title: Vestibular evoked myogenic potentials in patients suffering from an unilateral acoustic neuroma: a study of 170 patients.
abstract: OBJECTIVE
  To determine the value of investigating the vestibular evoked myogenic potentials (VEMP's) induced by clicks and 500 Hz short tone burst (STB) for the diagnosis of acoustic neuromas.
  
  
  METHODS
  We studied the average responses to 100dB clicks and 500 Hz STB in the ipsilateral sternomastoid muscle. Ninety-five healthy subjects and 170 patients suffering from a unilateral acoustic neuroma were included in that study. Caloric and audiometric tests results were also analyzed.
  
  
  RESULTS
  Thirty-six/170 patients (21.2%) exhibited normal responses to clicks and to STB whereas 134/170 (78.8%) gave abnormally low or no responses. 78/170 (45.9%) showed no responses to both clicks and STB. In 56/170 patients (32.9%), VEMP's induced by high level clicks and STB were discordant: STB VEMP's were either normal (n=32) or low (n=24) in patients with an abnormal response to clicks (no response n=40 or low response n=16). In contrast, STB-induced VEMP's were always normal in cases of normal responses to clicks. No strong, systematic correlation could be found between saccular nerve dysfunction and either the degree of 4-8 kHz hearing loss or the extent of horizontal canalar impairment.
  
  
  CONCLUSIONS
  These data indicate that high level clicks and STB provide complementary information about the functionality of the saccular nerve. Clicks are useful to detect a minor saccular nerve dysfunction. In cases in which there is no response to clicks, STB gives valuable information about a potential residual function of the saccular nerve.
authors.affiliation: Service ORL, Hopital Lariboisière, 2 rue Ambroise Paré, Paris 75010, France.
authors.forename: Tamàs
authors.initials: T
authors.lastname: Patko
authors.forename: Pierre-Paul
authors.initials: PP
authors.lastname: Vidal
authors.forename: Nicolas
authors.initials: N
authors.lastname: Vibert
authors.forename: Patrice
authors.initials: P
authors.lastname: Tran Ba Huy
authors.forename: Catherine
authors.initials: C
authors.lastname: de Waele
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D002150:Caloric Tests / Q000379:methods; D016022:Case-Control Studies; D004576:Electromyography / Q000379:methods; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006320:Hearing Tests; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009334:Neck Muscles / Q000294:innervation / Q000503:physiopathology; D009464:Neuroma, Acoustic / Q000175:diagnosis* / Q000503:physiopathology*; D009760:Nystagmus, Physiologic / Q000502:physiology; D011930:Reaction Time; D012016:Reference Values; D012189:Retrospective Studies; D012444:Saccule and Utricle / Q000503:physiopathology; D012680:Sensitivity and Specificity; D014724:Vestibular Function Tests