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Benign neonatal ocular flutter7/22/2023 ![]() 15 Furthermore, initial upbeat nystagmus may evolve into permanent DBN. In Wernicke's encephalopathy, spontaneous upbeat nystagmus often changes into downbeat nystagmus (DBN) during eccentric gazes and convergence, or after vestibular stimulation. 5, 6, 8, 10 The present review provides an update of the major findings in nystagmus and other oscillatory eye movements since 2017. Identifying and characterizing nystagmus and saccadic intrusions/oscillations provide valuable information about lesion sites and pathophysiology. In contrast, saccadic intrusions/oscillations may be ascribed to instability of the networks involved in generating saccades. Nystagmus may occur when the subsystems involved in slow eye movements (smooth pursuit, the VOR, optokinetic eye movements, and vergence) or the gaze-holding mechanisms are impaired. 11 Dysfunction of these structures and the resultant imbalance or instability in each subclass of eye movements may generate involuntary eye movements. 8 The eye-velocity signals generated for each eye movement are integrated in the neural structures (neural integrators) in order to hold the gaze steady in the required position. 8 Human eye movements include saccades, smooth pursuit, the vestibulo-ocular reflex (VOR), optokinetic eye movements, vergence, and fixation, and each such subclass of eye movements is generated and modulated by its own neural network. 5, 6, 8Įye movements are generated by signals transmitted from the eyes and inner ears to structures located in the brainstem and cerebellum, where they are closely monitored and modulated. 5, 8 Unlike in nystagmus, the initial abnormal eye movement is a saccade in saccadic intrusions/oscillations. 8 Nystagmus should be distinguished from other oscillatory eye movements, especially saccadic intrusions and oscillations. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 Nystagmus refers to repetitive and involuntary to-and-fro eye movements that are initiated by a slow drift of the eyes away from the object of interest. Ocular oscillations mainly comprise nystagmus and saccadic intrusions/oscillations.
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