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Involuntary Eye Movement Oscillations
Rhythmic or arrhythmic involuntary sustained to and tegmental pathway of the upward vestibulo-ocular reflex.
fro oscillations of the eyes are classified as either nys- Multiple sclerosis, tumour, infarction and cerebellar tagmus or saccadic (rapid conjugate eye movements) degeneration are the commonest causes9. This type of oscillations. There is an important distinction between nystagmus is occasionally suppressed by clonazepam.
them. Saccadic oscillations are initiated by saccadic eye Torsional nystagmus is a jerk nystagmus around the movements, whereas in nystagmus the oscillations are ini- anteroposterior axis. It is commonly associated with other tiated by smooth eye drifts and the fast phase in jerk nys- types of nystagmus. However, when it is pure it indicates tagmus is corrective and not primary (Table 1) (Figure 1).
a lesion of the lateral medulla, involving the vestibular This short review will describe the commonest types of nuclei. Occasionally it may be due to a midbrain-thalam- these ocular oscillations, their causation and manage- ic lesion, involving the interstitial neucleus of cajal (INC.) Professor Christopher
is Professor of
Gaze-evoked nystagmus is a common clinical observa- tion with limited localising value. It is a jerk nystagmus which is absent in the primary position and is only pre- Faculty of Medicine,Imperial College London Nystagmus is an oscillation initiated by a slow drift of the sent on eccentric gaze. It is due to abnormal functioning eye. This drift may be sinusoidal (pendular nystagmus) or of the gaze-holding integrator neurons in the paramedian be followed by a fast corrective (saccadic) eye movement pontine reticular formation (PPRF) region, resulting (jerk nystagmus). Although the direction of the nystag- from impaired inputs from the cerebellar flocculus.
mus is conventionally described by the direction of its Bilateral horizontal, together with vertical, gaze-evoked quick phases (for example upbeat nystagmus) it is impor- nystagmus commonly occurs with structural brainstem tant to remember that it is the smooth eye movement and cerebellar lesions, diffuse metabolic disorders and Centre, Charing CrossHospital, London. He is imbalance which reflects the underlying disorder (Table drug intoxication. Treatment is not required since this 2). Nystagmus usually results from a disturbance in one of type of nystagmus rarely causes severe visual problems.
the three mechanisms which hold gaze still – visual fixa- Periodic alternating nystagmus (PAN) is a primary Neurologists. He has aparticular interest in tion, vestibulo-ocular reflex and the eccentric gaze hold- position horizontal nystagmus that changes direction in a crescendo-decrescendo manner, characteristically The commonest form of jerk nystagmus is peripheral approximately every 90 sec. Between each directional the scientific and clinicalliterature on various vestibular nystagmus, which most frequently results from change there is a null period of 0 to 10 sec. It is usually labyrinth or vestibular nerve dysfunction. Tonic vestibu- associated with lesions affecting the nodulus or uvula of lar input from the intact side is unopposed by input from the cerebellum. There is a congenital form10, and acquired the affected side causing drift of the eyes to that side. This forms are due to Chiari malformations, multiple sclerosis, type of nystagmus is usually mixed i.e. various combina- fourth ventricle tumours, spinocerebellar degenerations tions of horizontal, vertical and torsional components; it and anticonvulsant intoxication. Baclofen has been is always unidirectional, the quick phases beating away shown to be an effective treatment for the acquired from the underactive labyrinth; its intensity increases when the eyes are turned in the direction of the quickphases; it is markedly suppressed by visual fixation (byusing Frenzel goggles); it is usually accompanied by verti- Figure 1. Wave forms and saccadic
oscillations of nystagmus. (a)
go, which is of limited duration due to central compensa- Constant velocity drift of the eyes.
