著者

岡田 智幸

出版者

一般社団法人 日本めまい平衡医学会

雑誌

Equilibrium Research (ISSN:03855716)

巻号頁・発行日

vol.77, no.4, pp.201-219, 2018-08-31 (Released:2018-10-02)

参考文献数

83

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Congenital nystagmus (CN) is known as an involuntary to-and-fro movement of the eyes characterized by a wide variation in waveforms ranging from jerk to pendular types. CN is presumed to be present at birth. In antiquity, midwives or shaman occasionally noticed CN. The first description of CN, popularly known in china as “shiji,” was made around 2000 years ago. Despite its various waveforms, people with CN do not develop visual symptoms and rarely complain of oscillopsia. CN can be idiopathic but is most likely caused by gaze stability, although some reports have suggested familial cases. No detailed mechanisms have been proposed to explain the generation of CN waveforms in people with CN in whom the vestibulo-ocular reflex (VOR) cannot be established. The vestibular time constant showed a good correlation between VOR and perception in normal subjects when assessed using perceptual measures. The time constant (TC) of decay of vestibular sensation in individuals with CN was half the duration of the TC found in normal subjects. Thus, individuals with CN have short vestibular time constants, probably due to changes induced in velocity storage processing by the persistent retinal image motion present in individuals with CN. There is a fascinating paper showing that FRMD7, also known as the CN gene, is necessary for optokinetic nystagmus (OKN) in humans and mice. In the retina of FRMD7-mutant mice, horizontal direction selectivity and asymmetry of inhibitory inputs to horizontal direction-selective retinal ganglion cells (HDSCs) are both lost. This could be a hidden essential characteristic of CN. HDSCs are responsible for horizontal OKN and project to the nucleus of the optic tract (NOT), and NOT, in turn, is related to the velocity storage mechanism, vestibular adaptation, and habituation. Inversion of OKN and suppression of nystagmus with eye closure are characteristics of CN. Both of these features can be explained by abnormalities in HDSCs. So, HDSCs can only play the role in the light. In the future, innovative ideas could help to elucidate the nature of CN.

著者

小宅 大輔 岡田 智幸 深澤 雅彦 佐藤 成樹 肥塚 泉

出版者

耳鼻咽喉科臨床学会

雑誌

耳鼻咽喉科臨床 (ISSN:00326313)

巻号頁・発行日

vol.101, no.8, pp.617-620, 2008-08-01 (Released:2011-10-07)

参考文献数

10

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This study retrospectively investigated the value of both endoscopically visible oropharyngeal secretions in the hypopharynx and miss-swallowing frequency in the prediction of food and liquid aspiration. Videoendoscopy was performed in Fourty-three patients. A four-level rating scale was employed to determine the severity of accumulated oropharyngeal secretions. On this secretion scale patients graded 0 and 1 could eat, but those graded 3 could not. It was found that the accumulation of endoscopically visible oropharyngeal secretions located within the laryngeal vestibule was highly predictive of the aspiration of food or liquid. The Results are discussed in terms of integrating this information with clinical bedside examinations.

著者

岩沢 寛 加藤 功 岡田 智幸 上杉 恵介 竹山 勇

出版者

Japan Society for Equilibrium Research

雑誌

Equilibrium Research (ISSN:03855716)

巻号頁・発行日

vol.46, no.4, pp.366-371, 1987 (Released:2009-10-20)

参考文献数

26

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We report here a rare case of vertical nystagmus, dysarthria and broad-based gait due to after-effects of lithium intoxication.A 65-year-old man was admitted with dysarthria and gait disturbance. About 14 years ago, he had begun treatment with lithium carbonate for manic psychosis. Ten years ago, he developed dysarthria and a broad-based gait due to lithium intoxication.Neuro-otological examination demonstrated, downbeat nystagmus in the primary position, rebound nystagmus and direction changingopposing vertical positioning nystagmus.Failure of fixation-suppression of caloric nystagmus was noted in both sides. Eye-tracking test revealed saccadic eye movements, and slow phase OKN velocity was limited billaterally. The equilibrium disturbances observed in this patient's neurological and ENG findings might be attributed to pathological conditions of cerebellar vermis, flocculus and partly brainstem.He was treated with thyroid stimulating hormone (2mg/day) for 18 days.Thereafter, gradually he recovered from some of his neurological symptoms : dysarthria, gait disturbance, rebound nystagmus and direction changing opposing vertical positioning nystagmus.His vertical nystagmus, however, remained unchanged.