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PubMed1992

Electronystagmographic features in some peripheral and central vestibular disorders: application of multiple discriminant analysis of electronystagmographic parameters.

In routine clinical electronystagmographic (ENG) tests (postrotatory, optokinetic, caloric and tracking tests), eye movement signals were analyzed and a multiple discriminant analysis was carried out with the aid of a microcomputer. Six parameters were selected and, based on these, two functions for discriminating between peripheral and central disorders were established. Discrimination between 35 patients with peripheral lesions and 15 patients with central lesions was made with a correct classification rate of 97.1 and 86.7%, respectively. These rates are significantly higher than that of any single ENG test analysis. Our results indicate that the clinical application of ENG can be improved by searching for more sensitive ENG parameters and adopting the comprehensive analysis approach.

Adult↗

PubMed1997

[The relationship between ocular abnormalities and MRI findings in patients with spinocerebellar degeneration].

We studied the relationship between MRI findings and ocular abnormalities in 46 patients with spinocerebellar degeneration. MRI was performed for all patients. In order to evaluate the severity of atrophy in the brainstem and cerebellum, we delineated the region of the pons, mesencephalic tegmentum, medulla oblongata, cerebellar hemisphere, and vermis on a typical section of their T1 weighted image. Each area or the longest diameter of each regions were measured by using a computed graphic analyzer. The data were compared with those of 10 normal subjects and the severity of atrophy in each region was quantitatively estimated. In all of the patients, electro-oculographic tests including gaze nystagmus, positional and positioning nystagmus, smooth pursuit eye movements (smooth pursuit), optokinetic nystagmus test (OKN), horizontal saccade test, and visual suppression of the caloric nystagmus test (VS test) were examined. Eight patients with rebound nystagmus showed more severe atrophy than those of 38 patients without rebound nystagmus in the cerebellar hemisphere and vermis. Nine patients with apogeotrophic derection changing nystagmus indicates more severe atrophy than those of 35 patients without it in the cerevellar hemisphere, pons, mesencephalic tegmentum, medulla oblongata. Twenty three patients who showed severe impairments of OKN, 11 patients with a burst phenomenon on VS test and 19 patients with significantly reduced saccade velocity showed particularly severe pontine atrophy. A significant atrophic change in the pons and medulla oblongata was seen in 4 patients with severely impaired pursuit eye movements. Our finding that there is good correlation between ocular abnormalities and markedly atrophic regions on MRI support the neurophysiological findings which had been reported concerning the generation of ocular abnormalities in humans and animals.

Adult↗

PubMed1984

Effects of rectilinear acceleration and optokinetic and caloric stimulations in space.

During the flight of Spacelab 1 the crew performed a number of experiments to explore changes in vestibular function and visual-vestibular interactions on exposure to microgravity. Measurements were made on the threshold for detection of linear oscillation, vestibulo-ocular reflexes elicited by angular and linear movements, oculomotor and posture responses to optokinetic stimulations, and responses to caloric stimulation. Tests were also conducted on the ground, during the 4 months before and on days 1 to 6 after flight. The most significant result was that caloric mystagmus of the same direction as on the earth could also be evoked in the weightless environment.

Acceleration↗

PubMedDate not supplied

[Effect of caloric stimulation of the vestibular apparatus on hearing function].

Changes of bone-conduction thresholds for tonal signals (250 and 2000 Hz) in each car due to caloric vestibular tests were studied in 60 healthy test subjects (32 men and 28 women). These changes were found in 48 subjects. In most cases perceptual thresholds decreased (by 7.3 dB on the average) and in few cases increased (by 8.3 dB on the average). The sign of alteration was independent of the tonal vestibular test or the number of examinations. The threshold returned to the norm for a long time (30 min or more). These findings suggest that the interaction may be governed by the principles that function in other sensory systems. It is recommended to carry out audiological examinations prior to vestibular tests in order to avoid distortions of the results.

Adolescent↗

PubMedDate not supplied

Quantification of slow compensatory eye movements in patients with bilateral vestibular loss. A study with a broad frequency-band rotatory test.

Seven patients with bilateral vestibular dysfunction were investigated with a new broad frequency oscillatory test. The vestibular stimulation was of two types: a pseudo-random oscillation in the frequency range 0.5-4 Hz and a sinusoidal frequency sweep from 0.5 to 3.5 Hz. Compensatory eye movements were recorded by EOG. Gain and phase values between eye and head movements were extracted using power spectral analysis technique. Two different visual conditions were used: 1) fixating a stationary target and /) fixating a moving target (visual suppression test). At high frequencies all patients showed a reduced VOR gain compared to normal subjects. At low frequencies gain values were close to normal when using a predictable (sinusoidal) stimulation. With a non-predictable (pseudo-random) stimulation gain values were significantly reduced even at low frequencies. The patients with the most severe loss showed a phase lag at higher frequencies (condition 1). The results in the oscillatory test were compared to subjective symptoms and caloric responses. The new test appears to be better suited to assess the vestibular function in patients with suspected bilateral vestibular loss than the caloric test or other traditional procedures.

Adult↗

PubMed1993

Audiovestibular findings in patients with vestibular neuritis: a long-term follow-up study.

