Nystagmus
Michael J. Puk
Nystagmus is an involuntary, rhythmically repeated oscillation of one or both eyes in any or all fields of gaze. Eye movements are coordinated by smooth pursuit and saccadic eye systems (1). An example of these two systems is fixating on a picket fence while moving in a car. Smooth pursuit targets the fence and saccades allow refixation to the next fence post.
Approach
Nystagmus can be classified into two basic types, jerk and pendular (2).
A. Jerk nystagmus consists of an initial slow phase, followed and named by the direction of the fast phase. This is seen in most neuropathologic causes of nystagmus.
B. Pendular nystagmus consists of smooth back-and-forth movement of the eye and is usually caused by poor vision or it is congenital.
History
A. Age of onset. Congenital nystagmus is either caused by poor vision (sensory) or motor nystagmus. Both develop early in life but sensory nystagmus does not present until 2 to 3 months of age. Nystagmus developing later in life (acquired nystagmus) is neuropathologic.
B. Family history. Is there a history of nystagmus, strabismus, or visual problem present at an early age in other family members? Hereditary motor nystagmus is not too uncommon.
C. Associated symptoms. Is oscillopsia (the sensation of environment “jiggling”) present? If present, then the nystagmus is likely acquired. Vertigo implies vestibular disease. Previous episodes of weakness, numbness, or loss of vision implicate multiple sclerosis. Associated ptosis suggests myasthenia.
D. Medications. Medications that can induce nystagmus include lithium, barbiturates, phenytoin, salicylates, benzodiazepines, phencyclidine, and other anticonvulsants or sedatives.
E. Social history. Alcohol intoxication produces a gaze-evoked nystagmus as well as alcohol-induced thiamin deficiency in Wernicke’s encephalopathy.
Physical examination
A. Visual acuity. Visual acuity is more depressed in acquired sensory nystagmus than in congenital nystagmus.
B. Ocular motility. The direction, plane, and amplitude of the eye movement are described. Nystagmus is conjugate if both eyes demonstrate the same movement and dissociated if they have different movements. Look for a null zone (field of gaze in which the nystagmus is minimal) or a neutral zone (field of gaze where nystagmus reverses direction).
C. Eye examination. Evaluate for any cause of poor vision that will help confirm sensory nystagmus. Look for aniridia (absence of iris) or iris transillumination as seen in albinism; both are associated with poor vision and nystagmus at an early age. Congenital cataracts or corneal opacities will have poor red reflexes. Analyze the optic nerve to assess for hypoplasia or atrophy. Latent nystagmus (seen only when one eye is covered) is present in congenital esotropia.
D. Other examinations. Head bobbing is usually present with congenital motor nystagmus and spasmus nutans (see below). A complete neurologic assessment should be done to screen for associated signs seen in cerebellar disease, multiple sclerosis, and so on.
Diagnostic assessment
(3,4). An accurate description of the nystagmus will help to categorize the type of eye movement disorder and to determine if any further diagnostic testing is needed.
A. Congenital nystagmus. The nystagmus develops at birth or in the perinatal period with small binocular and conjugate pendular eye movements. Over the first year of life, a jerk nystagmus develops with a null point. The nystagmus decreases with convergence and is abolished during sleep. Head nodding develops at any point up to age 20 years. Any cause of poor vision can cause sensory nystagmus. Two forms of acquired nystagmus when seen in the young merit concern.
1. Opsoclonus. Repetitive, irregular, and multidirectional (“dancing eyes” or saccadomania), opsoclonus is associated with cerebellar or brainstem disease, postviral meningitis, or neuroblastoma.
2. Spasmus nutans. Triad of head turn, nystagmus, and head bobbing that begins between 6 months to 3 years is seen in spasmus nutans. The nystagmus can be monocular or binocular and dissociated; of low amplitude and high frequency; and with horizontal or vertical pendular movements. This usually resolves between age 2 and 8 years. An identical clinical picture can be produced by a glioma of the optic chiasm.
B. Acquired nystagmus. The following are acquired forms of nystagmus with localized pathology.
1. See-saw. One eye rises and rotates in whereas the other descends and rotates out. Movements are pendular. This is frequently seen with lesions of the chiasm or third ventricle.
2. Downbeating. The fast phase of the nystagmus beats down and localizes the lesion at the cervicomedullary junction at the level of the foramen magnum. Arnold-Chiari malformation is the most common cause but spinocerebellar degeneration, brainstem stroke, multiple sclerosis, and platybasia will induce this type of nystagmus.
3. Upbeat. The fast phase beats up and can be of large or small amplitude. The lesion commonly involves the brainstem or vermis of the cerebellum.
