The oscillations are termed ocular flutter when they exist in the horizontal plane only and opsoclonus whey they are multidirectional in horizontal, vertical, and torsional planes. Opsoclonus and ocular flutter are saccadic intrusions characterized by bursts of involuntary, back-to-back saccades without an intersaccadic interval. Rucker, in Progress in Brain Research, 2019 1 Introduction Flutter and opsoclonus occasionally may respond to thiamine, clonazepam, and antiepileptic agents. Responsiveness probably depends on the degree of the inflammatory component rather than on neuronal loss. However, in addition to treatment of the underlying neoplasm, early and aggressive immunotherapy, including the use of immunoadsorption therapy with plasma exchange, may be effective. The efficacy of immunotherapy in adults with paraneoplastic syndromes is difficult to assess. In children, the opsoclonus-myoclonus-cerebellar syndrome is often a manifestation of neuroblastoma and may be responsive to adrenocorticotropic hormone. Several paraneoplastic antibodies are associated with flutter and opsoclonus in adults however, antibodies are often not detected. Parainfectious states are typically accompanied by emotional lability, myoclonus, and ataxia. The most common causes ( Box 18.17 and Table 18.6) of flutter and opsoclonus include viral or postviral encephalitis and toxic, metabolic, and paraneoplastic disorders. Increased sensitivity of the GABA A receptor in a circuit involving the cerebellum, inferior olives, and EBNs provides a link between the various brainstem and cerebellar dysfunctions that can result in flutter and opsoclonus ( Optican and Pretegiani, 2017). These oscillations result from pathology that disinhibits saccadic EBNs, which have an inherent tendency to oscillate due to membrane properties of postinhibitory rebound firing and reciprocal synaptic feedback loops ( Shaikh etВ al., 2008). When it is persistent, patients should be evaluated for occult neoplasms and have long-term follow-up. It is reported with cerebellar degeneration and MS and as a benign phenomenon in some individuals. Patients complain of episodes of вЂњshimmeringвЂќ vision. Usually these oscillations are large enough to be seen on clinical examination however, ocular microflutter, previously called microsaccadic ocular flutter, is a rare symptomatic ocular oscillation requiring magnification for detection ( Ashe etВ al., 1991). Rarely, they are triggered by a change in posture ( Martins etВ al., 2019) or occur only in eccentric gaze ( Rizzo et al., 2019). Flutter and opsoclonus are often are precipitated by gaze shifts (see Fig. Ocular flutter, by definition, occurs only in the horizontal plane, whereas opsoclonus has horizontal, vertical, and torsional trajectories. 18.25, A) and opsoclonus occur with brainstem or cerebellar disease and consist of conjugate back-to-back saccades without an intervening intersaccadic interval they occur spontaneously in intermittent bursts. Joseph Jankovic MD, in Bradley and Daroff's Neurology in Clinical Practice, 2022 Ocular flutter and opsoclonus ( Videos 18.12 and 18.13 )