Saccadic visual suppression and down-beat nystagmus: a case of Arnold-Chiari malformation

A case is reported in which visual disturbances associated with the sole physical finding of downbeat nystagmus led to investigation of a patient for a foramen magnum lesion. The Arnold-Chiari malformation was suggested by air study and confirmed at surgery. It is suggested that the phenomenon of saccadic suppression was responsible for the patient's visual disability. This was unaccompanied by any of the other neurological manifestations of the Arnold-Chiari malformation. Cases presenting in this manner, with only visual disturbances, may run the risk of being unrecognized for some time as a result.