Reported benefits and problems experienced with bone-anchored hearing aids

Understanding the low uptake of bone-anchored hearing aids: a review

BACKGROUND

Bone-anchored hearing aids improve hearing for patients for whom conventional behind-the-ear aids are problematic. However, uptake of bone-anchored hearing aids is low and it is important to understand why this is the case.

METHOD

A narrative review was conducted. Studies examining why people accept or decline bone-anchored hearing aids and satisfaction levels of people with bone-anchored hearing aids were reviewed.

RESULTS

Reasons for declining bone-anchored hearing aids included limited perceived benefits, concerns about surgery, aesthetic concerns and treatment cost. No studies providing in-depth analysis of the reasons for declining or accepting bone-anchored hearing aids were identified. Studies of patient satisfaction showed that most participants reported benefits with bone-anchored hearing aids. However, most studies used cross-sectional and/or retrospective designs and only included people with bone-anchored hearing aids.

CONCLUSION

Important avenues for further research are in-depth qualitative research designed to fully understand the decision-making process for bone-anchored hearing aids and rigorous quantitative research comparing satisfaction of people who receive bone-anchored hearing aids with those who receive alternative (or no) treatments.

Third-window vibroplasty with an active middle ear implant: assessment of physiologic responses in a model of stapes fixation in Chinchilla lanigera

HYPOTHESIS

Mechanical stimulation through a cochlear third window into the scala tympani in a chinchilla model with normal and fixed stapes can generate cochlear responses equivalent to acoustic stimuli.

BACKGROUND

Cochlear stimulation via the round window (RW) using active middle ear implants (AMEIs) can produce physiologic responses similar to acoustic stimulation including in a model of stapes fixation. However, pathologic conditions, such as advanced otosclerosis, can preclude delivery of sound energy to the cochlea through the oval window and/or the RW.

METHODS

Cochlear microphonic (CM) and laser Doppler vibrometer measurements of stapes and RW velocities were performed in 6 ears of 4 chinchillas. Baseline measurements to acoustic sinusoidal stimuli (0.25-8 kHz) were made. Measurements were repeated with an AMEI driving the RW or a third window to the scala tympani before and after stapes fixation.

RESULTS

AMEI stimulation of the third window produced CM waveforms with morphologies similar to acoustic stimuli. CM thresholds with RW and third-window stimulation were frequency dependent but ranged from 0.25 to 10 and 0.5 to 40 mV, respectively. Stapes fixation, confirmed by laser Doppler vibrometer measurements, resulted in a significant frequency dependent impairment in CM thresholds up to 13 dB (at <3 kHz) for RW stimulation and a nonsignificant frequency-dependent improvement of up to 10 dB (at >3 kHz) via third-window stimulation.

CONCLUSION

AMEI mechanical stimulation through a third window into the scala tympani produces physiologic responses nearly identical to acoustic stimulation including in a model of stapes fixation with decreased efficiency.

Active middle ear implant application in case of stapes fixation: a temporal bone study

HYPOTHESIS

Driving the oval window directly with an active middle ear implant (AMEI) can produce high levels of input to the inner ear.

BACKGROUND

Treatment of otosclerosis bypasses the stapes with a piston that penetrates the vestibule. Although this treats the conductive component of hearing loss, it does not treat the sensorineural part, which can be improved using an additional conventional hearing aid. Active middle ear implants have been proposed to be an alternative in treating otosclerosis in cases of mixed hearing losses.

METHODS

Seven temporal bones were prepared to expose the stapes and round window (RW). Stapes and RW velocities were measured while driving with an AMEI the stapes head with a bell-shaped tip. The stapes footplate was then fixed with acrylic cement; fixation was confirmed through attenuated RW velocities. A cylinder tip (0.5 mm) was then used to drive the inner ear through a stapedotomy with and without interposition of fascia.

RESULTS

Driving the stapes with an AMEI produced mean maximum equivalent ear canal sound pressure levels (SPL) of 138 dB (0.25-8 kHz at 1 V [RMS]). Stapes fixation caused a approximately 25-dB attenuation. Driving with a cylinder tip through the stapedotomy produced 114 dB SPL (24 dB less than normal) and 110 dB SPL (28 dB less than normal) performance with and without fascia, respectively. Performance with fascia was greater than without.

CONCLUSION

Driving the oval window with an AMEI in a scenario of stapes fixation was demonstrated to be feasible, with performance comparable to traditional AMEI coupling to the incus or stapes. These possibilities offer new perspectives to treat mixed hearing loss in case of fixed footplate.

