Nystagmus

Background

• Nystagmus = involuntary eye movement
• The semicircular canals of the vestibules and the extraocular muscles of the eye function together physiologically to help control gaze locked when the head is in motion
• Nystagmus is an aberration in this stabilization of the ocular muscles when in motion

Clinical Features

• Rapid, uncontrolled, rhythmic oscillation of the eye
• May be horizontal, vertical, and/or rotary

Differential Diagnosis

Congenital Nystagmus

• Optic nerve hypoplasia
• Macular disease
• Noonan syndrome

Acquired Nystagmus

• Head trauma, tympanic membrane rupture
• Brain tumor
• Stroke
• Chiari malformation
• Meniere's disease, BPPV, labyrinthitis, Vestibular Neuritis
• Multiple sclerosis
• Wernicke–Korsakoff syndrome, thiamine deficiency
• Tox causes:
  • Alcohol intoxication, benzodiazepines, barbiturates, GHB
• Ketamine, Phencyclidine
• Amphetamines, MDMA
• Marijuana
• Lithium
• Phenytoin, fosphenytoin, carbamazepine, oxcarbazepine, lacosamide, gabapentin
• Salicylates, NSAID toxicity

Evaluation

"H in space" Test

• Trace H in space

Caloric Reflex Test (also known as Vestibular Caloric Stimulation)

• The best clinical test for the Vestibulo-Optic reflex
• Water irrigated into the external auditory canal will exaggerate nystagmus if present
• Temperature of the irrigated water will control the direction.
  • Cold water will exaggerate a nystagmus to move contralaterally
  • Warm water will exaggerate a nystagmus to move ipsilaterally

COWS: Cold Opposite, Warm Same.

Management

Stabilize patient and manage primary cause of illness.

See Also

• Focal neurologic deficits