Use of Bonebridge Implant in a Child with Congenital Cholesteatoma: A Case Report

Introduction

Congenital cholesteatoma is a relatively rare condition estimated to account for approximately 2–5% of all cholesteatomas [1,2]. It is described as a non-neoplastic, keratinized squamous epithelial lesion, most commonly located in the middle ear region, mastoid process, or, less commonly, within the external auditory canal [2,3]. The cause of congenital cholesteatomas is unclear [2,4]. The most common theory is that they arise from embryonic remnants of epithelial tissue. Initially, the lesion is usually located in the anterior superior quadrant of the middle ear. The current Potsic classification systems for congenital cholesteatomas includes:

In the pediatric population, cholesteatomas tend to be more aggressive due to faster tissue growth and dysfunction of the auditory tubes, which contribute to frequent ear infections [7].

Surgery is the primary treatment [8,9]. The choice of procedure depends on the severity and area occupied by the cholesteatoma. Exploratory tympanotomy, modified radical mastoidectomy, ossicular chain reconstruction, or tympanoplasty are used to prevent further growth of the white mass and destruction of ear structures and tend to improve hearing [9]. However, recurrence of cholesteatomas is common and the need for reoperation ranges from 13% to 67%, depending on the stage of the cholesteatoma [6]. A common complication of the condition, even after surgical treatment, is conductive, sensorineural, or mixed hearing loss.

Due to the initial lack of symptoms and an often-intact eardrum, congenital cholesteatoma presents a serious problem. Failure to diagnose a cholesteatoma in its early stages can lead to progressive, severe damage to the middle ear structures, resulting in hearing loss as well as other more serious complications, such as damage to the skull. At this point, the effectiveness of surgery depends largely on how early the condition is diagnosed. The earlier it is detected, the better the chances of avoiding permanent damage and improving the quality of hearing [1,10,11].

Although hearing loss is a handicap at any stage of life, its effects are particularly severe in children. Hearing loss in childhood can lead to developmental disorders at many levels: problems with language acquisition, learning, and social or emotional difficulties, all of which highlight the importance of appropriate treatment and rehabilitation [12,13]. In some cases, hearing can be improved by traditional air conduction hearing aids; alternatively, improvement can sometimes come from surgery on the eardrum or ossicular chain, or reconstruction of the middle ear conductive apparatus (using passive prostheses or custom-made materials). However, there are still situations where these methods are inadequate [5,14,15], and in such cases bone implants are an effective solution.

Bone implants offer high treatment efficacy for conductive and mixed hearing losses, are aesthetically pleasing, and are well tolerated by patients. As a result, the patient’s subjective quality of life is improved [16–18]. The Bonebridge implant is a technically advanced device that transmits vibrations directly to the cochlea via a subcutaneous transducer [19]. This new solution not only improves hearing, but also provides a high level of comfort, which is particularly important for children who may have difficulty accepting assistive listening devices [16]. There have been reports in the literature of individual cases of bone conduction implants being used in patients with cholesteatoma, but these are limited and do not include children with congenital cholesteatoma. Depending on the anatomical conditions, it may first be necessary to fill the mastoid cavity with bioactive glass before implanting the Bonebridge system [20,21]. A study by Thomas et al (2018) [22] found that Bonebridge implantation is not possible in up to 41% of patients with perloma due to anatomical limitations. Despite the fact that they can be an effective solution in cases where conventional treatment or BTE hearing aids are insufficient, reports on active bone conduction implants in this group of patients are scarce. In recent years, reports of new devices have also emerged, such as the OSIA OSI300. Thanks to its compatibility with 3T MRI, this device may be a viable option for patients requiring regular radiological follow-up due to the risk of recurrence [23]. To date, there are no case reports in the literature of children with congenital perloma who have been treated with active bone conduction implants. Given the more aggressive course of this condition and the young age of patients affected by it, such cases may present significant diagnostic and therapeutic challenges, as well as being an important reference point for the further development of surgical treatment with implants.

The aim of this study was to analyze the surgical implications, efficacy, and safety of the Bonebridge implant in a 10-year-old girl with a congenital cholesteatoma.

Case Report

PATIENT ASSESSMENT AND BONEBRIDGE ELIGIBILITY:

Prior to the assessment visit, she had had no experience with assistive listening devices. A bone conduction hearing aid on a softband was used to simulate bone conduction during the diagnostic evaluation. To assess the effects, a speech comprehension test was performed, which showed a significant improvement. In a free-field speech audiometry test, speech discrimination was 75% with a conventional hearing aid on the left ear (at 65 dB SPL) and 95% with the bone conduction device on a softband on the same side. To ensure accurate measurement, the contralateral ear was actively masked during testing.

