Nystagmus and Saccadic Intrusions.

Area of Science:

• Ophthalmology and Neurology
• Neuroscience
• Clinical Medicine

Background:

• Nystagmus and saccadic intrusions are abnormal eye movements that can indicate underlying neurologic disease.
• Accurate diagnosis and treatment are crucial for alleviating associated visual impairment.

Observation:

• Provocative maneuvers can enhance or unmask nystagmus.
• Acquired pendular nystagmus in demyelinating disease differs in behavior and treatment response from oculopalatal myoclonus.
• Oculopalatal myoclonus involves dual mechanisms: abnormal inferior olivary gap junction formation and maladaptive cerebellar learning.

Findings:

• Recent advances have improved understanding of the etiologies and mechanisms of nystagmus.
• Clinical trials have evaluated pharmacologic interventions for specific types of nystagmus, including memantine for acquired pendular nystagmus and 4-aminopyridine for downbeat nystagmus.

Implications:

• Familiarity with examination techniques to unmask these eye movements is critical for accurate diagnosis.
• Evidence-based, specific treatments for oscillopsia can be developed based on improved pathophysiologic understanding.
• Advances in understanding pathophysiology are leading to pharmacologic treatments rooted in physiologic principles.