Downbeat Nystagmus

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Identifier 927-2
Title Downbeat Nystagmus
Ocular Movements Downbeat Nystagmus
Creator Shirley H. Wray, M.D., Ph.D., FRCP, Professor of Neurology Harvard Medical School, Director, Unit for Neurovisual Disorders, Massachusetts General Hospital
Contributor Primary Shirley H. Wray, MD, PhD, FRCP, Professor of Neurology, Harvard Medical School; Director, Unit for Neurovisual Disorders, Massachusetts General Hospital
Subject Downbeat Nystagmus; Oscillopsia; Chiari-1 Malformation; Primary Position Downbeat Nystagmus; Vertical Saccadic Dysmetria; Horizontal Saccadic Dysmetria; Ataxia
Supplementary Materials PowerPoint presentation: Chiari-1 Malformation: Shirley H. Wray, M.D., Ph.D., FRCP Harvard Medical School
Presenting Symptom Oscillopsia
History The patient is a 59 year old woman who carried a diagnosis of: 1. Congenital anomaly of the occipito-cervical junction with occipitalization of the C1 ring 2. Basilar invagination with Chiari Type I 3. A syrinx in the center of the cervical-thoracic spinal cord extending from C2 to T4 In 1957, at age 24 years, she presented with headache, jumping vision (oscillopsia), unsteady gait and a tendency to fall to the right. She was given a misdiagnosis of multiple sclerosis. In March 1992 she was seen by her local neurologist who made a diagnosis of Chiari Type I. She was referred to the Neurosurgery Clinic at the Massachusetts General Hospital. Her symptoms and signs on admission were those of a Chiari malformation: 1. Headache due to increased intracranial pressure 2. Progressive cerebellar ataxia 3. Progressive spastic quadriparesis 4. Oscillopsia In addition, she had a 2 year history of severe interscapular pain due to a syrinx in the spinal cord. Neuro-ophthalmological examination: Visual acuity 20/60 OS, 20/50 OD Visual fields, pupils and fundi normal Eye movements: • Downbeat nystagmus in primary gaze and in all directions of gaze • Eyes most stable on full down or upgaze • Alternating exophoria partially corrected by prism glasses Past History: 1996 Mastectomy for adenocarcinoma of the breast 1970 Basal cell carcinoma A cervical MRI scan: Cranio-vertebral junction anomaly with Chiari Type I malformation and basilar impression. MRI in flexion and extension showed occipitalization of the atlas and subluxation of the cerebellar tonsils further downwards into her spinal canal particularly in extension. Bone scan: No evidence of metastatic disease. Treatment: A trial of halo traction relieved her symptoms. Surgery: A posterior fossa decompression and dural graft as well as an occipital-cervical fusion was performed. She was placed in a halo vest and the pain in her back improved and her gait became steady. Post-operatively, when in bed she had 5 pounds of traction attached to her halo ring and disconnected the weight herself as desired. The treatment relieved her interscapular back pain and gradually increased her range of walking. There was no improvement in her downbeat nystagmus and vertical oscillopsia. The disturbances of eye movements in Type I Chiari include: 1. Downbeat nystagmus 2. Divergence nystagmus 3. Convergence nystagmus 4. Periodic alternating nystagmus 5. Gaze-evoked nystagmus 6. Rebound nystagmus 7. Seesaw nystagmus 8. Internuclear ophthalmoplegia 9. Positional nystagmus Table 12-1 Disturbances in eye movements in the Arnold- Chiari malformation. Pg. 610 (8).
Clinical This patient with Chiari Type I has: • Downbeat nystagmus with the eyes in central position • Large amplitude downbeat nystagmus on gaze to the right and left • Full upgaze with no nystagmus • Full downgaze with small amplitude downbeating nystagmus Box 10-2 Clinical Features of Downbeat Nystagmus Pg 484 (8). Three forms of nystagmus caused by lesions affecting the central vestibular pathways are: 1. Downbeat nystagmus 2. Upbeat nystagmus 3. Torsional nystagmus Downbeat nystagmus is occasionally disjunctive, being more vertical in one eye and torsional in the other. Downbeat nystagmus is caused by a central vestibular imbalance due to lesions of the vestibulocerebellum, especially the flocculus and paraflocculus and brainstem pathways. The Purkinje cells of the flocculus preferentially discharge for downward movements and it has been suggested that there is an underlying upward eye velocity bias in the central vestibular or pursuit system or in the peripheral vestibular system which is normally inhibited by the cerebellum. With lesions of the vestibulocerebellum, cerebellar inhibition is disrupted and the upward bias uncovered, resulting in spontaneous downbeat nystagmus. Downbeat nystagmus in cerebellar cases may be modified by a number of factors, including orbital position, head position and movement, head shaking and caloric stimulation. Table 10-1 Etiology of Downbeat Nystagmus, Pg 482 (8). Downbeat nystagmus may be suppressed, or converted to upbeat nystagmus, by potassium channel blockers such as 3,4-diaminopyridine and 4-aminopyridine.
