Correlation between hearing loss and middle ear volume in patients with a tympanic membrane perforation

Objective To investigate a possible correlation between the degree of conductive hearing loss (CHL) caused by an isolated tympanic membrane (TM) perforation and mastoid-middle ear volume. Study Design Retrospective chart, audiometry, and computed tomography (CT) imaging review. Methods Adult patients with a diagnosis of isolated TM perforation between 2010 and 2018 were identified and their audiometric data collected. Mastoid-middle ear volume (MMEV) was then calculated based on segmentation analysis from the patient's head or temporal bone CT. Calculated MMEV was compared to MMEV derived by tympanometry. A Student's t-test was performed to determine a correlation between the calculated MMEV on CT imaging and the degree of conductive hearing loss as measured by the air bone gap on standard audiometry. Results There was a statistically significant difference between MMEV as determined by segmentation analysis compared to that determined by tympanometry (absolute average percent difference = 33.8%; range -49.5% to +155.2%; P = .03). Greater MMEV determined by segmentation analysis correlated with smaller air bone gap; this trend approached but did not reach statistical significance (P = .09). Conclusions Calculated MMEV by segmentation analysis on CT imaging may be a more accurate estimate of MMEV than tympanometry. MMEV may be correlated to the degree of conductive hearing loss in the setting of isolated TM perforation where greater volume was associated with better hearing. Level of Evidence 4 Laryngoscope, 130:E228-E232, 2020