Figure 53: Vascular Distribution and Anatomy Relevant to the Lateral Medullary (Wallenberg) Syndrome

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Identifier gold_textbook_figures_053
Title Figure 53: Vascular Distribution and Anatomy Relevant to the Lateral Medullary (Wallenberg) Syndrome
Creator Daniel R. Gold, DO
Affiliation (DRG) Departments of Neurology, Ophthalmology, Neurosurgery, Otolaryngology - Head & Neck Surgery, Emergency Medicine, and Medicine, The Johns Hopkins School of Medicine, Baltimore, Maryland
Description This axial section of the medulla highlights those structures that, when damaged, are responsible for the vestibular and ocular motor features of the Wallenberg syndrome. The nucleus prepositus hypoglossi (NPH) and medial vestibular nucleus (MVN) complex is important for horizontal gaze-holding (neural integration). Fibers from the horizontal semicircular canals project to the MVN, thus providing an explanation for an abnormal ipsilateral head impulse test (HIT), 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 (left) peripheral utricle also synapse in the (left) vestibular nucleus, explaining why a skew deviation is common in a Wallenberg syndrome. With a left Wallenberg skew, the left hypotropic eye is predictably ipsilateral to the injury because the lesion is caudal to the pontomedullary decussation of the utricle ocular motor fibers (and the ocular tilt reaction [OTR] will be ipsiversive - e.g., head tilt, ocular counterroll are toward the left). If the same pathway (that originated in the left peripheral utricle) is affected rostral to the utricle fiber decussation (e.g., right medial longitudinal fasciculus or right interstitial nucleus of Cajal lesion), the right hypertropic eye is predictably ipsilateral to the injury ( causing a skew deviation with a right hypertropiawith a , and is also responsible for the hypertropic eye being ipsilateral to the injury rostral to its decussation (e.g., and the OTR will contraversive - e.g., head tilt, ocular counterroll are toward the left). Although various pathways exist from the utricle and semicircular canals to their respective ocular motor nuclei, many of these pathways travel through the medial longitudinal fasciculus (MLF, which is not yet carrying interneurons from the 6th nucleus). Involvement of the (left) inferior cerebellar peduncle (ICP) may result in asymmetry of the saccade facilitation/inhibition pathways, resulting in ipsilateral (left) ocular lateropulsion, ipsilateral (leftward) saccadic hypermetria and contralateral (rightward) saccadic hypometria in a (left) Wallenberg syndrome.
Date 2022
References Gold D. (2022). Neuro-ophthalmology and neuro-otology : a case-based guide for clinicians and scientists. Springer International Publishing AG. Retrieved September 16 2022 from https://online.statref.com/p/1057?grpAlias=.
Language eng
Format image/jpeg
Type Image
Relation is Part of Neuro-Ophthalmology and Neuro-Otology: A Case-Based Guide for Clinicians and Scientists
Collection Neuro-Ophthalmology Virtual Education Library: Dan Gold Collection: https://novel.utah.edu/Gold/
Publisher North American Neuro-Ophthalmology Society
Holding Institution Spencer S. Eccles Health Sciences Library, University of Utah
Rights Management Copyright 2016. For further information regarding the rights to this collection, please visit: https://NOVEL.utah.edu/about/copyright
ARK ark:/87278/s6sm2bjr
File Name gold_textbook_figures_053.png
Setname ehsl_novel_gold
ID 2050032
Reference URL https://collections.lib.utah.edu/ark:/87278/s6sm2bjr
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