Conventional Bone-conduction Hearing Aids Research Articles

Results of a Novel, Nonsurgical Bone-Conduction Hearing Aid for the Treatment of Conductive Hearing Loss in Australian Children.

To determine and compare the benefits a novel adhesive bone-conduction system and a conventional bone-conduction hearing aid (BCHA) on a softband for children with conductive hearing loss. Prospective, single-subject randomized, crossover trial. Tertiary referral center in Australia. Eight children aged from 4 to 17 years with conductive hearing loss. Rehabilitative with participants using the novel adhesive bone-conduction aid and a BCHA. Aided thresholds, as well as speech perception in quiet, unaided and aided with the novel adhesive bone-conduction aid and BCHA on a softband. For the six older children, speech in noise testing was also conducted. The mean unaided four frequency average hearing levels was 48 dB HL for air conduction, 10.5 dB HL for bone conduction, with a mean air-bone gap in the aided ear of 37.5 dB HL.Four-frequency average hearing level aided thresholds were 20.2 dB for the novel device and 19.8 dB for the BCHA, with no significant difference between the devices. Aided monosyllabic word scores improved from an average of 45% in the unaided condition to 81.6 and 85% for the novel adhesive and BCHA devices, respectively. Aided speech in noise performance improved, on average, by 1.6 dB SNR when wearing the BCHA and the novel adhesive device, with no significant difference in performance between the two devices. The novel device provided equivalent performance to the BCHA on all measures and can be considered as an alternative device for pediatric patients with conductive hearing loss.

The Effects of Utilizing Cartilage Conduction Hearing Aids among Patients with Conductive Hearing Loss

The cartilage-conduction hearing aid (CC-HA) is a new hearing device that is suitable for use in patients with conductive hearing loss. It has been 5 years since the introduction of the CC-HA. Although the number of users has increased, the CC-HA is not yet widely known. This study examines the effects of CC-HA on patients with conductive hearing loss and investigates factors that affect the willingness to use the device by comparing purchasers and non-purchasers of CC-HA in patients with unilateral conductive hearing loss. Eight patients had bilateral conductive hearing loss, and 35 had unilateral conductive hearing loss. Each patient underwent sound field tests and speech audiometry, and the effects of the CC-HA were compared with those of conventional bone conduction hearing aids (BC-HA). In patients with bilateral conductive hearing loss, the CC-HA was non-inferior to BC-HA. The CC-HA improved the hearing thresholds and speech recognition in patients with unilateral conductive hearing loss. Moreover, in patients with unilateral conductive hearing loss, experiencing the effect of wearing the CC-HA under conditions such as putting noise in the better ear could affect patients’ willingness to use the CC-HA.

The Use of a Novel, Nonsurgical Bone Conduction Hearing Aid System for the Treatment of Conductive Hearing Loss

Conventional bone conduction hearing aid solutions often require a cumbersome retention system such as a headband or cap. This study aims to determine if a novel, nonsurgical bone conduction aid utilizing an adhesive attachment over the mastoid is equivalent to the conventional bone conduction hearing aid (BCHA) for the management of conductive hearing loss. Prospective, single-subject randomized, crossover trial. Tertiary referral center. Eleven adults and 1 child between 11 and 70 years of age with unilateral conductive hearing loss were enrolled. Patients had their baseline hearing assessed and were randomized to receive either the novel device or BCHA headband system. Hearing loss etiologies were varied and included cholesteatoma, otosclerosis, chronic otitis media, and previous head and neck surgery. Patients had their baseline hearing assessed and trialled both the novel device or the BCHA headband system. Patients were randomly assigned one device which was worn for 2 weeks followed by a 2-week trial with the alternate device. Pure-tone thresholds and speech discrimination in quiet and noise were tested and patients also completed the short form of the Speech Spatial and Quality of Hearing (SSQ) questionnaire. The mean unaided 4 frequency pure-tone average (PTA) air conduction threshold was 53.9 dB, bone conduction was 11.9 dB, and the mean air bone gap was 42 dB in the target ear. One patient with an adhesive skin reaction could not complete the protocol. Aided PTA and threshold testing between 250 Hz to 8000 Hz showed statistically equivalent results between both devices. The aided CNC word score, signal-to-noise ratio, and SSQ scores were also equivalent between both devices. The novel bone conduction aid demonstrates equivalent performance to the conventional BCHA headband solution. The novel device should be considered an alternative option where the cosmetic and comfort issues of a headband worn device are a concern.

