Surgery for the bone-anchored hearing aid

Implantable hearing devices in clinical practice. Systematic review and consensus statements

Objective

Implantable hearing devices represent a modern and innovative solution for hearing restoration. Over the years, these high-tech devices have increasingly evolved but their use in clinical practice is not universally agreed in the scientific literature. Congresses, meetings, conferences, and consensus statements to achieve international agreement have been made. This work follows this line and aims to answer unsolved questions regarding examinations, selection criteria and surgery for implantable hearing devices.

Materials and methods

A Consensus Working Group was established by the Italian Society of Otorhinolaryngology. A method group performed a systematic review for each single question to identify the current best evidence on the topic and to guide a multidisciplinary panel in developing the statements.

Results

Twenty-nine consensus statements were approved by the Italian Society of Otorhinolaryngology. These were associated with 4 key area subtopics regarding pre-operative tests, otological, audiological and surgical indications.

Conclusions

This consensus can be considered a further step forward to establish realistic guidelines on the debated topic of implantable hearing devices.

Swallowed by the bone - Is skin reaction the "tip of the iceberg"?

The most frequent complications of osseointegrated implantation include implant-site infections, soft tissue overgrowth and failure of osseointegration. Bone overgrowth is also a complication at the abutment site and infrequently reported. We describe a rare case of difficult control and exuberant bone overgrowth, with total implant involvement, in a short period of time never before described in the literature. Bone growth around the implant is frequently underestimated and can be the cause of difficult control of skin reactions, that in some cases is just the "tip of the iceberg". Timely surgical review with removing excess bone may lead to implant preservation and control of skin reaction and healing.

Predisposing factors for adverse skin reactions with percutaneous bone anchored hearing devices implanted with skin reduction techniques

We present an analysis of adverse events after implantation of bone anchored hearing device in our patient population with focus on individual risk factors for peri-implant skin reactions. The investigation involved a chart review of adult Baha patients (n = 179) with 203 Bahas implanted with skin reduction techniques between 1993 and 2009, a questionnaire (n = 97) and a free clinical examination (n = 47). Skin reactions were graded by severity from 0 (no skin reaction) to 4 (implant loss resulting from infection) according to Holgers. We analyzed the skin reaction rate (SRR) defined as the number of skin reactions per year and the worst Holgers grade (WHG), which indicates the grade of the worst skin reaction per implant. We defined 20 parameters including the demographic characteristics, surgery details, subjective benefits, handling and individual factors. The most frequent adverse events (85 %) were skin reactions. The average SRR was 0.426 per Baha year. Six parameters showed an association with the SRR or the WHG. The clinically most relevant factors are an elevated Body Mass Index (BMI, p = 0.02) and darker skin type (p = 0.03). The SRR increased with the distance between the tragus and the implant (p = 0.02). Regarding the identified risk factors, the SRR might be reduced by selecting a location for the implant near the pinna and by specific counseling regarding post-operative care for patients with darker skin type or an elevated Body Mass Index (BMI). Few of the factors analyzed were found to influence the SRR and WHG. Since most adverse skin reactions could be treated easily with local therapy, our results suggest that in adult patients, individual risk factors for skin reactions are not a contraindication for Baha implantation. Thus, patients can be selected purely on audiological criteria.

Skin reactions caused by bone-anchored hearing aid (BAHA) implantation

Objective

To report a case of intractable skin reactions caused by bone-anchored hearing aid (BAHA) implantation to improve our understanding and treatment of BAHA implantation-caused skin reactions.

Methods

We reported a case of severe skin reactions caused by BAHA implantation. Related literature were also reviewed.

Results

We found grade IV skin reactions, including hyperplasia around the implant, which led to the removal of the BAHA implant 10 months after implantation. The findings indicated poor skin hygiene, allergy to titanium and inadequate surgicals skills as the possible causes of the skin reaction.

Conclusion

Skin adverse reactions, usually rare in BAHA implantation patients, may cause implant removal and implantation failure. We suggest to further investigate the mechanisms underlying titanium allergy.

Mitigation of informational masking in individuals with single-sided deafness by integrated bone conduction hearing aids

OBJECTIVES

To confirm an increased susceptibility to informational masking among individuals with single-sided deafness (SSD). To demonstrate a reduction in informational masking when SSD is treated with an integrated bone conduction hearing aid (IBC). To identify the acoustic cues that contribute to IBC-aided masking release. To determine the effects of device experience on the IBC advantage.

DESIGN

Informational masking was evaluated with the coordinate-response measure. Participants performed the task by reporting color and number coordinates that changed randomly within target sentences. The target sentences were presented in free field accompanied by zero to three distracting sentences. Target and distracting sentences were spoken by different talkers and originated from different source locations, creating two sources of information for auditory streaming. Susceptibility to informational masking was inferred from the error rates of unaided SSD patients relative to normal controls. These baseline measures were derived by testing inexperienced IBC users without the device on the day of their initial fitting. The benefits of IBC-aided listening were assessed by measuring the aided performance of users who had at least 3 months' device experience. The acoustic basis of the listening advantage was isolated by correlating response errors with the voice pitch and location of distracting sentences. The effects of learning on cue effectiveness were evaluated by comparing the error rates of experienced and inexperienced users.

RESULTS

Unaided SSD participants (inexperienced users) performed as well as normal controls when tested without distracting sentences but produced significantly higher error rates when tested with distracting sentences. Most errors involved responding with coordinates that were contained in distracting sentences. This increased susceptibility to informational masking was significantly reduced when experienced IBC users were tested with the device. The listening advantage was most strongly correlated with the availability of voice pitch cues, although performance was also influenced by the location of distracting sentences. Directional asymmetries appear to be dictated by location-dependent cues that are derived from the distinctive transmission characteristics of IBC stimulation. Experienced users made better use of these cues than inexperienced users.

CONCLUSIONS

These results suggest that informational masking is a significant source of communication impairment among individuals with SSD. Despite the lateralization of auditory function, unaided SSD subjects experience informational masking when distractors occur in either the deaf or normal spatial hemifield. Restoration of aural sensitivity in the deaf hemifield with an IBC enhances speech intelligibility under complex listening conditions, presumably by providing additional sound-segregation cues that are derived from voice pitch and spatial location. The optimal use of these cues is not immediate, but a significant listening advantage is observed after 3 months of unstructured use.