Audiometric evaluation of bilaterally fitted bone-anchored hearing aids

Bilateral fittings of bone-anchored hearing aids (BAHA) were evaluated in 25 patients with at least 3 months experience with using two BAHAs. For all patients, air conduction hearing aids were contraindicated due to either recurrent otorrhoea or otitis externa (19 cases) or to congenital aural atresia (six cases). Candidacy for bilateral fitting was primarily based on symmetry of bone conduction thresholds. For all patients, measurements comprised sound localisation, speech recognition in quiet and in noise. In addition, in a subgroup of nine patients, release from masking for pure-tone stimuli in noise with interaural phase differences (binaural masking level difference. BMLD) was measured. The percentage of correct localisation judgments with 500-Hz and 2-kHz noise bursts increased significantly (p<0.01) from 22.2 per cent and 24.3 per cent for unilateral fittings to 41.8 per cent and 45.3 per cent for bilateral fittings, respectively. With unilateral fittings sound localisation judgments appeared to be strongly biased to the ipsilateral BAHA side. whereas with bilateral fittings, judgments were far more symmetrical. The speech reception threshold for sentences in quiet was significantly (p<0.01) better for the bilateral fittings compared to the unilateral fittings: 37.5 dBA versus 41.7 dBA. Speech recognition in noise was measured with the speech signal presented in front of the listener and a 65-dBA masking noise at either +90 degrees or -90 degrees azimuth. For noise presented at the ipsilateral side of the first fitted BAHA, the signal-to-noise ratio was significantly reduced (p<0.01) from -0.7 dB for the unilateral fitting to -4.0 dB for the bilateral fitting. The speech reception threshold in noise was not significantly different (p>0.05) for unilateral and bilateral fittings when the noise was presented at the contralateral side of the first fitted BAHA. The results for the six patients with congenital atresia are comparable with those for the other patients. So, directional hearing and speech recognition in noise improve significantly with a second BAHA. The BMLD measurements showed a significant (p<0.01) release from masking of 6.1, 6.0 and 6.6 dB for 125-Hz, 250-Hz and 500-Hz stimuli, respectively. The BMLD effect of 4.1 dB at 1,000 Hz was not significant at the 5 per cent level. The positive results with the bilateral fittings in quiet can be ascribed to increased stimulus levels due to diotic summation of signals from either side. The results for localisation, speech recognition in noise and BMLD measurements indicate that bilaterally fitted BAHAs do indeed (to some extent) result in binaural hearing.

Multicenter audiometric results with the Vibrant Soundbridge, a semi-implantable hearing device for sensorineural hearing impairment

The Vibrant Soundbridge, a semi-implantable hearing device for subjects with moderate to severe sensorineural hearing impairment was introduced commercially. First audiologic results are presented on 63 patients from 10 European implant centers. Hearing loss was at 0.5, 1, 2, and 4 kHz varying between 43 and 81 dB HL. The patients used the analogue audio processor, type 302. Measured sound-field gain was compared with NAL-R target values. For most patients an acceptable agreement was found. There was a subgroup of patients, however, with relatively low gain. The results suggest that this was related to the suboptimal positioning and fixation of the transducer to the incus.

The bone-anchored hearing aid: a solution for previously unresolved otologic problems

A major challenge for otologists treating middle ear infection is to obtain a dry ear and optimal hearing. If the patient needs amplification and uses an air conduction hearing aid, the ear mold, occluding the ear canal, may provoke or aggravate the infection in the middle ear and thus cause otorrhoea. Continuous otorrhoea may cause cochlear damage in the long run. Bone conduction hearing aids offer an alternative for such patients.

A solitary manifestation of mastocytosis in the head and neck

Solitary mastocytosis in adulthood is a rare finding. Only two such lesions have been reported in the head and neck. We describe a 27-year-old woman who had a 10-year history of a forehead swelling that had fluctuated in size. Light trauma or pressure on the lesion resulted in an increase in its size. A mass was found to be situated just below the galea and was successfully removed surgically using a high forehead lift. Histologically, the specimen contained predominantly mast cells. A systemic mastocytosis was excluded by a multidisciplinary diagnostic approach and measurement of the 24-h urinary excretion of histamine metabolites. After 36 months of follow-up there has been no recurrence.

