Nystagmus
Nystagmusis the rhythmic to and fro oscillation of the eyes in any or allfields of gaze.Described by type (jerk or pendular),direction (horizontal, vertical, torsional), amplitude (small, medium,large), frequency (low, moderate, high), and gaze (conjugate ordysconjugate).In jerk nystagmus, movement in 1 directionis faster that movement in the other direction. By convention, nystagmusis named in direction of the fast component. Movements are equalin velocity in both directions in pendular nystagmus.In conjugate nystagmus, both eyes movein same direction with equal frequency and amplitude, whereas indysconjugate nystagmus, monocular or binocular oscillations aredissimilar in amplitude, frequency, and direction. Principal Causes of Nystagmus
- Physiologicnystagmus
- Voluntarynystagmus
- End-point nystagmus
- Opticokinetic nystagmus
- Evoked vestibular nystagmus
- Pathologic nystagmus
- Idiopathiccongenital nystagmus
- Latent nystagmus
- Nystagmus associated with visual loss
- Neurologic disorders associated withnystagmus
- Acquiredfixation nystagmus
- Periodic alternating nystagmus
- Gaze-evoked nystagmus
- Seesaw nystagmus
- Vestibular nystagmus
- Peripherallesions
- Central lesions
- Spasmus nutans
Clinical Features and Diagnosis
Physiologic Nystagmus
Voluntary Nystagmus
Some individuals can voluntarily producebrief pendular nystagmus, which is usually rapid and horizontal.
End-Point Nystagmus
Is a jerk nystagmus of fine amplitude thatoccurs on extreme lateral gaze. It is brief and usually occurs innormal individuals who are anxious or tired. Fast phase is towardfield of gaze.
Opticokinetic Nystagmus
Is a jerknystagmus produced by watching repetitive visual stimuli movingacross field of vision.Can be produced by watching movinglights or sequence of vertical stripes on rotating drum or cloth.Following the moving object produces slow phase. Fast phase occurswhen eyes return to see next moving object.Nystagmus is horizontal or verticaldepending on direction of moving objects.Can be elicited to determine if inattentiveinfant sees or in cases of functional visual loss. Evoked Vestibular Nystagmus
Is a jerk nystagmus that can be producedin normal individuals by caloric (irrigation of ear canal with warmor cold water) or rotatory testing to determine integrity of labyrinthand its central connections. Direction of nystagmus (fast component)can be remembered by mnemonic COWS (cold, opposite; warm, same).
Pathologic Nystagmus
Idiopathic Congenital Nystagmus
Onset ofidiopathic congenital nystagmus is typically at 6–8 wksof age. It is frequently jerk nystagmus, but occasionally pendular.Different waveforms may be seen atvarious times in same individual. Almost always conjugate and mostoften horizontal.Often dampened by convergence, it isfrequently associated with a "null" point in whichintensity of oscillations decreases and visual acuity improves.Although amplitude and frequency ofnystagmus usually increase during first few months after presentation,they decrease later on. Many children have significant refractiveerrors, strabismus, or amblyopia, but there is no association withrecognizable structural lesions of the eye or anterior visual pathways.Eye muscle surgery is performed forany associated strabismus and sometimes to compensate for markedhead turns associated with nystagmus.Amplitude of nystagmus is not relatedto visual acuity, and many individuals have acuity sufficient toobtain driver's license. Latent Nystagmus
Is a congenitalnystagmus that is seen under conditions of monocular fixation. Etiologyis unknown but is most often seen in individuals with infantileesotropia. Generally not recognized until early childhood, whencover testing is done.It is a conjugate jerk nystagmus thathas its fast phase directed toward uncovered eye. Direction reverseswhen opposite eye is covered.Latent nystagmus may be superimposedon idiopathic congenital nystagmus. Nystagmus Associated with Visual Loss
Many eyedisorders can cause nystagmus, especially those that cause significantbilateral visual loss. These disorders include aniridia, congenitalcataract, retinopathy of prematurity, retinal dysplasia, macularcoloboma, glaucoma, optic nerve hypoplasia or atrophy, albinism,retinoblastoma, and strabismus. Because many of these causes ofimpaired vision are congenital, nystagmus may be the finding thatleads to their diagnosis.Before 2 yrs of age, lack of developmentof normal vision or visual loss is usually associated with nystagmus,which is usually horizontal and conjugate.From 2 to 6 yrs of age, nystagmus mayoccur after onset of visual loss.Acquired visual loss does not usuallycause nystagmus after 6 yrs of age.Severity of ocular oscillations doesnot predict visual acuity; rather, severity of visual pathway diseasedetermines severity of visual loss. Neurologic Disorders Associated with Nystagmus
Acquired Fixation Nystagmus
Posterior fossa lesion (e.g., tumor) mayproduce pendular or jerk, horizontal or vertical nystagmus withattempted fixation.
