title: The posterior attic: An observational study of aboriginal Australians with chronic otitis media (COM) and a theory relating to the low incidence of cholesteatomatous otitis media versus the high rate of mucosal otitis media.
abstract: OBJECTIVE
  The incidence of COM without cholesteatoma in Australian aboriginals is quoted as being between 25 and 47%. The incidence of cholesteatomatous OM is very low in comparison (between 1 and 3%). A comprehensive literature search found no studies offering an explanation for the large discrepancy between these two types of OM. We offer a theory to account for the disproportionate rates of the two types of OM together with an observational study on aboriginals with COM to substantiate our argument.
  
  
  RESULTS
  The crux of our hypothesis centres on the anatomy of the posterior attic. We found that in a study of 40 aboriginal patients undergoing tympanoplasty with audiometric evidence of an intact ossicular chain that, after posterior tympanomeatal flap elevation, no part of the incudostapedial assembly was visible in 95% of cases denoting its location behind the posterior attic wall.
  
  
  CONCLUSIONS
  We hypothesise that in aboriginal ears the resulting 'crowding' of the posterior attic by the incudostapedial assembly results in narrowing of the epitympanic space which compromises atticoantral drainage, thus leading to mucosal COM, however supporting the posterior-superior segment of the tympanic membrane, impeding the formation of a retraction pocket, and cholesteatoma formation migrating into the mastoid antrum.
authors.affiliation: Hull Royal Infirmary, Hull, UK.
authors.forename: Patrick
authors.initials: P
authors.lastname: Jassar
authors.forename: Patrick
authors.initials: P
authors.lastname: Murray
authors.forename: D
authors.initials: D
authors.lastname: Wabnitz
authors.forename: C
authors.initials: C
authors.lastname: Heldreich
mesh_terms: D000293:Adolescent; D000328:Adult; D001315:Australia / Q000453:epidemiology; D002648:Child; D018424:Cholesteatoma, Middle Ear / Q000208:ethnology* / Q000473:pathology*; D002908:Chronic Disease; D004432:Ear, Middle / Q000473:pathology; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009092:Mucous Membrane / Q000473:pathology; D010033:Otitis Media / Q000208:ethnology* / Q000473:pathology*