BONE CONDUCTION IMPLANTS FACULTY: DR PRAWIN KUMAR PRESENTER: VIDYA GOWDA SL INTRODUCTION Bone-conduction Implants are semi-implantable devices for the treatment of hearing losses in patients who either cannot wear or underperform with conventional hearing aids. These devices must be surgically implanted, based on the principle of osseointegration, and work by enhancing natural bone conduction. Since their first introduction in 1977, even the surgical technique has undergone several modifications. OSSEOINTEGRATION Branemark defined osseointegration as a direct structural and functional connection between ordered living bone and the surface of a load-carrying implant. Most materials fail to osseointegrate, and, instead, a foreign body reaction leads to formation of a fibrous capsule around the material. Titanium has proven to be the material of choice for osseointegration. Osseointegration is reliably achieved in the BCI system using commercially pure titanium (99.75 %), which is machined, then covered with an extremely biocompatible thin oxide layer. Osseointegration is dynamic process that develops gradually over 6-12 weeks following fixture implantation. Many factors influence successful osseointegration, including the material, the macrostructure and microstructure of the implant, the quality of bone at the site of implantation, and surgical factors. The implant must remain completely immobile during the initial period of osseointegration. This is critical; otherwise, osseointegration fails, with the formation of a fibrous capsule around the implant instead of new bone formation. The initial stability of the implant is mechanically achieved via the use of a screwshape implant that is secured to bone with precise torque parameters. OSSEOINTEGRATION https://www.youtube.com/watch?v=kVF8ci9m8ak https://www.youtube.com/watch?v=Q4ULda4KgbQ NEED Otologic Condition Associated Problems with Traditional Hearing Aids Draining ear, unresponsive to treatment. Use of an earmould with an air-conduction aid prevents adequate aeration of ear. Maximal conductive component in only hearing ear Risk of possible loss of remaining hearing prohibits surgical treatment; BCI is an alternative to traditional aid. Postoperative ear defect: large mastoid bowl, as results from mastoidectomy Ill-fitting earmould leads to unmanageable feedback. Spitzer et al, 2002 Congenital aural atresia Use of bone-conduction aid often results in discomfort, pressure sores, headache, or poor hearing caused by inadequate band pressure. Postoperative ear defect: absence of auricle, closure of ear canal, as in temporal bone resection Discomfort caused by earmolud, including itching or moisture There may be no solution to this problem using hypoallergenic earmould materials. Discomfort from sound quality, especially from sound of one’s own voice Occlusion effect accompanies use of earmould or custom aid that occupies ear canal. Spitzer et al, 2002 COMPONENTS BAHA has 3 components. They are: 1. The sound processor: A detachable electronic hearing aid with a snap-fit coupling to the abutment. The user takes the sound processor on and off as required, for example for hair washing or swimming. 2. The abutment: A socket attached by an internal screw to the fixture. The abutment penetrates the surface of the scalp and is shaped to hold the snap-fit coupling of the sound processor. The abutment can be unscrewed from the fixture for maintenance or replacement by the specialist audiologist. 3. The fixture (or implant): A small titanium screw, four millimetres long, implanted into the bone behind the ear. The fixture is permanent, it is not adjusted or removed. The metal becomes firmly anchored to living bone by the process of osseointegration. How does BCI work? The principle for bone conduction hearing aids comes from the basis that when a sound source is placed directly on the bones of the skull, sound will travel through the skull using the bone itself as a medium, where in it turn causes fluids of the inner ear to move, leading to production of neural impulses and sound perception. BCI system works by taking the sound from the outside and transmitting it to the inner ear through the bone. This bypasses the ear canal and the middle ear. In BCI the titanium implant is placed during a short surgical procedure and over time osseointegrates with the skull bone. For hearing, the sound processor transmits sound vibrations through the external abutment to the titanium implant. The vibrating implant sets up vibrations within the skull and inner ear that finally stimulate the nerve fibres of the inner ear, allowing hearing. BONE CONDUCTION HEARING AIDS BONE CONDUCTION IMPLANTS 1 There is pressure against the skin and the skull No such pressure present. with BC hearing aids 2 Damping of signal present due to presence better sound quality of skin, which affects the sound quality with a bone-anchored hearing, as there is no damping of the signal via the skin. 3 These hearing aids are concerned with Bone-anchored system is much more discrete. cosmetic appearance issues. 