title: [Clinical evaluation of primary position upbeat nystagmus].
abstract: BACKGROUND
  Primary position upbeat nystagmus is a vertical nystagmus presenting in the primary position. However, cases of primary position upbeat nystagmus have rarely been reported.
  
  
  METHODS
  We evaluated the locations of lesions and pathogenesis in 11 patients with primary position upbeat nystagmus. The lesions were located mostly in the median portion of the cerebellum and medulla oblongata. In 7 out of 11 patients, intracranial lesions were identified by computed tomography and magnetic resonance imaging. They were located in the median portion of the cerebellum and medulla oblongata except for one adult patient with astrocytoma. The etiologies were 4 tumors, 3 intracranial vascular disorders, 2 Wernicke encephalopathies, 1 congenital anomaly, and 1 inflammation.
  
  
  CONCLUSIONS
  The lesions were located mostly in the median portion of the cerebellum and medulla oblongata, and especially in the cerebellum in children. The main etiologies were tumors in children and vascular disorders and Wernicke encephalopathy in adults.
authors.affiliation: Department of Ophthalmology, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Noriko
authors.initials: N
authors.lastname: Koga
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ishikawa
mesh_terms: D000328:Adult; D000368:Aged; D001254:Astrocytoma / Q000150:complications; D001932:Brain Neoplasms / Q000150:complications; D002531:Cerebellum / Q000473:pathology; D002561:Cerebrovascular Disorders / Q000150:complications; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D008526:Medulla Oblongata / Q000473:pathology; D008875:Middle Aged; D009759:Nystagmus, Pathologic / Q000209:etiology / Q000473:pathology*