title: A case of apogeotropic nystagmus with brainstem lesion: An implication for mechanism of central apogeotropic nystagmus.
abstract: We report a case showing apogeotropic nystagmus with the lesion of the brain stem, and discuss a possible mechanism of central apogeotropic nystagmus. The case was a 73-year-old male. We analyzed his nystagmus three-dimensionally. He showed apogeotropic nystagmus. Axis angles of slow phase eye velocity of his apogeotropic nystagmus were not in line with the axes perpendicular to the plane of horizontal semicircular canals, but with the patient's vertical axis. We then found that his nystagmus including the apogeotropic nystagmus was positioning, but not positional and that the direction of his positioning nystagmus was the same direction of postrotatory nystagmus after his head movement. His MRI scans showed an infarction around the prepositus hypoglossi nucleus of the brain. His apogeotropic nystagmus seemed to consist of a combination of prolonged postrotatory nystagmus after his head rotation to the left and right lateral position because the axis of postrotatory nystamus was in line with the axis of the head rotation. Therefore, it is suggested that a possible mechanism of central apogeotropic nystagmus is a prolonged postrotatory nystagmus after his head movement in the supine position due to the brain lesion involving the velocity storage mechanisms.
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita-shi, Osaka, Japan. imaitakao@hotmail.com
authors.forename: Takao
authors.initials: T
authors.lastname: Imai
authors.forename: Arata
authors.initials: A
authors.lastname: Horii
authors.forename: Noriaki
authors.initials: N
authors.lastname: Takeda
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kitahara
authors.forename: Kayoko
authors.initials: K
authors.lastname: Higashi-Shingai
authors.forename: Hidenori
authors.initials: H
authors.lastname: Inohara
mesh_terms: D000368:Aged; D001933:Brain Stem / Q000473:pathology*; D002544:Cerebral Infarction / Q000150:complications* / Q000175:diagnosis*; D005133:Eye Movements; D019416:Head Movements; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009759:Nystagmus, Pathologic / Q000209:etiology* / Q000473:pathology* / Q000503:physiopathology; D009760:Nystagmus, Physiologic; D012665:Semicircular Canals / Q000473:pathology; D016683:Supine Position; D013997:Time Factors; D014743:Videotape Recording