[Choice of ear drops in chronic otorrhea]

In chronic otitis, the use of ear drops has certain advantages over the use of systemic antibiotics. The choice of ear drop depends on the condition of the eardrum, microbial pathogens present and the efficacy of the components of the ear drop. Ototoxicity, contact allergy and the development of bacterial resistance have to be taken into account. Ototoxicity is a rare complication of the application of ear drops, most often described when aminoglycosides were applied. Contact allergy is also most often seen in aminoglycoside-containing eardrops. Evaluation of ear swabs demonstrated a 5% resistance of Pseudomonas aeruginosa to ciprofloxacin. The appearance of resistant strains may impede systemic use of fluoroquinolones. Therefore, this class of antibiotics should be considered as reserve medication only. The first choice in local application of antiseptics in case of an open eardrum is aluminium acetotartrate 1.2% and, of a combination preparation, bacitracin-colistin-hydrocortisone. In case of a closed eardrum (external otitis) aluminium acetotartrate 12%--combination preparations with corticosteroids are advised against in these cases.

The use of eardrops in an ENT department

A survey of the pattern of usage of ototopical preparations in out-patients of the ENT department of a Dutch University Hospital has been performed. Data on clinical presentation and previous treatment of the patient, otoscopic results, prescribed current treatment and, if available, results of microbiological examination were collected. One-hundred and twenty-one evaluable patients were prospectively included. For 20% of the patients it concerned a first manifestation of the symptoms, 35% had a recurrence after a period free of symptoms and in 37% it concerned patients with persisting symptoms despite treatment. Forty-five percent of the patients' ears concerned had an intact tympanic membrane, in 25% a perforation was present and in 12% middle ear ventilation tubes were in situ. Thirty-five percent had already received previous treatment with ear drops. The species most often isolated was Staphylococcus aureus, followed by Pseudomonas aeruginosa. A wide range of products were prescribed. While previous treatment occurred with combination preparations, for current prescriptions, ofloxacin was most often used. Most patients received 2 to 3 drops 3 times a day for 7 to 10 days, which is in accordance with recommendations in the literature. Potentially ototoxic substances are regularly used in daily practice. Ofloxacin is widely used even thought it is not registered for this indication in the Netherlands and the development of resistance has to be taken into account. A new policy based on this survey is proposed, which will reduce the number of different preparations used and will eliminate ofloxacin from first the treatment.

Percutaneous implants in the temporal bone for securing a bone conductor: surgical methods and results

Clinical results of an extended follow-up of percutaneous titanium implants for application of bone conductors are presented. A simplified 1-stage surgical procedure is introduced. This study entails a consecutive series of 163 implants in 155 patients 9 to 80 years old who received a bone conductor coupled to a percutaneous titanium implant since June 1988 at the University Hospital Nijmegen. The maximum follow-up is 7 years. The bone conductor can be connected to a percutaneous abutment fixed to a titanium fixture anchored in the temporal bone. Several clinical trials from different clinics have shown its efficacy in patients with a conductive or mixed hearing loss. In this study attention is paid to the following issues: the occurrence of skin reactions, the condition of the skin around the abutment, the stability of the fixture, and a simplified surgical technique.

Transalar sphenoidal encephalocele and respiratory distress in a neonate: a case report

We present a full-term newborn infant who suffered from immediate postpartum severe respiratory distress. The infant had an inspiratory stridor as a result of a swelling of the soft palate, extending from the roof of the nasopharynx. Transoral endotracheal intubation resulted in normal saturation levels. Histologic examination after an open biopsy showed mature neuroglial tissue. Radiology demonstrated the presence of a right parapharyngeal process obstructing the nasopharynx and oropharynx and extending to the right middle and posterior fossa, via the foramen ovale. After transoral debulking, the infant was extubated successfully. After an uneventful period of 5 months, the patient was readmitted at our hospital for treatment of meningitis. Subsequently, the inspiratory stridor recurred, and staged surgery was performed. First, a transcranial approach was used to remove a large intradural part of the process and close the defect at Meckel's cave. Two weeks later the retro- and parapharyngeal part of the process were removed transorally. Given the site of the defect of the skull base and the intradural location of the process, the diagnosis is a transalar sphenoidal encephalocele. This is a rare type of basal encephalocele, and has never been reported in an infant nor known to present with respiratory distress. The pathogenesis, clinical presentation, pathology, and therapeutic implications of basal encephaloceles are discussed.

