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PubMed1984

[Combined computer-assisted neuro-otologic diagnosis of inner ear function in children].

Among 10 284 data files of neuro-otological patients of our neuro-otological data bank NODEC III, 8,6% pertain to children between 0 and 15 years of age. 350 (3,5%) of these are in the age group of 0-5 years, 261 (2,5%) in the group of 6-10 years and 267 (2,6%) in the group of 11-15 years. Modern inner ear functional diagnostic methods combine computerised neuro-otological audiometric as well as equilibriometric tests. Ranking of diagnostic applicability and efficiency comprises the following 6 steps of neuro-otological equilibriometric and audiometric tests: Child-adapted psychophysical hearing tests, Perrotatory nystagmus tests via electronystagmography, Postrotatory nystagmus tests via electronystagmography, Acoustic brain-stem evoked potentials ( ABEP ) with 2-channel averager, Caloric vestibular test via electronystagmography, Optokinetic nystagmus test via electronystagmography. It has been proved both clinically and statistically that the perrotatory as well as the postrotatory nystagmus recordings are accepted much better by the preschool children than the caloric test. The latter, however, provides us with superior topodiagnostic information. Acoustically evoked potentials usually require to be performed under sedation in preschool children. Automatic nystagmus evaluation via the computer system NYDIAC immediately yields all the important monocular nystagmus parameters and synoptical test charts, i.e. the butterfly calorigram . The computerbased neuro-otological equilibriometric as well as audiometric investigations should be performed by an experienced and specifically trained otolaryngologist. This diagnostic method promotes intense co-operation with colleagues in paediatrics, ophthalmology, neurology and traumatology.

Adolescent↗
PubMed2003

Dizziness: relating the severity of vertigo to the degree of handicap by measuring vestibular impairment.

OBJECTIVE: We sought to correlate the severity of vertigo and handicap in patients with vestibular pathology according to measures of impairment. STUDY DESIGN AND SETTING: We conducted a prospective assessment of patients with dizziness by means of caloric, rotatory test, and computerized dynamic posturography to estimate impairment. Handicap and severity of vertigo were determined with specific questionnaires (Dizziness Handicap Inventory and UCLA-DQ). RESULTS: A fair relationship were found between severity of dizziness and vestibular handicap. When impairment was taken into consideration, values were still fair and only moderate for a group of patients with an abnormal caloric test as the only pathologic finding. The composite score from the sensory organization test portion of the computerized dynamic posturography is fairly correlated to severity of vertigo and handicap in the whole population of patients, but no correlation was found when they were assigned to groups of vestibular impairment. CONCLUSION: To assess vestibular impairment, the results from several tests must be taken into account. However, vestibular handicap is not solely explained with measurements of impairment and/or severity.

Adult↗
PubMedDate not supplied

Temporary phantom limbs evoked by vestibular caloric stimulation in amputees.

OBJECTIVE: Relationships between the vestibular system and the body schema have been suggested but never demonstrated in amputees. We studied the effects of vestibular stimulation on body representation in amputees focusing on the phantom limb phenomenon. METHOD: Prospective study in 31 amputated subjects of one or several limbs before the age of 16 years. The amputees underwent a caloric vestibular stimulation test, ipsilateral (n = 31) and contralateral (n = 8) to the side of amputation. Amputees were asked to report their perceptions spontaneously and to answer open questions. Four types of perceptions were analyzed: normal phantom, deformed phantom, painful phantom, and no phantom, before, during, and after the vestibular stimulation test. Data were compared between the two groups for pre- and post-test perceptions (chi2 test). RESULTS: Vestibular caloric stimulation provoked temporary perception of a normal phantom limb in 16 of 17 amputees who previously did not experience phantoms. For 12 of 12 amputees who currently experienced deformed or painful phantom limbs, caloric stimulation led to temporary replacement of the abnormal phantom with a non-painful normal phantom. CONCLUSIONS: The phenomena observed: 1) throw light on assumed mechanisms controlling construction of static and dynamic engrams used to produce the body schema; 2) complete the neuromatrix theory proposed to explain the phantom limb phenomenon; and 3) suggest that the vestibular system triggers the procedure of reconstruction of the global body schema.

Adult↗
PubMedDate not supplied

Alcohol and the oculomotor system.

The influence of alcohol on the oculomotor system was observed by means of the caloric eye tracking pattern (CETP) test, the visual suppression test on caloric nystagmus, and the positional nystagmus, eye tracking and gaze nystagmus tests. In Group A (nine cases whose CETP before the intake of alcohol was normal), the influence of alcohol consumption appeared regularly and consistently in the following order: abnormality of CEPT greater than or equal to positional alcohol nystagmus greater than or equal to abnormality of the eye tracking pattern greater than or equal to alcohol gaze nystagmus. On the contrary, in Group B (eight cases whose CETP before the consumption of alcohol was already abnormal), with one exception, the regularity noted in Group A was not observed. This phenomenon may be attributable to the presence of latent disorders of the oculomotor system. In both groups, the duration of the caloric nystagmus itself was slightly shortened and its amplitude somewhat suppressed after the consumption of alcohol. The results were confirmed by experiments in which the subjects kept their eyes open in darkness. On the other hand, when the eyes were kept open in light surroundings, the duration and amplitude of the caloric nystagmus were exaggerated in appearance because the mechanism of visual suppression was disturbed by alcohol.

