A Comparison of Nystagmus and Saccadic Intrusions/Oscillations

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Identifier Nystagmus_vs_Intrusions_and_Oscillations
Title A Comparison of Nystagmus and Saccadic Intrusions/Oscillations
Subject Jerk Nystagmus, Flutter, Pendular Nystagmus, Square Wave Jerks, Opsoclonus,
Creator Roksolyana Tourkevich, MD, Department of Neurology The Johns Hopkins School of Medicine , Daniel R. Gold, DO, Departments of Neurology, Ophthalmology, Neurosurgery, Otolaryngology - Head & Neck Surgery, The Johns Hopkins School of Medicine
Description Nystagmus can be classified into pendular and jerk waveforms, where both are generated by a slow, pathologic phase. Corrective phase (the position reset mechanism) differs. In pendular nystagmus, the eyes move back and forth with about the same velocity and amplitude, similar to that of a pendulum. Jerk nystagmus can have constant, increasing or decreasing slow phase velocity: vestibular nystagmus has a linear slow phase velocity due to vestibulo-ocular reflex imbalance; gaze-evoked nystagmus has a decreasing slow phase velocity due to a leaky neural integrator (the gaze-holding machinery); congenital nystagmus and certain posterior fossa disorders can cause an increasing slow phase velocity due to an unstable neural integrator. In jerk nystagmus, the slow (pathologic) phase is followed by the fast (named) phase. Nystagmus should be distinguished from oscillations and intrusions, particularly given disparate localizations and etiologies. These include saccadic intrusions (e.g., square wave jerks) and saccadic oscillations (e.g., ocular flutter, opsoclonus). Saccadic intrusions consist of saccades with an intersaccadic interval (i.e., a brief pause between movements), while saccadic oscillations lack this interval. Square wave jerks are small saccades that move the line of sight away from the target and then return to fixation 200 ms later. Macrosaccadic oscillations are saccades that take the eye off target and oscillate the line of sight about the object of regard - these movements straddle fixation, and are related to hypermetria. Ocular flutter is confined to the horizontal vector whereas opsoclonus has horizontal, vertical and torsional components, and occurs in bursts; however, the differential diagnosis, implications, and treatment of flutter and opsoclonus are essentially the same.
Publisher Spencer S. Eccles Library
Date 2017
Format image/jpeg
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/s6hx56nc
Setname ehsl_novel_gold
Date Created 2017-08-10
Date Modified 2018-08-01
ID 1260009
Reference URL https://collections.lib.utah.edu/ark:/87278/s6hx56nc
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