Intraindividual comparison of the bone-anchored hearing aid and air-conduction hearing aids

BACKGROUND

Some patients have to stop using their air-conduction hearing aid(s) because it causes or exacerbates chronic otitis. Then, a solution is the use of a bone-conduction hearing aid such as the percutaneous bone-anchored hearing aid (BAHA).

OBJECTIVE

To compare patients' performance with their previous air-conduction hearing aid(s) and their BAHA using audiometric tests and a questionnaire.

DESIGN

Prospective clinical evaluation in a single subject design.

PATIENTS

The results of 34 consecutive patients from the Nijmegen, the Netherlands, BAHA series were included. The patients had bilateral conductive or mixed hearing loss and chronic ear problems. Before the BAHA was fitted, the patients used air-conduction hearing aids.

RESULTS

The results of the speech recognition in noise test showed a small but significant improvement with the BAHA. This improvement was related to the size of the air-bone gap. The greater the air-bone gap, the poorer the results with the air-conduction hearing aid(s). The questionnaire demonstrated that the majority of patients preferred the BAHA; diminished occurrence of ear infections played a significant role. The patients did not express an evident preference concerning speech recognition.

CONCLUSIONS

In patients with chronic ear problems a BAHA is an acceptable alternative if an air-conduction hearing aid is contraindicated. Preoperative assessment of the size of the air-bone gap is of some help to predict whether speech recognition may improve or deteriorate with the BAHA compared with the air-conduction hearing aid.

Binaural application of the bone-anchored hearing aid

Most, but not all, hearing-impaired patients with air conduction hearing aids prefer binaural amplification instead of monaural amplification. The binaural application of the bone conduction hearing aid is more disputable, because the attenuation (in decibels) of sound waves across the skull is so small ( 10 dB) that even one bone conduction hearing aid will stimulate both cochleas approximately to the same extent. Binaural fitting of the bone-anchored hearing aid was studied in three experienced bone-anchored hearing aid users. The experiments showed that sound localization, and speech recognition in quiet and also under certain noisy conditions improved significantly with binaural listening compared to the monaural listening condition. On the average, the percentage of correct identifications (within 45 degrees ) in the sound localization experiment improved by 53% with binaural listening; the speech reception threshold in quiet improved by 4.4 dB. The binaural advantage in the speech-in-noise test was comparable to that of a control group of subjects with normal hearing listening monaurally versus binaurally. The improvements in the scores were ascribed to diotic summation (improved speech recognition in quiet) and the ability to separate sounds in the binaural listening condition (improved sound localization and improved speech recognition in noise whenever the speech and noise signals came from different directions). All three patients preferred the binaural bone-anchored hearing aids and used them all day.

Removal of titanium implants from the temporal bone: histologic findings

OBJECTIVE

This study aimed to evaluate the histologic examination of bone tissue surrounding three titanium implants, which were removed since the patients presented with long-standing pain in the implant area. The histologic examination was both qualitatively and quantitatively performed. Furthermore, could an explanation be obtained for the pain in the implant area, which, after removal of the percutaneous implant, disappeared immediately?

STUDY DESIGN

Retrospective case review; clinical histomorphometric.

SETTING

University Hospital Nijmegen, Göteborg University, Sweden.

PATIENTS

Three patients of a consecutive series of 189; 1 man and 2 women who had received a bone-anchored, percutaneous, skin-penetrating, commercially pure titanium implant in the temporal bone, on which a transducer was mounted. The implants were removed because of pain in the implant area from the three patients after 31 months, 18 months, and 8 months, respectively.

MAIN OUTCOME MEASURES

The percentage of direct bone-to-metal contact was 81%, 59%, and 42%, respectively. The percentage of bone volume between the threads of the screw was 90, 78, and 75, respectively.

