BASICS

DESCRIPTION

Involuntary oscillation of the eyes that may be either motor or sensory in etiology.

EPIDEMIOLOGY

Incidence

Idiopathic motor infantile/congenital nystagmus: 1 in 2,850 (1).

Prevalence

Approximately 0.5%, including those associated with strabismus and other diseases.

RISK FACTORS

• Low vision

– Strabismus (2)

– Developmental delay

– Down, Asperger (2 reported cases), and other syndromes

– Neurological anomalies

– Family history of nystagmus

Genetics

• Isolated nystagmus: Autosomal dominant (loci 6p12, 7p11, 13q31–33, 18q22.3–23), autosomal recessive (6p12), and X-linked (locus Xp11.3-11.4; gene FRMD7 at Xq26–q27; gene GPR143 at Xp22.3) (2)

• Genetics of underlying syndrome would otherwise apply.

GENERAL PREVENTION

Genetic counseling

PATHOPHYSIOLOGY

• Low vision results in inability to use visual information to maintain stable fixation.

• Neuronal mechanism of motor nystagmus is a field active research. Currently, there is no unified theory.

ETIOLOGY

• Isolated congenital/infantile motor nystagmus may or may not have genetic etiology.

• Acquired nystagmus

– Sensory: Vision loss before age 2 years

– Central nervous system anomalies

– Degenerative brain disorders, stroke, tumor

– Vestibular

COMMONLY ASSOCIATED CONDITIONS

• Low vision due to pre-chiasmal pathology (e.g., retinal dystrophy, optic nerve hypoplasia, untreated cataract)

• Albinism

• Central nervous system anomalies or other disorders

• Developmental delay

• Multiple syndromes (e.g., Cornelia de Lange syndrome) and chromosomal aberrations (e.g., trisomy 21)

DIAGNOSIS

HISTORY

• Age of onset. Congenital/infantile nystagmus is usually noticed by parents between 8–12 weeks old and before 6 months of age.

– Photophobia (e.g., achromatopsia, cone dystrophy, albinism, macular hypoplasia)

– Poor night vision (e.g., Congenital stationary night blindness [CSNB])

– Better night than day vision (e.g., achromatopsia)

• History of neurologic signs, brain injury, brain tumor

• Family history

• Medication or illicit drug use

PHYSICAL EXAM

• Systemic and neurology evaluation for anomalies, developmental delay, and hypotonia

• Complete ophthalmologic evaluation to look for

– Ocular anomalies and media opacities

– Strabismus (e.g., from poor vision in sensory nystagmus or with infantile esotropia in nystagmus blockage syndrome)

• Evaluation for head positions, null point (may shift over time, e.g., periodic alternating nystagmus)

• Amplitude, frequency, and direction in all gazes

– Type of nystagmus: Pendular, jerk

– Amplitude

– Symmetry

– Direction (vertical horizontal, see saw, opsoclonus)

– Changes in character with convergence or monocular viewing

– Increase beneath closed eyelids – vestibular or brainstem pathology

DIAGNOSTIC TESTS & INTERPRETATION

Lab

• Not required unless systemic disorder which warrants laboratory tests

• If opsoclonus, do urine catecholamines.

Imaging

Initial approach

– Brain MRI in cases of

– Vertical and asymmetric nystagmus

– Nystagmus with optic nerve hypoplasia

Neurologic signs

Unusual patterns of nystagmus (e.g., see saw, opsoclonus – if so, also scan neck and thorax and possibly abdomen for paraspinal neuroblastoma)

Follow-up & special considerations

For progressive neurologic disease

Diagnostic Procedures/Other

• Eye movement recording (3)

• Electrophysiology studies for nystagmus associated with decreased vision without identifiable ocular pathology or suspect CSNB

– 3-lead visual evoked potentials (VEP) help to establish the diagnosis of albinism

DIFFERENTIAL DIAGNOSIS

• Congenital/infantile nystagmus

• Nystagmus due to vision deprivation before age 2 years

– Ocular anterior segment pathologies: Corneal opacity, cataract, glaucoma

– Retinal diseases

– Optic nerve diseases/congenital anomalies

• Latent nystagmus

– Usually associated with strabismus

– Affected by monocular occlusion and reverse direction when the covered eye is changed

• Spasmus nutans

– Onset during the first year of life in otherwise healthy children

– Transient high frequency often asymmetric nystagmus with head nodding and abnormal head position

– Chiasmal, suprachiasmal, or third ventricle gliomas may mimic spasmus nutans.

• Gaze-evoked nystagmus

• Vestibular diseases

• Nystagmus due to brain, brainstem, and cerebellum diseases

– Trauma

– Tumor: Glioma, neuroblastoma

– Inflammation

– Ischemic

– Demyelination: Multiple sclerosis

– Degeneration

– Malformation

• Toxins and drugs induced oscillations of eyes: Alcohol, lithium, antiseizure medications

• Idiopathic

TREATMENT

MEDICATION

• Medical treatment is not usually included in treatment for congenital nystagmus.

• Baclofen and 5-hydroxytryptophan have been tried with limited effect.

ADDITIONAL TREATMENT

General Measures

• Correct refractive error. Contact lens may damp the nystagmus in some patients.

• Obtain ocular alignment by refractive correction, prisms, or surgery – may eliminate manifest latent component.

• Treat amblyopia.

• Photochromic lenses and sun glasses for cone disorders and macular hypoplasia

• Prism

– Correct face turn.

– Stimulate fusional convergence: Base out prisms for both eyes.

Issues for Referral

• Genetic counseling for cases with family history, albinism, or other genetic causes

• Low vision

• Neurology referral as needed

• ENT referral in cases of vestibular nystagmus

COMPLEMENTARY & ALTERNATIVE THERAPIES

• Acupuncture

• Biofeedback (4)

SURGERY/OTHER PROCEDURES

• To correct face turn: Transfer the null position into primary gaze – Kestenbaum-Andersen procedure.

• To dampen the movement: Large recession of all 4 horizontal recti

• Artificial divergence surgery to produce a large exophoria that allows the patient to use fusional convergence to dampen the nystagmus (5)

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

• As needed for monitoring vision, head position, and amblyopia treatment

• As needed for associated ocular, central nervous system, or systemic disease

– Low vision

• Scheduled ophthalmology evaluation for monitoring and treatment of coexisting ocular condition, strabismus, and amblyopia

Patient Monitoring

School performance and development.

PATIENT EDUCATION

• Genetic counseling where indicated

• Low vision intervention

• Patient support network – American Nystagmus Network, Inc. (ANN) http://www.nystagmus.org/

• Underlying disease specific support groups

PROGNOSIS

• Visual acuity varies and depends on etiology

• Most forms of nystagmus, including congenital/infantile isolated motor nystagmus, dampen with age but rarely resolve.

• Anomalous head positions usually worsen as demand increases with age.

COMPLICATIONS

• Visual blur

– Only when acquired later in childhood does oscillopsia occur

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