Impact of Tympanostomy Tubes on Pediatric Otoacoustic Emission Testing

Introduction: The effect of tympanostomy tubes (TT) on otoacoustic emissions (OAE) is not well-understood and the limited previous reports are mixed in methodology. We evaluated the impact of TTs on OAEs by strictly including pediatric patients with patent TTs and normal hearing on pure tone audiometry.

Methods: A retrospective review was performed with inclusion criteria of unilateral or bilateral TT placement followed by post-op audiogram paired with OAE data at 1, 2, 4, and 8 kHz. Subjects were excluded if audiometry hearing thresholds were >25 dB or if tympanometry indicated non-patent TTs. OAEs were graded by signal-to-noise ratio (SNR) and distortion product (DP) data as “present” (SNR ≥6 + DP ≥0), “absent” (SNR < 6 dB + any DP value), or “reduced” (SNR ≥6 + DP < 0). Chi-square analysis was used for non-parametric variables and simple logistic regression for parametric variables.

Results: Between Oct. 2018 and Mar. 2021, 124 patients (217 ears) were included with a mean age (SD) of 3.9 (3.2) years. TTs were placed for recurrent acute otitis media (53.5%) or chronic otitis media with effusion (46.5%). Paired audiogram and OAEs were obtained an average of 4.5 (4.7) months post-op. Overall, 17.1% of patients had 1 absent OAE, 12.0% had 2 absent OAEs, 17.6% had 3 absent OAEs, and 32.7% of patients had 4 absent OAEs. At 1 kHz (n=166), 84% of OAEs were absent, 3% reduced, and 13% present. At 2 kHz (n=204), 57% were absent, 2% reduced, and 41% present. At 4 kHz (n=207), 56% were absent, 1% reduced, and 43% present. At 8 kHz OAEs (n=138), 83% were absent, 9% reduced, and 8% present. No significant relationship existed between OAE outcomes and operative indication, age, or gender.

Conclusions: Absent OAEs were most common at 1 and 8 kHz, but >50% of OAEs were also absent at 2 and 4 kHz. Overall, 79.3% of patients failed testing at ≥1 OAE frequency. Given that all subjects had normal audiometric pure tone thresholds, this suggests TTs may directly impact OAE results more than previously reported. Clinicians may need to exercise caution when interpreting OAEs in patients with patent TTs, and further research may call for a re-evaluation of its utility in this context.