tion. If nystagmus persists for more than a few weeks, it is usually due to an abnormality of the central vestibular by peripheral or central vestibulardisease and also with lesions of pathways. Treatment with diphenhydramine, promet- hazine, or prochlorperazine is appropriate for relief of the accompanying nausea and should be stopped as soon as sawtooth appearance. (b) Drift ofthe eyes back from an eccentric possible since they can impair the normal compensatory Several different types of central vestibular nystagmus Eye position
are described, all of which show no change in intensity exponential time-course withdecreasing velocity. This waveform with the removal of visual fixation in contrast to periph- eral vestibular nystagmus. Downbeat nystagmus may or may not be present in the primary position. It beats impaired neural integrator. (c)Drift of the eyes away from the directly downwards and is often accentuated in lateral gaze. When present in the primary position a disturbance of the vestibulocerebellum, drug intoxication or an (increasing velocity). Thiswaveform suggests an unstable abnormality at the cranio-cervical junction, such as a Type 1 Chiari malformation, are usually found6. These causes include cerebellar degenerations, anticonvulsant drugs, lithium intoxication and intra-axial brainstem vertically in cerebellar disease. (d)Pendular nystagmus, which is lesions. In about half of the patients with downbeat nys- tagmus, no cause can be found. Treatment can be attempted with clonazepam, baclofen, trihexyphenidyl or acquired disease. (e)Macrosaccadic oscillations: acetazolomide for the nystagmus associated with episod- Upbeat nystagmus when present in the primary posi- flutter: to-and-fro, back-to-backsaccades without an intersaccadic tion, is usually associated with focal brain-stem lesions in the tegmental gray matter, either at the pontomesen- cephalic junction or at the pontomedullary junction, involving the nucleus prepositus hypoglossi or the ventral Pendular nystagmus is either congenital or acquired due Oscillations without any intersaccadic interval (back- to cerebellar and brainstem disease, usually multiple scle- to-back) include opsoclonus, ocular flutter and conver- rosis12. Acquired pendular nystagmus may have both hor- gence-retraction saccadic pulses. Opsoclonus consists of izontal and vertical components, and the amplitude and multidirectional (including oblique and torsional) back- phase relationships of the two sinewaves determine the to-back saccades of varying amplitude. It has been sug- trajectory of the eyes e.g. oblique, circular or elliptical13. It gested that the disorder arises due to disordered pause cell can affect one eye or both, equally or unequally, and is function in the PPRF20. A variety of posterior fossa disor- often symptomatic resulting in oscillopsia. It may be asso- ders can give rise to the condition, including parainfec- ciated with oscillations of other structures such as the tious brain stem encephalitis, metabolic-toxic states or as palate, head or limbs14. In some patients gabapentin or a paraneoplastic (non-metastatic) disorder; in children it memantine may reduce the amplitude of nystagmus and is associated with occult neuroblastoma and in adults with small cell carcinoma of the lung and carcinoma of Congenital nystagmus is almost invariably a horizontal the breast and uterus22,23. Both anti-Ri and anti-Hu anti- conjugate nystagmus, which is unaltered by vertical posi- bodies have been identified in paraneoplastic opsoclonus tion. It is generally of jerk type with accelerating slow in adults. It can also occur in neonates associated with phases, and has an eccentric null position often leading to myoclonus - 'dancing eyes and dancing feet.'24 This a head turn or occasionally a head oscillation16. Fixation appears to be a maturational deficit which usually effort enhances congenital nystagmus. Less commonly the resolves over approximately 6 weeks. Treatment may be nystagmus is of a pendular type. Reversed optokinetic with plasmapheresis or intravenous immunoglobulins21 nystagmus, beating in the direction of the target motion, and drug treatments have included corticosteroids, is a feature of congenital nystagmus17.
propanolol, verapamil, clonazepam and gabapentin.
Latent nystagmus is a type of congenital nystagmus that Ocular flutter consists of bursts of back-to-back saccades is only present on monocular viewing and which then in the horizontal plane only, observed in patients with beats toward the viewing eye18. It is absent on binocular multiple sclerosis and signs of cerebellar disease25. It can viewing. If the patient has amblyopia in one eye latent also be observed in patients recovering from opsoclonus.
nystagmus is present with both eyes viewing, when it is A voluntary form of flutter (voluntary flutter) can be induced by about 8% of the population, usually by con-vergence. It consists of salvoes of horizontal back-to-back saccades. Lesions of the dorsal midbrain are often associ- Saccadic oscillations are bursts of saccades, which may be ated with upward gaze palsies and convergence-retraction intermittent or continuous, causing a disruption of fixa- nystagmus (Parinaud’s syndrome). This is incorrectly tion. Two main types can be identified, those with brief termed a nystagmus since it actually consists of asynchro- periods of fixation between saccades (intersaccadic inter- nous adducting saccades and should be redesignated con- val approximately 200 msec) and those composed of vergence-retraction saccadic pulses26. It may alternatively be due to opposed vergence movements27.
The oscillations with intersaccadic intervals include square wave oscillations consisting of sequences of References
square wave jerks (SWJ), which can occur in Alzheimer’s Kaminski HJ and Leigh RJ. (2002) The neurobiology of eye move- disease and progressive supranuclear palsy. Macrosaccadic ments: from molecules to behaviour. Ann N Y Acad Sci 956: 1-615.
oscillations (up to 40 deg) straddle the intended fixation Leigh RJ and Zee DS. (1999) The neurology of eye movements.
New York: Oxford University Press.
position and show a crescendo-decrescendo pattern. This Buttner U and Fuhry L. (1999) Drug therapy of nystagmus and type of oscillation is usually observed in acute damage to saccadic intrusions. Adv Otorhinolaryngol 55: 195-227.
the dorsal cerebellum involving the deep cerebellar Leigh RJ and Tomsak RL. (2003) Drug treatments for eye move- nuclei, as in demyelination, tumour or haematoma19.
ment disorders. J Neurol Neurosurg Psychiatry 74: 1-4.
