Changes in external ear resonance after ventilation tube (Grommet) insertion in children with otitis media with effusion.
As otitis media with effusion is common in children, the effects of a ventilation tube should be taken into account in the prescription of hearing aids for children. In ears with a ventilation tube, the external auditory canal communicates directly with the middle ear space, and so the impedance of the middle ear may change. Consequently, this will affect external-ear resonance. The aim of this study is to observe the effects of the tympanic membrane perforations caused by the ventilation tube on external-ear resonance. We selected 30 ears with otitis media with effusion to measure external-ear resonance before and after ventilation tube insertion. We compared the external-ear resonance of a control group with that of the otitis media with the effusion group and two types of ventilation-tube groups, respectively. In the subjects who have otitis media with effusion, the average gain of the peak resonance was larger than that in the control group. After ventilation-tube insertion, the amplitude of the gain decreased to the same level as the control group, but a characteristic negative gain appeared around 1000 Hz in about half of all cases. This negative gain was observed more frequently in the ventilation tube with a larger diameter. The raised peak resonance gain in the otitis media with effusion group decreased to a level roughly the same as that of the control group after ventilation-tube insertion. Provision of an additional gain in the low frequencies around 1000 Hz should be considered for patients with a ventilation tube when prescribing hearing aids.
Hong
S H
SH
Department of Otorhinolaryngology--Head and Neck Surgery, Sungkyunkwan University School of Medicine, Samsung Medical Center, 50 Ilwon-Dong, Kangnam-Gu, Seoul, South Korea.
Cho
Y S
YS
Chung
W H
WH
Koh
S J
SJ
Seo
I S
IS
Woo
H C
HC
D000161:Acoustic Stimulation; D000162:Acoustics; D002648:Child; D002675:Child, Preschool; D004431:Ear, External / Q000503:physiopathology*; D006320:Hearing Tests; D006801:Humans; D008876:Middle Ear Ventilation; D010034:Otitis Media with Effusion / Q000503:physiopathology / Q000601:surgery*