Nystagmus is divided into congenital and acquired forms.

Congenital and acquired nystagmus may be symptomatic with decreased visual acuity. The environment may be noted to oscillate horizontally, vertically, or torsionally in cases of acquired nystagmus, but only occasionally in congenital cases.

Critical

Repetitive, rhythmic oscillations of the eye horizontally, vertically, or torsionally.

• Jerk nystagmus: The eye repetitively slowly drifts in one direction (slow phase) and then rapidly returns to its original position (fast phase).

• Pendular nystagmus: Drift occurs in two phases of equal speed, giving a smooth back-and-forth slow movement of the eye.

CONGENITAL FORMS OF NYSTAGMUS

INFANTILE NYSTAGMUS

Onset by age 2 to 3 months with wide, swinging eye movements. At age 4 to 6 months, small pendular eye movements are added. At age 6 to 12 months, jerk nystagmus and a null point (a position of gaze where the nystagmus is minimized) develop. Compensatory head positioning may develop at any point up to 20 years of age. Infantile nystagmus is usually horizontal and uniplanar (same direction in all gazes) and typically dampens with convergence. May have a latent component (worsens when one eye is occluded).

Differential Diagnosis

• Opsoclonus/saccadomania: Repetitive, conjugate, multidirectional rapid saccadic eye movements associated with cerebellar or brainstem disease, postviral encephalitis, visceral carcinoma, or neuroblastoma.

• Spasmus nutans: Head nodding and head turn with vertical, horizontal, or torsional nystagmus appearing between 6 months and 3 years of age and resolving between 2 and 8 years of age. Unilateral or bilateral (but asymmetric) rapid “shimmering nystagmus.” Spasmus nutans is a benign condition; however, gliomas of the anterior visual pathway may produce an identical clinical picture and need to be ruled out with MRI.

• Latent nystagmus (see below).

• Nystagmus blockage syndrome (see below).

Etiology

• Idiopathic.

• Albinism: Iris transillumination defects and foveal hypoplasia. See 13.8, Albinism.

• Aniridia: Bilateral, near-total congenital iris absence. See 8.14, Developmental Anterior Segment and Lens Anomalies/Dysgenesis.

• Leber congenital amaurosis: Markedly abnormal or flat electroretinogram (ERG).

• Others: Bilateral optic nerve hypoplasia, bilateral congenital cataracts, rod monochromatism, or optic nerve or macular disease.

Workup

1. History: Age of onset? Head nodding or head positioning? Known ocular or systemic abnormalities? Medications? Family history?

2. Complete ocular examination: Observe the head position and eye movements, perform iris transillumination, and carefully inspect the optic disc and macula.

3. Consider obtaining an eye movement recording if the diagnosis is uncertain.

4. If opsoclonus is present, obtain abdominal and chest imaging (e.g., US, CT, MRI) to rule out neuroblastoma and visceral carcinoma. Refer to primary medical doctor or pediatrician for additional workup (e.g., urinary vanillylmandelic acid) as appropriate.

5. In selected cases and in all cases of suspected spasmus nutans, obtain an MRI of the brain (axial, coronal, and parasagittal views) to rule out an anterior optic pathway lesion.

Treatment

1. Maximize vision by refraction.

2. Treat amblyopia if indicated.

3. If small face turn: Prescribe prism in glasses with base toward direction of face turn.

4. If large face turn: Consider muscle surgery. 

LATENT NYSTAGMUS

Occurs when only one eye is viewing. Conjugate horizontal nystagmus with fast phase beating toward viewing eye.

Manifest latent nystagmus occurs in children with strabismus or decreased vision in one eye, in whom the nonfixating or poorly seeing eye behaves as an occluded eye.

NOTE When testing visual acuity in one eye, fog (e.g., add plus lenses in front of) rather than occlude the opposite eye to minimize induction of latent nystagmus.

Treatment

1. Maximize vision by refraction.

2. Treat amblyopia if indicated.

3. Consider muscle surgery if symptomatic strabismus or cosmetically significant head turn exists.

NYSTAGMUS BLOCKAGE SYNDROME

Any nystagmus that decreases when the fixating eye is in adduction and demonstrates an esotropia to dampen the nystagmus.

Treatment

For large face turn, consider muscle surgery.

ACQUIRED FORMS OF NYSTAGMUS

Etiology

• Visual loss (e.g., dense cataract, trauma, cone dystrophy): Usually monocular and vertical nystagmus (Heimann–Bielschowsky phenomenon).

• Toxic/metabolic: Alcohol intoxication, lithium, barbiturates, phenytoin, salicylates, benzodiazepines, phencyclidine, other anticonvulsants or sedatives, Wernicke encephalopathy, and thiamine deficiency.

