title: Positional nystagmus of central origin.
abstract: Audiometric, electrophysiologic, and radiographic findings for a 68-year-old male with an "imbalance" concern are presented. This paper has a two-fold purpose: (1) to present an unusual electronystagmography case study and (2) to highlight the importance of test conditions in lesion localization. The specific disease pathophysiology remains obscure. Repeated hearing tests documented a known hearing impairment with worsening word-recognition ability of the right ear. An initial electronystagmographic exam was normal except for a mild ageotropic direction-changing positional nystagmus with eyes open and fixed. No repeatable click-evoked auditory brainstem response waveforms could be collected. A magnetic resonance imaging of the brain documents diffuse ischemic white matter disease. A repeated vestibular examination some months later supports the initial findings. The case illustrates the importance of following diagnostic protocol, of repeated measures, and of using both a visual fixation and a nonfixation condition for select electronystagmographic subtests.
authors.affiliation: Bay Pines VA Health Care System, Florida 33744, USA.
authors.forename: Frederick E
authors.initials: FE
authors.lastname: Cobb
authors.forename: Lauren B
authors.initials: LB
authors.lastname: Friedman
mesh_terms: D000368:Aged; D001301:Audiometry, Pure-Tone; D001921:Brain / Q000473:pathology*; D015140:Dementia, Vascular / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D004244:Dizziness; D004584:Electronystagmography; D016057:Evoked Potentials, Auditory, Brain Stem; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009760:Nystagmus, Physiologic / Q000502:physiology; D004856:Postural Balance; D012678:Sensation Disorders / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D011795:Surveys and Questionnaires