What Causes Nystagmus?

Background and Purpose: Nystagmus is a commonly encountered clinical finding both in children and adults. Despite its complexities, a fundamental understanding of the basic etiology and underlying pathophysiology of nystagmus is critical to manage these patients appropriately.Patients and Method: The subset of ocular motility disorders that constitutes true nystagmus is identified and delineated from saccadic intrusions. Once defined, we explore the causes of commonly encountered forms of nystagmus and their clinical features.Results: Three separate mechanisms work to integrate sensory input and calibrate ocular movements: the afferent visual pathway, the neural integrator, and the vestibular system. Specific neuroanatomical pathways and corresponding pathologic changes are reviewed.Conclusion: A basic understanding of the underlying pathophysiology of nystagmus is essential to clinical practice. Three main mechanisms utilize multifactorial sensory input to produce a normally functioning ocular motor system. Both congenital and acquired forms of nystagmus result from pathology within these systems causing insufficient or asymmetric input to the central nervous system.