| Identifier |
003-3 |
| Title |
Downbeat Nystagmus |
| Creator |
Shirley H. Wray, MD, PhD, FRCP |
| Affiliation |
(SHW) Professor of Neurology, Harvard Medical School; Director, Unit for Neurovisual Disorders, Massachusetts General Hospital, Boston, Massachusetts |
| Subject |
Downbeat Nystagmus; Lid Nystagmus; Oscillopsia; Chiari-1 Malformation; Primary Position Downbeat Nystagmus; Chiari Malformation |
| History |
This patient carries a diagnosis of Type I Chiari malformation. Neurological symptoms of a Chiari malformation may not develop until adolescence or adult life as in this man. The symptoms may be those of: 1. Increased intracranial pressure, mainly headache 2. Progressive cerebellar ataxia 3. Progressive spastic quadriparesis 4. Downbeating nystagmus or 5. Cervical syringomyelia This patient presented with: 1. Difficulty focusing due to oscillopsia and 2. Mild intermittent headaches An examination of the central nervous system was normal apart from the ocular motor system which showed the important diagnostic sign - downbeat nystagmus in primary gaze. Patients with downbeat nystagmus often complain of illusory motion of their visual environment (oscillopsia), as in this patient. Disturbances of Eye Movements in Type I Chiari Malformation 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) |
| Disease/Diagnosis |
Type I Chiari malformation; Downbeat Nystagmus |
| Clinical |
This elderly patient with Type I Chiari malformation has: • Small amplitude downbeat nystagmus in central position best visualized with the ophthalmoscope • Lid nystagmus • Large amplitude downbeat nystagmus evident on gaze to the right and left • Full upgaze with no nystagmus • Full downgaze with downbeating nystagmus Box 10-2 Clinical Features of Downbeat Nystagmus. Pg 484 (8). There are three forms of nystagmus caused by lesions affecting the central vestibular pathways: 1. Downbeat nystagmus 2. Upbeat nystagmus 3. Torsional nystagmus 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. (8) 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 is occasionally disjunctive, being more vertical in one eye and torsional in the other. Downbeat nystagmus may be suppressed, or converted to upbeat nystagmus, by potassium channel blockers such as 3,4-diaminopyridine and 4-aminopyridine. |
| Presenting Symptom |
Oscillopsia |
| Ocular Movements |
Downbeat Nystagmus Lid Nystagmus |
| Neuroimaging |
An 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 studies were not available in this patient. Illustrative images in another case are shown here. Figure 1. Sagittal T1WI shows a classic Chiari I 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. |
| Treatment |
The treatment of a Chiari malformation is far from satisfactory. If clinical progression is slight or uncertain, it is probably best to do nothing. If progression is certain and disability is increasing, upper cervical laminectomy and enlargement of the foramen magnum are indicated. |
| Etiology |
Developmental anomaly |
| Supplementary Materials |
Chiari-I Malformation: https://collections.lib.utah.edu/details?id=2174188 |
| Date |
1977 |
| References |
1. Albers FW, Ingels KJ. Otoneurological manifestations in Chiari-I malformation. J. Laryngol Otol 1993;107:441-443. http://www.ncbi.nlm.nih.gov/pubmed/8326227 2. Arnold AC, Baloh RW, Yee RD, Helper RS. Internuclear ophthalmoplegia in the Chiari type II malformation. Neurology 1990;40:1850-1854. http://www.ncbi.nlm.nih.gov/pubmed/2247233 3. Baloh RW, Yee RD. Spontaneous vertical nystagmus. Rev Neurol (Paris) 1989;145:527-532. http://www.ncbi.nlm.nih.gov/pubmed/2682931 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. http://www.ncbi.nlm.nih.gov/pubmed/3982633 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. http://www.ncbi.nlm.nih.gov/pubmed/12900124 7. Halmagyi GM, Rudge P, Gresty MA, Sanders MD. Downbeating nystagmus: a review of 62 cases. Arch Neurol 1983;40:777-784. http://www.ncbi.nlm.nih.gov/pubmed/6639406 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. http://www.ncbi.nlm.nih.gov/pubmed/2310320 10. Pedersen RA, Troost BT, Abel LA, Zorub D. Intermittent downbeat nystagmus and oscillopsia reversed by suboccipital craniectomy. Neurology 1980;30:1239-1242. http://www.ncbi.nlm.nih.gov/pubmed/7191521 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. http://www.ncbi.nlm.nih.gov/pubmed/7675239 12. Spooner JW, Baloh RW. Arnold-Chiari malformation. Improvement in eye movements after surgical treatment. Brain 1981; 104:51-60. http://www.ncbi.nlm.nih.gov/pubmed/7470844 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. http://www.ncbi.nlm.nih.gov/pubmed/4591431 15. Zimmerman CF, Roach ES, Troost BT. See-saw nystagmus associated with Chiari malformation. Arch Neurol 1986;43:299-300. http://www.ncbi.nlm.nih.gov/pubmed/3947282 |
| Language |
eng |
| Format |
video/mp4 |
| Type |
Image/MovingImage |
| Source |
16 mm Film |
| Relation is Part of |
170-53, 919-1, 922-5, 927-2 |
| Collection |
Neuro-Ophthalmology Virtual Education Library: Shirley H. Wray Collection: https://novel.utah.edu/Wray/ |
| Publisher |
North American Neuro-Ophthalmology Society |
| Holding Institution |
Spencer S. Eccles Health Sciences Library, University of Utah |
| Rights Management |
Copyright 2002. For further information regarding the rights to this collection, please visit: https://NOVEL.utah.edu/about/copyright |
| ARK |
ark:/87278/s66719s6 |
| Setname |
ehsl_novel_shw |
| ID |
188575 |
| Reference URL |
https://collections.lib.utah.edu/ark:/87278/s66719s6 |
