title: The influence of unilateral versus bilateral clicks on the vestibular-evoked myogenic potentials.
abstract: OBJECTIVE
  Because a continuous muscular effort is required during recording of vestibular-evoked myogenic potentials, we assume vestibular-evoked myogenic potentials elicited by simultaneous bilateral clicks can be used as a more convenient mode compared with respective unilateral clicks. To investigate whether bilateral clicks provide the same information as unilateral clicks, we examined whether the responses are different between them in normal subjects and whether bilateral clicks have the same diagnostic value as vestibular-evoked myogenic potentials elicited by unilateral clicks in detecting retrolabyrinthine lesions.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  Academic tertiary referral center.
  
  
  METHODS
  Fourteen healthy volunteers and four patients with unilateral cerebellopontine angle tumors were enrolled in this study.
  
  
  METHODS
  Recordings of vestibular-evoked myogenic potential responses.
  
  
  METHODS
  The latency of each peak (p13, n23), the peak-to-peak interval, and amplitude (p13-n23).
  
  
  RESULTS
  Both unilateral and bilateral click stimulation of 28 ears (100%) produced vestibular-evoked myogenic potentials in normal subjects. The mean latencies of p13 and n23, peak-to-peak interval, and amplitude of vestibular-evoked myogenic potentials elicited with unilateral clicks were 11.62 +/- 0.99 ms, 19.74 +/- 1.30 ms, 8.12 +/- 1.66 ms, and 110.79 +/- 61.37 microV, respectively, whereas those elicited with bilateral clicks were 11.16 +/- 0.51 ms, 19.22 +/- 1.61 ms, 8.06 +/- 1.66 ms, and 111.77 +/- 40.98 microV, respectively. There was a significant difference (p < 0.05) in the latencies, but not for the interval and amplitude (p > 0.05). Four patients with unilateral cerebellopontine angle tumors and prolonged latencies of unilateral clicks vestibular-evoked myogenic potentials also showed latency prolongation in bilateral clicks vestibular-evoked myogenic potentials.
  
  
  CONCLUSIONS
  Although the use of bilateral acoustic stimulation shortens the vestibular-evoked myogenic potential latencies in normal subjects, it does not affect the bilateral clicks vestibular-evoked myogenic potential ability to detect retrolabyrinthine lesions. Bilateral clicks vestibular-evoked myogenic potentials are a more convenient mode with which to help diagnose both labyrinthine and retrolabyrinthine lesions than unilateral clicks vestibular-evoked myogenic potentials.
authors.affiliation: Department of Otolaryngology, Far Eastern Memorial Hospital, Taipei, Taiwan.
authors.forename: Tsung-Wei
authors.initials: TW
authors.lastname: Huang
authors.forename: Po-Wen
authors.initials: PW
authors.lastname: Cheng
authors.forename: Hsuan-Chao
authors.initials: HC
authors.lastname: Su
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D002528:Cerebellar Neoplasms / Q000503:physiopathology*; D002530:Cerebellopontine Angle; D004576:Electromyography / Q000379:methods; D004814:Epidermal Cyst / Q000503:physiopathology; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology; D009464:Neuroma, Acoustic / Q000503:physiopathology*; D011446:Prospective Studies; D014722:Vestibule, Labyrinth / Q000502:physiology*