Rebound Upbeat Nystagmus After Lateral Gaze in Episodic Ataxia Type 2
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Rebound nystagmus is a transient nystagmus that occurs on resuming the straight-ahead position after prolonged eccentric gaze. Even though rebound nystagmus is commonly associated with gaze-evoked nystagmus (GEN), development of rebound nystagmus in a different plane of gaze has not been described. We report a patient with episodic ataxia type 2 who showed transient upbeat nystagmus on resuming the straight-ahead position after sustained lateral gaze that had induced GEN and downbeat nystagmus. The rebound upbeat nystagmus may be ascribed to a shifting null in the vertical plane as a result of an adaptation to the downbeat nystagmus that developed during lateral gaze.
KeywordsGaze-evoked nystagmus Rebound nystagmus Lateropulsion Episodic ataxia
Conflict of Interest
On behalf of all authors, the corresponding author states that there is no conflict of interest.
Gaze-evoked and downbeat nystagmus during lateral gaze and rebound upbeat nystagmus on resuming the straight-ahead position. The patient shows gaze-evoked and downbeat nystagmus during lateral gazes and upbeat nystagmus on resuming the straight-ahead position after lateral gaze in either direction. (WMV 40763 kb)
Leftward pulsion during upward saccades. The patient shows leftward pulsion only during upward saccades, giving rise to a curved trajectory, in the presence of normal downward and horizontal saccades. (WMV 16911 kb)
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