Implantable Middle ear and bone conduction hearing devices

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  • 3. • Bone Conduction Hearing Aids: - Mild hearing loss • Middle ear implants : - Mild to profound • Cochlear Implant : - Profound hearing loss
  • 4. Why MEI required?? Because of following limitations of conventional hearing aids :- • Insufficient amplification • Acoustic feedback • Spectral distortion • Non linear/ harmonic distortion • Occlusion of EAC • Appearance/ Visibility • Lack of directionality
  • 5. Insufficient Amplification • The maximum gains for digital in-the-ear (ITE) , in-the-canal (ITC), & completely-in-canal (CIC) aids currently are about 55-65 dB, 45-55 dB, 35-50 dB, respectively.
  • 6. Acoustic Feedback • Acoustic waves from the hearing aid speaker leak through the air space between the hearing aid body & the EAC wall back to the microphone, where ( for a subset of frequencies ) they add to existing microphone input & are amplified further. • The resulting positive feedback loop causes a low-frequency hum or high-frequency squeal. • Fitting aids tightly into the EAC can decrease feedback, but this decrease comes at the cost of increased incidence of discomfort, otitis externa, autophony, & blockage of natural sound input.
  • 7. Limitations of conventional hearing aids • Occlusion • Feedback • Wax problems • Placement loss • Social stigma • Discomfort • Maintenance • Poor sound quality • Distortion • Insufficient gain
  • 8. The Output Transducer The Only Difference Between M.E.I & H.A
  • 9. Middle Ear Implants • Can be distinguished according to • Type of hearing loss(CHL,Mixed,SNHL) • Visibility (partially or fully implantable) • Mode of stimulation (electeromagnetic or piezoelectric)
  • 10. Mode of transmission  Coil and magnet (electromagnetic) • The electrical signal is used to produce an electromagnetic field by means of a transduction coil. • This then drives a magnet that can be attached to the ossicles in a variety of ways to transfer the vibrations. Piezoelectric • When a voltage is applied to a particular ceramic • It causes a proportional deformation and hence displacement of that ceramic. • This voltage-dependent displacement can then be coupled to the ossicles to drive them
  • 12. VIBRANT SOUND BRIDGE • An active semi-implantable hearing device • It consists of an internal, surgically implanted part – the vibrating ossicular prosthesis (VORP) and an external audio processor. • The VORP consists of a receiving coil, conductor link and transducer • The transducer employs a small electromagnetic coil and enclosed magnet to produce vibrations in this floating mass transducer (FMT), which can be coupled to the ossicles or round window
  • 13. Audio Processor TM Receiver (VORPTM) Conductor lead FMTTM Floating Mass Transducer
  • 14. Vibrating Ossicular Prosthesis (VORP) Demodulator Receiver coil Magnet SiliconeFloating Mass Transducer
  • 15. Audio processor contains- • Microphone • speech-processing capabilities • Magnet • Battery
  • 16. ADVANTAGES- • No occlusion of the ear canal. • Easily hidden under the hair. • Held in place by magnetic attraction. • No interference with glasses.
  • 17. SAMBA AUDIO PROCESSOR • SAMBA offers wireless connectivity via Bluetooth or telecoil and plugs into external devices. • Through this new feature users can connect to their mobile phones, MP3 players, FM systems or other wireless devices without losing any quality of sound • SAMBA Remote Control-Users can simply control the volume and change between programs with the easy-to operate remote control, which is supplied with SAMBA. • Adaptive Directional Microphones—Minimizes Background Noise • Intelligent Sound Adapter—SAMBAAdapts to Users’s Listening Habits
  • 18. Floating mass transducer • 2.3 mm long,1.6 cm large, 25 mg of weight • Including 2 coils would around a hermetically sealed titanium alloy ,bobbin shaped housing and a set of silicone elastomer springs. • Typically attached to long process of incus • Implanted using a transmastoid ,facial recess approach to the middle ear
  • 19. Vibroplasty TYPE A • Involves the coupling of an AMEI on an intact ossicular chain • Different attachment points to the ossicular chain (e.g. umbo, incus or stapes)are used • VSB and carina TYPE B • Aided hearing by means of an AMEI • Coupled to a remnant of the ossicular chain, which is in most cases the stapes or its footplate • Mostly the VSB •The coupling of the actuator On one of the middle ear window membranes •VSB is the only implantable actuator •Direct coupling of an AMEI to the inner ear fluid •OVAL window is mostly used •DACI system TYPE C TYPE D
  • 20. INDICATIONS • In case of conductive or mixed hearing loss, the main objective of AMEI placement is to overcome the residual sensorineural component
  • 21. BENEFITS • High frequency gain without feedback • Elimination of the occlusion effect • Improved comfort and ease of use • Distortion-free signal – No electronic receiver in the ear canal, which is a major source of distortion wi hearing aids • More natural sound quality • Takes advantage of any low frequency residual hearing – Low frequencies are still transmitted through the ear canal • FMT is designed to be linear – Mimics the natural vibratory pattern of the ossicular chain through 8000Hz
  • 22. Direct acoustic cochlear implant (DACI) • Initially called the direct acoustic cochlear stimulator this device • Consists of an implantable electromagnetic transducer, which transfers acoustic energy directly to the inner ear via a conventional stapes prosthesis • Indicated for profound mixed hearing loss. • Beside the original use of the device, further applications involving the stimulation of mobile middle ear structures or the round window are imaginable
  • 23. • The external behind-the-ear unit containing the sound processor receives the acoustical signal by two microphones and transmits it transcutaneously to the implant by an induction coil. • The electro-magnetic Codacs actuator held by a fixation system generates the vibration. • The vibration is transmitted to the perilymph fluid by a piston prosthesis crimped to the angled Codacs actuator rod tip, the artificial incus (AI), and inserted into the inner ear through a stapes footplate fenestration
  • 24. Codacs actuator • An electromagnetic actuator based on the “balanced armature principle” • A disk-like part of the rod inside the actuator is positioned between two permanent ring magnets • A titanium diaphragm encloses the rod and acts as a spring
  • 25. Middle ear transducer • The semi-implantable MET uses an external unit called the button external audio processor, containing a microphone,battery,signal processor and transmitter. • The transducer drives an electromagnetic probe coupled to the body of the incus. • The tip of the probe is made of aluminium oxide, which forms a fibrous connection with the incus body.
