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Biomedical subjects

K Mizukoshi

Publications and source records attributed to K Mizukoshi.

107 records · Page 6Linked to original sources
PubMed1980

Failure of fixation suppression of caloric nystagmus and ocular motor abnormalities.

Caloric nystagmus is substantially suppressed by visual fixation. The degree of suppression of caloric nystagmus is influenced by the condition of visual fixation. We studied the percent reduction in slow-phase velocity of caloric nystagmus by visual fixation and certain abnormalities in optokinetic nystagmus, smooth pursuit, and maintenance of ocular position of gaze in 38 patients with disorders of the CNS. The inability to suppress caloric nystagmus by visual fixation correlated with reduction in optokinetic nystagmus, deficit in smooth pursuit eye movements, and presence of gaze nystagmus. It seems probable that modulation of the vestibulo-ocular reflex is influenced by the same mechanisms that are concerned with optokinetic nystagmus, maintenance of ocular position of gaze, and smooth pursuit eye movements.

Brain Diseases↗
PubMed1979

Epidemiological survey of definite cases of Meniere's disease collected by the seventeen members of the Meniere's Disease Research Committee of Japan in 1975--1976.

Between Aril 1975 and December 1976, the second nationwide survey of Meniere's disease in Japan was made by the 17 members of the Meniere's Disease Research Committee of Japan. The epidemiological data from 520 patients with definite Meniere's disease were analyzed in comparison with those from the 126 patients in the non-Meniere vertiginous group (Control A) and the 228 patients in the rhinolaryngological group (Control B). The male:female ratio of definite cases of Meniere's disease was almost the same, and the age distribution peaked at the age group of 40--49 years for males, while the peak for females was at the age group of 30--39 years. 5.8% of the 520 patients had a close relative who also suffered from Meniere's disease. From the epidemiological features, it may appear that the occurrence of vertiginous attacks in Meniere's disease is influenced much more by individual than by environmental factors. However, this feature can be considered as another evidence of the psychosomatic disorders involved in Meniere's disease.

Age Factors↗
PubMed1979

Caloric pattern test with special reference to failure of fixation-suppression.

Fixation-suppression of caloric nystagmus was studied in 1230 consecutive cases. An analysis of caloric nystagmus with failure of fixation-suppression (FFS) made it possible to classify patterns of FFS into three types: Type I: FFS was observed bilaterally in caloric nystagmus; Type II: FFS was recognized unilaterally on either side; Type III: FFS was seen in either direction of nystagmus. On the basis of these three types, the underlying neuroanatomical substrate responsible for FFS is discussed.

Brain Diseases↗
PubMed1979

Neurotological studies on Meniere's disease and sudden deafness.

During the period from January 1973 to June 1975, 60 cases with definite Meniere's disease and 30 cases with sudden deafness were listed according to such criteria for the diagnosis of both diseases as determined by the Research Committee of Japan. A neurootological assessment for both diseases were performed in our series. In patients with definite Meniere's disease, hearing impairment was characterized by deficiency in detecting low- and middle-pitched tones and fluctuation of auditory threshold in low frequency range. In sudden deafness, highly impaired hearing loss, i.e., total deafness, was frequently observed (45%). However, recruitment occurred at the same incidence (80%) in both diseases tested. The incidence of spontaneous nystagmus was almost the same regardless of associated vertigo and the course of both diseases. Moreover, it was also recognized that a reduction of caloric responses was a better indication for assessment of the affected ear in both diseases.

Audiometry↗
PubMed1977

The influence of optokinetic training upon vestibular responses induced by repetitive sinusoidal stimuli.

Optokinetic and vestibular training alternatively applied during two cycles, using sinusoidal pendular rotation and a stationary projection optokinetic stimulator, resulted in a progressive vestibular response decline. This response decrement was only revealed by the parameter of the slow-phase velocity. Combined optokinetic and vestibular training shows a facilitating effect upon vestibular habituation which cannot be induced by repetitive pendular rotation alone. Both a response decline, expressed by the parameter of the slow-phase velocity and a response increment, expressed by the number of nystagmus beats, were observed during one cycle of the pendular rotation. Both phenomena could be induced by alternative optokinetic and vestibular training and were interpreted as typical visual-vestibular interaction mechanisms.

Eye Movements↗
PubMed1975

Neurotological studies upon intoxication by organic mercury compounds.