Adult↗
PubMed1982

Variability and habituation of nystagmic responses to hot caloric stimulation of normal subjects. Evidence that this test may be inapplicable to monitoring drug-induced vestibular toxicity.

Experiments were performed on 25 otoneurologically "normal' subjects to evaluate the hot caloric test as a screening test for aminoglycoside vestibular toxicity. Using portable equipment under non-ideal conditions, it was found that there was a large inter-subject variability in nystagmic response and that, instead of a random test-retest variability, a systematic variation in response occurred on repeated caloric stimulation with water at 44 degrees C. A response decline (habituation) evident in both the maximum slow phase velocity and the maximum frequency occurred at second test, although the inter-test interval ranged from 24 to 72 hours. After a 3-month interval with no intervening tests, the mean value of the maximum frequency reverted back to the original level. However, there was still a significant reduction in maximum slow phase velocity at this time. Some individuals had a sustained reduction in both parameters. Hence it is concluded that the hot caloric test, used under the conditions described in this study, is not a suitable serial screening method for aminoglycoside vestibular toxicity. The reproducibility of this test under other conditions, or any other caloric test, should be established in normal subjects before employing it as a serial screen for aminoglycoside vestibular toxicity.

Adult↗
PubMedDate not supplied

Caloric-eye tracking pattern test: I. Visual suppression and the possibility of simplified differential diagnosis between peripheral and central vertigo.

During the examination of patients who complain of vertigo or who have equilibrium disorders, it is often difficult to determine the etiology of the disorders, that is, to determine whether it is dependent on a peripheral or central vestibular disorder. To attempt to guess the etiology in these cases, we devised a new method: the caloric eye-tracking pattern test. In normal subjects and in patients with peripheral disorders, as is well known, caloric nystagmus has little influence on the eye-tracking pattern. In contrast, in patients with central vestibular disorders, caloric nystagmus evoked abnormalities on the eye-tracking pattern, either superimposed or saccades, in spite of the fact that the eye-tracking pattern before the caloric stimulation is normal. These findings result from the visual suppression mechanism to the vestibular nystagmus. We can say that the visual suppression to the vestibular nystagmus is evoked more strongly bu pursuing a moving visual stimulus than by gazing at a stationary target. These results are interesting, not only form the physiological view point, but also from the clinical view point. There is a possibility of the differential diagnosis between peripheral and central vertigo.

Adult↗
PubMedDate not supplied

Vestibular findings in sensorineural hearing disorders. Results of caloric, oculomotor and hearing tests in 205 patients with unilateral hearing dysfunction.

In 205 patients with unilateral hearing loss, 117 of cochlear and 88 of retrocochlear origin, thorough audiovestibular examinations were performed to establish the occurrence and severity of vestibular dysfunction. The results were also analysed with the aim of determining the relationships between the severity of the hearing loss, the etiology and the topical location of the hearing disorder, on the one hand, and vestibular dysfunction, recorded as reduced caloric sensitivity and occurrence of oculomotor disturbances, on the other. No correlation was found between severity of hearing loss and recordable vestibular dysfunction, in either the cochlear or retrocochlear group of patients, or in the etiological subgroups of these main groups. With respect to the relations between the topic locations of the lesions and the results of vestibular tests, distinct characteristics were observed. In the affected ears, totally extinguished caloric reactions were more than six times as frequent in the retrocochlear group as in the cochlear group and appeared as a specific but rather insensitive sign of acoustic neurinoma. Oculomotor disturbances were only exceptionally observed in patients with cochlear lesions, but were noted in nearly half of the retrocochlear group; when only those patients with lesions of the brain stem or cerebellum were considered, all were found to exhibit such disturbances. The relations between audiometric hearing test pattern, caloric sensitivity and oculomotor disturbances seem to form interesting diagnostic paradigms of great value for the topical localization of audiovestibular disorders.

Auditory Pathways↗
PubMed1976

Acute flexion-extension injury of the neck. Electronystagmographic study of 309 patients.

Three hundred and nine patients, whose chief complaint was dizziness following a flexion-extension type of acceleration neck injury, were examined in the Neurosensory Laboratory of Temple University Health Sciences Center between 1965 and 1972. Specific attention was devoted to vestibular tests, including a search for latent and positional nystagmus, bithermal calorics, and rotatory tests. All tests were performed with the aid of electronystagmography; latent nystagmus was present in 29 percent of the patients, caloric tests were abnormal in 57 percent, and rotatory tests were abnormal in 51 percent. These findings suggest that many of these patients have a verfiable objective vestibular disturbance as a cause of dizziness, even though the neurologic examination may be normal. Furthermore, in order to detect this objective vestibular dysfunction, the patient should be tested with aid of electronystagmography since nystagmus may be inhibited by visual fixation.

