title: Clinical value of tone burst vestibular evoked myogenic potentials at threshold in acute and stable Ménière's disease.
abstract: BACKGROUND
  The objectives of this preliminary, prospective, cohort study were to ascertain the characteristics of vestibular evoked myogenic potentials at threshold levels in two groups of Ménière's disease patients - acute and stable - and to identify whether vestibular evoked myogenic potentials can provide any specific, objective information to distinguish acute from stable Ménière's disease.
  
  
  METHODS
  The study was based at a tertiary neuro-otology centre. Twenty adult patients who fulfilled the American Academy of Otolaryngology-Head and Neck Surgery criteria for Ménière's disease were divided into two groups: 11 patients with acute Ménière's disease and nine patients with stable Ménière's disease. Eighteen healthy adult volunteers served as controls. All subjects underwent vestibular evoked myogenic potential testing with ipsilateral, short tone burst stimuli at 500 Hz, as well as pure tone audiometry. The patients also underwent caloric testing.
  
  
  RESULTS
  Vestibular evoked myogenic potentials were present in all controls, and were present in 65 per cent of patients but absent in 35 per cent. The mean absolute threshold (Tvestibular evoked myogenic potential) +/- standard deviation in normal controls was 116 +/- 7.7 dBSPL; this did not differ statistically from that in patients, nor did it differ between acute and stable Ménière's disease. The p13/n23 latencies at the threshold levels in the normal, acute and stable groups (mean +/- standard deviation) were respectively: 15 +/- 2.2 ms/23.0 +/- 2.5 ms; 15.7 +/- 0.9 ms/23.7 +/- 0.9 ms; and 15.3 +/- 2.0 ms/24.2 +/- 1.9 ms. The mean interaural amplitude difference ratio (IAD) +/- standard deviation was significantly higher in the stable group compared with the acute group (0.54 +/- 0.33 vs -0.15 +/- 0.22; p = 0.007) and with the controls (0.54 +/- 0.33 vs 0.1 +/- 0.22; p = 0.05).
  
  
  CONCLUSIONS
  The parameter that best differentiated acute from stable Ménière's disease at threshold was the interaural amplitude difference ratio. Therefore, this parameter may be used to monitor the clinical course of Ménière's disease.
authors.affiliation: Department of Neuro-Otology, National Hospital for Neurology and Neurosurgery, London, UK. vicabe@lycos.co.uk
authors.forename: V
authors.initials: V
authors.lastname: Osei-Lah
authors.forename: B
authors.initials: B
authors.lastname: Ceranic
authors.forename: L M
authors.initials: LM
authors.lastname: Luxon
mesh_terms: D000328:Adult; D001301:Audiometry, Pure-Tone / Q000379:methods; D016022:Case-Control Studies; D015331:Cohort Studies; D004576:Electromyography; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008575:Meniere Disease / Q000503:physiopathology / Q000628:therapy*; D008875:Middle Aged; D009334:Neck Muscles / Q000503:physiopathology; D011446:Prospective Studies; D013223:Statistics as Topic; D014724:Vestibular Function Tests / Q000379:methods* / Q000592:standards