eMedicine Specialties > Ophthalmology > Extraocular Muscles

Nystagmus, Congenital

Author: Theodore Curtis, MD, Assistant Professor, Department of Ophthalmology, University of Colorado; Consulting Staff, Rocky Mountain Lions Eye Institute
Coauthor(s): David T Wheeler, MD, Associate Professor, Departments of Ophthalmology and Pediatrics, Oregon Health & Science University
Contributor Information and Disclosures

Updated: Oct 13, 2006

Introduction

Background

Congenital or infantile nystagmus is a clinical sign that may take many different forms. Involuntary, rhythmic eye movements are characteristic, as they are in acquired nystagmus. Waveform, amplitude, and frequency can vary with changes in focal distance, direction of gaze, and under monocular or binocular viewing conditions.

Oscillations are usually horizontal in direction but may be primarily vertical, torsional, or any combination of these three. Infantile nystagmus often is associated with other ocular conditions that impair visual acuity and occasionally can herald life-threatening conditions. Prompt assessment by an ophthalmologist with knowledge of infantile nystagmus to establish the need for and urgency of additional evaluation is extremely important.

Pathophysiology

Few patients are noted to have nystagmus onset at birth. The term infantile is probably more accurate than congenital and includes nystagmus that presents within the first 6 months of life. This disorder classically has been divided into afferent (sensory deficit) nystagmus, which is due to visual impairment, and efferent (idiopathic infantile) nystagmus, which is due to oculomotor abnormality, with most cases being sensory in origin. It is believed that the nystagmus may reflect a failure of early sensorimotor integration.

Data from eye movement recordings have conclusively shown that waveform alone is not a reliable method of distinguishing between these 2 entities. Therefore, it is essential that all infants with nystagmus be evaluated thoroughly for a primary sensory cause. In addition, it recently has been suggested that the following 3 additional subtypes of infantile nystagmus exist: (1) nystagmus associated with albinism, (2) latent and manifest latent nystagmus, and (3) spasmus nutans.

Frequency

United States

The precise incidence and prevalence of nystagmus is unknown.

Mortality/Morbidity

Visual morbidity associated with nystagmus relates most closely to the underlying disorder affecting the visual or ocular motor system, which is responsible for the fixation instability. Infantile nystagmus rarely is associated with a life-threatening disorder.

Race

No reported racial predilection exists among patients with infantile nystagmus.

Sex

Infantile nystagmus affects males and females equally.

Age

Most patients with infantile nystagmus present within the first several months of life.

• Nystagmus present at birth or prior to age 2 months is more likely to be idiopathic in nature or due to neurologic dysfunction. Sensory deficit nystagmus most commonly presents at age 2-3 months. Further investigation of the visual system is warranted in these cases. Nystagmus associated with albinism has characteristics similar to idiopathic nystagmus but usually is absent until after age 2 months.
• Nystagmus that presents after age 6 months is considered late infantile or childhood nystagmus and carries a graver prognosis. The exception is spasmus nutans, with onset in children aged 4 months to 3 years. Resolution of this condition usually occurs within a year of onset. Chiasmal glioma can present in an identical manner to spasmus nutans.
• Latent or manifest latent nystagmus often is discovered after the first few months of life, but it most often is associated with infantile strabismus and can be identified by its unique characteristics.

Clinical

History

• Establishing the precise age of onset is helpful in differentiating between sensory deficit and idiopathic infantile forms. Spasmus nutans rarely is seen prior to age 4 months.
• Onset prior to age 2 months, particularly in the setting of gaze-associated variable intensity and torticollis, strongly suggests idiopathic infantile nystagmus.
• Patients with infantile nystagmus due to albinism may have a positive family history and often appear photosensitive.
• A history of infantile strabismus increases the likelihood of latent or manifest latent nystagmus.
• A history of abnormal head movements (bobbing or nodding) or torticollis raises the possibility of spasmus nutans.
• CNS disease can produce many other forms of nystagmus and always must be considered. A history of failure to thrive or other evidence of neurologic dysfunction should prompt immediate investigation.
• Older children and adults with a history of infantile nystagmus typically deny oscillopsia but frequently may have signs and symptoms of accommodative dysfunction. These signs and symptoms include asthenopia, headaches, avoidance of near tasks, tearing, and blurry vision.
• Both idiopathic infantile nystagmus and many forms of sensory deficit nystagmus have a familial pattern. X-linked, autosomal dominant, and autosomal recessive modes of inheritance have been reported.

