Kyoko Ohtsu

Positional Nystagmus of Benign Paroxysmal Type (BPPN) Due to Cerebellar Vermis Lesions: Pseudo-BPPN

Positioning nystagmus accompanied by severe vertigo has been reported in patients with partial lesions of the inner ear, especially otolith lesions. Typically, this type of nystagmus shows a latent period and subsequent fatiguability. We concur with this finding and have constantly emphasized the significance of this phenomenon in clinical diagnosis. Since we started using CT-scanning, this type of nystagmus has been noted in 47 patients, all of whom had cerebellar vermis lesions. Attention should be focused on this association; if such a combination were seen in only 1 or 2 patients, it could simply be attributed to coincidence. But its occurrence in as many as 47 patients indicates a causal role of cerebellar vermis lesions. Its mechanism may be explained by incomplete inhibition of the vestibulo-oculomotor system including the cerebellar flocculonodular lobe or vestibulo-cerebellum.

Positional nystagmus of benign paroxysmal type (BPPN) due to cerebellar vermis lesions. Pseudo-BPPN.

Positioning nystagmus accompanied by severe vertigo had been reported in patients with partial lesions of the inner ear, especially otolith lesions. Typically this type of nystagmus represents a latent period and subsequent fatiguability. We concur with this finding and have constantly emphasized the significance of this phenomenon in clinical diagnosis. Since we started to use CT-scanning, this type of nystagmus has been noted in 20 patients, all of whom had cerebellar vermis lesions. Attention should be focused on this association. A simple coincidence could not be excluded if such a combination were seen in only 1 or 2 patients, it could be attributed to simple coincidence. But its occurrence in as many as 20 patients a causal role of cerebellar vermis lesions. Its mechanism may be explained by incomplete inhibition of the vestibulo-oculomotor system including the cerebellar flocculonodular lobe or vestiburo-cerebellum.

Use of the visual suppression test using post-rotatory nystagmus to determine skill in ballet dancers

Twelve ballet dancers with various levels of dancing experience and skill were examined with the visual suppression test using post-rotatory nystagmus (PRVST) and caloric stimulation (CVST). The PRVST results showed a suppression rate that was higher than in untrained subjects. The CVST results showed a suppression rate similar to that in untrained subjects. A correlation between the PRVST and CVST suppression rates and the length of dancing experience showed that the suppression rate increased as the level of experience and skill rose. These results indicate that the PRVST and CVST can aid in the clinical and quantitative assessment of the function of the central nervous system in visual-vestibular interactions in ballet dancers. Additionally, testing may have determined function of vestibulo-cerebellar pathways through habituation of visual-vestibular interactions. Findings indicate that it may be possible to use suppression rates of PRVST and CVST to determine the approximate level of a dancers experience and skill.

Vertical Ocular Dysmetria —Vertical Rebound Nystagmus and Optokinetic Vertical Ocular Dysmetria

Ocular dysmetria in vertical eye movement was confirmed by electronystagmographic recording in 100 cases. Ocular dysmetria in spontaneous vertical ocular movement was reported in seven cases. It can be called vertical rebound nystagmus. This phenomenon was more prominent in vertical movement of the eyes returning from upward gazing to mid-position than in the movements of downward gazing. Optokinetic vertical ocular dysmetria induced by vertical optokinetic stimulation was observed in 93 cases. This phenomenon was far more prominent in upward optokinetic nystagmus than in downward optokinetic nystagmus. The pattern of optokinetic vertical ocular dysmetria was classified into the following four types: the dysrhythmic type, the overshoot type, the ataxic type and the saccadic (semi-inversive) type. The pathophysiological mechanism of horizontal ocular dysmetria should be different from the mechanism of vertical ocular dysmetria.

Visual Suppression Test Using Post-Rotatory Nystagmus: Clinical Course in Patients with Motion Sickness

With the results of VS test (%) we were able to classify patients into three groups as follows: Group I, hyper range of visual suppression, VS (%) = 100-90; Group II, normal range of VS (%) = 89-45; Group III, reduced or abolished range of VS (%) = less than 44. The results with VS test using post-rotatory nystagmus (PRN) were in Group I 58 cases, in Group II 28 cases and in Group III 1 case, and using caloric nystagmus (CN) the results in Group I were 39 cases, Group II 29 cases, and Group III 1 case. With the correlation of VS test between PRN and CN we were able to classify patients into four types as follows: Type I, hyper range of VS in both PRN and CN; Type II, hyper range of VS in PRN; however, normal range of VS in CN; Type III, normal range of VS in both PRN and CN; Type IV reduced or abolished range of VS in both PRN and CN. It was very interesting in the clinical course of motion sickness that patients under 11 years of age (18 cases) of Type I (31 cases) showed marked improvement to Type III (11 cases) at the time of disappearance of symptoms; however, patients over 12 years of age (13 cases) of Type I remained stationary Type I (9 cases) at the time of disappearance of symptoms.

