Kristine Elisabeth Eberhard1,2, Salwa Fatima Masud1, Inge M Knudson3, Keshinisuthan Kirubalingam3,4, Hamza Khalid3, Aaron K Remenschneider3,5, Hideko Heidi Nakajima1. 1. Department of Otolaryngology-Head and Neck Surgery, Harvard Medical School and Massachusetts Eye and Ear, Boston, Massachusetts, USA. 2. Copenhagen Hearing and Balance Centre, Department of Otorhinolaryngology-Head and Neck Surgery and Audiology, Copenhagen University Hospital-Righospitalet, Copenhagen, Denmark. 3. Massachusetts Eye and Ear, Boston, Massachusetts, USA. 4. School of Medicine, Queen's University, Kingston, Canada. 5. Department of Otolaryngology, University Massachusetts Medical School, Worcester, Massachusetts, USA.
Abstract
OBJECTIVE: Poor hearing outcomes often persist following total drum replacement tympanoplasty. To understand the mechanics of the reconstructed eardrum, we measured wideband acoustic immittance and compared the mechanical characteristics of fascia-grafted ears with the normal tympanic membrane. STUDY DESIGN: Prospective comparison study. SETTING: Tertiary care center. METHODS: Patients who underwent uncomplicated total drum replacement with temporalis fascia grafts were identified. Ears with healed grafts, an aerated middle ear, and no other conductive abnormalities were included. All patients underwent pre- and postoperative audiometry. Wideband acoustic immittance was measured with absorbance and impedance computed. Fascia-grafted ears were compared with normal unoperated ears. RESULTS: Eleven fascia-grafted ears without complications were included. Postoperatively, the median air-bone gap was 15 dB (250-4000 Hz), with variation across frequency and between ears. Fifty-six control ears were included. Absorbance of fascia-grafted ears was significantly lower than that of normal ears at 1 to 4 kHz (P < .05) but similar below 1 kHz. Impedance magnitude demonstrated deeper and sharper resonant notches in fascia-grafted ears than normal ears (P < .05), suggesting lower mechanical resistance of the fascia graft. CONCLUSION: The mechanics of fascia-grafted ears differ from the normal tympanic membrane by having lower absorbance at mid- to high frequencies and thus poor sound transmission. The lower resistance in fascia-grafted ears may be due to poor coupling of the graft to the malleus. To improve sound transmission, grafts for tympanic membrane reconstructions would benefit from refined mechanical properties.
OBJECTIVE: Poor hearing outcomes often persist following total drum replacement tympanoplasty. To understand the mechanics of the reconstructed eardrum, we measured wideband acoustic immittance and compared the mechanical characteristics of fascia-grafted ears with the normal tympanic membrane. STUDY DESIGN: Prospective comparison study. SETTING: Tertiary care center. METHODS: Patients who underwent uncomplicated total drum replacement with temporalis fascia grafts were identified. Ears with healed grafts, an aerated middle ear, and no other conductive abnormalities were included. All patients underwent pre- and postoperative audiometry. Wideband acoustic immittance was measured with absorbance and impedance computed. Fascia-grafted ears were compared with normal unoperated ears. RESULTS: Eleven fascia-grafted ears without complications were included. Postoperatively, the median air-bone gap was 15 dB (250-4000 Hz), with variation across frequency and between ears. Fifty-six control ears were included. Absorbance of fascia-grafted ears was significantly lower than that of normal ears at 1 to 4 kHz (P < .05) but similar below 1 kHz. Impedance magnitude demonstrated deeper and sharper resonant notches in fascia-grafted ears than normal ears (P < .05), suggesting lower mechanical resistance of the fascia graft. CONCLUSION: The mechanics of fascia-grafted ears differ from the normal tympanic membrane by having lower absorbance at mid- to high frequencies and thus poor sound transmission. The lower resistance in fascia-grafted ears may be due to poor coupling of the graft to the malleus. To improve sound transmission, grafts for tympanic membrane reconstructions would benefit from refined mechanical properties.
Entities:
Keywords:
absorbance; conductive hearing loss; fascia graft; reflectance; total drum replacement; tympanoplasty; wideband acoustic immittance
Authors: Sarah A Lyons; Tanly Su; Linda E T Vissers; Jeroen P M Peters; Adriana L Smit; Wilko Grolman Journal: Laryngoscope Date: 2015-11-06 Impact factor: 3.325
Authors: Sam Van der Jeught; Joris J J Dirckx; Johan R M Aerts; Adrian Bradu; Adrian G H Podoleanu; Jan A N Buytaert Journal: J Assoc Res Otolaryngol Date: 2013-05-15
Authors: Elliott D Kozin; Nicole L Black; Jeffrey T Cheng; Max J Cotler; Michael J McKenna; Daniel J Lee; Jennifer A Lewis; John J Rosowski; Aaron K Remenschneider Journal: Hear Res Date: 2016-03-16 Impact factor: 3.208