Serra A and Leigh RJ. (2002) Diagnostic value of nystagmus: spon-taneous and induced ocular oscillations. J Neurol Neurosurg Table 1 – Definitions of types of ocular oscillation
Nystagmus – a sustained to and fro oscillation initiated Halmagyi GM, Rudge P, Gresty MA, and Sanders MD. (1983) Downbeating nystagmus. A review of 62 cases. Arch Neurol 40: Saccadic oscillations – sustained oscillations initiated by Averbuch-Heller L, Tusa RJ, Fuhry L, Rottach KG, Ganser GL,Heide W, Buttner U, and Leigh RJ. (1997) A double-blind con-trolled study of gabapentin and baclofen as treatment for acquirednystagmus. Ann Neurol 41: 818-825.
Table 2 - Types of nystagmus and their mechanism
Table 3 – Types of saccadic oscillations
Peripheral vestibularCentral vestibular – downbeat, upbeat, torsional, Convergence-retraction pulses (nystagmus)Ocular bobbing Barton JJ, Huaman AG, and Sharpe JA. (1994) Muscarinic antag- 18. Gresty MA, Metcalfe T, Timms C, Elston J, Lee J, and Liu C.
onists in the treatment of acquired pendular and downbeat nys- (1992) Neurology of latent nystagmus. Brain 115 ( Pt 5): 1303- tagmus: a double-blind, randomised trial of three intravenous drugs. Ann Neurol 35: 319-325.
19. Dell'Osso LF and Daroff RB. Nystagmus and saccadic intrusions Fisher A, Gresty M, Chambers B, and Rudge P. (1983) Primary and oscillations. 1999 In: Neuro-ophthalmology (3 ed.), edited position upbeating nystagmus. A variety of central positional nys- by Glaser JS. Philadelphia: Lippincott, Williams & Wilkins, 1999, tagmus. Brain 106 (Pt 4): 949-964.
10. Gradstein L, Reinecke RD, Wizov SS, and Goldstein HP. (1997) 20. Averbuch-Heller L and Remler B. (1996) Opsoclonus. Semin Congenital periodic alternating nystagmus. Diagnosis and Management. Ophthalmology 104: 918-928; discussion 928-919.
21. Bataller L, Graus F, Saiz A, and Vilchez JJ. (2001) Clinical out- 11. Halmagyi GM, Rudge P, Gresty MA, Leigh RJ, and Zee DS.
come in adult onset idiopathic or paraneoplastic opsoclonus- (1980) Treatment of periodic alternating nystagmus. Ann Neurol myoclonus. Brain 124: 437-443.
22. Hersh B, Dalmau J, Dangond F, Gultekin S, Geller E, and Wen 12. Lopez LI, Bronstein AM, Gresty MA, Du Boulay EP, and Rudge PY. (1994) Paraneoplastic opsoclonus-myoclonus associated with P. (1996) Clinical and MRI correlates in 27 patients with acquired anti-Hu antibody. Neurology 44: 1754-1755.
pendular nystagmus. Brain 119 (Pt 2): 465-472.
23. Luque FA, Furneaux HM, Ferziger R, Rosenblum MK, Wray SH, 13. Averbuch-Heller L, Zivotofsky AZ, Das VE, DiScenna AO, and Schold SC, Jr., Glantz MJ, Jaeckle KA, Biran H, Lesser M, and et Leigh RJ. (1995) Investigations of the pathogenesis of acquired al. (1991) Anti-Ri: an antibody associated with paraneoplastic pendular nystagmus. Brain 118 ( Pt 2): 369-378.
opsoclonus and breast cancer. Ann Neurol 29: 241-251.
14. Schwartz MA, Selhorst JB, Ochs AL, Beck RW, Campbell WW, 24. Hoyt CS, Mousel DK, and Weber AA. (1980) Transient supranu- Harris JK, Waters B, and Velasco ME. (1986) Oculomasticatory clear disturbances of gaze in healthy neonates. Am J Ophthalmol myorhythmia: a unique movement disorder occurring in Whipple's disease. Ann Neurol 20: 677-683.
25. Schon F, Hodgson TL, Mort D, and Kennard C. (2001) Ocular Correspondence to:
15. Bandini F, Castello E, Mazzella L, Mancardi GL, and Solaro C.
flutter associated with a localised lesion in the paramedian pontine (2001) Gabapentin but not vigabatrin is effective in the treatment reticular formation. Ann Neurol 50: 413-416.
of acquired nystagmus in multiple sclerosis: How valid is the 26. Ochs AL, Stark L, Hoyt WF, and D'Amico D. (1979) Opposed GABAergic hypothesis? J Neurol Neurosurg Psychiatry 71: 107- adducting saccades in convergence-retraction nystagmus: a patient with sylvian aqueduct syndrome. Brain 102: 497-508.
16. Gresty M, Page N, and Barratt H. (1984) The differential diagno- 27. Rambold H, Kompf D, and Helmchen C. (2001) Convergence sis of congenital nystagmus. J Neurol Neurosurg Psychiatry 47: retraction nystagmus: a disorder of vergence? Ann Neurol 50: 677- 17. Halmagyi GM, Gresty MA, and Leech J. (1980) Reversed optoki- netic nystagmus (OKN): mechanism and clinical significance. Ann C O N T I N U I N G
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