In 1965, a strange illness, which afterwards was diagnosed as the intoxication caused by organic mercury compounds, began to affect the inhabitants of the riverside areas of the Aganogawa River, Niigata, Japan. The authors have investigated the neurotological disturbances, which occurred in 144 cases intoxicated with organic mercurials. The results obtained are summarized as follows: (1) Recruitment (in SISI and other tests) was negative in all the cases except for 32 with inner ear deafness, and Békèsy's AUDIOMETRY (TTS) showed type II: unsettled wide amplitude in 17 cases and severe abnormal adaptation characterizing the type III pattern in nine cases. (2) Spontaneous and positional nystagmus were recorded with ENG in 94 of 144 cases. In 62 of 144 cases, pathological findings of horizontal optokinetic nystagmus were recorded, and those of vertical optokinetic nystagmus were frequently observed in 81 of the 118 cases tested (69 percent). Judging from the authors' observations, neurotological disturbances due to chronic mercurial intoxication may be considered mainly as lesions of the retrocochlea and of the oculomotor system in the brain stem and the cerebellum.

Adolescent↗
PubMedDate not supplied

Optokinetic test comprising both acceleration and constant velocity stimulation (ACV-OKN test).

Normal subjects were exposed to two kinds of optokinetic stimulation, viz. at speeds of 60 degrees/s and 90 degrees/s preceded by acceleration at 6 degrees/s2 and 4.5 degrees/s2, respectively. In most subjects the speed of the eye in the slow nystagmus phase equalled the speed of the rotating device during the acceleration at velocities up to about 60 degrees/s. The eye then lagged behind the speed of the optokinetic stimulus. The upper limit for linear increase in the eye speed of the slow nystagmus phase has been named the "optokinetic fatigue threshold". A new clinical test permitting quantitative assessment of the optokinetic response has been introduced. The maximum eye speed in the slow nystagmus phase has been found to be the most appropriate parameter. Presentation of the results in the form of special charts, named optokinograms, is recommended. Optokinetic disturbances of varying kinds were noted mostly in patients with CNS disorders, but also in patients with diseases of the inner ear.

Acceleration↗
PubMedDate not supplied

Visual suppression of caloric nystagmus in normal individuals.

The effects of opening of the eyes and of ocular fixation upon caloric nystagmus were investigated during the period of maximum intensity of caloric nystagmus in a series of 32 normal individuals. The percentage reduction in slow-phase velocity induced depended upon the test conditions, but, on the other hand, did not depend upon the temperature of the water applied as caloric stimulus. This latter fact favors the theory of visual suppression of the caloric test. Another striking finding was that a clear correlation definitely existed between the percentage reduction of suppression in slow-phase velocity and that in the multiplication product of amplitude by nystagmus frequency (P.A.F.) during the period of eye opening and ocular fixation. The percentage of suppression in slow-phase velocity is interchangeable with that in P.A.F., which broadens the practical scope of the routine test.

Adolescent↗
PubMedDate not supplied

Loss of visual suppression of caloric nystagmus in cats.

Loss of visual suppression (VS) of caloric nystagmus was produced after creating flocculus lesions. The flocculus receives visual signals through a climbing fiber pathway via the inferior olive (IO) and through a mossy fiber pathway (MF) presumably via the superior colliculus (SC). In order to elucidate the prefloccular nuclei responsible for VS of caloric nystagmus, VS of caloric nystagmus was investigated after making lesions in such nuclei as the SC and the IO in 42 cats. After the IO lesion, VS of caloric nystagmus was revealed in all IO-lesioned cats throughout the whole experimental course. After the SC lesion, loss of VS was constantly observed and persisted in 7 out of 9 cats. Hence, the MF pathway via the SC is believed to be the most likely candidate for the immediate modification of the vestibuloocular reflex by visual stimuli.

Animals↗
PubMedDate not supplied

Quantitative comparison between saccadic and ataxic pursuits.

Smooth pursuit has been determined by the examiners' visualization as 'smooth pursuit', 'saccadic pursuit', or 'ataxic pursuit' according to the shapes of the eye movements on the ENG (electronystagmography) recording paper. Even since the introduction of computers for the measurement of smooth pursuit, however, no trial to compare quantitatively between smooth pursuit, saccadic pursuit and ataxic pursuit had been made up to the present. In the present work we analysed 10 smooth (normal) pursuits, 23 saccadic pursuits and 7 ataxic pursuits quantitatively with a microcomputer and found that the phase relationship between target movements and eye movements was the most prominent factor for distinguishing smooth pursuit pattern differences.

Brain Diseases↗
PubMedDate not supplied

Prediction in smooth pursuit.

A quantitative analysis of prediction in smooth pursuit was made in 23 normal subjects. The target wave (random sinusoidal wave), which contains a predictive portion and a nonpredictive portion, was developed by the authors, using a microcomputer. Five parameters were established quantitatively after microcomputer A/D conversion of the eye movements every 10 ms. There was no significant difference in amplitude gain, retinal error velocity, velocity gain or acceleration gain between the predictive and the non-predictive portions. However, a significant difference between the predictive portion and the nonpredictive portion was found in phase lag. We therefore concluded that the predictive function in smooth pursuit, in normal subjects, is the most important factor in the phase relationship between target wave and eye movements.

Eye Movements↗