title: Laser Doppler vibrometric assessment of middle ear motion in Thiel-embalmed heads.
abstract: OBJECTIVE
  Thiel-embalmed human whole head specimens represent an alternative model in middle ear research.
  
  
  BACKGROUND
  Research into middle ear mechanics and the evaluation of active middle ear implants are generally performed on fresh human temporal bone specimens. A drawback of this method is the limited period during which the specimen can be used before tissue decay begins. Tissue conservation that preserves mechanical properties is desirable.
  
  
  METHODS
  Using laser Doppler vibrometry, the movement of the tympanic membrane, stapes, and round window were measured in 23 ears from 15 human whole head specimens embalmed according to Thiel. The ears were acoustically stimulated through the intact external auditory canal. The measurement results were compared with data from the literature.
  
  
  RESULTS
  The results were similar to those measured in living subjects and from fresh temporal bones, after excluding measurements with nontypical shapes or low amplitudes, that is, 9% for tympanic membrane, 38% for stapes, and 67% for round window. The best agreement was found for the tympanic membrane (mean difference between 0 and 5.2 dB) and for the stapes measurements (mean difference between 0 and 7.4 dB). Larger differences were found for the round window measurements (mean difference between 3 and 19 dB). For the stimulation levels used, the Thiel specimens behaved linearly in amplitude. The results remained reproducible for more than 20 hours in ambient air, and when the specimen was put back into Thiel solution, the measurements were stable for up to several months between measurements.
  
  
  CONCLUSIONS
  Our results showed that the middle ears of Thiel-embalmed human whole head specimens can be used to study human middle ear mechanics; however, significant differences in some frequencies, particularly at the round window, have to be considered.
authors.affiliation: ARTORG Center, Department of ENT, Head and Neck Surgery, University of Bern, Switzerland.
authors.forename: Christof
authors.initials: C
authors.lastname: Stieger
authors.forename: Claudia
authors.initials: C
authors.lastname: Candreia
authors.forename: Martin
authors.initials: M
authors.lastname: Kompis
authors.forename: Gudrun
authors.initials: G
authors.lastname: Herrmann
authors.forename: Flurin
authors.initials: F
authors.lastname: Pfiffner
authors.forename: Daniel
authors.initials: D
authors.lastname: Widmer
authors.forename: Andreas
authors.initials: A
authors.lastname: Arnold
mesh_terms: D000161:Acoustic Stimulation; D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D016001:Confidence Intervals; D003627:Data Interpretation, Statistical; D004424:Ear Canal / Q000502:physiology; D004432:Ear, Middle / Q000502:physiology*; D004615:Embalming; D005260:Female; D006801:Humans; D017078:Laser-Doppler Flowmetry; D008297:Male; D008875:Middle Aged; D011180:Postmortem Changes; D015203:Reproducibility of Results; D012405:Round Window, Ear / Q000502:physiology; D013199:Stapes / Q000502:physiology; D013701:Temporal Bone / Q000502:physiology; D014432:Tympanic Membrane / Q000502:physiology