Tympanic membrane retraction and middle-ear pressure.
MHA assessment and LR observation are poor indicators of MEP. Clinical assessment of the MHA in normal living ears, within the range 30 degrees to 75 degrees, correlates poorly with MEP measured by impedance tympanometry, within the range of -300 to +160 mm H2O. Variation of MEP in fresh temporal bones demonstrated that MHA, LR and postero-superior segment retraction remained unchanged between -50 and -400 mm H2O and between +50 and +400 mm H2O. The change in position of the TM over the range +50 to -50 mm H2O corresponded to the maximum compliance change on the tympanogram i.e. the width of the tympanometric notch.
D000158:Acoustic Impedance Tests; D004432:Ear, Middle / Q000502:physiology*; D006801:Humans; D008307:Malleus / Q000033:anatomy & histology; D011312:Pressure; D014432:Tympanic Membrane / Q000033:anatomy & histology*