4. Convergence-retraction. Here, is seen convergence of the eyes with jerk nystagmus and retraction of the globe on upgaze. Eyelid retraction, limitation in upgaze, and large unreactive pupils are associated with the nystagmus. Papilledema may be present. This is caused by midbrain abnormalities loosely correlated with age 10 years, pinealoma; 20 years, head trauma; 30 years, brainstem vascular malformation; 40 years, multiple sclerosis; 50 years, basilar artery stroke.
5. Periodic alternating. Jerk nystagmus has the fast phase in one direction with a head turn for 60 to 90 seconds, then reverses direction (neutral zone). The cycles repeat continuously with the nystagmus being horizontal throughout. This can be seen with vestibulocerebellar disease (stroke, multiple sclerosis, spinocerebellar degeneration), severe bilateral visual loss (optic atrophy, dense vitreous hemorrhage), or it can be congenital.
6. Gaze-evoked. Jerk nystagmus is present only when eyes look to the side. This is most commonly seen with alcohol or other central nervous system depressants. Cerebellar disease and brainstem disease can be associated with this nystagmus.
7. Vestibular. Nystagmus is caused by dysfunction of inner ear, nerve, or central nuclear complex. Peripheral vestibular disease produces unidirectional jerk nystagmus with fast phase opposite the lesion and usually horizontal. This is commonly associated with vertigo, tinnitus, and deafness (Chapters 6.8 and 6.9). It is caused by labyrinthitis, Ménière’s disease, neuronitis, vascular ischemia, trauma, or toxicity. Central (nuclear) disease is characterized by uni- or bidirectional nystagmus that may be purely horizontal jerk, vertical, or rotatory. Vertigo, tinnitus, and deafness are mild, if present, and symptoms are not relieved with eye fixation as in peripheral disease. This implies bilateral brainstem disease including demyelinating tumor, trauma, or stroke.
8. Latent nystagmus. As discussed, latent nystagmus is found in congenital esotropia.
9. Dissociated. The nystagmus in one eye is different than the other. This is seen in posterior fossa lesions; if an abduction nystagmus is present with an internuclear ophthalmoplegia, multiple sclerosis is likely.
C. Other ocular oscillations
1. Ocular bobbing is characterized by fast, conjugate, downward movement of the eye followed by a slow drift to primary position of gaze. This is seen in comatose patients with large pontine lesions (hemorrhage, stroke, or tumor). Obstructive hydrocephalus or metabolic encephalopathy can cause this type of eye movement.
2. Superior oblique myokymia is present with small unilateral, vertical, and rotatory movements of one eye. Symptoms of oscillopsia worsen when looking down and in. This is usually benign and self-limited, but has been noted with multiple sclerosis.
Testing
A. Laboratory. Urine drug screening for alcohol or barbiturates can be helpful in gaze-evoked nystagmus. High serum levels of phenytoin or lithium produce a gaze-evoked nystagmus. Ocular albinism can be associated with a bleeding disorder secondary to platelet dysfunction (Hermansky-Pudlak syndrome) or white blood cell dysfunction with increased susceptibility to infection and lymphoma (Chediak-Higashi syndrome). A bleeding time and a polymorphonuclear leukocyte function test should be ordered in consultation with a pathologist. Urinary vanillylmandelic acid should be obtained in an opsoclonus patient to look for by-products of neuroblastoma.
B. Imaging studies. Magnetic resonance imaging (MRI) scan must be obtained for any nystagmus having localized pathology. A child with spasmus nutans must have glioma of the chiasm ruled out by computed tomography (CT) or MRI. For vertical nystagmus, especially downbeating, order an MRI with sagittal views to look for cerebellar vermis herniating through the foramen magnum as seen in Arnold-Chiari malformations. An abdominal or a head CT or MRI should be done to look for neuroblastoma in the adrenal glands or brain in a patient with opsoclonus. Abdominal ultrasound or CT is needed to evaluate the kidneys in aniridia, for which a significant incidence of Wilm’s tumor is seen.
References
1. Friedberg MA, Rapuano CJ. Wills Eye Hospital office and emergency room diagnosis and treatment of eye disease. Philadelphia: JB Lippincott, 1990:268–271.
2. Bajandas FJ, Kline LB. Neuro-ophthalmology review manual. Thorofare, NJ: Slack Inc., 1988:67–75.
3. Vaughn D, Asbury T, Tabbara KF. General ophthalmology. Norwalk: Appleton & Lange, 1989:270–272.
Book Source Details
- Book Title: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter
- Author(s): Robert B. Taylor (editor)
- Year of Publication: 2000
- Copyright Details: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter, Copyright © 2000 Lippincott Williams & Wilkins.
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Copyright Details: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter, Copyright © 2008 Williams & Wilkins.
More About Causes of Eye symptoms
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