• CNS disorders in brainstem or cerebellum: Hemorrhage, tumor, stroke, trauma, MS, and others.

• Peripheral vestibular disease: Typically worsened by head movements and positional, often accompanied by tinnitus, hearing loss. Fast phase is contralateral to pathology.

• Nonphysiologic: Voluntary, rapid, horizontal, small oscillatory movements of the eyes that usually cannot be sustained >30 seconds without fatigue.

Nystagmus With Localizing Neuroanatomic Significance

• Seesaw: One eye rises and intorts while the other descends and extorts. Lesion typically involves the parasellar region and chiasm. Typically pendular when chiasmal region involved and jerk if involving the midbrain. One proposal suggests a unilateral lesion of the interstitial nucleus of Cajal or its connections are responsible for this nystagmus subtype. May have a bitemporal hemianopsia resulting from chiasmal compression. May be congenital or associated with septo-optic dysplasia.

• Convergence retraction: Not a true nystagmus, but convergence movements accompanied by globe retraction when the patient attempts an upward saccade. May be associated with limitation of upward gaze, eyelid retraction, and bilateral mid-dilated pupils that react poorly to light but constrict better with convergence. Usually, a pineal region tumor or other dorsal midbrain abnormality is responsible. See 10.4, Adie (Tonic) Pupil.

• Downbeat: The fast phase of nystagmus is down and most prominent looking down and to the right and left. Most commonly, either a manifestation of cerebellar degeneration or associated with a lesion at the cervicomedullary junction (e.g., Arnold–Chiari malformation).

• Periodic alternating: In primary position, fast eye movements are in one direction for 60 to 90 seconds and then reverse direction for 60 to 90 seconds. The cycle repeats continuously. Patients may attempt to minimize nystagmus with periodic head turning. May be congenital. Acquired forms are most commonly the result of lesions of the cervicomedullary junction and posterior fossa. Other causes include MS, medication side effects, and rarely blindness.

• Gaze evoked: Absent in primary gaze, but appears as the eyes look to the side. Nystagmus increases when looking in the direction of fast phase. Slow frequency. Most commonly the result of alcohol intoxication, sedatives, and cerebellar or brainstem disease.

• Peripheral vestibular: Horizontal or horizontal-rotary nystagmus. May be accompanied by vertigo, tinnitus, or deafness. May be due to dysfunction of vestibular end organ (inner  ear disease), eighth cranial nerve, or eighth cranial nerve nucleus in brainstem. Destructive lesions produce fast phases opposite to lesion. Irritative lesions (e.g., Ménière disease) produce fast phase in the same direction as the lesion. Vestibular nystagmus associated with interstitial keratitis is called Cogan syndrome.

• Spasmus nutans: See above.

• Others: Rebound nystagmus (cerebellar lesions), Bruns nystagmus (CPA), oculomasticatory myorhythmia (Whipple disease), oculopalatal myoclonus (prior brainstem stroke).

Differential Diagnosis

• Superior oblique myokymia: Small, unilateral, vertical, and torsional movements of one eye can be seen with a slit lamp or ophthalmoscope. Patients complain of unilateral oscillopsia. Symptoms and signs are more pronounced when the involved eye looks inferonasally. Usually benign, resolving spontaneously, but rarely due to a mass lesion so requires neuroimaging. Consider treating with carbamazepine.

• Opsoclonus/saccadomania: Rapid, chaotic conjugate saccades in multiple directions. Etiology in children is a paraneoplastic effect of neuroblastoma or encephalitis. In adults, in addition to paraneoplastic or infectious, it can be seen with drug intoxication or following infarction.

Workup

1. History: Nystagmus, strabismus, or amblyopia in infancy? Oscillopsia? Drug or alcohol use? Vertigo? Episodes of weakness, numbness, or decreased vision in the past? MS?

2. Family history: Nystagmus? Albinism? Eye disorder?

3. Complete ocular examination: Careful motility examination. Slit-lamp or optic disc observation may be helpful in subtle cases. Iris transillumination should be performed to rule out albinism.

4. Consider an eye movement recording if diagnosis unclear.

5. Visual field examination, particularly with seesaw nystagmus.

6. Consider a drug/toxin/nutritional screen of the urine, serum, or both.

7. CT scan or MRI as needed with careful attention to appropriate area of interest.

NOTE The cervicomedullary junction and cerebellum are best evaluated with sagittal MRI.

Treatment

1. The underlying etiology must be treated.

2. The nystagmus of periodic alternating nystagmus may respond to baclofen. Baclofen is not recommended for pediatric use. Other medications may be tried empirically for other nystagmus types.

3. Severe and disabling nystagmus can rarely be treated with retrobulbar injections of botulinum toxin.

Follow-Up

Appropriate follow-up time is dictated by the condition responsible for the nystagmus.