RESULTS

The qualitatively histologic findings showed no major differences among the three investigated samples. Quantitatively, the amount of osseointegration depended on the duration of implantation.

CONCLUSIONS

Direct bone-to-metal contact and the bone volume between the threads increased as the implantation time increased. No explanation was found for the longstanding pain in the implant area and the relief of pain after removal of the percutaneous implant.

Patients' opinions of bone-anchored vs conventional hearing aids

OBJECTIVE

To evaluate patients' opinions of the bone-anchored hearing aid (BAHA) compared with a conventional hearing aid.

DESIGN

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.

PATIENTS

Sixty-five consecutive patients who had used conventional hearing aids.

SETTING

Tertiary referral center.

INTERVENTION

A percutaneous titanium implant in the temporal bone for the BAHA.

MAIN OUTCOME MEASURE

Qualitative descriptive results of questionnaire A and difference scores from questionnaire B comparing conventional hearing aids and the BAHA.

RESULTS

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.

CONCLUSION

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.

Air-bone gap in patients with X-linked stapes gusher syndrome

It is often possible to elicit the stapedius reflex in patients suffering from recessive X-linked progressive mixed deafness syndrome with stapes gusher. The presence of an air-bone gap in the audiogram and the ability to elicit the stapedius reflex are conflicting. Measurements were performed on two patients who were suffering from this syndrome, to establish whether the hearing loss was of the mixed or purely sensorineural type. It was argued that, owing to congenital malformations, the audiovestibular system might act as a more than normally efficient transducer, to convert skull vibrations into inner ear fluid motions, leading to bone conduction thresholds that are better than expected. The results of tone and speech audiometry, stapedius reflex measurements, and brainstem evoked response audiometry in this study showed a pattern similar to that generally seen in patients with purely sensorineural hearing loss. This supports the hypothesis that the air-bone gap in the audiogram does not have the usual significance of a conductive hearing loss component.

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.

The bone-anchored hearing aid compared with conventional hearing aids. Audiologic results and the patients' opinions

The bone-anchored hearing aid (BAHA) was evaluated in 65 patients by comparing speech recognition and questionnaire results with those obtained with the patients' own previous hearing aids. In the majority of patients who previously used a conventional bone conductor, significantly improved speech recognition scores were found with the BAHA. The majority preferred the BAHA to their previous bone conductors. For the patients who previously used air conduction hearing aids but had to stop because of chronic draining ears, the results were ambiguous. Nevertheless, the BAHA seems to be the best solution for this subgroup as well. It is concluded that the BAHA is a valuable addition to the audiologists' tools.

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.

Aided free-field thresholds in children with conductive hearing loss fitted with air- or bone-conduction hearing aids

Although conductive hearing loss is often found in children, few reports have appeared on the fitting of hearing aids in these children. In the present study, aided thresholds were determined in 40 children and 30 adults with pure conductive hearing loss (bone-conduction thresholds of 20 dB HL or less) who were successfully fitted with hearing aids. The patient group was split into subgroups according to the type of hearing aid used (bone-conduction hearing aid, binaural or monaural air-conduction hearing aids). Within each subgroup, the aided thresholds proved to be comparable between the adults and children and were nonconsistently related to the degree of (air-conduction) hearing loss. In the patients with a bone-conduction hearing aid, the aided free-field thresholds at the most important frequencies for speech perception (1, 2 and 4 kHz) were found to be between 20 and 30 dB HL, while in the patients with an air-conduction hearing aid, irrespective of whether it was applied monaurally or binaurally, these thresholds were between 15 and 20 dB HL. It is suggested that these values should be considered as target thresholds when fitting hearing aids in children with conductive hearing loss.

Percutaneous titanium implantation in the skull for the bone-anchored hearing aid

In the 1980s, a new type of bone conduction hearing aid was developed in Göteborg, Sweden. With this new bone-anchored hearing aid (BAHA) system, sound waves are transmitted directly to the skull by means of a titanium screw implanted into the skull. The advantages and disadvantages of the conventional hearing aid and the BAHA are described here. In the 25 patients presented, all the percutaneous implants remained firmly anchored in the skull. One screw was lost through trauma. The scores on the speech recognition-in-noise and the speech recognition-in-quiet tests were significantly higher in 64% and 32% of the patients with a BAHA, respectively.

