Medullary structures relevant to the ocular motor and vestibular consequences of lateral medullary (Wallenberg) syndrome

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Identifier Medulla_Structures_important_to_Wallenberg
Title Medullary structures relevant to the ocular motor and vestibular consequences of lateral medullary (Wallenberg) syndrome
Subject Medulla OMS; figures
Creator Daniel R. Gold, DO, Departments of Neurology, Ophthalmology, Neurosurgery, Otolaryngology - Head & Neck Surgery, Emergency Medicine, and Medicine, The Johns Hopkins School of Medicine
Description This is an axial section of the medulla showing the structures that, when damaged, are responsible for the vestibular and ocular motor features of the lateral medullary or Wallenberg syndrome. The nucleus prepositus hypoglossi (NPH) and medial vestibular nucleus (MVN) complex is important for horizontal gaze-holding. Fibers from the horizontal semicircular canals project to the MVN, thus providing an explanation for a + ipsilateral head impulse test, which is occasionally seen with a lesion involving the vestibular nucleus. Gaze-evoked nystagmus and loss of the horizontal vestibulo-ocular reflex in Wernicke's encephalopathy can also be explained by NPH-MVN dysfunction. Fibers coming from the peripheral utricle also synapse in the vestibular nucleus and may be damaged in this vicinity. In a Wallenberg syndrome, when a skew is present, the hypotropic eye is ipsilateral to the injury - this occurs caudal to the decussation of the utricle ocular motor fibers, and is also responsible for the hypertropic eye being ipsilateral to the injury rostral to its decussation (e.g., a right medial longitudinal fasciculus [MLF] or interstitial nucleus of Cajal lesion causing a skew deviation with a right hypertropia). Although various pathways exist from the utricle and semicircular canals to their respective ocular motor nuclei, many of these pathways travel through the MLF. A lesion involving the inferior cerebellar peduncle (ICP) may result in asymmetry of the saccade facilitation/inhibition pathways, resulting in ipsilateral ocular lateropulsion, ipsilateral saccadic hypermetria and contralateral saccadic hypometria in a Wallenberg syndrome.
Contributor Daniel R. Gold, D.O.
Publisher Spencer S. Eccles Health Sciences Library, University of Utah
Format image/jpeg
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/s6x38rgb
Setname ehsl_novel_gold
Date Created 2017-08-10
Date Modified 2018-01-22
ID 1260006
Reference URL https://collections.lib.utah.edu/ark:/87278/s6x38rgb
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