title: Influence of thresholds on amplitudes in vestibular evoked myogenic potentials.
abstract: OBJECTIVE
  To investigate the relationship between the threshold and the interaural amplitude difference ratio (IADR) in cervical vestibular evoked myogenic potential (cVEMP) testing and pursuit the clinical significance of the parameters.
  
  
  METHODS
  cVEMP responses were recorded while the SCM contraction was controlled using a pressure cuff. The intensities of the sound stimulation decreased from 95 dB n HL by 5 dB, until no responses were evoked. Thresholds, interaural threshold difference (ITD), amplitudes, and interaural amplitude difference ratio at the stimulation of 95 dB n HL were calculated and the relationship between them was examined.
  
  
  RESULTS
  All subjects showed cVEMP responses bilaterally. Thresholds measured were overall 76 dB n HL and most (92%) ears showed the ITD of 0 or 5 dB. The amplitudes of cVEMP responses showed a positive correlation with the sound intensities, and more specifically with the sound intensity above each threshold value. There was no significant difference in IADR values by the ITD.
  
  
  CONCLUSIONS
  Based on our study, the ITD is less than 10 dB in most normal subjects and estimation of threshold should be added to cVEMP testing for probing vestibular asymmetry. Getting a threshold might be helpful in determining whether the abnormal interaural amplitude difference ratio is related to the abnormal ITD.
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Republic of Korea.
authors.forename: Jung Eun
authors.initials: JE
authors.lastname: Shin
authors.forename: Chang-Hee
authors.initials: CH
authors.lastname: Kim
authors.forename: Hong Ju
authors.initials: HJ
authors.lastname: Park
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001309:Auditory Threshold; D005260:Female; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D009334:Neck Muscles / Q000502:physiology*; D012444:Saccule and Utricle / Q000502:physiology*; D058585:Vestibular Evoked Myogenic Potentials / Q000502:physiology*; D055815:Young Adult