Downbeat nystagmus

Abstract

A case of downbeat nystagmus occurring in relation with an abnormality of the cranio-cervical junction and ectopy of cerebellar tonsils is reported. The literature on downbeat nystagmus is reviewed and the principal clinical, etiological and physiopathological features are discussed. The Occurrence of downbeat nystagmus without any other oculomotor disturbances appears to be highly suggestive of a malformation of the cranio-cervical junction, and its occurrence associated with other abnormalities of ocular movements makes this diagnosis highly improbable.