During the years 1980-1981, 19 patients with a mean age of 39 years, given the diagnosis vestibular neuritis were subjected to a caloric bithermal test, a pure tone audiogram and stapedius reflex measurements within 1 week, 3 weeks, 9 weeks and 1 year after the onset of symptoms, respectively. In a majority of the patients the feeling of dysequilibrium and vertigo diminished within the first 3 weeks and the difference in caloric reaction between the two sides also diminished during this period. In 9 of the patients, a uni- or bilaterally elevated stapedius reflex threshold was found. The return of the caloric response was somewhat slower in this group of patients.

Adult↗

PubMed1988

Clinico-statistical study on acoustic tumors with sudden hearing loss.

Acoustic tumors associated with sudden hearing loss were studied clinico-statistically to clarify the differential diagnosis between so-called sudden deafness and acoustic tumor of this type. A significant difference was found in the frequency of such abnormalities as gaze nystagmus, canal paresis in the caloric (nystagmus) test, inhibition of optokinetic nystagmus, dilatation of the internal auditory canal, and cranial nerve signs. However, there was no significant difference in such symptoms as preceding upper respiratory tract infection and rotatory vertigo at the onset of sudden deafness. In this study, most of the patients with sudden deafness had tumors of 2 cm or larger in diameter. Apart from the atypical feature of sudden onset, the acoustic tumors of this type have several characteristics. Therefore, the differential diagnosis of two diseases is not difficult if the possibility of acoustic tumor is taken into consideration and the above tests are performed for equivocal cases. The CT scan provides the most useful information for making a definite diagnosis of acoustic tumors in cases of this type.

Audiometry, Pure-Tone↗

PubMed2000

Caloric eye-tracking pattern test: 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, often identifying the etiology of the disorders is difficult (i.e., determining whether it is dependent on a peripheral or a central vestibular disorder). To attempt to determine 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 in the eye-tracking pattern, either superimposed or as saccades, despite the fact that the eye-tracking pattern before caloric stimulation was normal. These findings result from the visual suppression mechanism to vestibular nystagmus. We can conclude that the visual suppression to vestibular nystagmus is evoked more strongly by pursuing a moving visual stimulus than by gazing at a stationary target. These results are interesting, not only from the physiological viewpoint but from the clinical viewpoint. The differential diagnosis should include both peripheral and central vertigo.

Adult↗

PubMed2000

Audiovestibular findings and location of an acoustic neuroma.

Forty-one patients with unilateral acoustic neuroma (AN) were diagnosed by magnetic resonance imaging (MRI) between 1992 and 1997. All cases were analyzed with respect to tumor location and the results of audiometric examinations, auditory brainstem response (ABR) testing, and electronystagmography (ENG). Tumor location was determined by MRI and cases were divided into intracanalicular and extracanalicular sites. Intracanalicular tumors were significantly smaller than the extracanalicular ones The pure-tone hearing thresholds were better in ears with intracanalicular lesions than in those with extracanalicular ones. Respectively, speech reception thresholds were 33 dB and 45 dB, and speech discrimination scores 79% and 65%. ABR was abnormal in 98% of ANs, but was insufficient for determining tumor location. The ENG pursuit test was more frequently normal and the caloric side difference was smaller in ears with intracanalicular than extracanalicular AN. These findings show that the results of pure-tone and speech audiometry and ENG are better in ears with intracanalicular AN, while ABR results are similar regardless of tumor location.

Audiometry, Evoked Response↗

PubMed2002

[Neurotological long-term follow-up in Minamata disease in Niigata, Japan].

To determine the long-term influence of organic mercurial intoxication on audiological and equilibrium findings, we followed up 36 patients neurotologically during 1980-1987 and 1991-2000 at Kido Hospital in Niigata. Typical findings were as follows: 1. In pure-tone audiometry, 24 of 72 ears (33%) showed slight hearing deterioration and 3 (4%) showed improvement. 2. Spontaneous nystagmus had disappeared in 5 patients (14%), but appeared in new 13 patients (36%). Positional nystagmus did not improve in any patient, and deteriorated in 11 (31%). 3. In optokinetic nystagmus (OKN) tests, especially in vertical OKN test showing significant deterioration (44%). 4. The caloric nystagmus test showed marked deterioration (47%). Body-equilibrium testing showed slight deterioration in 11 patients (31%) and improvement in 5 (14%). Neurotological findings thus varied widely among patients and we were concluded that these differences were caused both by duration of methyl mercury contamination and by aging factors in patients.

Adult↗

PubMed1987

Caloric-induced nystagmus with isoelectric electroencephalogram.

Caloric vestibular testing induced nystagmus in a patient with an isoelectric electroencephalogram after cardiopulmonary arrest. This has been demonstrated previously in patients in a chronic persistent vegetative state with intact brainstem reflexes, but never in a patient with an isoelectric electroencephalogram. Animal studies indicate that the quick phase of nystagmus and horizontal saccades are generated in the paramedian pontine reticular formation. The present case supports the conclusion that caloric-induced nystagmus originates in the brainstem in rudimentary form.

Brain Death↗

PubMed1993