Abnormal visually-enhanced VOR in cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS)

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Identifier Abnormal_vVOR_in_CANVAS
Title Abnormal visually-enhanced VOR in cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS)
Subject Abnormal Pursuit, Abnormal VOR, Abnormal HIT, Cerebellar, Jerk Nystagmus, Gaze Evoked Nystagmus,
Creator Daniel R. Gold, DO, Departments of Neurology, Ophthalmology, Neurosurgery, Otolaryngology - Head & Neck Surgery The Johns Hopkins School of Medicine ; Nathan H. Kung Department of Ophthalmology and Visual Sciences Washington University School of Medicine, St. Louis, Missouri, USA ; Gregory P. Van Stavern, MD, Associate Professor, Ophthalmology & Visual Sciences and Neurology, Washington University School of Medicine
Description A 67 year old woman presented with 1 year of progressive numbness, gait instability, and oscillopsia when walking or with head movements. Examination showed excessive square-wave jerks, bilateral horizontal gaze-evoked nystagmus, impairment of the visually-enhanced vestibular ocular reflex (vVOR - see with slow head turning to the right and left, which is a combination of pursuit and the VOR), and impairment of the vestibular ocular reflex (VOR) during head impulse testing, in the planes of all 6 canals (horizontal, posterior and anterior). Normally, when a high velocity but low amplitude movement of the head is applied (i.e., high enough velocity that the smooth pursuit system fails while the VOR system is isolated), the patient's eyes stay on their intended target, which is typically the examiner's nose (https://collections.lib.utah.edu/details?id=187678). This is a normal or negative head impulse test and suggests a normal VOR toward the side of the impulse. In contrast, if the eyes initially move with the head in the direction of the impulse and then need to make a catch-up saccade, this is an abnormal or positive impulse test (https://collections.lib.utah.edu/details?id=187723) and suggests an abnormal VOR toward the side of the impulse. In this particular patient's case, sensory testing also showed impaired vibration in the distal extremities. A clinical diagnosis of cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS) was made. An impaired or saccadic vVOR suggests that there is failure of both the pursuit and (bilateral) vestibular systems, and CANVAS should be considered, especially when neuropathy is present. Other conditions that should be considered if the vVOR is impaired include Wernicke's encephalopathy if the symptom onset is acute, and if the course is more chronic, the neurodegenerative processes including multiple system atrophy as well as some of the spinocerebellar ataxias (types 1, 3, 4, 6 among several others) could be responsible.
Imaging 1, patient with impaired smooth pursuit and VOR function
Contributor Daniel R. Gold, D.O.
Publisher Spencer S. Eccles Health Sciences Library, University of Utah
Date 2017
Type Image/MovingImage
Format video/mp4
Rights Management Copyright 2017. For further information regarding the rights to this collection, please visit: https://NOVEL.utah.edu/about/copyright
Collection Neuro-ophthalmology Virtual Education Library: NOVEL http://NOVEL.utah.edu
Language eng
ARK ark:/87278/s6s50fth
Setname ehsl_novel_gold
Date Created 2017-04-04
Date Modified 2018-02-22
ID 1213434
Reference URL https://collections.lib.utah.edu/ark:/87278/s6s50fth
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