Periodic Alternating Nystagmus
Is a horizontal jerk nystagmus in which directionof fast phase changes in cyclic fashion every few minutes and isoften accompanied by alternating face turn. Can be seen with Chiarimalformations, demyelinating diseases, and cerebellar disorders.
Gaze-Evoked Nystagmus
Common causes are drugs (e.g., barbiturates,phenothiazines, tranquilizers, and anticonvulsants). If the drughistory is negative, other causes are brainstem or cerebellar dysfunction.
Seesaw Nystagmus
Unusual type of nystagmus in which 1 eyeelevates and intorts while other eye depresses and extorts. Maybe associated with parasellar tumors that compress optic chiasm(craniopharyngioma) or lesions of rostral midbrain.
Vestibular Nystagmus
Caused by disturbances in peripheral or centralportion of vestibular system.
Peripheral Lesions
With peripheralvestibular nystagmus (lesions of the labyrinth or eighth nerve),the jerk nystagmus is usually horizontal, with fast phase oppositethe side of the lesion.Common associated findings are vertigo,tinnitus, and hearing loss. Visual fixation inhibits nystagmus.Trauma and labyrinthitis are most commoncauses. Central Lesions
Lesionsinvolving vestibular nuclei, cerebellum, or their connections withcerebral cortex usually produce jerk nystagmus, which may be horizontal,vertical, or torsional.Hearing loss, tinnitus, and vertigodo not usually occur, and visual fixation does not inhibit nystagmus.Common causes include viral encephalitis,cerebellar or brainstem lesions, and multiple sclerosis. Spasmus Nutans
This disorderof unknown cause is characterized by the triad of nystagmus, headnodding, and torticollis.Usually begins after 4 mos of age andresolves by 5 yrs of age. Appears to only involve 1 eye, but finemovements also occur in other eye (dysconjugate nystagmus).Acquired mononuclear nystagmus maybe seen with chiasmal glioma, so that MRI may need to be performedif this tumor cannot be excluded on clinical exam by experiencedophthalmologist. Diagnostic Approach
Nystagmuscan usually be detected by simple observation, and type, direction,amplitude, frequency, and gaze should be determined.Whether nystagmus is physiologic orpathologic can usually be determined by history and physical exam.Careful eye exam can diagnose eye disordersassociated with nystagmus. If results of eye exam are normal, aneurologic disorder including a vestibular disturbance should beinvestigated.Association of nystagmus with hearingloss and vertigo suggests disturbance of peripheral vestibular system.Nystagmus associated with ataxia withouttinnitus and hearing loss suggests disturbance in brainstem or cerebellarfunction.CT and MRI are useful in diagnosisof neurologic disorders that may be associated with nystagmus.When considering causes of gaze-evokednystagmus, positive drug history may be diagnostic.Idiopathic congenital nystagmus isdiagnosis of exclusion. References
- Aicardi J. Diseases of the nervous systemin childhood, 2nd ed. London: Mac Keith Press, 1998.
- American Academy of Ophthalmology. Neuro-ophthalmology1999–2000. San Francisco: American Academy of Ophthalmology,1999.
- Awner S, Catalano RA. Nystagmus. In: Nelson LB, ed.Harley's pediatric ophthalmology, 4th ed. Philadelphia:WB Saunders, 1998:466–481.
- Burde RM, et al. Clinical decisions in neuro-ophthalmology.St. Louis: CV Mosby, 1985.
- Hoyt CS. Nystagmus and other abnormal ocular movementsin children. Pediatr Clin North Am 1987;34:1415–1423.
- Online Mendelian Inheritance in Man (OMIM). McKusick-NathansInstitute for Genetic Medicine, Johns Hopkins University (Baltimore,MD) and National Center for Biotechnology Information, NationalLibrary of Medicine (Bethesda, MD), 2000. World Wide Web URL: http://www.ncbi.nlm.nih.gov/omim.
- Simon JW, Calhoun JH. A child's eyes: a guideto pediatric primary care. Gainesville, FL: Triad Publishing, 1998.
Book Source Details
- Book Title: The Diagnostic Approach to Symptoms and Signs in Pediatrics
- Author(s): Paul S. Bellet
- Year of Publication: 2006
- Copyright Details: The Diagnostic Approach to Symptoms and Signs in Pediatrics, Copyright © 2006 Lippincott Williams & Wilkins.
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Read excerpts from these other book chapters related to Eye symptoms:
Copyright Details: The Diagnostic Approach to Symptoms and Signs in Pediatrics, Copyright © 2008 Williams & Wilkins.
More About Causes of Eye symptoms
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