Tympanometric volume as a useful tool for the evaluation of middle ear status in chronic otitis media

Tympanometric volume is a useful tool for evaluating middle ear status in otitis media. However, its usefulness in chronic otitis media (COM) has not been well evaluated. This study aimed to investigate whether tympanometric volume reflects the status of the middle ear and mastoid or can provide clinical information about patients with COM and subsequent tympanic membrane perforation. A prospective cohort study including 50 adult patients with COM and subsequent tympanic membrane perforation was performed. The volumes of the middle ear and mastoid were preoperatively calculated using tympanometry and three- dimensional computed tomography (CT) reconstruction of the temporal bone, respectively. During surgery for COM, the patency of the middle ear and mastoid antrum was evaluated. The volumes of the middle ear and mastoid measured by tympanometry and CT were compared with the surgical findings. When the mastoid antrum was patent, the volumes of the middle ear and mastoid measured by tympanometry and CT were well correlated. Moreover, the difference in the volumes measured by tympanometry between the affected and unaffected ears was large. However, when the mastoid antrum was poorly aerated, the difference in the volumes measured by tympanometry between the affected and unaffected ears was small. Middle ear status can be evaluated according to the difference in tympanometric volume between the two ears. If the tympanometric volume suggests poor aeration of the middle ear and mastoid, clinicians should consider procedures for mastoid aeration.