Ventilation tube non-function due to blockage in children: the frequency, course and effect on hearing. A prospective
M Merven1, J W Loock1, G G Browning2
1Department of Otorhinolaryngology, Tygerberg Hospital, Faculty of Health Sciences, University of Stellenbosch, Cape Town, South Africa.
Insights
Non-functioning ventilation tubes are common after surgery and can impact hearing. Tympanometry is more reliable than otoscopy for detecting blocked tubes, which may require intervention if otorrhoea or hearing loss recurs.
Area of Science:
- Otolaryngology
- Pediatric Audiology
- Medical Devices
Background:
- Ventilation tubes are crucial for managing middle ear conditions in children.
- Tube non-function, often due to blockage, can affect hearing outcomes.
- UK national guidelines emphasize monitoring post-operative hearing and tube patency.
Purpose of the Study:
- To evaluate the impact of non-functioning ventilation tubes on hearing thresholds.
- To compare the diagnostic accuracy of tympanometry and otoscopy in identifying tube blockage.
- To assess the frequency of ventilation tube non-function within six months post-insertion.
Main Methods:
- Prospective observational study of 37 children undergoing bilateral ventilation tube insertion.
- Measurement of air and bone conduction thresholds pre- and post-operatively (1, 3, 6 months).
- Assessment of tube function using tympanometry and otoscopy.
Main Results:
- 21% of ventilation tubes were non-functioning post-operatively.
- Non-functioning tubes correlated with significantly poorer air conduction thresholds (6 dB HL difference).
- Otoscopy underdiagnosed blockage by 22% compared to tympanometry; otorrhoea affected 15% of ears.
Conclusions:
- Frequent non-function of ventilation tubes can be missed by otoscopy.
- While non-functioning tubes impact air conduction, intervention is typically unnecessary unless otorrhoea or recurrent hearing impairment is present.
- Tympanometry is a more sensitive method for detecting ventilation tube blockage.
Objective:
To assess the effect on hearing of non-functioning ventilation tubes due to blockage during the first six months post-operatively, using UK national guidelines.
Method:
A prospective, observational study was conducted on 37 children who underwent bilateral ventilation tube insertion. Air and bone conduction thresholds were measured before and following surgery, and at one, three and six months post-operatively. Tube non-function was assessed by tympanometry supported by otoscopy.
Results:
Post-operatively, an average of 21 per cent of ventilation tubes were non-functioning. Ears with non-functioning tubes had significantly (p = 0.0001) poorer mean air conduction thresholds than functioning tubes, with a magnitude of 6 dB HL. Ears with otorrhoea were most affected (15 per cent). At any one visit, the air-bone gap was closed to 10 dB or less in 76 per cent of ears. Non-functioning tubes reduced this to 56 per cent. Compared with tympanometry, otoscopy underdiagnosed tube non-function due to blockage by 22 per cent.
Conclusion:
Non-functioning of ventilation tubes occurs frequently and can be missed on otoscopy. Although it is associated with poorer air conduction thresholds, the magnitude of this difference is unlikely to warrant further intervention unless there is otorrhoea or recurrence of bilateral hearing impairment.
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