Transient-evoked otoacoustic emissions from ears with tympanostomy tubes.

OBJECTIVE

Otoacoustic emissions (OAEs) are low-level acoustic signals which emanate from the cochlea and can be recorded in the ear canal. The two types of OAEs are spontaneous and evoked otoacoustic emissions.

METHODS

In this retrospective study, transient-evoked otoacoustic emissions (TEOAEs) were measured in 385 ears from 204 children with normal hearing and tympanostomy tubes.

RESULTS

The results indicate that, when using the Quick Screen option on the Oto-Dynamics ILO88 Otoacoustic Emission Analyzer, postoperative TEOAEs were present at all measured frequencies in 81% of the ears. The remaining 19% of ears showed the absence of an observable emission at one or more of the measured response frequencies. The overwhelming factor contributing to an absent emission was insufficient stimulus energy at 4 kHz. The use of T-type tympanostomy tubes also appeared to decrease the probabilities obtaining normal TEOAEs in ears with normal peripheral auditory function. The use of grommet-type tympanostomy tubes, the type of middle ear effusion, the age and gender of the child, and the physical volume of the ear canal as measured by tympanometry with the tympanostomy tube patent and in place had negligible effects on the measurement of TEOAEs.

CONCLUSIONS

Clinicians must be cautious when interpreting click-evoked TEAOEs if the patient has a T-tube in place and may need to modify this testing to rule out high-frequency hearing loss when using TEOAEs with these patients. For those patients who have tympanostomy tubes and fail to meet the "pass criteria" for TEOAEs at 4 kHz in the Quick Screen option, TEOAE should be repeated either in the Diagnostic mode or by using a 4 kHz tone-burst stimulus centered at 4 kHz to recover the loss of energy in this region due to the high-frequency roll-off of the stimuli used in the Quick Screen option.