Pons: 6th and 7th nerve anatomy and the central tegmental tract

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Identifier Pons
Title Pons: 6th and 7th nerve anatomy and the central tegmental tract
Subject Sixth Nerve Palsy, INO, One and a Half, Horizontal Gaze Palsy, OMS Pons, Facial Nerve, Oculopalatal
Creator Daniel R. Gold, DO, Departments of Neurology, Ophthalmology, Neurosurgery, Otolaryngology - Head & Neck Surgery, The Johns Hopkins School of Medicine
Description From this cross-section of the pons, the proximity of the 6th nucleus to the 7th nerve fascicles is apparent. This is the basis of the so-called facial colliculus syndrome, where an ipsilesional horizontal gaze palsy from a nuclear 6th lesion (usually related to stroke or demyelination) can be seen with an ipsilesional lower motor neuron (i.e., upper and lower face) facial palsy.; ; Ex) A right-sided lesion would cause inability to 1) abduct OD or 2) adduct OS, in addition to a right facial palsy.; ; Or, if the nucleus of 6 is affected in addition to the ipsilateral medial longitudinal fasciculus (MLF), there is an ipsilesional horizontal gaze palsy + an ipsilateral internuclear ophthalmoplegia (INO), the so-called "one-and-a-half" syndrome.; ; Ex) A right-sided lesion would cause inability to 1) abduct OD or 2) adduct OS due to right 6th nucleus lesion, and inability to adduct OD (INO) due to right MLF lesion. Commonly, a lower neuron facial palsy will be seen with a one-and-a-half syndrome as well. ; ; Also, it's important to note that the central tegmental tract (CTT) courses through the vicinity of cranial nerves 6 and 7, so months following a lesion (usually hemorrhagic stroke>ischemic stroke>>demyelination or other), vertical-torsional pendular nystagmus and palatal tremor (together known as oculopalatal tremor) will develop given disruption within Mollaret's triangle, where the cerebellum normally has an inhibitory influence over the inferior olives via the CTT - i.e., with CTT damage, there is less inhibition of the inferior olives, resulting in inferior olivary hypertrophy on MRI, which is demonstrated by T2/FLAIR hyperintensity of one or both medullary olives.
Contributor Daniel R. Gold, D.O.
Publisher Spencer S. Eccles Health Sciences Library, University of Utah
Date 2017
Format image/jpeg
Rights Management Copyright 2016. 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/s6hm936q
Setname ehsl_novel_gold
Date Created 2017-07-26
Date Modified 2018-01-22
ID 1256242
Reference URL https://collections.lib.utah.edu/ark:/87278/s6hm936q
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