Physical

• Both sensory deficit nystagmus and idiopathic infantile nystagmus are almost always bilateral, symmetric, and conjugate.
• Eye movements usually are horizontal and remain so during vertical gaze (uniplanar) rather than changing to a gaze-evoked vertical nystagmus. The nystagmus disappears during sleep.
• Nystagmus intensity (a product of the frequency and amplitude) often increases with fixation effort, attention, or anxiety, and diminishes with convergence.
• Various waveforms have been described.
  • Both pendular and jerk types have been documented to occur in idiopathic infantile and sensory deficit nystagmus. Nystagmus associated with albinism has characteristics similar to idiopathic infantile nystagmus.
  • Latent and manifest latent nystagmus always are jerk-type with the fast phase in the direction of the fixing eye and decreasing velocity of the slow phase; the nystagmus is larger in the amblyopic or nonfixing eye, and amplitude decreases in adduction.
  • Spasmus nutans classically is a triad of nystagmus, head nodding, and torticollis. The nystagmus is disconjugate, high frequency, small amplitude, pendular, and intermittent. It is suppressed with head nodding. A head tilt often is present.
• The hallmark of idiopathic infantile nystagmus is a gaze-dependent, variable intensity resulting in a "null zone" where nystagmus is least marked and visual acuity is maximized. This often corresponds to adoption of an anomalous head posture and is frequently the stated reason for referral.

Causes

• Idiopathic infantile nystagmus is believed to be due to a primary abnormality in oculomotor control. Increasing evidence suggests a genetic mechanism with one gene mapped to the X chromosome and another gene mapped to band 6p12.
• Many ocular disorders have been associated with sensory deficit nystagmus. This is not meant to be an exhaustive listing. The variety of sensory causes suggests that the underlying cause is a failure of sensorimotor integration due to reduced vision and/or contrast sensitivity.
  • Early (usually bilateral) visual deprivation (eg), congenital cataracts, severe glaucoma, Peters anomaly
  • Foveal hypoplasia (eg, aniridia, albinism [nystagmus associated with albinism has characteristics similar to idiopathic infantile nystagmus])
  • Retinal disease (eg, Leber congenital amaurosis, achromatopsia, macular toxoplasmosis [especially if bilateral])
  • Retinal detachment (eg, severe retinopathy of prematurity, posterior persistent hyperplastic primary vitreous, familial exudative vitreoretinopathy)
  • Optic nerve abnormalities (eg, hypoplasia, coloboma, atrophy)
  • Cortical visual impairment from perinatal insult or structural CNS abnormality
• Nystagmus associated with albinism is the result of multifactorial visual impairment. Anatomical findings include abnormal ocular pigmentation, foveal hypoplasia, abnormally increased chiasmal decussation, and high cylindrical refractive errors. Several subtypes have been described. Most are autosomal recessive, but all modes of inheritance have been described.
• Latent nystagmus is a benign condition that appears when one eye is covered, or when light stimulus to one eye is diminished. Latent nystagmus can coexist with manifest nystagmus (in which case the nystagmus amplitude increases with occlusion). Latent nystagmus is a jerk nystagmus with the fast phase toward the side of the fixing eye. It often is seen following surgery for infantile esotropia and probably results from subnormal binocular interaction. Visual acuity measurement should be performed using the polarized vectograph or blurring one eye with a high plus lens to avoid iatrogenic reduction of acuity with occlusion. So-called manifest latent nystagmus can occur if monocular visual loss occurs in this setting.
• The cause of spasmus nutans is unknown. Some studies have found an association with children from lower socioeconomic status, as well as coexisting strabismus and refractive error. Chiasmal glioma can present with an identical appearing nystagmus prior to affecting the anterior visual pathway.

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