Eosinophilic Inflammation in the Middle Ear Induces Deterioration of Bone-Conduction Hearing Level in Patients With Eosinophilic Otitis Media

Abstract

Eosinophilic otitis media (EOM) is characterized by the extensive accumulation of eosinophils in the middle ear mucosa and middle ear effusion and is usually associated with bronchial asthma. Eosinophilic otitis media patients show gradual or sudden deterioration of hearing. In our previous study, we reported that high-tone loss was more frequently found and more severe in EOM patients than in control patients with chronic otitis media. These findings suggest that not only bacterial infection but also eosinophilic inflammation in the middle ear may damage the inner ear. The present study was performed to determine whether eosinophilic inflammation is indeed related to deterioration of bone-conduction hearing level (BCHL). Fifty-five ears of 28 patients with EOM associated with bronchial asthma were included in this study. Middle ear effusion (MEE) samples were collected from all the patients, and the concentrations of eosinophilic cationic protein (ECP) and immunoglobulin E (IgE) were measured by fluorescence enzyme immunoassay. The BCHLs at 2 and 4 kHz for the worse-hearing ear of each patient were correlated with the concentrations of ECP and IgE. The concentration of IgE in MEE significantly and positively correlated with BCHL at 2 and 4 kHz. The ears with a higher concentration of ECP in MEE also tended to show deterioration of BCHL at 4 kHz. Other clinical risk factors for BCHL deterioration were male sex, long duration of EOM, association with bacterial infection, severe inflammatory changes of the middle ear mucosa, and high serum IgE concentration. Eosinophilic-inflammation-related substances such as ECP and IgE are closely related to the deterioration of BCHL at high frequencies. Particularly, IgE concentration in MEE is a good indicator of BCHL elevation. We should always pay attention to the hearing acuity of EOM patients with the risk factors.