| 1. |
- Eeg-Olofsson, Måns, 1967, et al.
(författare)
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BCI-bone conduction implant.
- 2013
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Ingår i: The Fourth International Symposium on Bone Conduction Hearing – Craniofacial Osseointegration. Newcastle, UK.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 2. |
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| 3. |
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| 4. |
- Eeg-Olofsson, Måns, 1967, et al.
(författare)
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Evaluation of bone tissue formation in a flat surface attachment of a Bone Conduction Implant - A pilot study in a sheep model
- 2014
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Ingår i: Audiology & Neurotology Extra. - : S. Karger AG. - 1664-5537. ; 4:3, s. 62-76
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Tidskriftsartikel (refereegranskat)abstract
- The Bone Conduction Implant (BCI) is a new bone conduction hearing device implanted under intact skin. The transducer has a flat direct contact to the mastoid part of the temporal bone and no screws are used. The sound signal is transmitted from the external audio processor to the implant by means of magnetic induction. In this study, osseointegration of a flat passive BCI transducer dummy in sheep skulls was assessed using quantitative and qualitative histology as well as Cone Beam Computed Tomography (CBCT) and Computed Tomography (CT). The histology results were also related to the mechanical properties of the bone to implant interface. Eight months after the surgical implantation, histology sections of the bone close to the implant showed bone remodelling, compact bone and some degree of osseointegration. The histological findings corresponded well to the mechanical measurements indicating stiffer bone close to the implant, and unaffected skull vibration transmission. Neither CBCT nor CT had enough resolution to visualize the bone to implant interface in detail. In this study, using an animal model, it is shown that a flat implant in contact with bone, can be a feasible method for efficient vibration transmission to the skull bone.
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| 5. |
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| 6. |
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| 7. |
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| 8. |
- Eeg-Olofsson, Måns, 1967, et al.
(författare)
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Transmission of bone conducted sound – Correlation between hearing perception and cochlear vibration
- 2013
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Ingår i: Hearing Research. - : Elsevier. - 0378-5955 .- 1878-5891. ; 306, s. 11-20
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Tidskriftsartikel (refereegranskat)abstract
- The vibration velocity of the lateral semicircular canal and the cochlear promontory was measured on 16 subjects with a unilateral middle ear common cavity, using a laser Doppler vibrometer, when the stimulation was by bone conduction (BC). Four stimulation positions were used: three ipsilateral positions and one contralateral position. Masked BC pure tone thresholds were measured with the stimulation at the same four positions. Valid vibration data were obtained at frequencies between 0.3 and 5.0 kHz. Large intersubject variation of the results was found with both methods. The difference in cochlear velocity with BC stimulation at the four positions varied as a function of frequency while the tone thresholds showed a tendency of lower thresholds with stimulation at positions close to the cochlea. The correlation between the vibration velocities of the two measuring sites of the otic capsule was high. Also, relative median data showed similar trends for both vibration and threshold measurements. However, due to the high variability for both vibration and perceptual data, low correlation between the two methods was found at the individual level. The results from this study indicated that human hearing perception from BC sound can be estimated from the measure of cochlear vibrations of the otic capsule. It also showed that vibration measurements of the cochlea in cadaver heads are similar to that measured in live humans.
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| 9. |
- Fredén Jansson, Karl-Johan, 1988, et al.