The Polish Matrix Sentence Test is a tool for assessing understanding of speech under impaired conditions. During the test, the level of speech intensity and noise is varied to assess the ability to understand speech under difficult conditions. A lower score indicates a better ability to understand speech in noise. The test determines the speech reception threshold (SRT), which is the signal-to-noise ratio (SNR) that gives 50% speech intelligibility [24–26]. The Matrix test result for our patient was SRT=+4.5 dB SNR without the softband and SRT=+3.2 dB SNR with the device. To reliably assess the benefit of a bone conduction device in patients with conductive or mixed hearing loss and normal or better hearing on the contralateral side, it is essential to apply masking to the better-hearing ear during testing. The Polish Matrix Sentence Test was conducted in a free-field setting, with a fixed noise level of 65 dB SPL. To isolate auditory input to the implanted side and prevent cross-hearing, a double-blocking method was used. This involved inserting a foam earplug into the better-hearing ear (for passive attenuation), followed by the application of masking noise at 60 dB SPL via a supra-aural headphone, ensuring that the patient could not perceive the test sentences through the normal-hearing ear. The effectiveness of the masking was verified by confirming the patient’s inability to repeat any sentences in the unaided condition. This approach allowed for an accurate measurement of the speech reception threshold (SRT), reflecting the true benefit of the implant on the impaired side without influence from the better ear.

The girl met the audiological criteria to qualify for an implantable bone conduction device. The Bonebridge implant is intended for individuals with a bone conduction threshold of less than 45 dB HL [27]. The results of the pure-tone audiometry for the right and left ear are shown in Figure 1. Analysis of the anatomical conditions in the temporal bone tomographic images confirmed the feasibility of the Bonebridge device.

The girl had been free of ear inflammation for several months prior to the procedure, which is an absolute prerequisite for Bonebridge implantation. The treatment suggested was approved by the Bioethics Committee of the Institute of Hearing Physiology and Pathology (IFPS/KB/7/2020).

SURGERY:

Although BCI 602 is widely available, BCI 601 was chosen due to anatomical conditions that permitted full implantation without a lift. BCI 601 is often preferred, as BCI 602 can cause increased skin tension and related complications. The final decision was made by the surgeon based on an intraoperative assessment and clinical experience. The operation to place the Bonebridge 601 implant proceeded without complications. The implant was positioned in the mastoid process of the temporal bone such that it did not contact or compress the dura mater of the brain or the sigmoid sinus. The implant was fixed in the temporal bone using standard screws, without the need for shims. The thickness of the subcutaneous tissue was 5 mm, which posed no risk of postoperative complications or issues with retaining the processor. Additionally, a revision after modified radical surgery was performed during the procedure, with no recurrence of the cholesteatoma found. To monitor for possible recurrence, a follow-up revision in 3–6 months was scheduled, along with regular evaluation of the appended cavity every 4 weeks after surgery to determine the need for further follow-up. Healing of the postoperative wound proceeded well.

AUDIOLOGICAL EVALUATION OF THE BONEBRIDGE:

At the activation visit, which took place 1 month after surgery, the audio processor was fitted based on the results of pure-tone audiometry, the vibrogram and the patient’s subjective feedback. During this visit, as well as at the follow-up visit 3 months after activation, the following tests were performed: free-field audiometry, free-field speech audiometry and the Polish Matrix Sentence Test.

The hearing thresholds obtained from the free-field audiometry test are shown in Figure 2. Results showed that the hearing thresholds with the active Bonebridge implant were significantly lower at both the activation and follow-up visits compared to the pre-surgery results when the patient was not using a hearing aid. This indicates a significant improvement in hearing after implantation.

The WRS was 80% during activation and 95% at follow-up. Figure 3 shows a comparison of the free-field speech audiometry results during implant activation and at follow-up. Compared to the results without the Bonebridge implant (0%), the patient achieved a significant improvement in speech understanding.

The Matrix test result for the left ear in the active device was SRT=−2.3 dB SNR and at the follow-up visit, several weeks after activation, the Matrix test result for the left ear in the active device was SRT=−3 dB SNR. The results are shown in Figure 4.

In an interview with the audiologist, the patient and her parents reported an improvement in hearing and speech understanding, particularly in difficult listening environments. A significant increase in the patient’s comfort level in daily functioning was noted, including improvement in age-appropriate situations such as school and social interactions. In addition, the patient accepted the device, which is particularly important during adolescence.

