title: Round window atresia and its effect on sound transmission.
abstract: OBJECTIVE
  To document isolated round window atresia and to discuss its impact on current theories of inner ear function.
  
  
  METHODS
  Retrospective analysis of isolated round window atresia suggesting an autosomal dominant inheritance pattern and review of current concepts of cochlear macromechanics.
  
  
  METHODS
  Tertiary referral center.
  
  
  RESULTS
  The unexpected finding of isolated round window atresia in two female patients of the same family was confirmed intraoperatively as well as postoperatively using high-resolution computed tomography. The current audiograms and the review of the literature highlight a mixed, but predominantly conductive, hearing impairment with thresholds at 30 to 40 dB. Implying that there is no pressure release mechanism for inner ear fluid displaced by the stapes footplate, a total conductive hearing loss would be expected.
  
  
  CONCLUSIONS
  The rare finding of round window atresia can be overlooked at surgery because of insufficient exposure of the round window niche. High-resolution computed tomography confirms the round window obliteration. It seems that an alternative way of cochlear stimulation takes place besides the concept of fluid bulk shifting. Surgery seems not to guarantee favorable results.
authors.affiliation: Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Zürich, Frauenklinikstrasse 24, 8091 Zürich, Switzerland. Thomas.Linder@ksl.ch
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Linder
authors.forename: Furong
authors.initials: F
authors.lastname: Ma
authors.forename: Alex
authors.initials: A
authors.lastname: Huber
mesh_terms: D001306:Auditory Pathways / Q000503:physiopathology*; D001307:Auditory Perception / Q000502:physiology*; D001309:Auditory Threshold / Q000502:physiology; D001844:Bone Conduction / Q000502:physiology; D002648:Child; D005260:Female; D006312:Hearing Loss, Bilateral / Q000235:genetics / Q000503:physiopathology*; D006314:Hearing Loss, Conductive / Q000235:genetics / Q000503:physiopathology*; D006801:Humans; D008875:Middle Aged; D012189:Retrospective Studies; D012405:Round Window, Ear / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000503:physiopathology*; D013063:Speech Discrimination Tests; D014057:Tomography, X-Ray Computed; D014636:Valsalva Maneuver / Q000502:physiology