(författare)
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MRI Induced Torque and Demagnetization in Retention Magnets for a Bone Conduction Implant
- 2014
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Ingår i: IEEE Transactions on Biomedical Engineering. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9294 .- 1558-2531. ; 61:6, s. 1887-1893
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Tidskriftsartikel (refereegranskat)abstract
- Performing magnetic resonance imaging (MRI) examinations in patients who use implantable medical devices involve safety risks both for the patient and the implant. Hearing implants often use two permanent magnets, one implanted and one external, for the retention of the external transmitter coil to the implanted receiver coil to achieve an optimal signal transmission. The implanted magnet is subjected to both demagnetization and torque, magnetically induced by the MRI scanner. In this paper, demagnetization and a comparison between measured and simulated induced torque is studied for the retention magnet used in a bone conduction implant (BCI) system. The torque was measured and simulated in a uniform static magnetic field of 1.5 T. The magnetic field was generated by a dipole electromagnet and permanent magnets with two different types of coercive fields were tested. Demagnetization and maximum torque for the high coercive field magnets was 7.7% +/- 2.5% and 0.20 +/- 0.01 Nm, respectively and 71.4% +/- 19.1% and 0.18 +/- 0.01 Nm for the low coercive field magnets, respectively. The simulated maximum torque was 0.34 Nm, deviating from the measured torque in terms of amplitude, mainly related to an insufficient magnet model. The BCI implant with high coercive field magnets is believed to be magnetic resonance (MR) conditional up to 1.5 T if a compression band is used around the skull to fix the implant. This is not approved and requires further investigations, and if removal of the implant is needed, the surgical operation is expected to be simple.
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| 10. |
- Håkansson, Bo, 1953, et al.
(författare)
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A novel bone conduction implant (BCI): engineering aspects and pre-clinical studies.
- 2010
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Ingår i: International journal of audiology. - : Informa UK Limited. - 1499-2027 .- 1708-8186. ; 49:3, s. 203-15
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Tidskriftsartikel (refereegranskat)abstract
- Percutaneous bone anchored hearing aids (BAHA) are today an important rehabilitation alternative for patients suffering from conductive or mixed hearing loss. Despite their success they are associated with drawbacks such as skin infections, accidental or spontaneous loss of the bone implant, and patient refusal for treatment due to stigma. A novel bone conduction implant (BCI) system has been proposed as an alternative to the BAHA system because it leaves the skin intact. Such a BCI system has now been developed and the encapsulated transducer uses a non-screw attachment to a hollow recess of the lateral portion of the temporal bone. The aim of this study is to describe the basic engineering principals and some preclinical results obtained with the new BCI system. Laser Doppler vibrometer measurements on three cadaver heads show that the new BCI system produces 0-10 dB higher maximum output acceleration level at the ipsilateral promontory relative to conventional ear-level BAHA at speech frequencies. At the contralateral promontory the maximum output acceleration level was considerably lower for the BCI than for the BAHA.
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| 11. |
- Reinfeldt, Sabine, 1978, et al.
(författare)
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Bone conduction hearing sensitivity in normal-hearing subjects: Transcutaneous stimulation at BAHA vs BCI position
- 2014
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Ingår i: International journal of audiology. - : Informa UK Limited. - 1708-8186 .- 1499-2027. ; 53:6, s. 360-369
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Bone conduction (BC) stimulation closer to the cochlea has previously been shown to give higher cochlear promontory acceleration measured by laser Doppler vibrometry (LDV). This study is investigating whether stimulation closer to the cochlea also gives improved hearing sensitivity. Furthermore, the study compares shifts in hearing sensitivity (BC thresholds) and ear-canal sound pressure (ECSP). Design: BC hearing thresholds and ECSP have been measured for stimulation at two positions: the existing bone-anchored hearing aid (BAHA) position, and a new bone conduction implant (BCI) position that is located closer to the cochlea. Study sample: The measurements were made on 20 normal-hearing subjects. Results: Depending on frequency, the ipsilateral hearing threshold was 3-14 dB better, and the ipsilateral ECSP was 2-12 dB higher for the BCI than for the BAHA position, with no significant differences between threshold and ECSP shifts at group level for most frequencies, and individually only for some subjects. Conclusions: It was found that both the objective ECSP and the subjective hearing threshold measurements gave similar improvement as previous LDV measurements for stimulation closer to the cochlea. One exception was that the LDV measurements did not show the improved sensitivity for frequencies below 500 Hz found here.
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| 12. |
- Reinfeldt, Sabine, 1978, et al.