Afferent Pathways↗
PubMedDate not supplied

[Significance of comparing the results of caloric and vestibulometric rotation tests].

The use of modified, less laborious, easier endured vestibulometric tests made it possible to facilitate diagnosing Menière's disease and neurinomas of the vestibular nerve. Comparison of nystagmometric findings recorded in the same patient during caloric and rotation tests using the diagnostic model of a bithermal test permitted some assumptions to be made in relation to the mechanisms for nystagmogenesis associated with pathologic states in ear labyrinth and vestibular portion craniocerebral (VIII) nerve. It is found that in the majority of Meniere's disease cases (61%) there is a decrease in an intensity of caloric nystagmus induced by Lasix dehydration effect. This phenomenon can be explained by a reduced difference in energy levels of two complexes of vestibular nuclei and, therefore, by an attenuated afferents to peripheral compartment of vestibular system. In neurinoma of aural nerve, the phenomenon of vestibular recruitment (20%) was noted. The diagnostic model of a bithermal test makes it possible to explain an effect of smoothing out the nystagmic responses induced by an intensive stimulus when used a sinusoidal stepwise test. The observed vestibular recruitment results from the severe disorder of one of the afferent inputs due to destruction of induced by tumor pressure.

Adult↗
PubMed1986

European vestibular experiments on the Spacelab-1 mission: 1. Overview.

During the flight of Spacelab-1 a series of vestibular experiments was performed on the crew by a group of European investigators. Control experiments were carried out on the same subjects pre- and postflight. The tests included caloric stimulation of the ears, threshold measurements of response to linear acceleration, motion sickness provocative stimuli, vestibulo-ocular reflexes during linear and angular stimulation, estimation of the subjective vertical (luminous line measurements) and static ocular counterrotation at various tilt angles. The caloric experiment proved the existence of a nonthermoconvective mechanism of caloric nystagmus in space. Most of the other test results point to a greater dependence on visual and somatosensory than on otolith cues in the microgravity environment. Some results, in particular the raised threshold to perception of linear acceleration in flight and the temporary reduction of ocular counterrotation at lateral tilts postflight, suggest a decreased gain of the otolith system as a possible effect of space vestibular adaptation.

Acceleration↗
PubMed1978

Auditory and vestibular damage in head injuries at work.

A series of 50 unselected patients who reported a head injury to the Workers' Compensation Board of British Columbia were referred to the AudioVestibular Unit of the Vancouver General Hospital for studies of auditory and vestibular function. All patients were interviewed and examined by a neuro-otology team during the course of their investigation. It was found that dizziness was the most common symptom of which they complained (60%), and bleeding from the ear was the least common (4%). Of the 50 patients studied, 32% showed evidence of either auditory and/or vestibular injury. Of the total number studied, 16% had auditory injuries and 26% had vestibular injuries. The most common auditory injury was unilateral partial loss of hearing. Central vestibular dysfunction was the most common vestibular injury. A study of the most effective means of selecting patients from the population with head injuries for referral for audiology and vestibular testing was undertaken. The most effective combination of symptoms for referral is the presence of one or more of the triad: hearing loss, unsteadiness, or loss of consciousness/amnesia.

Accidents, Occupational↗
PubMed1989

[Differential heat diffusion as a factor in the etiology of the caloric nystagmus phenomenon].

Despite the significance of the caloric vestibular test in clinical practice, the origin of the caloric nystagmus phenomenon is still unclear. Several theories which try to explain the functional pathways have been published. However, the bandwidth of the reaction pattern and response times from the start of stimulation to the first responses question their plausibility. Therefore, the present investigation examines and analyses the specific reaction pattern and associated response times in 84 patients. On the basis of this information a simplified computer simulation model involving lumped tissue parameters has been created to study the heat diffusion process during stimulation. Consequently, an attempt was made to utilize the simulated diffusion times to identify those anatomical structures which could participate in the origin of the caloric nystagmus phenomenon and we developed a new hypothesis about its origin.

Body Temperature Regulation↗
PubMed2002

Observations on conduction of caloric stimulation to the middle ear cavity by thermoscanning.

OBJECTIVE: To elucidate the ways in which caloric stimulation conducts and the temperature recovers on the temporal bone by the caloric stimulation test. METHODS: Four cases examined temperature changes of the bony lateral semicircular canal eminence with thermal images by caloric stimulation tests. Changes in the heat distribution were observed by means of a Thermoscan (Nihondenki Sanei Thermotracer 6T67R, Tokyo, Japan). RESULTS: The temperature began to decrease from the external canal and the decrease reached the posterior cranial fossa plate through the middle ear cavity while the stimulation continued. After the end of stimulation, the stimulation advanced in the direction opposite to the order in which it was transmitted and recovered in a manner resembling a mirror image despite the difference in speed. CONCLUSIONS: The way in which the caloric stimulation was conducted and the way in which the temperature recovered were in the opposite direction.

Body Temperature Regulation↗