Audiological benefit and subjective satisfaction of children with the ADHEAR audio processor and adhesive adapter

ObjectivesThe main objective of this study was to evaluate the audiological benefit of the ADHEAR system in a group of children with a uni- or bilateral conductive hearing loss (CHL) during a short-term exposure of three weeks, and to compare it to a conventional bone conduction hearing aid (BCHA) on a softband. The secondary aim was to assess the quality of life improvement and patient satisfaction with the ADHEAR system. Methods and materialsThe study was designed as a prospective study with repeated measures, where each subject served as his/her own control. Ten children (4–17 y/o) with a uni- or bilateral congenital or acquired CHL were included in this study. Pure tone audiometry and speech audiometry in quiet, both unaided and aided, were performed initially with the ADHEAR system and a BCHA on a softband, and after three weeks with the ADHEAR alone. Furthermore, patient satisfaction and quality of life were assessed using the SSQ12 and the ADHEAR questionnaire. ResultsThe mean unaided free field hearing threshold of 50 dB HL (with 95%CI between 41.7 and 57.5 dB HL) expressed in ‘Bureau International d’Audiophonologie’ (BIAP), improved significantly by 22 dB (13.0–29.9) with the ADHEAR and by 23 dB (13.6–32.9) with the BCHA (p < 0.001). Furthermore, the mean unaided speech recognition threshold (SRT) in quiet improved significantly by 19 dB (10.3–28.1) with the ADHEAR and by 21 dB (12.6–29.4) with the BCHA (p < 0.001). For both audiological tests, there were no significant differences between the ADHEAR and the BCHA.After three weeks of use, the mean pure tone threshold of 28 dB HL (20.0–36.5) and the mean SRT of 47 dB SPL (41.9–51.5) with the ADHEAR system were comparable and not significantly different than the outcomes during the first visit.Speech understanding in noise and in multiple streams, sound localization and sound quality were rated significantly better with the ADHEAR, compared to the ratings without the ADHEAR system (p < 0.001). None of the children reported skin irritations or pain. ConclusionsThe children included in our study had significantly improved hearing thresholds, speech perception in quiet and quality of life with the ADHEAR. The device can be an effective treatment method and a valuable alternative to other BCHA for children with a CHL, although the subjective experience of each child has to be taken into account. Clinical trial registration numberNCT03327194.

Evaluation of a photoacoustic bone-conduction vibration system.

This article proposes a bone conduction vibrator that is based on a phenomenon by which audible sound can be perceived when vibrations are produced using a laser beam that is synchronized to the sound and these vibrations are then transmitted to an auricular cartilage. To study this phenomenon, we measured the vibrations using a rubber sheet with similar properties to those of soft tissue in combination with an acceleration sensor. We also calculated the force level of the sound based on the mechanical impedance and the acceleration in the proposed system. We estimated the formant frequencies of specific vibrations that were synchronized to five Japanese vowels using this phenomenon. We found that the vibrations produced in the rubber sheet caused audible sound generation when the photoacoustic bone conduction vibration system was used. It is expected that a force level that is equal to the reference equivalent threshold force level can be achieved at light intensities that lie below the safety limit for human skin exposure by selecting an irradiation wavelength at which a high degree of optical absorption occurs. It is demonstrated that clear sounds can be transmitted to the cochlea using the proposed system, while the effects of acoustic and electric noise in the environment are barred. Improvements in the vibratory force levels realized using this system will enable the development of a novel hearing aid that will provide an alternative to conventional bone conduction hearing aids.

