Congenital

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



REFERENCES


1. Stang HJ. Developmental disabilities associated with congenital nystagmus. J Dev Behav Pediatr 1991;12(5):322–323.


2. Fingert JH, Roos B, Eyestone ME, et al. Novel intragenic FRMD7 deletion in a pedigree with congenital X-linked nystagmus. Ophthalmic Genet 2010;31(2):77–80.


3. Hertle RW, Maldanado VK, Maybodi M, et al. Clinical and ocular motor analysis of the infantile nystagmus syndrome in the first 6 months of life. Br J Ophthalmol 2002;86(6):670–675.


4. Sharma P, Tandon R, Kumar S, et al. Reduction of congenital nystagmus amplitude with auditory biofeedback. J AAPOS 2000;4(5):287–290.


5. Spielmann A. Clinical rationale for manifest congenital nystagmus surgery. J AAPOS 2000;4(2):67–74.

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Nov 9, 2016 | Posted by in OPHTHALMOLOGY | Comments Off on Congenital

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