title: Spatial orientation in patients with chronic unilateral vestibular hypofunction is ipsilesionally distorted.
abstract: Acute unilateral peripheral-vestibular hypofunction (UVH) shifts the subjective visual vertical (SVV) ipsilesionally, triggering central compensation that usually eliminates shifts when upright. We hypothesized that compensation is worse when roll-tilted.
  
  
  
  We quantified SVV errors and variability in different roll-tilted positions (0°, ±45°, ±90°) in patients with chronic UVH affecting the superior branch (SVN; n=4) or the entire (CVN; n=9) vestibular nerve.
  
  
  
  Errors in SVN and CVN were not different. When roll-tilted ipsilesionally 45° (9.6±5.4° vs. -0.2±6.4°, patients vs. controls, p<0.001) and 90° (23.5±5.7° vs. 16.8±8.8°, p=0.003), the patient's SVV was shifted significantly towards the lesioned ear. When upright, only a trend was noted (3.6±2.2° vs. 0.0±1.2°, p=0.099); for contralesional roll-tilts shifts were not different from controls. Variability was larger for CVN than SVN (p=0.046). With increasing disease-duration, adjustment errors decayed for ipsilesional roll-tilt and upright (p⩽0.025).
  
  
  
  The reason verticality perception was distorted for ipsilesional roll-tilts, may be the insufficient integration of contralesional otolith-input. Similar errors in SVN and CVN suggest a dominant utricular role in verticality perception, albeit the sacculus may improve precision of SVV estimates.
  
  
  
  With deficiencies in central compensation being roll-angle dependent, extending SVV-testing to roll-tilted positions may improve identifying patients with chronic UVH.
authors: Department of Neurology, University Hospital Zurich and University of Zurich, Frauenklinikstr. 26, 8091 Zurich, Switzerland.
authors: Julia A
authors: JA
authors: Müller
authors: Department of Neurology, University Hospital Zurich and University of Zurich, Frauenklinikstr. 26, 8091 Zurich, Switzerland; Department of Otorhinolaryngology, University Hospital Zurich and University of Zurich, Frauenklinikstr. 26, 8091 Zurich, Switzerland; Department of Ophthalmology, University Hospital Zurich and University of Zurich, Frauenklinikstr. 26, 8091 Zurich, Switzerland.
authors: Christopher J
authors: CJ
authors: Bockisch
authors: Department of Neurology, University Hospital Zurich and University of Zurich, Frauenklinikstr. 26, 8091 Zurich, Switzerland. Electronic address: alexander.tarnutzer@access.uzh.ch.
authors: Alexander A
authors: AA
authors: Tarnutzer
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010037:Otolithic Membrane / Q000503:physiopathology; D013028:Space Perception; D065854:Spatial Navigation; D015837:Vestibular Diseases / Q000503:physiopathology*
keywords: Graviception; Otolith organs; Sacculus; Subjective visual vertical; Utriculus; Vestibular neuropathy