Discussion

The surgical management of cholesteatomas is a never-ending debate, especially in pediatric patients. Surgeons choose different methods of lesion removal depending on the severity of the disease and their experience [11]. However, the surgeon’s flexibility and individual approach to each case is important. A number of factors need to be considered, including the extent and location of the cholesteatoma, the function of the Eustachian tube, the pneumatization of the bone, and the patient’s anatomy [20,21,28]. When anatomically possible, the Bonebridge implant should be positioned to avoid disturbing the dura mater of the brain and the sigmoid sinus. Detailed imaging studies are essential for accurate surgical planning and proper implant placement [29].

Studies indicate that early diagnosis of congenital cholesteatomas is important in increasing the effectiveness of surgeries. Surgical intervention during the early stages reduces the risk of complications and improves the patient’’s prognosis [10,11]. This is especially important for children who are just developing their communication skills. Regular monitoring of the patient’s hearing status after surgery, as well as frequent middle ear examinations, are key to preventing serious complications. One of the limitations of the Bonebridge device is that it can potentially rule out the use of MRIs to monitor the middle ear for cholesteatoma recurrence. With the Bonebridge 601, an MRI cannot be performed in a magnetic field greater than 1.5 T [23,30,31]. Postoperative revisions, as planned in this case, allow for early detection of abnormalities and prompt intervention to prevent further deterioration of the patient’s hearing [32–34].

Pericarditis is also a challenge for hearing care professionals because it is a recurrent disease that leads to progressive hearing loss [35]. A hearing screening program for first graders in elementary schools in Mazovia province, Poland, showed that chronic otitis media and cholesteatoma affected 5.7% of children [36]. In this group, help needs to be quick and effective. Binaural hearing is particularly important for school-age children as it enables them to function properly in the school and social environment, to localize sounds effectively, and to understand speech in noise [37,38]. Children are a diverse group in terms of hearing loss, and traditional hearing aids are not an effective solution for everyone. In cases where the hearing loss is associated with frequent inflammation and leakage, as was the case with this patient, it is important to keep the ear open. With the Bonebridge implant, such a condition is achievable. Studies by Cywka et al and Skarzynski et al [16–18,39] show that its benefits are satisfactory and stable over time in both children and adults. Similar results were found in the studies by Sprinzl (2016) [27] and Brooks (2025) [40]. They showed that the Bonebridge implant provides significant audiological benefits in children under 12 years of age as well as in older patients, both improving speech recognition threshold and audiometric scores with a low rate of postoperative complications. Due to its design, the Bonebridge implant provides a higher and more stable auditory gain than traditional percutaneous implants while being associated with a lower risk of postoperative complications [27,40]. In a study by Cywka (2024), which considered the case of a child with a Bonebridge implant, the researcher found great benefits in sound localization in space [41]. Although Bonebridge implantation is becoming more common in cases of conductive and mixed hearing loss, anatomical limitations, particularly in patients who have undergone multiple surgeries of the middle ear, may restrict candidacy for implantation. Król et al (2020) [42] demonstrated that reconstructing the posterior wall of the external auditory canal with S53P4 bioactive glass can create the necessary anatomical conditions for Bonebridge placement in patients who were previously considered unsuitable for implantation. This case highlights the importance of an individual and multidisciplinary approach.

In our patient, Bonebridge implantation proved to be an effective treatment for hearing loss and congenital cholesteatoma. She had undergone multiple surgical procedures with no lasting results. Use of the Bonebridge implant resulted in significant improvement in hearing and speech understanding, as shown by the audiological results.

The subjective evaluation of a hearing aid user and their caregivers is the final stage of verifying treatment efficacy. The interview is the primary way for this to be done. Doctors and hearing care professionals should be attentive to the patient’s signals and needs, as patient satisfaction is a key factor in the long-term success of hearing therapy. Only by working together with the patient and family can clinical success be achieved.

Conclusions

This case report demonstrates the effectiveness of the Bonebridge implant in treating and improving hearing in patients with recurrent congenital cholesteatoma who have not responded to conventional treatments. The girl’s diagnostic and audiological tests showed significant improvements in both hearing thresholds and speech understanding. The implantation procedure was uneventful and regular check-ups were scheduled to monitor for recurrence of cholesteatoma. Acceptance of the implant reflects the effectiveness of the treatment in overcoming hearing loss and improving the patient’s quality of life.