4 Not comfortable It is more comfortable. 5 Not so advanced technology used. Today’s bone-anchored systems utilize the same advanced technology that is found in a premium hearing instrument. Eg: wireless accessories, directional microphones. TYPES Percutaneous Transducer Transcutaneous Transducer Percutaneous: The BCI uses a percutaneous bone anchored implant. The percutaneous implant protrudes out of the skin and therefore, there is high risk of granulations and peri- implant infection. Additionally, the processor cannot be loaded until the fixture implant is osseointegrated. 1-Mastoid bone 2-soft tissue 3-titanium fixture 4-titanium abutment 2. Transcutaneous: Here, the device lies completely under the skin, leaving the skin intact. So, the implant site closes and heals completely obviating the need for an abutment. It transmits the signal to a permanently implanted transducer with an induction loop system through the intact skin Mastoid bone soft tissue titanium anchored magnet transducer In study by Timo, et. al. (2016), the audiological results of the Bonebridge transcutaneous bone conduction implant (MED-EL) were compared to the generally used percutaneous device BP100 (Cochlear Ltd., Sydney, Australia). 10 patients implanted with the transcutaneous hearing implant were compared to 10 matched patients implanted with a percutaneous device. Tests included pure-tone AC and BC thresholds and unaided and aided sound field thresholds. with a minor sensorineural hearing loss component. Speech intelligibility was determined in quiet and in noise in sound field. The subjective benefit was assessed with the Abbreviated Profile of Hearing Aid Benefit. They concluded that the transcutaneous bone conduction hearing implant is an audiologically equivalent alternative to percutaneous bone-anchored devices in conductive hearing loss Study by Orhan et al(2015) Transcutaneous bone-anchored hearing aids versus percutaneous ones: multicenter comparative clinical study. Otology & Neurotology Aim of the study is to compare the audiological and surgical outcomes in the percutaneous Dermalock and transcutaneous Baha Attract system. 37 patients who underwent BCI surgery over percutaneous bone conduction implant (pBCI) group of 21 patient and transcutaneous bone conduction implant (tBCI) group of 16 patients. Findings: tBCI patient group have relatively better aesthetic appearance, easy to use, and hygiene maintenance advantages. When tBCI device is removed , many of them have an almost normal appearance of the skin over an invisible subdermal implant. However the audiological limitation of these devices ( they are only used for patient with equal or better than 30dB hearing loss) & is the biggest drawback. On the other hand, pBCI is a good alternative with shorter surgical time and better hearing results. However this implant need of daily hygienic care is the main disadvantage of the system. MODELS Currently, 4 companies across the world market the bone conduction hearing implants: Cochlear’s BAHA system Oticon’s Ponto, Ponto Pro, Ponto pro power MED-EL GmbH’s Bonebridge Sophono Inc. – Otomag Alpha 1 Cochlear’s BAHA system Models of oticon MODELS OF MED-EL: The BCI 601 is the implanted part of the Bonebridge system consisting of: an internal coil a magnet to hold the SAMBA audio processor in place over the implant a demodulator to convert the signal from the SAMBA audio processor a Bone Conduction Floating Mass Transducer (BC-FMT) to cause vibrations of the skull. CANDIDACY The BCI is used to rehabilitate people with conductive and mixed hearing impairment. This includes people with, chronic infection of the ear canal, absence of or a very narrow ear canal as a result of a congenital ear malformation, infection, or surgery, or a single sided hearing loss as a result of surgery for a vestibular schwannoma Studies suggest that candidates with an airbone gap of more than 30 dB (PTA) will experience significant advantages from the BCI System, compared to using an air conduction (AC) hearing aid. Conductive hearing loss: BCI is frequently the ideal choice for conductive hearing loss. Because conductive loss is often concomitant with various outer and middle ear abnormalities (e.g. atresia) or middle ear pathologies like continuously draining ear that prelude the wearing of conventional hearing aids. In cases, wherein the ear discharge fails to respond to treatment or recurs with the use of conventional hearing aid, BCI could be an option for rehabilitation. Conventional hearing aids can aggreveate the ear discharge by obstruction of the canal and the resulting excessive humidity and lack of drainage. With BCI, the conductive element of the hearing loss is bypassed by sending sound vibrations directly from the BCI through the skull to the cochlea. BCI often provides benefits over conventional hearing aids in large conductive losses due to their technical limitations of insufficient gain, saturation, feedback and necessity of wearing a tight ear mould. Mixed hearing loss: BCI provides two-fold solution to all such patients: 1. It closes the air-bone gap by bypassing the conductive element. 