title: [Microsurgical middle ear operations : Variability of the audiometric results from frequency variations].
abstract: BACKGROUND
  The audiometric results after reconstructive tympanic surgery on 504 patients carried out between October 2005 and October 2007, including 190 cases of tympanoplasty type I and 314 cases of tympanoplasty type III according to Wullstein, were retrospectively analyzed at the Department of Otolaryngology, Ruprecht-Karls-University in Heidelberg.
  
  
  METHODS
  To investigate the influence of the frequencies used to compare the outcome, the pure tone average air-bone gaps (PTA-ABG) of the preoperative and postoperative audiograms of tympanoplasties type I and III were analyzed. The frequencies covered the ranges of 0.5 kHz, 1 kHz, 2 kHz, 4 kHz and 6 kHz. In each case the 3-frequency, 4-frequency and 5-frequency analyses were calculated for the different surgical groups.
  
  
  RESULTS
  The 3-frequency analysis (0.5 kHz, 1 kHz and 2 kHz) of the type 1tympanoplasties were 18.8 ± 11.8 dB preoperative and 12.3 ± 11.8 dB postoperative. In 58.9% of cases the PTA-ABG ≤ 10 dB and in 86.7% it was ≤ 20 dB. The 3-frequency analysis showed that the tympanoplasties type III had a PTA-ABG of 30.6 ± 15.3 dB preoperatively and 21.8 ± 15.1 dB postoperatively. In 30.4% of cases the PTA-ABG was ≤ 10 dB and ≤ 20 dB for 56%.
  
  
  CONCLUSIONS
  The detailed itemization of frequencies in this study and the consequent opportunity to modify the frequency range, allowed the impact of this selection on the PTA-ABG to be illustrated and various comparisons with other studies could be carried out. In this article, the exclusion criteria were dealt with liberally and risk patients were also included and data from patients who displayed prognostic risks regarding the successful surgery in terms of the audiometric reports were integrated. These prognostic risks were due to the poor aeration of the tympanum and recent (sometimes diverse), pre-surgery as well as chronic inflammatory processes. This study has proved that all surgery collectives showed significant improvements of the PTA-ABG. Therefore, all surgery collectives (measured against the audiometric evaluation) benefited from the surgery.
authors.affiliation: Sektion Otologie und Neurootologie, Klinik für Hals-Nasen-Ohren-Heilkunde mit Poliklinik, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Deutschland.
authors.forename: L
authors.initials: L
authors.lastname: von Gierke
authors.forename: I
authors.initials: I
authors.lastname: Baumann
authors.forename: P K
authors.initials: PK
authors.lastname: Plinkert
authors.forename: M
authors.initials: M
authors.lastname: Praetorius
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001299:Audiometry / Q000379:methods*; D002675:Child, Preschool; D003638:Deafness / Q000175:diagnosis* / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D008866:Microsurgery / Q000379:methods*; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D014433:Tympanoplasty; D055815:Young Adult