(författare)
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New developments in bone-conduction hearing implants: a review
- 2015
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Ingår i: Medical Devices: Evidence and Research. - 1179-1470. ; 8, s. 79-93
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Tidskriftsartikel (refereegranskat)abstract
- The different kinds of bone-conduction devices (BCDs) available for hearing rehabilitation are growing. In this paper, all BCDs currently available or in clinical trials will be described in categories according to their principles. BCDs that vibrate the bone via the skin are referred to as skin-drive devices, and are divided into conventional devices, which are attached with softbands, for example, and passive transcutaneous devices, which have implanted magnets. BCDs that directly stimulate the bone are referred to as direct-drive devices, and are further divided into percutaneous and active transcutaneous devices; the latter have implanted transducers directly stimulating the bone under intact skin. The percutaneous direct-drive device is known as a bone-anchored hearing aid, which is the BCD that has the largest part of the market today. Because of some issues associated with the percutaneous implant, and to some extent because of esthetics, more transcutaneous solutions with intact skin are being developed today, both in the skin-drive and in the direct-drive category. Challenges in developing transcutaneous BCDs are mostly to do with power, attachment, invasiveness, and magnetic resonance imaging compatibility. In the future, the authors assume that the existing percutaneous direct-drive BCD will be retained as an important rehabilitation alternative, while the transcutaneous solutions will increase their part of the market, especially for patients with bone-conduction thresholds better than 35 dB HL (hearing level). Furthermore, the active transcutaneous direct-drive BCDs appear to be the most promising systems, but to establish more detailed inclusion criteria, and potential benefits and drawbacks, more extensive clinical studies are needed.
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| 13. |
- Reinfeldt, Sabine, 1978, et al.
(författare)
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Study of the Feasible Size of a Bone Conduction Implant Transducer in the Temporal Bone
- 2015
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Ingår i: Otology and Neurotology. - 1531-7129 .- 1537-4505. ; 36:4, s. 631-637
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Tidskriftsartikel (refereegranskat)abstract
- Hypothesis: The aim was to assess the temporal bone volume to determine the suitable size and position of a bone conduction implant (BCI) transducer. Background: A BCI transducer needs to be sufficiently small to fit in the mastoid portion of the temporal bone for a majority of patients. The anatomical geometry limits both the dimension of an implanted transducer and its positions in the temporal bone to provide a safe and simple surgery. Methods: Computed tomography (CT) scans of temporal bones from 22 subjects were virtually reconstructed. With an algorithm in MATLAB, the maximum transducer diameter as function of the maximum transducer depth in the temporal bone, and the most suitable position were calculated in all subjects. Results: An implanted transducer diameter of 16 mm inserted at a depth of 4 mm statistically fitted 95% of the subjects. If changing the transducer diameter to 12 mm, a depth of 6 mm would fit in 95% of the subjects. The most suitable position was found to be around 20 mm behind the ear canal. Conclusion: The present BCI transducer casing, used in ongoing clinical trials, was designed from the results in this study, demonstrating that the present BCI transducer casing (largest diameter [diagonal]: 15.5 mm, height: 6.4 mm) will statistically fit more than 95% of the subjects. Hence, the present BCI transducer is concluded to be sufficiently small to fit most normal-sized temporal bones and should be placed approximately 20 mm behind the ear canal.
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| 14. |
- Reinfeldt, Sabine, 1978, et al.
(författare)
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The bone conduction implant: Clinical results of the first six patients.
