Positional Ocular Flutter Associated With Middle Cerebellar Peduncle Demyelination

Ocular flutter (OF) consists of back-to-back horizontal saccadic intrusions lacking an intersaccadic interval. OF usually occurs spontaneously, as continuous or intermittent bursts (1). Spontaneous OF has been associated with brainstem and cerebellar lesions and is presumed to reflect an intrinsic membrane receptor malfunction of the pontine saccadic burst neurons (SBN), omnipause neurons, and/or cerebellar vermis/fastigial nucleus complex leading to SBN increased firing (1). Rarely, OF may be precipitated exclusively by head position, having been described in one patient with undetermined degenerative ataxia and one other with Krabbe disease (2,3). In both cases, a focal parenchymal strategic lesion was not found, and the putative mechanism was not detailed. We describe a patient with a right middle cerebellar peduncle (MCP) demyelinating lesion associated with positional OF.