Overview
The term nystagmus is used mainly to refer to jerk nystagmus, abnormal rhythmic eye movements that may be a sign of cerebellar disease.
Jerk Nystagmus
How to Perform
- Ask the patient to look at your finger, held ~50cm in front of their eyes (in primary position). Repeat in the extremes of left and right lateral gaze, as well as in superior and inferior gaze.
Look For
- Slow drifting movements of the eye interspersed with corrective fast saccadic movements.Note whether these movements are horizontal, vertical or torsional.
The direction of the nystagmus is describes as the direction of the fast-beating movement.
Interpretation
- Physiologic nystagmus - a few beats of horisontal nystagmus at the extremes of lateral gaze
- Positional nystagmus - transient (
- Upbeat nystagmus - downward slow movements with upward fast movements in primary position
- Downbeat nystagmus - upward slow movements with downward fast movements
Causes of Jerk Nystagmus
- Physiologic
- Congenital
- Central (brainstem / cerebellum) - multiple sclerosis, stroke, trauma, tumour
- Visual impairment - intra-ocular, optic nerve (II), total blindness
- Vestibular disturbance - Meniere's, benign paroxysmal positional vertigo, labyrinthitis
- Drugs - alcohol, sedatives, phenytoin
Pendular Nystagmus
Pendular nystagmus is less common, and manifests as equal movement to both sides (i.e. no fast or slow phase).
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