Bone-anchored hearing aid (Baha) in patients with Treacher Collins syndrome: Tips and pitfalls

ObjectivesTreacher Collins syndrome, also known as mandibulofacial dysostosis, is an autosomal dominant disorder of the cranio-facial morphogenesis affecting 1 of 50,000 live newborns. Most children with this disease present with bilateral, severe conductive hearing loss due to bilateral aural atresia. Auditory rehabilitation of these children can be effectively carried out with bone-anchored hearing aids (Baha). The aim of this retrospective study is to review the “Bambino Gesù” Children's Hospital's experience with Baha in Treacher Collins patients, highlighting the tips and pitfalls of Baha surgery in this particular population. MethodsThe clinical charts were reviewed of all children with a Treacher Collins syndrome diagnosis receiving a Baha in the “Bambino Gesù” Children's Hospital from January 1995 to January 2010. Data were collected concerning patients’ anagraphics and medical history, comorbidities, surgical technique, complications and functional outcome. Results23 Treacher Collins children were included. A two-stage surgery was adopted in 51% (n=12) cases, while a one-stage approach was chosen in 49% (n=11). 2 children underwent 1st stage surgery as they were younger than 5. There were neither cases of osseointegration failure, nor cases of traumatic implant loss. Overall, the local complication rate was not different in the one-stage and in the two-stage group. The functional gain was significantly better with the Baha than with the conventional bone-conduction hearing aids (p<0.0002). There was no difference in terms of functional outcome between the 7 patients receiving Baha at an age younger than 5years and the rest (p=0.23). ConclusionsBaha can provide effective auditory rehabilitation for children with Treacher Collins syndrome, as long as it is performed in a tertiary care center where a multidisciplinary approach to the frequent comorbidities is possible. The main challenge of Baha surgery in this population is the poor or irregular thickness of the patient's calvarial bone, which often makes it necessary to drill additional holes, to place the fixture in contact with the dura or to use materials for bone augmentation.

Pediatric BAHA in Italy: the “Bambino Gesù” Children’s Hospital’s experience

The "Bambino Gesù" Children's Hospital offers the largest Italian cohort of children using a BAHA. This paper retrospectively reviews the center's experience with pediatric BAHA from its start in 1995 to December 2009, especially focusing on most debated issues, all the way from candidate selection to functional outcome and complications. A total of 47 children (21 females and 26 males) were implanted. From 1995 to 2000, a two-stage procedure was adopted in 100% (n = 22) cases. From 2001 onwards, one-stage surgery was chosen for 10 patients. Implant loss occurred in two patients (4.2%) after a two-stage surgery. Overall, the local complication rate was not different in the one-stage and in the two-stage group. The functional gain was significantly better with BAHA than conventional bone-conduction hearing aids and there was no significant difference in terms of functional outcome between the seven patients receiving a BAHA at an age younger than 5 years and the rest. The study results suggest that children presenting an indication to auditory rehabilitation with BAHA should be referred to specialized tertiary care centers. Only in such settings, a complete, multidisciplinary approach to associated comorbidities and syndromes is possible, and implantation of children at an age younger than five and one-stage surgery can be conducted safely and effectively.

Bone-anchored hearing aids (Baha) in congenital aural atresia: Personal experience

Aims Aural atresia is a congenital disease constituted by partial or complete lack of development of the external auditory canal, which is generally associated with malformations of the auricle and middle ear. Reconstruction of the auditory canal and correction of any deformities of the middle ear have yielded unpredictable results and variable functional outcomes, and there is a high rate of complications. Therefore, the use of bone-conduction hearing aids, such as the Baha, may represent a valid alternative for subjects who have conductive hearing loss with cochlear reserve that, as a rule, is fully conserved. The aim of this work is to reexamine our experience with the management of conductive and mixed hearing loss using the Baha system in children with bilateral aural atresia. Methods We examined 31 patients with bilateral congenital aural atresia in whom a Baha system had been implanted. The patients, 16 males and 15 females, were between 5 and 14 years of age (mean 8.7). The following parameters were assessed for each patient: mean preoperative air and bone conduction for frequencies between 0.5 and 4 kHz; mean preoperative threshold with conventional bone-conduction hearing aids; mean postoperative threshold with the Baha system; improvement in quality of life evaluated with the Glasgow Children's Benefit Inventory; rate and type of surgical complications. Results The mean preoperative air- and bone-conduction thresholds were 51.2 ± 12.5 and 14.1 ± 6.3 dB HL, respectively. The mean preoperative threshold with a conventional bone-conduction hearing aid was 29.3 ± 7.2 dB HL, and the mean postoperative threshold with the Baha system was 18.1 ± 7.5 dB HL. Quality of life improved for all operated patients. Conclusions The results of our study of the Baha system to treat patients with bilateral aural atresia were extremely satisfactory compared both with those of surgical reconstruction of the auditory canal and those of traditional bone-conduction hearing aids. Furthermore, great improvement was noted in quality of life, while the rate of complications was very low. Therefore, we are convinced that the Baha system is the treatment of choice for hearing loss due to bilateral congenital aural atresia.

