title: Ocular vestibular evoked myogenic potentials in response to three test positions and two frequencies.
abstract: OBJECTIVE
  To determine how eye closure, test positions, and stimulus frequencies influence ocular vestibular evoked myogenic potentials.
  
  
  METHODS
  This study used a within-subjects repeated measures design.
  
  
  METHODS
  Twenty asymptomatic subjects were each tested on ocular vestibular evoked myogenic potentials in three head/eye conditions at 500 Hz and 1,000 Hz using air-conducted sound: 1) sitting upright, head erect, eyes open, looking up; 2) lying supine, neck flexed 30°, eyes open, looking up; and 3) lying supine, neck flexed 30°, eyes closed, relaxed. The four dependent variables measured were n10, p16, amplitude, and threshold.
  
  
  RESULTS
  Supine/eyes open was comparable to sitting/eyes open and better than supine/eyes closed. Eyes closed resulted in lower amplitude, higher threshold, and prolonged latency. Significantly fewer subjects provided responses with eyes closed than with eyes open. No significant differences were found between both eyes open conditions. Both n10 and p16 were lower at 1,000 Hz than at 500 Hz. Amplitude and threshold were higher at 1,000 Hz than at 500 Hz.
  
  
  CONCLUSIONS
  Supine/eyes open is a reliable alternative to sitting/eyes open in patients who cannot maintain a seated position. Testing at 1,000 Hz provides a larger response with a faster onset that fatigues faster than at 500 Hz. The increased variability and decreased response in the eyes closed position suggest that the eyes closed position is not reliable.
  
  
  METHODS
  3b.
authors.affiliation: University of Texas Medical Branch at Galveston, School of Medicine, Galveston, Texas, U.S.A.
authors.forename: Janvi K
authors.initials: JK
authors.lastname: Todai
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Congdon
authors.forename: Haleh
authors.initials: H
authors.lastname: Sangi-Haghpeykar
authors.forename: Helen S
authors.initials: HS
authors.lastname: Cohen
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods*; D000328:Adult; D015331:Cohort Studies; D005133:Eye Movements / Q000502:physiology*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008875:Middle Aged; D056888:Patient Positioning; D011187:Posture; D011446:Prospective Studies; D012016:Reference Values; D012684:Sensory Thresholds; D016683:Supine Position / Q000502:physiology*; D058585:Vestibular Evoked Myogenic Potentials / Q000502:physiology*; D055815:Young Adult
keywords: Diagnostic testing; labyrinth; stimulus frequency; vestibular evoked myogenic potential