title: Why do patients with PSP fall? Evidence for abnormal otolith responses.
abstract: BACKGROUND
  Patients with progressive supranuclear palsy (PSP) fall frequently, beginning early in the course of their disease. Abnormal vestibulospinal reflexes are suspected, but the angular vestibulo-ocular reflex, which is mediated by the labyrinthine semicircular canals, survives late into the course of the disease.
  
  
  OBJECTIVE
  To test the hypothesis that otolithic-mediated reflexes are abnormal in PSP.
  
  
  METHODS
  We tested otolith-ocular reflexes (the translational vestibulo-ocular reflex [tVOR]) during combined rotation-translation in nine patients with PSP and nine age-matched control subjects; subjects viewed far and near targets. We also tested click-induced otolith-spinal reflexes (vestibular-evoked myogenic potentials [VEMPs]) in 10 patients with PSP and 30 age-matched controls.
  
  
  RESULTS
  All patients with PSP had small tVOR responses during near viewing that were, on average, only 12% of those of control subjects (p = 0.001). Patients with PSP also showed a reduction of the amplitude of VEMPs compared to control subjects (median [range]: 54.3 [16.8 to 214] vs 149 [11.6 to 466], p = 0.001).
  
  
  CONCLUSIONS
  Taken together, these results indicate that abnormal otolith-mediated reflexes may be at least partly responsible for frequent falls in progressive supranuclear palsy, and deserve further study.
authors.affiliation: Neurology Service and Daroff-Dell'Osso Laboratory, Veterans Affairs Medical Center and University Hospitals, Case Western Reserve University, Cleveland, OH, USA.
authors.forename: K
authors.initials: K
authors.lastname: Liao
authors.forename: J
authors.initials: J
authors.lastname: Wagner
authors.forename: A
authors.initials: A
authors.lastname: Joshi
authors.forename: I
authors.initials: I
authors.lastname: Estrovich
authors.forename: M F
authors.initials: MF
authors.lastname: Walker
authors.forename: M
authors.initials: M
authors.lastname: Strupp
authors.forename: R J
authors.initials: RJ
authors.lastname: Leigh
mesh_terms: D000058:Accidental Falls; D000368:Aged; D004525:Efferent Pathways / Q000503:physiopathology; D005260:Female; D019416:Head Movements / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009801:Oculomotor Muscles / Q000294:innervation / Q000503:physiopathology; D010037:Otolithic Membrane / Q000503:physiopathology*; D004856:Postural Balance / Q000502:physiology; D012021:Reflex, Abnormal / Q000502:physiology; D012027:Reflex, Vestibulo-Ocular / Q000502:physiology; D012444:Saccule and Utricle / Q000503:physiopathology; D054776:Semicircular Ducts / Q000503:physiopathology; D013494:Supranuclear Palsy, Progressive / Q000150:complications* / Q000503:physiopathology*; D015837:Vestibular Diseases / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology*; D014724:Vestibular Function Tests; D014726:Vestibular Nuclei / Q000503:physiopathology; D014722:Vestibule, Labyrinth / Q000503:physiopathology*