Baha, when conventional devices won't do

FigureThere is a different type of hearing device called the Baha® bone conduction implant, also known as an osseointegrated auditory prosthesis, that is made especially for people with a long history of sick ears and ear surgeries. Such patients tend to be frustrated with their poor hearing and are often nervous about the risk of another ear infection. They also want to avoid more ear surgery at all costs. If the health of the ear can be stabilized, which is often a challenge, a conventional hearing aid may be used. Unfortunately, ear infections tend to recur, making regular hearing aids contraindicated for long periods of time. Years ago we fitted people who had this problem with a bone conductor on a headband attached to a high-power, body-worn hearing aid. Some of these fittings brought much happiness to patients who after not hearing sound for many years suddenly could hear well. The down side of this type of fitting is the wear and tear that the vibrator and the headband inflict on the wearer's head. The band is often too loose or too tight. It is hard to keep in place, and it is uncomfortable to wear. Extended use of the vibrator leads to an indentation in the patient's head created by the constant pressure exerted by the bone vibrator, which eventually erodes the bone directly under the vibrator. We usually try to fix this problem by moving the vibrator to the opposite side of the head, but eventually patients move it back to the original spot because it allows them to hear better. Developed in Sweden in 1977, Baha received FDA clearance for use in this country in 1996. Cochlear purchased Entific, the company that made it, in 2005. HOW IT WORKS Implanting the Baha is a relatively simple surgical procedure. A prosthesis is screwed into the mastoid. Then, 3 to 6 months later, the Baha sound processor is attached to the prosthesis with a coupler. For people who have good hearing via bone conduction and poor hearing via air conduction, this can work extremely well. The amplified sound bypasses the defective outer and middle ear and goes directly into both inner ears. The quality of hearing is described as quite good. Currently, Baha implantation is restricted to people age 5 years and above. Before that age, a child may use a Baha sound processor worn on a soft band and used similarly to a conventional bone-conduction hearing aid. After surgery, the child may use the same Baha sound processor on the implant and abutment. The reason for restricting implantation by age is that younger children are thought to have immature bone density, which may not permit good osseointegration. To ensure osseointegration with pediatric patients, it is recommended that the sound processor not be attached to the prosthesis until 6 months after surgery. In adults the waiting period is usually 3 months. Figure 1 shows the parts of the Baha. The separate piece in the photo is the small titanium implant that is screwed into the bone behind the patient's ear. New bone tissue grows around the implant securing it to the head. The implant is attached to an abutment that connects it to the hearing aid. The main part of the system is the sound processor, which receives the sound, amplifies it, and then transfers it to the patient via vibrations.Figure 1: The Baha system.ADVANTAGES For appropriate candidates, Baha has several benefits over alternative fittings: Feedback is reduced or eliminated. There is no discomfort from wearing a large, tightly fitting earmold. The conductive hearing loss is bypassed so the power requirement is lower. Reducing the required gain results in less saturation and distortion. There is no headband to wear. Because Baha is perceived as a surgical procedure rather than a hearing aid, it is currently approved by Medicare and many insurance companies. ACCESSORIES Various accessories can be used with Baha. Direct audio input is available so the patient can connect to a stereo, TV, or MP3 player. The unit can be used with a Microlink FM receiver to help with classroom situations and hearing in noise. A telecoil unit can be used to improve telephone listening. SUMMARY If conventional hearing aids or ear surgery does not provide a patient with good hearing, then a Baha should be considered. Its use is indicated when feedback is intractable and/or when the patient suffers from irritated ears or has malformed ears or ear canals. The Baha is also sometimes recommended for single-sided deafness.

