title: Upbeat nystagmus changes to downbeat nystagmus with upward gaze in a patient with Wernicke's encephalopathy.
abstract: We describe a patient with Wernicke's encephalopathy who showed spontaneous upbeat nystagmus with decelerating slow phases that changed to downbeat nystagmus during upward gaze and increased during downward gaze. He also showed horizontal gaze-evoked nystagmus and impaired upward smooth pursuit. Magnetic resonance imaging demonstrated symmetric lesions involving the bilateral medial thalami, periaqueductal gray matters and inferior cerebellar peduncles. In this patient, the decelerating slow phases and disobedience to Alexander's law of upbeat nystagmus suggest both deficient (leaky) and unstable neural integrators subserving vertical eye motion. Dysfunction of the interstitial nucleus of Cajal or its descending pathway to the vestibulocerebellum via the paramedian tract cell groups may be responsible for the upbeat nystagmus and its modulation by gazes in our patient with Wernicke's encephalopathy.
authors.affiliation: Department of Neurology, College of Medicine, Chonbuk National University, Jeonju, Republic of Korea.
authors.forename: Byoung-Soo
authors.initials: BS
authors.lastname: Shin
authors.forename: Sun-Young
authors.initials: SY
authors.lastname: Oh
authors.forename: Ji Soo
authors.initials: JS
authors.lastname: Kim
authors.forename: Hyung
authors.initials: H
authors.lastname: Lee
authors.forename: Eui-Jung
authors.initials: EJ
authors.lastname: Kim
authors.forename: Seung-Bae
authors.initials: SB
authors.lastname: Hwang
mesh_terms: D002531:Cerebellum / Q000473:pathology; D005133:Eye Movements / Q000502:physiology; D006801:Humans; D056885:Interstitial Cells of Cajal / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000473:pathology; D009759:Nystagmus, Pathologic / Q000209:etiology*; D015835:Ocular Motility Disorders / Q000209:etiology; D010487:Periaqueductal Gray / Q000473:pathology; D013788:Thalamus / Q000473:pathology; D014899:Wernicke Encephalopathy / Q000150:complications*