The Role of Ventilation Tube Status in the Hearing Levels in Children Managed for Bilateral Persistent Otitis Media with Effusion

The study determined the effects on hearing of the status of ventilation tubes, using a combination of otoscopy and tympanometry to determine function, in children managed for bilateral persistent otitis media with effusion (OME). The subjects were aged between 3.5 and 7 years and had a documented history of bilateral OME over a 12-week watchful waiting period associated with a hearing impairment in both ears of >or= 20 dB HL. The children reported are those randomized to the two surgical arms, both of which had bilateral myringotomy, aspiration of middle ear fluid and insertion of Shepard ventilation tubes. One arm furthermore received adenoidectomy. The data were analysed 'as treated' to document therapeutic progress. Tubes confirmed to be functioning on otoscopy and tympanometry only partially alleviate the conductive impairment associated with childhood OME (AC mean 12 dB HL, SD 4; ABG 13 dB, SD 7, 3 months post operation). Thus, children with a functioning ventilation tube cannot be considered to have 'normal' hearing. Once the tube has extruded, ears that no longer have OME still have a small conductive hearing impairment (at 12 months AC 14 dB HL, SD 6; ABG 16 dB, SD 9) but this improves with time. In children with bilateral tubes, both remain functioning for a median duration of 21 weeks (IQR 10-40) and at least one for a median of 40 weeks (IQR 24-61). Tube blockage significantly (P = 0.001) increases the risk of extrusion (84% versus 44%). When inserted in children between 3.5 and 7 years for OME, the otoscopic incidence of tube infection is low (1%).