The Bone-Anchored Hearing Aid for children: Recent developments

In 1984 the Bone-Anchored Hearing Aid, or BAHA, system was introduced. Its transducer is coupled directly to the skull percutaneously to form a highly effective bone-conduction hearing device. Clinical studies on adults with conductive hearing loss have shown that the BAHA system outperforms conventional bone-conduction hearing aids. Therefore, the next step was to apply the BAHA system in children with congenital or acquired conductive hearing loss. Reviewed data showed that, on average, such children benefited significantly more from the BAHA than from reconstructive surgery. Thus, BAHA application appears to be the best option to achieve normal communication and speech and language development in children with bilateral conductive hearing loss. However, in children under the age of three to four years, a conventional solution must be applied, e.g. a bone conductor with a transcutaneous coupling, because they are too young to undergo BAHA implant surgery. In the case of unilateral congenital conductive hearing loss, there is no convincing evidence in the clinical literature for early intervention.In summary, the BAHA system can be considered a new, indispensable tool for children with bilateral conductive hearing loss.

The BAHA Softband: A new treatment for young children with bilateral congenital aural atresia

To evaluate the validity of a bone-anchored hearing aid (BAHA) Softband (fitted unilaterally and bilaterally) in young children with bilateral congenital aural atresia. Two children with severe bilateral congenital conductive hearing loss, who had been fitted with a transcutaneous BAHA Softband at the age of 3 and 28 months, respectively. The latter child had been fitted with a conventional bone-conduction hearing aid at the age of 3 months; at 28 months, this child had received the BAHA Softband and after 5 months of unilateral application, the BAHA Softband was fitted bilaterally. Follow-up in the two children was 31 and 17 months, respectively. Using the artificial mastoid, gain and maximum output were studied in this new transcutaneous application of the BAHA, with the BAHA Classic and the BAHA Compact as sound processor. Results were compared to those obtained with a conventional bone-conduction device (Oticon E 300 P). Aided thresholds and sound lateralization scores were assessed with double visual reinforcement audiometry (VRA). To test the validity of the BAHA Softband, the speech and language development of the children was assessed by means of age-appropriate tests (the preverbal Symbolic play test and the Dutch non-speech test for receptive and expressive language and the Dutch version of the Reynell language test). The electro-acoustic measurements showed minor differences in gain between the three devices. At a reduced volume setting, the mean input level at which the output levelled off was largely comparable between the BAHA Classic and the conventional device, but somewhat poorer with the BAHA Compact. Both children showed speech and language development that was in accordance with their cognitive development. The BAHA Softband was a valid intervention in children with congenital bilateral aural atresia who were too young for percutaneous BAHA application.

埋め込み型骨導補聴器（ＢＡＨＡ）２症例の経験―従来型補聴器との補聴効果の比較―

The bone-anchored hearing aid (BAHA) is an implantable bone-conduction device that vibrates the skull directly via a surgically implanted titanium screw behind the ear. The BAHA has advantages for patients with aural atresia or chronic ear drainage, who cannot wear air-conduction hearing aids. We compared the function of BAHA to conventional bone and air-conduction hearing aids based on functional gain and speech discrimination tests in quiet and noisy environments in 2 patients with chronic ear problems. All expressed a clear preference for the BAHA over conventional bone-conduction hearing aids. The BAHA and air-conduction hearing aid provided similar audiological performance when the functional gain of each hearing aid coincided. As the air-bone gap widens, however, audiological performance with the BAHA showed an evident preference, indicating that the width of the air-bone gap is of some help in BAHA preference compared to air-conduction hearing aids.