Neuroimaging MRI with sagittal views of the cranio-cervical junction in Type I Chiari malformation has a highly characteristic radiologic profile, particularly on T1-weighted MRI which shows the low-lying cerebellar tonsils below the foramen magnum and behind the upper cervical cord. Neuroimaging stdies were not available in this patient. Illustrative images in another case are shown here. Figure 1: Sagittal T1WI shows a classic Chiari malformation with "peglike" tonsils extending inferiorly through the foramen magnum. Figure 2: Sagittal T2WI shows exquisite detail of the low-lying tonsils. Note vertically-oriented cerebellar folia. There is no associated syrinx in this case. Figure 3: Sagittal FLAIR shows no signal abnormality in either the tonsils or medulla. Courtesy Anne Osborn, M.D.
Etiology Developmental anomaly
Disease/Diagnosis Type I Chiari malformation
Treatment The treatment of Chiari malformation is far from satisfactory. If clinical progression is slight or uncertain, conservative management is thought to be best. If progression is certain and disability increasing, posterior fossa craniectomy and decompression is recommended.
References 1. Albers FW, Ingels KJ. Otoneurological manifestations in Chiari-I malformation. J. Laryngol Otol 1993;107:441-443. 2. Arnold AC, Baloh RW, Yee RD, Helper RS. Internuclear ophthalmoplegia in the Chiari type II malformation. Neurology 1990;40:1850-1854. 3. Baloh RW, Yee RD. Spontaneous vertical nystagmus. Rev Neurol (Paris) 1989;145:527-532. 4. Bosley TM, Cohen DA, Schatz NJ. Zimmerman RA, Bilaniuk LT, Savino PJ, Sergott RS. Comparison of metrizamide computed tomography and magnetic resonance imaging in the evaluation of lesions at the cerviomedullary junction. Neurology 1985;35:485-492. 5. Cogan DG. Downbeat nystagmus. Arch Ophthalmol 1968;80:757-768. 6. Dones J. De Jesus O, Cohen CB, Toledo MM, Delgado M. Clinical outcomes in patients with Chiari I malformation a review of 27 cases. Surg Neurol 2003;60:142-147. 7. Halmagyi GM, Rudge P, Gresty MA, Sanders MD. Downbeating nystagmus: a review of 62 cases. Arch Neurol 1983;40:777-784. 8. Leigh RJ, Zee DS. Diagnosis of Nystagmus and Saccadic Intrusion. Chp 10; 475-558 and Chp 12;598-718. In: The Neurology of Eye Movements. 4th Ed. Oxford University Press, New York 2006. 9. Mossman SS, Bronstein AM, Gresty MA, Kendall B, Rudge P. Convergence nystagmus associated with Arnold-Chiari malformation. Arch Neurol 1990;47:357-359. 10. Pedersen RA, Troost BT, Abel LA, Zorub D. Intermittent downbeat nystagmus and oscillopsia reversed by suboccipital craniectomy. Neurology 1980;30:1239-1242. 11. Pujol J, Roig C, Capdevila A, Pou A, Marti-Vilalta JL, Kulisevsky J, Escartin A, Zannoli G. Motion of the cerebellar tonsils in Chiari type I malformation studies by cine phase-contrast MRI. Neurology 1995;45:1746-1753. 12. Spooner JW, Baloh RW. Arnold-Chiari malformation. Improvement in eye movements after surgical treatment. Brain 1981; 104:51-60. 13. Straumann D, Müller E. Torsional rebound nystagmus in a patient with type I Chiari malformation. Neuro-ophthalmology 1994;14:79-84. 14. Zee DS, Friendlich AR, Robinson DA. The mechanism of downbeat nystagmus. Arch Neurol 1974;30:227-237. 15. Zimmerman CF, Roach ES, Troost BT. See-saw nystagmus associated with Chiari malformation. Arch Neurol 1986;43:299-300. 16. Hans Chiari - 17. Julius Arnold -
Relation is Part of 3-3; 168-6, 170-53, 919-1, 922-5; 936-8
Contributor Secondary Anne Osborn, M.D. University of Utah, Salt Lake, UT; Steve Smith, Videographer; Ray Balhorn, Digital Video Compressionist
Publisher Spencer S. Eccles Health Sciences Library, University of Utah
Date 1992
Type Image/MovingImage
Format video/mp4
Source 3/4" Umatic master videotape
Rights Management Copyright 2002. 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/s60s2m0n
Setname ehsl_novel_shw
Date Created 2005-08-22
Date Modified 2017-11-27
ID 188530
Reference URL
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