- 2015
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Ingår i: International journal of audiology. - : Informa UK Limited. - 1708-8186 .- 1499-2027. ; 54:6, s. 408-416
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To investigate audiological and quality of life outcomes for a new active transcutaneous device, called the bone conduction implant (BCI), where the transducer is implanted under intact skin. Design: A clinical study with sound field audiometry and questionnaires at six-month follow-up was conducted with a bone-anchored hearing aid on a softband as reference device. Study sample: Six patients (age 18-67 years) with mild-to-moderate conductive or mixed hearing loss. Results: The surgical procedure was found uneventful with no adverse events. The first hypothesis that BCI had a statistically significant improvement over the unaided condition was proven by a pure-tone-average improvement of 31.0 dB, a speech recognition threshold improvement in quiet (27.0 dB), and a speech recognition score improvement in noise (51.2 %). At speech levels, the signal-to-noise ratio threshold for BCI was - 5.5 dB. All BCI results were better than, or similar to the reference device results, and the APHAB and GBI questionnaires scores showed statistically significant improvements versus the unaided situation, supporting the second and third hypotheses. Conclusions: The BCI provides significant hearing rehabilitation for patients with mild-to-moderate conductive or mixed hearing impairments, and can be easily and safely implanted under intact skin.
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| 15. |
- Taghavi, Hamidreza, 1981, et al.
(författare)
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A Novel Bone Conduction Implant - Analog Radio Frequency Data and Power Link Design
- 2012
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Ingår i: 9th IASTED International Conference on Biomedical Engineering, BioMed 2012; Innsbruck; Austria; 15 February 2012 through 17 February 2012. - 9780889869097 ; , s. 327-335
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Konferensbidrag (refereegranskat)abstract
- Patients who are suffering from conductive hearing loss and single sided deafness cannot sometimes be rehabilitated by conventional air conduction hearing aids. Today, percutaneous Bone Anchored Hearing Aid (BAHA) is an important alternative for such patients. BAHA uses a titanium implant which penetrates the skin and can cause skin infection, skin redness and requires life-long commitment of care every day. A novel Bone Conduction Implant (BCI) is designed as an alternative to the percutaneous BAHA, because it leaves the skin intact. It comprises an external audio processor and an implanted unit called the BCI Bone Bridge. Sound is transmitted to the implant via an inductive radio frequency (RF) link through the intact skin using amplitude modulation. This paper presents an analog RF data and power link design as a first implementation for the BCI. The RF link is designed to operate in critical coupling to transmit maximum power to the implant. Maximum Power Output of the BCI was measured at 2 mm skin thickness and was found to be 105 dB relative to 1 µN at the transducer resonance frequency. This output force is fairly robust in 2 mm to 6 mm skin thickness range.
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| 16. |
- Taghavi, Hamidreza, 1981
(författare)
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A Novel Bone Conduction Implant System
- 2012
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Bone conduction is the process by which an acoustic signal vibrates the skull bones to stimulate the cochlea. Patients with pure conductive hearing loss, mixed hearing loss, and single sided deafness are sometimes poorly rehabilitated by conventional air conduction hearing aids due to for example the functionality losses in the middle ear. With these hearing impairments, the cochlea may function perfectly and a bone conduction hearing device can transmit the sound signal more efficiently to the cochlea. Today, the percutaneous bone anchored hearing aid (BAHA) is an important alternative for such individuals. This device uses a percutaneous snap coupling together with a bone anchored implant to transmit the sound vibrations to the skull bone and has proven to offer very good hearing rehabilitation. However, such a system with permanent skin penetration requires a life-long commitment of care every day, may cause skin infections, and there is a risk for implant damage due to trauma and hence improvements are called for in these aspects.A novel bone conduction implant (BCI) device is designed as an alternative to the percutaneous BAHA device, because it leaves the skin intact. The BCI device provides a specific hearing aid digital signal processor, and analog signal processing parts. By applying amplitude modulation technique, the sound signal is transmitted to a permanently implanted transducer via an inductive link system through the intact skin. An efficient wireless power and data transmission system for the BCI device has been designed and implemented. Maximum power output (MPO) of the BCI was designed to occur at 4 mm skin thickness. The power output variability for 1 to 8 mm skin thickness variations was within 1.5 dB. Maximum MPO was found to be 109 dB relative to 1 μN at transducer resonance frequency. This implant system consumes 14.6 mA of battery current at 1 kHz at 65 dB input sound pressure level. It was also found that the gain headroom improvement with the BCI versus the BAHA was in the range of 10-30 dB, if the mechanical output of the devices were normalized at the cochlear level.