ＢＡＨＡ（埋め込み型骨導補聴器）装用者の聴覚機能

The bone-anchored hearing aid (BAHA) has proved to be a valuable alternative to conventional air and bone conduction hearing aids for patients suffering from chronic otitis media or bilateral aural atresia. The BAHA gave better sound quality and greater comfort than conventional hearing aids (HAs), but only 1 study has been done in Japan. We implanted BAHAs in 6 hard-of-hearing patients in the last 2 years. One patient suffered skin problems around the abutment and used the BAHA only briefly. Free-field audiometry, the speech discrimination test (SDT), and the speech recognition test (SRT) were conducted in all subjects. They were evaluated either with the HA or BAHA. The SDT and SRT showed better hearing results in quiet for the BAHA than the conventional HA, but there was a minimum difference in SDT and SRT in noise. Subjects assessed the HA and BAHA using questionnaires. Subjects reported that the BAHA offers a number of important advantages, including greater cosmetic acceptability, improved speech intelligibility, and better sound quality.

Ten-year experience with percutaneous bone-anchored hearing aids: a 3- to 10-year follow-up Markham Stouffville Hospital, 1990 to 2000.

Patients with bilateral conductive hearing losses continue to be a source of frustration for both otologists and audiologists. Efforts to rehabilitate their hearing have included medical and surgical treatment, as well as the use of conventional hearing aids and, less frequently, conventional bone-conduction hearing aids. In the late 1980s, a percutaneous bone-anchored hearing aid (BAHA) developed by Dr. A. Tjellström, as an offshoot of Dr. P. I. Brånemark's work on osseointegration of titanium and bone, became commercially available. The BAHA has become a high-performing, comfortable, and aesthetically pleasing sound processor. The results of a 10-year BAHA program based at Markham Stouffville Hospital are summarized. In particular, a retrospective review of the 76 patients implanted between 1990 and 1997 is reported (i.e., a 3- to 10-year follow-up). Recent innovations to the design of the BAHA will be described that will further improve the quality of life for these patients.

Percutaneous bone-anchored hearing aids at a pediatric institution.

The goals were to evaluate hearing, complications, and patient satisfaction with the percutaneous bone-anchored hearing aid (BAHA) and to monitor long-term successful use achieved by careful patient selection. This prospective longitudinal study included participants with inoperable congenital bilateral aural atresia, pure-tone average (PTA) bone conduction less than 45 dB HL, prior use of a conventional bone-conduction hearing aid (CBCA), and adequate intelligence, integration, and personal hygiene. Surgery for BAHA implantation was performed in two stages. Evaluation consisted of skin reactions, audiologic results with CBCA and BAHA, and patient satisfaction. Follow-up was at least 24 months. In 11 participants aged 5 to 17 years, the PTA free-field air conduction improved 37%, and free-field speech discrimination improved 23%. Successful integration and implant use were achieved in 10 cases but were lost in 1 case as a result of head trauma. All patients preferred the BAHA as opposed to the CBCA. The BAHA is a valuable device that can improve hearing and provide significant parent and patient satisfaction. Careful selection appears to correlate with successful long-term use.

Percutaneous bone-anchored hearing aids at a pediatric institution

Objectives: The goals were to evaluate hearing, complications, and patient satisfaction with the percutaneous bone-anchored hearing aid (BAHA) and to monitor long-term successful use achieved by careful patient selection. Methods: This prospective longitudinal study included participants with inoperable congenital bilateral aural atresia, pure-tone average (PTA) bone conduction less than 45 dB HL, prior use of a conventional bone-conduction hearing aid (CBCA), and adequate intelligence, integration, and personal hygiene. Surgery for BAHA implantation was performed in two stages. Evaluation consisted of skin reactions, audiologic results with CBCA and BAHA, and patient satisfaction. Follow-up was at least 24 months. Results: In 11 participants aged 5 to 17 years, the PTA free-field air conduction improved 37%, and free-field speech discrimination improved 23%. Successful integration and implant use were achieved in 10 cases but were lost in 1 case as a result of head trauma. All patients preferred the BAHA as opposed to the CBCA. Conclusions: The BAHA is a valuable device that can improve hearing and provide significant parent and patient satisfaction. Careful selection appears to correlate with successful long-term use. (Otolaryngol Head Neck Surg 2000;122:887-91.)

