title: Alternobaric vertigo--really a hazard?
abstract: OBJECTIVE
  To determine the prevalence of alternobaric vertigo (AV) in sport divers and to find out whether AV led to dangerous situations underwater. Furthermore, to examine whether objective neurootologic tests are associated with the manifestation of AV.
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  Sixty-three sport divers with an average diving experience of 10 years and 650 dives were questioned regarding their medical and diving history and the manifestation of vertigo during diving.
  
  
  METHODS
  Microscopic otoscopy, tympanometry, stapedius reflexes, hearing threshold for air and bone conduction, caloric video-oculography including analysis of the slow-phase velocity of the nystagmus, acoustic brain stem responses, and magnetic resonance imaging were performed to find possible differences between divers with and without AV.
  
  
  RESULTS
  We found 17 divers with AV (27%). There was no significant difference in all measured parameters apart from sex and history of middle ear equalization difficulty in divers with AV. Ten (59%) of 17 female divers and 7 (15%) of 46 male divers experienced AV, representing a significant sex difference (p < 0.001). Correlation with our divers' outpatient clinic revealed that female divers had a significantly higher incidence of middle ear equalization disorders which could be an explanation for the predominance of female divers with symptoms of AV. None of the divers reported any dangerous or life-threatening situations following AV. Whether AV leads to dangerous situations underwater remains unclear, but this hypothesis is not supported by our data.
  
  
  CONCLUSIONS
  Alternobaric vertigo is a common finding in divers. In our study group, female divers had a four-time higher risk to suffer AV. Our data do not support the thesis that AV is a life-threatening condition.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of Heidelberg, Heidelberg, Germany. christoph_klingmann@med.uni-heidelberg.de
authors.forename: Christoph
authors.initials: C
authors.lastname: Klingmann
authors.forename: Michael
authors.initials: M
authors.lastname: Knauth
authors.forename: Mark
authors.initials: M
authors.lastname: Praetorius
authors.forename: Peter K
authors.initials: PK
authors.lastname: Plinkert
mesh_terms: D000158:Acoustic Impedance Tests; D000328:Adult; D001309:Auditory Threshold; D002150:Caloric Tests; D015331:Cohort Studies; D004242:Diving / Q000009:adverse effects; D005260:Female; D006801:Humans; D015994:Incidence; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009760:Nystagmus, Physiologic; D038781:Otoscopy; D012022:Reflex, Acoustic; D012189:Retrospective Studies; D017678:Sex Distribution; D011795:Surveys and Questionnaires; D014717:Vertigo / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology*