Nystagmus refers to involuntary oscillations of one or both eyeballs. These oscillations may be rhythmic, horizontal, vertical, rotary, or mixed, and can be transient or sustained, occurring spontaneously or on eye deviation/fixation. Minor nystagmus at the extremes of gaze is normal; however, nystagmus with the eyes stationary and looking straight ahead is always abnormal. Patients may be unaware of it unless it affects vision.

Nystagmus is classified into pendular and jerk types:

• Pendular nystagmus: Equal oscillations in both directions. Subtypes include horizontal (pendular) or vertical (seesaw) movements.

• Jerk nystagmus: A fast phase followed by a slower corrective phase. Subtypes include convergence-retraction, downbeat, and vestibular nystagmus.

Nystagmus is considered a supranuclear ocular palsy, arising from pathology in the visual perceptual area, vestibular system, cerebellum, or brain stem, rather than in the extraocular muscles or cranial nerves III, IV, and VI. Causes include brain stem/cerebellar lesions, multiple sclerosis, encephalitis, labyrinthine disease, and drug toxicity.

Classifying Nystagmus

History and Physical Examination

History

• Duration and frequency of nystagmus

• Visual disturbances, diplopia

• Recent infections (ear, respiratory), head trauma, or cancer

• Family history of stroke or neurological disorders

• Associated symptoms: vertigo, dizziness, tinnitus, nausea/vomiting, numbness, weakness, bladder dysfunction, fever

Physical Examination

• Assess level of consciousness (LOC) and vital signs

• Look for signs of increased intracranial pressure (ICP): pupillary changes, drowsiness, elevated systolic pressure, altered respiration

• Test extraocular muscle function: follow finger up, down, and in “X” pattern; note direction, velocity, and occurrence of nystagmus

• Evaluate reflexes, motor and sensory function, cranial nerves

Medical Causes

Other causes

• Drug or alcohol toxicity: Barbiturates, phenytoin, carbamazepine, or alcohol can induce jerk nystagmus.

Special considerations

• Prepare the patient for diagnostic tests: electronystagmography, CT scan, or MRI.

• Monitor neurologic status, LOC, and vital signs.

Patient counseling

• Explain the condition, its causes, and potential complications.

• Advise on safety measures: avoid sudden movements, ensure proper support when walking.

• Reinforce adherence to prescribed diagnostic tests and follow-up appointments.

Pediatric pointers

• In children, pendular nystagmus may be idiopathic or related to early visual impairment from:

  • Optic atrophy

  • Albinism

  • Congenital cataracts

  • Severe astigmatism

References

1. Ansons AM, Davis H. Diagnosis and Management of Ocular Motility Disorders. West Sussex, UK: Wiley Blackwell; 2014.

2. Biswas J, Krishnakumar S, Ahuja S. Manual of Ocular Pathology. New Delhi, India: Jaypee–Highlights Medical Publishers; 2010.

3. Gerstenblith AT, Rabinowitz MP. The Wills Eye Manual. Philadelphia, PA: Lippincott Williams & Wilkins; 2012.

4. Roy FH. Ocular Differential Diagnosis. Clayton, Panama: Jaypee–Highlights Medical Publishers; 2012.