Audiometric thresholds measured with single and dual BAHA transducers: The effect of phase inversion

The bone-anchored-hearing-aid (BAHA) transduces airborne sound into skull vibration. Current bilateral BAHA configurations, for sounds directly facing listeners, will apply forces that are in-phase with each other and directed roughly towards the center of the head. Below approximately 1000 Hz the two cochleae respond in approximately the same direction and with approximately the same phase to each BAHA, thus it may be preferable to drive bilateral BAHAs such that when one pushes, the other pulls. This can be achieved by adjusting the relative phase offset of the BAHAs, and doing so results in greater vibration and improved hearing threshold. In this paper we compare performance of bilateral BAHAs driven in this configuration to the standard configuration. In twelve normal participants we show significant improvements in low-frequency (≤750 Hz) hearing thresholds using out-of-phase BAHAs. The threshold measurements are further supported by velocimetric measurements taken at the cochlear promontory in a cadaveric head. Comparing vibration arising from each configuration confirms that out-of-phase driving results in greater vibration. Neither dataset shows either improved or reduced threshold at high frequencies.

Prospective electrophysiologic findings of round window stimulation in a model of experimentally induced stapes fixation

HYPOTHESIS

Mechanical stimulation of the round window (RW) with an active middle ear implant (AMEI) with and without experimentally induced stapes fixation (SF) results in equivalent electrophysiologic measures of cochlear microphonic (CM), compound action potential (CAP), and auditory brainstem response (ABR).

BACKGROUND

Where normal oval window functionality is mitigated, the RW provides a pathway to mechanically stimulate the inner ear.

METHODS

Measurements of the CM, CAP, and ABR were made in 5 ears of 4 chinchillas with acoustic stimulation and with application of the AMEI to the RW with and without experimentally induced SF using pure-tone stimuli (0.25-20 kHz) presented at differing intensities (-20 to 80 dB SPL vs. 0.01 mV to 3.16 V).

RESULTS

Morphologies of the CM, CAP, and ABR were similar between acoustic and RW stimulation with and without SF. Stapes fixation increased CM thresholds relative to RW stimulation without fixation by a frequency-dependent 4- to 13-dB mV (mean, 7.9 +/- 3.2 dB mV). Although the thresholds changed with SF, CM sensitivities and amplitude dynamic range were identical to normal. The CAP in all conditions demonstrated equivalent decreasing amplitudes and increasing latency with decreasing intensity (decibel sound pressure level versus decibel millivolt). Stapes fixation increased the CAP thresholds at all frequencies, ranging from 9 to 24 dB mV (mean, 17.7 +/- 4.9 dB mV). Auditory brainstem response waveforms were preserved across experimental conditions.

CONCLUSION

Mechanical stimulation of the RW in an animal model of SF generates functionally similar inputs to the cochlea as normal acoustic and RW mechanical inputs but with increased thresholds. With further study, AMEIs may provide a surgical option for correction of otosclerosis and ossicular chain disruption.

Audiological performance with cochlear reimplantation from analogue single-channel implants to digital multi-channel devices

Cochlear implantation has been performed for almost two decades at the Vienna University Hospital. Until 1994, single-channel implants were used (Ball-Electrode, SC6/2SC6, Vienna/Epoxy, Med-E1, Innsbruck, Austria). The development of multi-channel devices (Combi 40/40+), which provide significantly improved speech recognition performance, led to the reimplantation of some patients who had previously received single-channel implants. It was of particular interest to find out if there was a deterioration of the central "learning process" by the reimplantation from the analogue single-channel device to the tonotopic pulsatile multi-channel stimulation. In this study, we attempted to demonstrate that single-channel implants have an impact on the neural organisation of the auditory system. Two groups of post-lingually deaf adult patients were tested. Group A had previously received single-channel implants and were reimplanted with the new Combi 40/40+ cochlear implant (Med-E1, Innsbruck, Austria) in the same ear. Group B was implanted only with the Combi 40/40+. Six different speech recognition tests were subsequently performed on all patients, and the two groups performed similarly. Furthermore, it was discovered that group A obtained significant speech recognition improvement (p<0.05) with monosyllabic words and number tests 1 month following reimplantation.

The use of outcome measures to formulate intervention strategies

OBJECTIVE

To investigate the relative value of the use of open-ended and structured questionnaires in the determination of the most appropriate management of patients in a busy audiological rehabilitation clinic.

DESIGN

An open set questionnaire was sent to 56 consecutive patients before clinic attendance, and they were asked to rate the severity of the problems listed on arrival at the clinic. They subsequently were administered the Hearing Disability and Handicap Scale (HDHS), which was not scored until after management decisions had been made. The implications of the results of both questionnaires separately and together for patient management were compared.

RESULTS

The Problem Questionnaire highlighted a number of areas in terms of Activity Limitation (Disability) not covered in the HDHS, some of which, such as employment effects, were considered to be of considerable importance to the patients. However, in the field of more general Participation Restriction (Handicap), the structured questionnaire highlighted a number of important areas not volunteered by the patient.

CONCLUSION

Although the open-set Problem Questionnaire approach is valid in the domain of Activity Limitation, it needs to be supplemented by an additional measure of Participation Restriction, either open-set or structured, to ensure optimal patient management.