Video head impulse testing

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Identifier NOVEL_vHIT
Title Video head impulse testing
Subject Normal VOR, Abnormal VOR, Vestibular Lab Testing, Video Head Impulse Testing
Creator Roksolyana Tourkevich, M.D., Departments of Neurology, Otolaryngology - Head & Neck Surgery, The Johns Hopkins School of Medicine; Daniel R. Gold, D.O., Departments of Neurology, Ophthalmology, Neurosurgery, Otolaryngology - Head & Neck Surgery, The Johns Hopkins School of Medicine
Description The video head impulse test (vHIT) is a clinical assessment technique used to assess the function of the semicircular canals-the angular acceleration detectors-which initiate the vestibulo-ocular reflex (VOR). The HIT and vHIT are performed similarly (see assessment of VOR using HIT video LINK), although the bedside HIT is subjective and covert saccades (compensatory saccades occurring with head movements) cannot be appreciated. vHIT has the advantages of allowing the clinician to visualize 1) the corrective overt saccades (those corrective or refixation saccades that are the only sign of vestibular loss that can be appreciated on the bedside HIT), 2) covert saccades, and 3) measurements of gain and relative gain asymmetry (Figure 1). Gain is a general term used to describe the ratio of output to input in dynamic systems. VOR gain can be calculated in a variety of ways, but the most commonly used methods include: 1) ratio of the area under the eye velocity curve to the area under the head velocity curve (which is the method used to calculate gains in the Figures below), 2) ratio of the eye velocity to the head velocity at a certain time (usually peak velocity). A gain of 1.0 suggests that the output (eye movement) perfectly matches the input (head movement).
Publisher Spencer S. Eccles Health Sciences Library, University of Utah
Date 2018-03
Format application/pdf
Rights Management Copyright 2018. 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/s62n91vq
Setname ehsl_novel_gold
Date Created 2018-03-15
Date Modified 2018-08-06
ID 1306744
Reference URL https://collections.lib.utah.edu/ark:/87278/s62n91vq
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