On fluctuation of hearing in otitis media with effusion after myringotomy.

Otitis media with effusion (OME) is known to occur in school or preschool children. Its chief symptom is hearing disturbance without otalgia. One of its effective therapies is myringotomy and suction of secretion out of its morbid tympanic cavities. This improvement differs with frequencies. The purpose of this paper is to present the mechanism of hearing recovery after myringotomy. The mean audiogram of OME showed a flat shape with 0 dB of bone conduction and 37.5 dB of air conduction. Hearing level after myringotomy recovered at high tones, but not recovered at low ones. One week later, the mean audiogram without perforations of eardrums showed hearing improvement at low tones. These findings suggested that slower recovery at low tones might be due to incision of an eardrum and closure of its perforation. To confirm this hypothesis we performed an experiment, by which the vibratory mechanism of a thin membrane was disclosed. The result showed that the vibratory modality of a membrane was influenced by incision of it. In conclusion, it is considered that though myringotomy of OME gets hearing improvement, it could result in hearing impairment, probably due to the vibratory modality of an eardrum.