title: The Erasmus atelectasis classification: proposal of a new classification for atelectasis of the middle ear in children.
abstract: OBJECTIVE
  Atelectasis presents a challenging, often progressive, problem in children. Because of the lack of a clinically practical classification, we introduce a new classification, which in our opinion is more useful in the pediatric age group. This alternative classification enables a more clinically relevant correlation between stage of disease and clinical sequelae and technical difficulty at surgery.
  
  
  METHODS
  Observational study of patients seen and operated at the Sophia Children's Hospital in Rotterdam, The Netherlands between 1989 and 2005.
  
  
  METHODS
  Based on clinical appearance, each ear was placed into one of the five groups of the proposed classification and into one of the four stages of Sadé's classification. Preoperative air and bone conduction thresholds and air-bone gaps (ABG) were calculated using the four-tone pure-tone (500, 1,000, 2,000, and 4,000 Hz) averages for bone and air conduction.
  
  
  RESULTS
  : Of the 248 ears in the study group, 72 were in stage I, with an ABG of 18.2 +/- 12.3 dB. Twenty-two were in stage II, with an ABG of 12.9 +/- 9.5 dB. In stage III, there were 32 ears, with an ABG of 11.6 +/- 10.0 dB. Thirty-one ears were in stage IV, with an ABG of 16.1 +/- 11.5 dB. Eighty-five ears were in stage V, with an ABG of 26.1 +/- 13.3 dB. When grouped according to Sadé's classification, 92 ears could not be classified.
  
  
  CONCLUSIONS
  We found the currently proposed classification more useful in that it follows the natural progression of the disease and is more practical in determining operative procedures at each stage.
authors.affiliation: Department of Pediatric Otolaryngology, Sophia Children's Hospital, Erasmus MC, Rotterdam, The Netherlands. j.borgstein@erasmusmc.nl
authors.forename: Johannes
authors.initials: J
authors.lastname: Borgstein
authors.forename: Tatjana V
authors.initials: TV
authors.lastname: Gerritsma
authors.forename: Marjan H
authors.initials: MH
authors.lastname: Wieringa
authors.forename: Iain A
authors.initials: IA
authors.lastname: Bruce
mesh_terms: D001284:Atrophy / Q000473:pathology; D001301:Audiometry, Pure-Tone; D001844:Bone Conduction / Q000502:physiology; D002648:Child; D018424:Cholesteatoma, Middle Ear / Q000473:pathology; D004427:Ear Diseases / Q000145:classification* / Q000503:physiopathology* / Q000601:surgery; D004429:Ear Ossicles / Q000473:pathology; D004432:Ear, Middle / Q000503:physiopathology* / Q000601:surgery; D005260:Female; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D009626:Terminology as Topic; D014432:Tympanic Membrane / Q000473:pathology