Extraction of a Foreign Body From the Middle Ear Following a Complicated Hearing Aid Fitting: A Case Report

Ear molding is a safe way to evaluate the ear for hearing aid fitting. A very rare complication of ear molding is the entry of a foreign body into the middle ear. We report the case of a three-year-old boy who had a perforated left tympanic membrane and bilateral sensorineural hearing loss that required the use of hearing aids. During the ear molding procedure, the molding material was unintentionally introduced into his middle ear cavity, necessitating immediate surgery to remove it. Such patients with tympanic membrane perforation must be handled cautiously while an aural impression is taken via ear molding to prevent introducing a foreign body into the middle ear.

The Mechanical Impedance of the Human Skull via Direct Bone Conduction Implants

Purpose

The mechanical skull impedance is used in the design of direct bone drive hearing systems. This impedance is also important for the design of skull simulators used in manufacturing, service, and fitting procedures of such devices.

Patients and Methods

The skull impedance was measured in 45 patients (25 female and 20 male) who were using percutaneous bone conduction implants (Ponto system or Baha system). Patients were recruited as a consecutive prospective case series and having an average age of 55.4 years (range 18–80 years). Seven patients were treated in Gothenburg, Sweden, and 38 patients in Edmonton, Canada. An impedance head (B&K 8001), driven by an excitation transducer with emphasized low-frequency response, was used to measure the mechanical point impedance with a swept sine from 100 to 10k Hz.

Results and Discussion

The skull impedance was found to have an anti-resonance of approximately 150 Hz, with a median maximum magnitude of 4500 mechanical ohms. Below this anti-resonance, the mechanical impedance was mainly mass-controlled corresponding to an effective skull mass of 2.5 kg at 100 Hz with substantial damping from neck and shoulder. Above the anti-resonance and up to 4 kHz, the impedance was stiffness-controlled, with a total compliance of approximately 450n m/N with a small amount of damping. At frequencies above 4 kHz, the skull impedance becomes gradually mass-controlled originating from the mass of the osseointegrated implant and adjacent bone. No significant differences related to gender or skull abnormalities were seen, just a slight dependence on age and major ear surgeries. The variability of the mechanical impedance among patients was not found to have any clinical importance.

Conclusion

The mechanical skull impedance of percutaneous implants was found to confirm previous studies and can be used for optimizing the design and test procedures of direct bone drive hearing implants.

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Hearing Rehabilitation Implementing a Transcutaneous Bone Conduction Device: Single-Center Experience

Bone conduction implants based on percutaneous abutment acoustic transmission have been implemented in patients with satisfactory outcomes. However, adverse soft tissue outcomes present a limitation. Transcutaneous bone conduction devices (t-BCDs) are an alternative that may mitigate these complications. A retrospective review was performed of patients who underwent implantation of a t-BCD from 2013 to 2017. Surgical outcomes were reviewed including wound complications, frequency of device use, patient concerns regarding the device, and reported patient satisfaction. A total of 37 patients were implanted with the bone-anchored hearing aids, BAHA Attract (Cochlear™ Baha® Implant System). Average follow-up time was 271.8 days. Postoperatively, 7 (18.9%) patients complained of soft tissue changes or issues with wound healing. Twelve (32.4%) patients requested adjustment of their devices. The t-BCD is an excellent option for hearing rehabilitation. Overall, the complication rate is low, patient satisfaction is high, and successful conversion from a percutaneous device is possible with minimal risk.

Technical design of a new bone conduction implant (BCI) system

OBJECTIVE

The objective of this study is to describe the technical design and verify the technical performance of a new bone conduction implant (BCI) system.

DESIGN

The BCI consists of an external audio processor and an implanted unit called the bridging bone conductor. These two units use an inductive link to communicate with each other through the intact skin in order to drive an implanted transducer.

STUDY SAMPLE

In this study, the design of the full BCI system has been described and verified on a skull simulator and on real patients.

RESULTS

It was found that the maximum output force (peak 107 dB re 1 μN) of the BCI is robust for skin thickness range of 2-8 mm and that the total harmonic distortion is below 8% in the speech frequency range for 70 dB input sound pressure level. The current consumption is 7.5 mA, which corresponds to 5-7 days use with a single battery.

CONCLUSIONS

This study shows that the BCI is a robust design that gives a sufficiently high output and an excellent sound quality for the hearing rehabilitation of indicated patients.

The SoundBite hearing system: patient-assessed safety and benefit study

OBJECTIVES/HYPOTHESIS

To determine the safety and efficacy of the SoundBite for patients over a 6 month period of use.

STUDY DESIGN

Prospective, multisite, nonrandomized patient enrollment with outcomes based on audiometric profile and self-reported assessment.

METHODS

Patients with single-sided deafness were eligible for the study. Patients were fit with the standard SoundBite sound transducer and were asked to wear the device regularly for 6 months. At the end of the trial period, patients completed both a self-assessment and the Abbreviated Profile of Hearing Aid Benefit (APHAB) questionnaires.

RESULTS

Thirty-four subjects completed the study. Mean APHAB scores improved significantly for ease of communication (P < 0.001), background noise (P < 0.001), reverberation (P < 0.001), and global benefit (P < 0.001). Patients reported high rates of auditory benefit in a variety of listening situations and high rates of overall satisfaction with the device. One adverse event with a superficial mouth sore was reported and resolved after appropriate dental care. Twelve patients (35%) reported acoustic feedback. In six of these patients, the feedback resolved after device adjustment.

CONCLUSION

The SoundBite is a new hearing prosthesis that delivers bone conduction energy. It offers advantages over traditional osseointegrated devices that require surgical placement. Patient satisfaction with the device after 6 months of regular use is high. The SoundBite provided improvement in ease of communication, hearing in background noise, sound reverberation, and an overall global hearing benefit. Acoustic feedback is the most commonly reported problem with the SoundBite, and this is minimized with proper fitting.

Reconstruction of middle ear malformations

Malformations of the middle ear are classified as minor and major malformations. Minor malformations appear with regular external auditory canal, tympanic membrane and aerated middle ear space. The conducting hearing loss is due to fixation or interruption of the ossicular chain. The treatment is surgical, following the rules of ossiculoplasty and stapes surgery. In major malformations (congenital aural atresia) there is no external auditory canal and a deformed or missing pinna. The mastoid and the middle ear space may be underdevelopped, the ossicular chain is dysplastic. Surgical therapy is possible in patients with good aeration of the temporal bone, existing windows, a near normal positioned facial nerve and a mobile ossicular chain. Plastic and reconstructive surgery of the pinna should proceed the reconstruction of the external auditory canal and middle ear. In cases of good prognosis unilateral aural atresia can be approached already in childhood. In patients with high risk of surgical failure, bone anchored hearing aids are the treatment of choice. Recent reports of implantable hearing devices may be discussed as an alternative treatment for selected patients.