9.4.1(3).Bone Conduction Devices (BCD’s) en middenoorimplantaten
De Wolf MJF, Hendrix S, Cremers CWRJ, SnikAFM. Better Performance with Bone-Anchored Hearing Aid than Acoustic Devices in Patients with severe air-Bone Gap. The Laryngoscope 03/2011;121:613-6.
A study performed in the 1990s with analogue linear hearing aids showed that in patients with mixed hearing loss and an air-bone gap that exceeded 25 to 30 dB, speech perception was better with a bone-anchored hearing aid (Baha) than with a conventional behind-the-ear (BTE) device. The objective of the present study was to investigate whether this conclusion applies to today’s digital BTEs with feedback cancellation and whether the crossover point still occurs at an air-bone gap of 25 to 30 dB. Case control. Experienced unilateral Baha users with the latest digital Baha processors were fitted with a powerful BTE with feedback cancellation. After an acclimatization period of 4 weeks, aided thresholds and speech recognition scores were determined and compared to those recorded previously with the Baha. To obtain patients’ opinions, a disability-specific questionnaire was used. Participants comprised 16 subjects with bilateral mixed hearing loss participated Audiometric and speech recognition data showed similar trends to those described previously, but the crossover point had shifted to an air-bone gap of 30 to 35 dB. In the questionnaire, the BTE was rated higher than the Baha, except by the patients with an air-bone gap that exceeded an average of 45 dB. In patients with mixed hearing loss whose air-bone gap exceeded 35 dB, speech recognition is likely to be better with a Baha than with a BTE. Therefore, the Baha should receive greater consideration when mixed hearing loss is combined with a significant air-bone gap, even when there are no contraindications for BTEs.
Stenfelt S. Transcranial Attenuation of Bone-Conducted Sound When Stimulation is at the Mastoid and at the Bone Conduction Hearing Aid Position. Otology and Neurotology 2011;33:105-14.
The transcranial attenuation of bone-conducted (BC) sound depends on the stimulation position and the stimulation frequency. Subjective transcranial attenuation of BC sound has previously only been measured at a few audiometric frequencies and with the stimulation at the mastoid. The results reported are on average of 5 to 10 dB with large intersubject variability and inconsistent with results obtained using vibration measurements of the cochlea. Pure tone hearing thresholds were measured in 28 unilateral deaf subjects at 31 frequencies between 0.25 and 8 kHz. The stimulation was provided at 4 positions: ipsilateral and contralateral mastoid, and ipsilateral and contralateral position for a bone conduction hearing aid. With stimulation at the mastoid, the median transcranial attenuation is 3 to 5 dB at frequencies up to 0.5 kHz; between 0.5 and 1.8 kHz, it is close to 0 dB. The attenuation increases at higher frequencies; it is close to 10 dB at 3 to 5 kHz and becomes slightly less at the highest frequencies measured (4 dB at 8 kHz). When measured at the bone conduction hearing aid position, the median transcranial attenuation is 2 to 3 dB lower than at the mastoid. The intersubject variability is large at each frequency (around 40 dB), but there are small differences in general trends of the transcranial attenuation between individuals. The median transcranial attenuation depends on stimulation position and frequency. However, the variability is great, both between individuals and within subjects for adjacent frequencies.
Håkonsson, B, Eeg-Olofsson M, Reinfeldt S, Stenfelt S, Granström G. Percutaneous Versus Transcutaneous Bone Conduction Implant System: A Feasibility Study on a Cadaver Head. Otology and Neurotology 2008;29:1132-9.
Percutaneous bone-anchored hearing aid (BAHA) is an important rehabilitation alternative for patients who have conductive or mixed hearing loss. However, these devices use a percutaneous and bone-anchored implant that has some drawbacks reported. A transcutaneous bone conduction implant system (BCI) is proposed as an alternative to the percutaneous system because it leaves the skin intact. The BCI transmits the signal to a permanently implanted transducer with an induction loop system through the intact skin. The aim of this study was to compare the electroacoustic performance of the BAHA Classic-300 with a full-scale BCI on a cadaver head in a sound field. The BCI comprised the audio processor of the vibrant sound bridge connected to a balanced vibration transducer (balanced electromagnetic separation transducer). Implants with snap abutments were placed in the parietal bone (Classic-300) and 15-mm deep in the temporal bone (BCI). The vibration responses at the ipsilateral and contralateral cochlear promontories were measured with a laser Doppler vibrometer, with the beam aimed through the ear canal. Results show that the BCI produces approximately 5 dB higher maximum output level and has a slightly lower distortion than the Classic-300 at the ipsilateral promontorium at speech frequencies. At the contralateral promontorium, the maximum output level was considerably lower for the BCI than for the Classic-300 except in the 1-2 kHz range, where it was similar. Present results support the proposal that a BCI system can be a realistic alternative to a BAHA.
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- Håkonsson, B,Eeg-Olofsson M, Reinfeldt S, Stenfelt S, Granström G. Percutaneous Versus Transcutaneous Bone Conduction Implant System: A Feasibility Study on a Cadaver Head. Otology and Neurotology 2011;33:105-14.
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- Mojallal H, Stieger C, Grasshof E, Bernhard H, Haller M, Häusler R, Lenarz T.DACS – Ein neues implantierbares Hörsystem für mittel- bis hochgradige kombinierte Schwerhörigkeiten. DGA Jahrestagung 2006.
- Reinfeldt S, Håkansson B, Taghavi H, Eeg-Olofsson M. New developments in bone-conduction hearing implants: a review. Med Devices (Auckl). 2015 Jan 16;8:79-93.
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- Snik Ad. Implantable Hearing Devices for Conductive and Sensorineural Hearing Impairment. In Zeng Fan-Gang, Popper Arthur A, Fay RA, Auditory Prostheses – New Horizons, Springer, 2011.
- Stenfelt S.Transcranial Attenuation of Bone-Conducted Sound When Stimulation Is at the Mastoid and at the Bone Conduction Hearing Aid Position. Otology and Neurotology 2011;33:105-14.
- De Wolf MJF, Hendrix S, Cremers CWRJ, Snik AFM. Better Performance with Bone-Anchored Hearing Aid than Acoustic Devices in Patients with severe air-Bone Gap. The Laryngoscope 03/2011;121:613-6.
- Zwartenkot JW, Snik AFM, Mylanus EAM, Mulder JJS. Amplification options for patients with mixed hearing loss. Otol Neurotol 2014;35:221-226.
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