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.

Audiologic results for the bone-anchored hearing aid HC220

Twenty-six patients with severe mixed hearing loss (PTA range 57 to 108 dB HL) were fitted with the "super-bass" bone-anchored hearing aid (BAHA) HC220 and divided into two groups. Group I contained 19 patients who previously used a conventional bone conduction hearing aid that had resulted in serious complaints. Group II contained 7 patients who had previously used an air conduction hearing aid that could no longer be used because of recurrent otorrhoea. Sound field speech audiometry for the patients in Group I revealed that for 7 patients the maximum phoneme score did not change, but that it improved for 12 patients with the HC220, compared with their conventional bone conduction hearing aid. In Group II, the maximum phoneme score improved for 3 patients, worsened for 3 patients and did not change for 1 patient with the HC220, compared with their air conduction hearing aid. Speech recognition in noise was difficult for most of the patients regardless of group. However, results were obtained from 10 patients, and 7 improved significantly with the HC220 compared with their previous aid. Overall, speech recognition with the HC220 was comparable with or better than a conventional bone conduction hearing aid; however, compared with an air conduction hearing aid the results were ambiguous.

Speech recognition with the bone-anchored hearing aid determined objectively and subjectively

Some patients with a bone-conduction hearing aid experience serious problems such as skin irritation or headaches and inconsistency in the sound quality due to shifting of the transducer over the mastoid. The Bone Anchored Hearing Aid (BAHA) provides direct bone-conduction and therefore evades these problems. Results of 58 patients fitted with either the head level BAHA HC200 or the more powerful HC220 were available for evaluation. Speech recognition-in-quite and in-noise tests were performed in order to make a comparison between the patients' performance with their individually adapted BAHA and their previous hearing aid. Furthermore, all the patients filled out a questionnaire, involving questions on speech recognition-in-quite and in-noisy surroundings. Individual comparisons of the audiological and questionnaire results in the subgroup of patients who had used a bone-conduction hearing aid showed that the results with the BAHA were comparable with or significantly better than those with the previous bone-conduction hearing aid. The results in the patients who had previously used an air-conduction hearing aid were ambiguous.

Clinical results of percutaneous implants in the temporal bone

The bone-anchored hearing aid is an alternative to the conventional bone-conduction hearing aid, without the disadvantages of pressure pain or skin irritation and with direct sound transmission to the skull. The bone-anchored hearing aid is coupled to a percutaneous titanium implant, which is placed in the mastoid process in two surgical stages. We analyzed the clinical results of 68 percutaneous implants in 65 patients. After a follow-up period of 8 to 45 months, 97% of the implants were anchored in the bone. In 86% of the implants, no potentially dangerous skin reactions occurred. The occurrence of skin reactions was not time dependent. Movement of the skin, thick skin, and poor skin condition around the implant were related to the onset of skin reactions. This study showed that the percutaneous titanium implant forms a stable link between the bone-anchored hearing aid and the skull.

Influence of the thickness of the skin and subcutaneous tissue covering the mastoid on bone-conduction thresholds obtained transcutaneously versus percutaneously

Percutaneous and transcutaneous bone-conduction thresholds were obtained at 0.25, 0.5, 1, 2, and 4 kHz in 57 patients who were fitted with the Bone Anchored Hearing Aid (BAHA). Additionally, the thickness of the skin and subcutaneous tissue covering the mastoid was determined. No relation was found between the thickness of the skin and subcutaneous tissue, and the improvement in bone-conduction thresholds at any of the frequencies, i.e. thresholds obtained percutaneously minus transcutaneously. The improvement (or deterioration) in speech recognition with the BAHA in a subgroup of patients who had previously used a (conventional) transcutaneous bone-conduction hearing aid was not related to the thickness of the skin and subcutaneous tissue layers. Therefore, the thickness of the skin and subcutaneous tissue layers measured pre-operatively cannot be used as a predictor of successful fitting with a BAHA.