Preservation of Distortion Product Otoacoustic Emissions in OTOF -Related Hearing Impairment

Abstract

Objectives: Attenuation of otoacoustic emissions over time has been reported for many patients with hearing impairment harboring mutations in the OTOF gene. In this study, the time course of changes of distortion product otoacoustic emissions (DPOAEs) has been analyzed in a cohort of patients in the light of tympanometry results.

Design: The changes of DPOAEs in 16 patients with OTOF -related hearing impairment were retrospectively analyzed.

Results: All but one subject showed DPOAEs bilaterally at the time of diagnosis. Three patients diagnosed as adults still had DPOAEs at ages of 27, 31, and 47 years, respectively. Follow-up was available for 7 children diagnosed at the age of 1 to 3 years, who still showed preservation of DPOAEs at ages of 5 to 16 years. The responses were absent or attenuated in amplitude at some follow-up appointments in association with type B or C tympanograms.

Conclusions: DPOAEs are preserved much longer than expected in a cohort of patients with OTOF -related hearing impairment. The previously reported loss of DPOAEs may have been caused in some children by increased middle ear impedance due to otitis media.

Fig. 1.

DPOAEs rates at the first and last follow-up appointments in the presence of normal tympanometry in patients with OTOF-related hearing impairment. Response rate was calculated as the percentage of frequency points showing a positive response. The DPOAEs recordings collected at ages of 2 and 5 mo in subjects nos. 5 and 6 were reported at the age of 1 for the sake of clarity. In this and in the subsequent figures, DPOAEs were recorded at 65/55 dB SPL intensity, except for the responses collected in subject no. 6 at the age of 5 mo, which were obtained at 75/70 dB SPL. DPOAEs indicate distortion product otoacoustic emissions; L, left ear; R, right ear.

Fig. 2.

DPOAEs recordings collected in 5 subjects (left ear) in the presence of normal tympanometry at different ages. For each patient, the SNR at each frequency was compared between the first and last appointment in the graph reported on the left. Subjects nos. 5, 6, and 7 were affected by profound deafness, whereas subjects nos. 9 and 10 had, respectively, mild and moderate hearing loss. DPOAEs indicate distortion product otoacoustic emissions; SNR, signal to noise ratio.

Fig. 3.

DPOAEs responses recorded at different ages in two patients with OTOF-related hearing impairment who suffered from recurrent episodes of OME. The type of tympanogram (A, As, B, C) was indicated for each DPOAE recording according to Jerger (1970) classification. Type B and C tympanograms were associated, respectively, with absence or attenuation of DPOAE responses. DPOAEs indicate distortion product otoacoustic emissions; OME, otitis media with effusion.

Fig. 4.

DPOAEs responses recorded in 3 adult patients together with the SNR at each frequency. On the left, the hearing thresholds obtained on the same session of DPOAEs recording are shown. SNR, signal to noise ratio.