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| 17. |
- Taghavi, Hamidreza, 1981, et al.
(författare)
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A vibration investigation of a flat surface contact to skull bone for direct bone conduction transmission in sheep skulls in vivo.
- 2013
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Ingår i: Otology & neurotology : official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology. - 1537-4505 .- 1531-7129. ; 34:4, s. 690-8
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Tidskriftsartikel (refereegranskat)abstract
- Hypothesis: Bone conduction implant (BCI) attached with a flat surface contact will offer efficient and linear vibration transmission over time. Background: Despite that percutaneous bone conduction devices (PBCD) are successful in treating patients with conductive hearing loss, there are some drawbacks related to the need of a permanent skin penetration. The BCI system is designed as an alternative to the PBCD because it leaves the skin intact. Methods: BCI dummy implants were installed in 3 sheep skulls in vivo to study the vibration transmission characteristics over time. Mechanical point impedances and vibration transfer response functions of the BCI implants were measured at the time of surgery and after a healing period of 8 months. Results: In 1 sheep both implants healed without complications. In the other 2 sheep, the implants were either partially loose or lost to follow up. In the sheep with stable implants, it was found by the resonance frequency shift of the mechanical point impedance that a firmer integration between the implant and bone tissue as seen in osseointegrated surfaces developed over time. It was also shown that the transcranial vibration transmission remains stable and linear. Providing bone chips in the contact between the implant and the bone did not enhance vibration transmission. The surgical procedure for installing the BCI dummy implants was uneventful. Conclusion: The mechanical point impedances and vibration transfer response functions indicate that the BCI implants integrate and that transmission conditions remain stable over time.
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| 18. |
- Taghavi, Hamidreza, 1981, et al.
(författare)
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Analysis and Design of RF Power and Data Link Using Amplitude Modulation of Class-E for a Novel Bone Conduction Implant
- 2012
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Ingår i: IEEE Transactions on Biomedical Engineering. - 0018-9294 .- 1558-2531. ; 59:11, s. 3050-3059
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents analysis and design of a radio frequency power and data link for a novel Bone Conduction Implant (BCI) system. Patients with conductive and mixed hearing loss and single-sided deafness can be rehabilitated by bone-anchored hearing aids (BAHA). Whereas the conventional hearing aids transmit sound to the tympanic membrane via air conduction, the BAHA transmits sound via vibrations through the skull directly to the cochlea. It uses a titanium screw that penetrates the skin and needs life-long daily care; it may cause skin infection and redness. The BCI is developed as an alternative to the percutaneous BAHA since it leaves the skin intact. The BCI comprises an external audio processor with a transmitter coil and an implanted unit called the bridging bone conductor with a receiver coil. Using amplitude modulation of the Class-E power amplifier that drives the inductive link, the sound signal is transmitted to the implant through the intact skin. It was found that the BCI can generate enough output force level for candidate patients. Maximum power output of the BCI was designed to occur at 5-mm skin thickness and the variability was within 1.5 dB for 1–8-mm skin thickness variations.
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| 19. |
- Taghavi, Hamidreza, 1981, et al.
