neuroma were studied preoperatively with both alternate and simultaneous binaural bithermal caloric tests using horizontal lead electronystagmography. Twenty-four patients had a significant reduced vestibular response on the side of the tumor utilizing the alternate binaural bithermal calorization of Fitzgerald-Hallpike. The addition of the simultaneous binaural bithermal stimulus improved the diagnostic accuracy of caloric testing from 56% to 86%. The simultaneous test was of particular accuracy in diagnosing the inferior vestibular nerve neuroma. The simultaneous stimulus, which adds only six and one-half minutes to overall testing time, is felt to be a valuable adjunct to the alternate test of Fitzgerald-Hallpike.

Adult↗
PubMed1978

Tobramycin in patients with various infections: a clinical evaluation.

22 patients with various gram-negative infections were treated with tobramycin at a dose of approximately 3 mh/kg body weight/24 h for 7 to 53 (mean 16) days. Therapy was monitored with determinations of drug serum concentrations and renal and audio-vestibular function tests. In 16 patients either cure of clinical improvement were achieved. Two patients did not improve. In another 4 patients the effect of tobramycin therapy could nto be evaluated. One patient exhibited a subclinical vestibular dysfunction and one patient experienced transient tinnitus. In one patient, slight but clinically significant renal impairment occurred.

Adolescent↗
PubMed1977

[The diagnostic value of the Stepping Test of Unterberger (author's transl)].

Of the vestibulo-spinal reactions, the "stepping test" is considered to be the most important, especially for unilateral peripheral vestibular disturbances. Electronystagmography was performed on seven patients after transtemporal neurectomy of the vestibular nerve, 17 patients with a nearly compensated vesitbular defect after vestibular neuronitis, and seven patients after suboccipital removal of acoustic neuromas. These results were then compared to the spontaneous stepping test. The test could not be performed on six of the seven patients with the operated acoustic neuroma, and on three other patients. The test was positive in only ten of the other 22 patients. It was incorrect in five patients and equivocal in seven. A reliable spontaneous vestibulo-spinal reaction with nearly compensated peripheral vestibular defects could not be determined during the present study.

Adult↗
PubMed1978

Criteria for the evaluation of nystagmus.

Suitable criteria are reported for the analysis and evaluation of the caloric nystagmus as well as for the differentiation of the pathological from the physiological spontaneous nystagmus. Relative values for the difference and the directional preponderance, related to the intensity of the total reaction, seem to be the most appropriate criteria for the evaluation of the caloric test. The values obtained in patients should be compared with interquantile areas of healthy subjects. The parameters 'maximum slow phase velocity' and 'maximum frequency' seem most suitable for the assessment of the reaction intensity in the ENG. At present, the examination with Frenzel's glasses represents the best possibility for differentiation between physiological and pathological spontaneous nystagmus.

Adolescent↗
PubMed1975

Superior vestibular nerve sectioning. Experimental studies in squirrel monkeys.

Spontaneous, positional, and paroxysmal positional nystagmus were studied before and after sectioning the superior division of the vestibular nerve and the anterior vestibular artery in squirrel monkeys. Histopathologic study of the temporal bones confirmed the degeneration of the macula utriculi with release of statoconia, but failed to identify the released utricular statoconia within the vestibular endolymphatic space in any animal. Postoperatively the animals consistently demonstrated direction-fixed spontaneous nystagmus until the end of the experiment (five months). Positional tests and Dix-Hallpike maneuver occasionally changed the intensity of the spontaneous nystagmus, but never elicited paroxysmal positional nystagmus. Possible reasons for not demonstrating paroxysmal positional nystagmus in the squirrel monkey are as follows: a resorption of statoconia; slight morphological alteration of the sensory epithelia of the posterior cristae; interference of the posterior crista function due to partial collapse of the membranous ampulla; the existence of interspecies difference; or possibly a faulty hypothesis regarding the etiologic mechanism of benign paroxysmal positional vertigo.

Animals↗
PubMed1976

Clinically relevant physiology of the vestibulo-ocular reflex.

This review attempts to explain those aspects of the physiology of the vestibulo-ocular reflex (VOR) which could be of future clinical value. The literature cited has been selected for its didactic worth to readers with limited time, preferring concise reviews to detailed reports wherever possible. Physiological data provide the background for the following possible improvements in clinical diagnosis: 1) In gaze analysis, coordination of the VOR with other motor patterns can be analyzed. 2) Precision of vestibular tests can be improved by selecting stimuli within the range of natural movements.3) Resolution of the caloric test can be imporved when the change of temperature at the semicircular canal mimics endolymph pressure changes during natural movements. 4) A direct test of the three neuron VOR pathways is possible, but not practicable. 5) Integration of the input signal (transformation from head acceleration to eye position information) can be directly tested. 6) Plasticity (the adaptation to visual requirements) of the VOR can be examined. 7) It is possible to quantify vestibular damage and detect the side of lesion in one test analyzing gain and binocular symmetry of the vertical VOR.

Cerebellum↗
PubMedDate not supplied

[Study on the nature of tonic ocular movement produced during pendular vestibular stimulation (author's transl)].

During vestibular function tests using the pendulum chair, electronystagmography has repeatedly shown that a tonic ocular deviation precedes the change in nystagmus. This tonic movement may be anticipated in respect to the change in the sinusoidal movement of the chair. Greiner, Conraux, Collard and more recently J.B. Causse, have proposed a hypothesis based on the own periodicity of the vestibular system. J. Max explained this phenomenon in terms of a difference in phase with the electronic system. Our investigation suggests another explanation of this phenomenon. Each half-period consists of a acceleration phase and a decelaration phase. Thus within half-period alone there are two successive forms of nystagmus induced. The succession of half-periods gives the usual systagmus response. We consider that the tonic response of the eyes is not an anticipated one in respect to the change in sinusoidal movement of the chair, but rather a delayed one in respect to the reversal in the direction of acceleration.

Acceleration↗
PubMedDate not supplied

Implications of Ewald's second law for diagnosis of unilateral labyrinthine paralysis.

The feasibility of replacement of the caloric test with sinusoidal rotatory stimulations of differing frequencies was investigated in ten normal subjects and seven patients with unilateral labyrinthine paralysis. Testing was performed at frequencies ranging from 0.0125 to 0.2 Hz at 60 degrees/sec and at 0.05 Hz at peak velocities of 30 degrees/sec to 180 degrees/sec. Gain, phase, and asymmetry of the nystagmic responses were measured in these groups. Results indicated that the rotatory test was not reliable enough to be used as the sole measure for identifying patients with unilateral labyrinthine lesions.

Analog-Digital Conversion↗