Paraflocculus (Tonsillar) Ocular Motor Syndrome and Dysmetria in a Chiari Malformation - Pre and Post-Operative Exams

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Identifier Paraflocculus_tonsillar_ocular_motor_syndrome_dysmetria_Chiari_malformation
Title Paraflocculus (Tonsillar) Ocular Motor Syndrome and Dysmetria in a Chiari Malformation - Pre and Post-Operative Exams
Subject Saccades; Skew Diviation; VOR Supression; Pursuit; Medulla
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 a 25-year-old woman presenting with 6 months or progressive imbalance, binocular vertical diplopia, and occipital headaches, which were brought on or aggravated by coughing or sneezing. Examination demonstrated hyperreflexia in the arms and legs with sustained clonus at the ankles and Babinski reflexes bilaterally in addition to gait and limb ataxia. There were a variety of ocular motor abnormalities as well (see below). Contrast-enhanced MRI demonstrated peg-like cerebellar tonsils extending 2.9 cm below the foramen magnum (more tonsillar herniation on the right), and flattening of the dorsal medulla (right>left). There was also syringohydromyelia of the cervical and proximal thoracic spinal cord with cord parenchymal thinning. Taken together, this was consistent with a Chiari type I malformation. ; Visual exam, eyelids, and pupils were normal. While there was bilateral tonsillar herniation, it was worse on the right. In fact, the following findings were suggestive of a right paraflocculus (tonsillar) ocular motor syndrome: 1) weak right-beating (ipsilateral) spontaneous nystagmus (not seen in the video); 2) strong and (slightly) asymmetric right more than left gaze-evoked nystagmus (ipsilateral>contralateral) - in her case, there was also downbeat and torsion in lateral and down/lateral gaze (perhaps due to bilateral paraflocculus compression); 3) impaired smooth pursuit and vestibulo-ocular reflex suppression (VORS) toward the right (ipsilateral); 4) there was also a fairly comitant right hypertropia (a skew deviation), ocular counterroll (top poles toward the left ear), and subjective visual vertical tilt 5 degrees to the left with the bucket test - taken together, this was consistent with a contraversive partial ocular tilt reaction (no clear head tilt). Head impulse test was normal. There was also saccadic dysmetria with hypermetria to the right and hypometria to the left (limb ataxia was worse on the right side as well). It was felt that this was due to compression of the right inferior cerebellar peduncle, affecting climbing fibers from left inferior olive to right dorsal vermis. ; She underwent suboccipital craniectomy and C1 laminectomy, and when she was seen 6 months following surgery, all ocular motor findings had resolved with the exception of mild residual gaze-evoked nystagmus.
Publisher Spencer S. Eccles Health Sciences Library, University of Utah
Date 2020
Type Image/MovingImage
Format video/mp4
Relation is Part of NOVEL: Neuro-ophthalmology Virtual Education Library Examination Collection
Rights Management Copyright 2020. For further information regarding the rights to this collection, please visit:
Holding Institution Spencer S. Eccles Health Sciences Library, University of Utah, 10 N 1900 E, SLC, UT 84112-5890
Collection Neuro-ophthalmology Virtual Education Library: NOVEL
Language eng
ARK ark:/87278/s64r3f70
Setname ehsl_novel_gold
Date Created 2020-07-09
Date Modified 2021-06-28
ID 1580490
Reference URL
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