2. It compensates for the remaining degree of sensorineural hearing loss. The overall amplification required for people with mixed hearing loss is less with BCI than conventional hearing aids and it is recommended when conductive component of the mixed hearing loss is greater than 30dB. For mixed hearing loss: Degree of conductive hearing loss - the air-bone gap is a good indicator of suitability for a Baha System. The greater the air-bone gap, the more the candidate will benefit from implantable bone conduction system. Studies suggest that candidates with an air-bone gap of more than 30-35 dB (PTA) derive greater benefit from a BCI System than a hearing aid. Extent of the sensorineural hearing loss – those with a mild-tomoderate sensorineural component in their hearing loss are suitable BCI candidates.. The most powerful BCI sound processor can compensate for a sensorineural element of up to 65 dB HL (measured at 0.5, 1, 2 and 3 kHz). SSD SSD causes significant communication difficulties for the patient due to inability to localize sound, more so when noise is directed towards the good ear and the talker is near the deaf ear. BCI is worn on the deaf side and transfers the signal directly across the skull via bone conduction thus eliminating the head shadow effect. But these patients must have normal hearing in the contralateral ear (20 dB HL air conduction pure tone averages). BCI provides better directional 360-degree hearing in these patients. Studies have shown that patients with BCI have better speech understanding than those with Contralateral Routing of Signal (CROS) hearing aids. The level of hearing in the good ear should be assessed. Candidates with normal hearing in their good ear will benefit from a BCI. In cases where there is a more pronounced hearing loss in the good ear, a bone conduction implant may not be the best solution. SURGERY FAST (Focussed Assessment with Two-stage surgery Selection Sonography in Trauma) surgery Good bone quality and a thickness Compromised or soft bone. greater than 3mm Irradiated bone Bone thickness less than 3mm In conjunction with other surgery (e.g. Acoustic Neuroma removal) SURGERY VIDEOS: https://www.youtube.com/watch?v=ZgH0WhjjozM&t=1s https://www.youtube.com/watch?v=KiqmqnqPKGA&has_verified=1 SUMMARY BCI can be used as a rehabilitation option in people who underbenefit from conventional AC/ BC hearing aids due to different conditions There are different types of BCIs from different companies selection of which depends on the degree of hearing loss & other factors BCIs have several advantages over BC hearing aids. Type of surgery to be performed is decided by the surgeon considering age, bone density & other factors Counseling about hygiene and attachment of the sound processor is an important factor. 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J., & Leonetti, J. P. (2006). Perioperative complications with the bone-anchored hearing aid. Otolaryngology—Head and Neck Surgery, 134(2), 236-239. Iseri, M., Orhan, K. S., Tuncer, U., Kara, A., Durgut, M., Guldiken, Y., & Surmelioglu, O. (2015). Transcutaneous bone-anchored hearing aids versus percutaneous ones: multicenter comparative clinical study. Otology & Neurotology, 36(5), 849-853. Rahim, S. A., Goh, B. S., Zainor, S., Rahman, R. A., & Abdullah, A. (2018). Outcomes of Bone Anchored Hearing Aid Implant at Universiti Kebangsaan Malaysia Medical Centre (UKMMC). Indian Journal of Otolaryngology and Head & Neck Surgery, 70(1), 28-32. Kruyt, I. J., Kok, H., Bosman, A., Nelissen, R. C., Mylanus, E. A. M., & Hol, M. K. S. (2019). Three-Year Clinical and Audiological Outcomes of Percutaneous Implants for Bone Conduction Devices: Comparison Between Tissue Preservation Technique and Tissue Reduction Technique. Otology & Neurotology, 40(3), 335 Rahim, S. A., Goh, B. S., Zainor, S., Rahman, R. A., & Abdullah, A. (2018). Outcomes of Bone Anchored Hearing Aid Implant at Universiti Kebangsaan Malaysia Medical Centre (UKMMC). Indian Journal of Otolaryngology and Head & Neck Surgery, 70(1), 28-32. Granström, G., Bergström, K., & Tjellström, A. (1993). The bone-anchored hearing aid and bone-anchored epithesis for congenital ear malformations. Otolaryngology—Head and Neck Surgery, 109(1), 46-53. The Bone Conduction Implant—First Implantation, Surgical and Audiologic Aspects Eeg-Olofsson, Måns*; Håkansson, Bo†; Reinfeldt, Sabine†; Taghavi, Hamidreza†; Lund, Henrik‡; Jansson, Karl-Johan Fredén†; Håkansson, Emil†; Stalfors, Joacim* 16. Percutaneous versus transcutaneous bone conduction implant system: a feasibility study on a cadaver head B Håkansson, M Eeg-Olofsson, S Reinfeldt… - Otology & …, 2008 - journals.lww.com THANK YOU!