Saccadic Intrusions and Oscillations

Visual fixation can be disrupted by a variety of involuntary saccadic eye movements that signify cerebellar, brainstem, or cerebral disease. Sustained oscillations of the eyes are called nystagmus only if they are generated and initiated by smooth eye movements. Sustained oscillation of the eyes that are initiated by fast eye movements (saccades) are termed saccadic oscillations. Sporadic fast eye movements that take the eyes off target are called saccadic intrusions. In some patients very frequent saccadic intrusions comprise a continuum with saccadic oscillations.