Patients' Opinions of Bone-Anchored vs Conventional Hearing Aids

To evaluate patients' opinions of the bone-anchored hearing aid (BAHA) compared with a conventional hearing aid. Prospective study with two questionnaires. Questionnaire A consisted of questions that compared patients' previous hearing aid with the BAHA. Questionnaire B consisted of questions about the patients' experiences with the hearing aids. Sixty-five consecutive patients who had used conventional hearing aids. Tertiary referral center. A percutaneous titanium implant in the temporal bone for the BAHA. Qualitative descriptive results of questionnaire A and difference scores from questionnaire B comparing conventional hearing aids and the BAHA. Patients favored the BAHA to the conventional bone-conduction hearing aid. Patients with BAHA reported a significant improvement in speech recognition in quiet and in noise, in sound quality, and in comfort (P < .01). The results with the BAHA compared with the air-conduction hearing aid were ambiguous for speech recognition, but all the patients reported a decrease in ear infections. The BAHA is a good alternative for the conventional bone-conduction hearing aid if a patient can no longer use an air-conduction hearing aid.

Bone-anchored hearing aids in patients with sensorineural hearing loss and persistent otitis externa

Recently, a new bone-conduction hearing aid has become available which can be connected percutaneously to the skull: the bone-anchored hearing aid or BAHA. Several clinical trials have shown its efficacy in patients with a conductive or mixed hearing loss. A second group of potential candidates are patients who suffer from an almost instantaneous skin reaction to any kind of earmould. Three such patients with a predominant sensorineural hearing loss were fitted with a BAHA. The aided free-field thresholds proved to be poor compared with the desired values using prescriptive rules. Speech recognition measured objectively (with tests) and subjectively (with a questionnaire) was comparable or better than with conventional bone-conduction hearing aids. Two patients were using their BAHA all day, whereas the third patient was only using it for a few hours per day. Although it did not produce optimal results, the BAHA seems to be the best solution for these patients.

A one-stage surgical procedure for placement of percutaneous implants for the bone-anchored hearing aid.

The bone-anchored hearing aid (BAHA) is an alternative to the conventional bone conduction hearing aid. The transducer is coupled to a percutaneous titanium implant which is traditionally inserted into the temporal bone in two stages. This study focusses on a one-stage surgical technique for the implantation of percutaneous implants. The preliminary clinical results of 33 one-stage implants in 33 patients are presented. Post-operative necrosis of the skin grafts did not occur. After a follow-up which varied from nine to 25 months, 31 out of the 33 fixtures (94 per cent) were anchored firmly in the skull. Twenty-six out of the 33 implants (79 per cent) remained free from potentially dangerous skin reactions. The results were statistically comparable to those obtained with two-stage implants at the same clinic. Although longer follow-up is needed before a general statement can be made about replacing the two-stage technique, the preliminary one-stage results are promising.

Audiological Results of the Bone-Anchored Hearing Aid HC200: Multicenter Results

Sixty-two patients with conductive or mixed hearing loss (average bone conduction threshold at 0.5, 1, and 2 kHz ranged from 1 to 44 dB hearing level) were fitted with a bone-anchored hearing aid (BAHA type HC200). Previously, 52 of them had used a conventional bone conduction hearing aid (CBHA) and 10 of them an air conduction hearing aid (ACHA). Audiological tests were conducted to compare the patients' performance with the BAHA to that with their previous conventional hearing aid. In the speech recognition in quiet test, only 5 patients in the CBHA group improved significantly: the majority had 100% scores with both hearing aids. In the speech recognition in noise test, 28 patients improved significantly. The mean improvement in the signal to noise ratio (S/N) in the CBHA group was -2.3 +/- 2.4 dB. That none of the patients in the CBHA group performed worse with the BAHA led us to the conclusion that the BAHA is superior to the CBHA. None of the patients in the ACHA group achieved a better speech recognition in quiet score using the BAHA. On average, there was no significant improvement in the S/N ratio in the ACHA group, although in 6 patients the S/N ratio improved significantly, and in 1 patient it worsened significantly. From the whole group, the performance of only 2 patients, both in the ACHA group, was significantly worse with the BAHA on one of the speech recognition tests.