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Nystagmus
Neuro-Ophthalmology
Key Points
- •Nystagmus is named by the fast phase (corrective saccade), but the slow phase is the pathological component - always describe the slow phase to understand the underlying mechanism
- •Downbeat nystagmus (worst in downgaze and lateral gaze) is the most common persistent acquired nystagmus - Arnold-Chiari malformation is the cause in 30–40% of cases; treat with 4-aminopyridine
- •Periodic alternating nystagmus (PAN) reverses direction every 90–120 seconds and responds specifically to baclofen - a rare but classic exam question
- •Infantile nystagmus syndrome (INS) stays horizontal in all gaze positions (including upgaze), has an accelerating slow phase, dampens with convergence, and patients do NOT report oscillopsia
- •Seesaw nystagmus (one eye up/intorts while other down/extorts) is a specific localizing sign for parasellar/chiasmal lesions - check for bitemporal hemianopia
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17 more sections are included with the Clinical plan.
- Definition
- Epidemiology
- Aetiology and causes
- Pathogenesis
- Classification
- Risk factors and associations