(författare)
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Feedback Analysis in Percutaneous Bone-Conduction Device and Bone-Conduction Implant on a Dry Cranium
- 2012
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Ingår i: Otology and Neurotology. - 1531-7129 .- 1537-4505. ; 33:3, s. 413-420
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Tidskriftsartikel (refereegranskat)abstract
- Hypothesis: The bone-conduction implant (BCI) can use a higher gain setting without having feedback problems compared with a percutaneous bone-conduction device (PBCD). Background: The conventional PBCD, today, is a common treatment for patients with conductive hearing loss and single-sided deafness. However, there are minor drawbacks reported related to the percutaneous implant and specifically poor high-frequency gain. The BCI system is designed as an alternative to the percutaneous system because it leaves the skin intact and is less prone to fall into feedback oscillations, thus allowing more high-frequency gain. Methods: Loop gains of the Baha Classic 300 and the BCI were measured in the frequency range of 100 to 10,000 Hz attached to a Skull simulator and a dry cranium. The Baha and the BCI positions were investigated. The devices were adjusted to full-on gain. Results: It was found that the gain headroom using the BCI was generally 0 to 10 dB better at higher frequencies than using the Baha for a given mechanical output. More specifically, if the mechanical output of the devices were normalized at the cochlear level the improvement in gain headroom with the BCI versus the Baha were in the range of 10 to 30 dB. Conclusion: Using a BCI, significantly higher gain setting can be used without feedback problems as compared with using a PBCD.
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| 20. |
- Taghavi, Hamidreza, 1981, et al.
(författare)
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Technical design of a new bone conduction implant (BCI) system
- 2015
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Ingår i: International Journal of Audiology. - : Informa UK Limited. - 1499-2027 .- 1708-8186. ; 54:10, s. 736-744
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The objective of this study is to describe the technical design and verify the technical performance of a new bone conduction implant (BCI) system. Design: The BCI consists of an external audio processor and an implanted unit called the bridging bone conductor. These two units use an inductive link to communicate with each other through the intact skin in order to drive an implanted transducer. Study sample: In this study, the design of the full BCI system has been described and verified on a skull simulator and on real patients. Results: It was found that the maximum output force (peak 107 dB re 1 N) of the BCI is robust for skin thickness range of 2-8 mm and that the total harmonic distortion is below 8% in the speech frequency range for 70 dB input sound pressure level. The current consumption is 7.5 mA, which corresponds to 5-7 days use with a single battery. Conclusions: This study shows that the BCI is a robust design that gives a sufficiently high output and an excellent sound quality for the hearing rehabilitation of indicated patients.
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| 21. |
- Taghavi, Hamidreza, 1981
(författare)
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The Bone Conduction Implant (BCI) - Preclinical Studies, Technical Design and a Clinical Evaluation
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Bone Conduction Implant (BCI) system has been developed as an alternative to the percutaneous bone anchored hearing aid (BAHA) with the advantage that the skin is kept intact. The transducer is permanently implanted and attached to the skull via a flat surface contact to the temporal bone. By applying amplitude modulation, the sound signal is transmitted to the implanted transducer through the intact skin via an efficient wireless inductive link. The external audio processor includes digital and analog signal processing units, and an Application Specific Integrated Circuit driving the inductive link. Its retention is provided by permanent magnets.Preclinical investigations of the BCI system have been performed on a skull simulator, a dry skull, cadaver heads and in an animal model study. In an extensive technical evaluation using a skull simulator, it was found that the power output from the BCI system was very robust for skin flap thicknesses from 2 to 8 mm with variability of less than 1.5 dB. Moreover, the peak of the maximum power output was 107 dB relative to 1 μN at transducer resonance frequency and at 5 mm skin flap thickness. This means that the highest output forces were produced in the "normal" skin thickness range, which in fact was one important design goal. The BCI system drains approximately 7.5 mA of battery current at 1 kHz and at 65 dB input sound pressure level, which corresponds to a battery lifetime of 5-7 days under normal use. It was found that significantly higher gain setting can be used without feedback problems for the BCI as compared to the BAHA. In an animal model (sheep), it was found that the implant-to-bone attachment became firmer over time and that the vibration transmission was stable over this period of eight months.Finally, in a clinical study, the results of the first patient were reported at one month follow up. The surgical procedure for installing the implant was found to be easy and safe, and the BCI gave a significant improvement in hearing over the unaided condition. The functional power output of the BCI was similar to most powerful ear level BAHA devices on headband at lower frequencies and superior at higher frequencies. In summary, it was found that the new BCI system can be an attractive alternative to the present percutaneous BAHA system.
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