title: Unilateral otolith centrifugation by head tilt.
abstract: BACKGROUND
  To test for otolith asymmetries, several studies described horizontal translation of the body and head en bloc during fast vertical axis rotation. This stimulus causes one otolithic organ to rotate on-axis, and the other to experience centripetal acceleration.
  
  
  OBJECTIVE
  To test a new, more simple method of unilateral stimulation with head tilt and the body remaining on axis.
  
  
  METHODS
  During stationary and during 360 deg/s rotation, 12 healthy blindfolded subjects had their heads tilted 30 degrees sideways, positioning one otolithic organ on the axis of rotation after the other. The haptic subjective vertical (SV) was recorded several times by means of a manually adjustable rod.
  
  
  RESULTS
  It was found that during stationary the SV tilted about 4 degrees on average in the direction of the head. During rotation, the SV tilted about 9 degrees on average. We therefore estimate the effect of eccentric otolith rotation to be 5 degrees on average.
  
  
  CONCLUSIONS
  Tilt of the subjective vertical induced by head tilt during on-axis body rotation can provide a relatively uncomplicated alternative to test unilateral otolithic function as compared to body and head translation during rotation. Moreover, unlike eccentric rotation of the entire body, somatosensory cues are minimized by keeping the body fixed on axis and by subtracting the effect of head tilt per se.
authors.affiliation: Department of Otorhinolaryngology and Head and Neck Surgery, Rudolf Magnus Institute of Neuroscience, University Medical Center, Utrecht, The Netherlands.
authors.forename: Stephanie M
authors.initials: SM
authors.lastname: Winters
authors.affiliation: TNO Human Factors, Soesterberg, The Netherlands Research Institute MOVE, Faculty of Human Movement Sciences, VU University, Amsterdam, The Netherlands.
authors.forename: Jelte E
authors.initials: JE
authors.lastname: Bos
authors.affiliation: Department of Otorhinolaryngology and Head and Neck Surgery, Rudolf Magnus Institute of Neuroscience, University Medical Center, Utrecht, The Netherlands.
authors.forename: Sjaak F L
authors.initials: SF
authors.lastname: Klis
mesh_terms: D000328:Adult; D002498:Centrifugation; D005260:Female; D019416:Head Movements / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009949:Orientation / Q000502:physiology*; D010037:Otolithic Membrane / Q000502:physiology*; D012399:Rotation
keywords: Unilateral centrifugation; otolith function test; subjective vertical