Nystagmus

Background

• 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

Acquired Nystagmus

• Neurological damage
• Psychoactive drugs
• Alcohol intoxication
• Head trauma
• Brain tumor
• Stroke
• Multiple sclerosis
• Thalamic hemorrhage

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 course of illness. If possible, reverse toxicology.