Clinical values in inversive type of optokinetic after-nystagmus(OKAN).

1) We examined patients with bilateral lesions in the otolith-semicircular canals, vertebro-basilar artery insufficiency and cerebellar atrophy who showed the inversive type of OKAN, and we discuss the clinical value of the inversive type of OKAN.2) As in animal experiments, patients with bilateral lesions in the otolith-semicircular canals also show the inversive type of OKAN.3) Unlike the animal experiments however, patients with cerebellar disturbances also show the inversive type of OKAN.In these patients, there is an imbalance between the brainstem and the eye movement system which leads to a decomposition of the cerebellar eye movement integration system causing the inversive type of OKAN.4) The inversive type of OKAN points to disturbances of integration and compensation when bilateral lesions in the otolith-semicircular canals or lesions in the central vestibular system affect visual-vestibular interaction.

Clinical study on congenital nystagmus. Statistical analysis.

There have been many case reports on so-called congenital nystagmus, but only a few papers have deal with the statistics and pathophysiology. May be that is the reason that some patients with congenital nystagmus are simply diagnosed as having a visual defect, and some have been sent to a school for the blind.Recently, our department has done precise neurootological examinations on 2, 400 subjects. Congenital nystagmus was found in 84 of them (3.5%); 45 had the jerking type, 19 the pendular jerking type, 11 the pendular type and 9 the latent type of nystagmus. The male/female ratio was 2:1.The congenital nystagmus in these 84 cases is analyzed statistically.

Neuro-otological examinations in nine patients with multiple sclerosis(MS) associated with vertigo and disequilibrium.

Nine MS patients with vertigo and disequilibrium were neuro-otologically examined.Examination of the vestibulo-oculomotor system revealed that these patients had i) conjugated eye movenents disorder (MLF syndrome), ii) bilateral fixation nystagmus, iii) OKN disorder, iv) ETT disorder, v) vertical positional nystagmus and vertical positioning nystagmus, vi) rebound nystagmus which suggested in the dorsal parts of the brain-stem (i-iii) and in the vermis and nuclei of cerebellum (iv-vi).On auditory examination, the prolongation of the wave III-V IPL and the increased wave ITV amplitude ratio were characteristic findings of ABR. Since the auditory pathway runs in the dorsal parts of the upper brain-stem, the latter components of ABR seemed to be markedly damaged by MS.Neuro-otological examinations appear to be more sensitive than rutine neurological examinations for detecting multi-focal lesions in MS patients with vertigo and disequilibrium.MRI was found to be the most satisfactory technique for diagnosing MS.

A case of gigantic meningioma improved after surgery.

Meningioma is a benign tumor with no symptoms in the initial stage. It is not unusual for a meningioma to show no objective signs even in the advanced stage. Neurootological examinations are often required.We examined a patient with a gigantic meningioma which displaced upward the tentorium on the affected side. In this case objective signs were minimal, and neurootological examinations were very important. The tumor was gigantic, but hearing, optokinetic nystagmus, smooth pursuit and ABR (auditory brainstem response) were restored after the operation. We report this unusual case and describe the neurootological examinations.

ALCOHOL AND THE OCULOMOTOR SYSTEM

It is known that alcohol affects the oculomoto system and elicits positionalacoholnystagmus Recently it has been shown that disturbance in smooth pursuit eye movements occurs depend-ing on the quantity of ingested alcohol.However, it is also known that test is normal at the early stage of alcohol-induced breakdown of smooth pursuit movements.This indicates that alcohol affects the cerebellum prior to affecting the midbrain and pons(WILKINSON et al., 1974).In order to further investigate the effect of alcohol on th cerebellum, subjects ingested alcohol(whisky)and their oculomotor function was tested.The followings are general findings obtained.1)Low blood-alcohol concentration causes slight disturbance in the caloric eye-tracking pattern and slight positional nystagmus is occasionally evident.2)As the blood-alcohol level increases, positional nystagmus becomes more apparent and the eye-tracking pattern begins to break down.The caloric eye-trackingpa ttern be-comes severely disturbed.3)Gaze nystagmus does not appear until the blood-alcohol level becomesmuch higher.hese findings indicate that alcohol affects the caloric eye-tracking patterns prior to the conventional eye-tracking patterns.Alcohol must therefore initially affect the areas of the cerebellum related tovisual suppression, namely the flocculo-nodular system.