Nystagmus and Saccadic Intrusions

This article describes the diagnosis and differentiation of the many possible localizations and causes of nystagmus.

The eyes move to keep the fovea on the object of visual regard. To account for the movement of targets, the environment, or the self, different classes of eye movement are necessary to achieve visual stability. These movements involve the vergence, smooth pursuit, saccadic, vestibular, and optokinetic systems, as well as the ability to suppress the vestibuloocular reflex and other movements for steady fixation. When the equipoise of one or more of these systems is disrupted, nystagmus or saccadic intrusions may result. The astute clinician can distinguish between benign (eg, infantile or peripheral vestibular nystagmus) and dangerous (eg, stroke, Wernicke encephalopathy) etiologies with a high degree of confidence at the bedside, making expensive eye movement recording equipment unnecessary in the majority of cases.

The recognition and interpretation of nystagmus and saccadic intrusions in the context of the history and a comprehensive ocular motor and neurologic examination is an essential skill in neurologic practice.