  • 26. Fully implantable MED
  • 27. CARINA • The fully implantable Carina uses the same electromagnetic transduction system, but consists of a subcutaneous microphone, battery and an electronic receiver connected to a transducer. • four main components: the implant,the programming system, the charger, and the remote control.
  • 28. • The microphone is housed under the skin behind the ear. • It collects sound and sends it to the processor. • The signal is then amplified, processed, and sent to the actuator At this stage, the electrical signal is transduced in a mechanical movement that will be transmitted to the ossicles or labyrinthine windows. • The transducer, which initially had a tip designed to couple it to the body of the incus, was modified for application with different extensions that allow coupling to the stapes, oval window , or round window. • This is used in patients with mixed hearing loss
  • 29. Procedure • implantation is performed through a post-auricular incision with a posterior small atticotomy (about 2 cm wide) to expose the body of the incus and the head of the malleus. • The arm of the mounting bracket of the device can be modified to place the device on the incus and is fitted to the mastoid cortex using bone screws.
  • 30. • Bone beds for the device and the microphone must be drilled so that the electronics capsule and the microphone can be positioned and secured • There are 3 convenient microphone placement locations: anterior and superior to the external auditory canal (temporalis region), posterior to the external auditory canal (retro-auricular region), and on the mastoid tip
  • 31. ESTEEM • A totally implantable hearing system that is implanted under the skin behind the ear and within the middle ear space • For moderate and severe sensorineural hearing loss • Sensorineural hearing loss -- Loss of hearing resulting from problems in the inner ear, the cochlear nerve, or in the brain. • Has no microphone • Uses the functioning eardrum to pick up vibrations • Adjusts vibrations to individual hearing needs • Pacemaker like battery • Needs replacement after 4.5 to 9 years of continuous use. • battery replaced in a minor outpatient surgical operation.
  • 32. Parts • Two piezoelectric transducers implanted in the middle ear • Sensor – surgically attached to incus • Driver – attached to stapes • Sound Processor • Implanted behind the ear in a bony well • Hold battery • Personal Programmer • Turns Esteem on/off • Select volume levels • Three program settings
  • 33. PROCEDURE • A post-auricular incision is made and a bone recess is fashioned posterior to the mastoid to house the sound processor • A tympanomastoidectomy is performed widely exposing the facial recess to accommodate the driver. • The incus and stapes are disarticulated and the distal 1 to 3 mm of the long process of the incus is gently removed using either malleus nipper or a cutting laser to prevent a mechanic feedback • Transducers are contained in the mastoid cavity with hydroxyapatite cement so their piezoelectric crystals are positioned.
  • 34. • The sensor is interfaced with the incus using glass ionomeric cement and the driver is cemented to the stapes • Maximum vibrational motion of the middle ear is deliverable to the piezoelectric transducer of esteem through the superior part of the malleus head, on the lateral part of the incus body, and on the superior part of the incus body near the incudomalleal joint
  • 35. How it works • Sound travels down ear canal and vibrates eardrum • Sensor • Picks up vibrations from incus. • Converts vibrations into electrical signals which are sent to the sound processor. • Processor • The digital signals are modified depending on patients individual needs • Determined by variety of hearing tests
  • 36. • Driver • Converts the new electrical signals into mechanical vibrations. • Transmits these signals to the stapes and the cochlea Sound Processor Sensor Driver Incus and Stapes surgically separated to prevent feedback.
  • 37. • Indication • Bilateral non progressive SNHL of moderate to severe degree , with at least 40%speech discrimination , age older than 18 years and a normal middle ear function(evaluated by impedance audiometry) • Contraindication • In case of allergy , abnormal tubal function or chronic naso- paranasal pathology , tendency to keloid and staph infections
  • 38. ADVANTAGES • Completely invisible to self and others • No acoustic feedback • Maintenance free
  • 39. DISADVANTAGES • Long surgical procedure with steep learning curve • Highly Invasive surgical procedure • Interruption of the ossicular chain • Causes additional hearing loss initially
  • 40. Bone Conduction Hearing Devices • The Bonebridge Bone Conduction Hearing Implant: indication criteria, surgery and a systematic review of the literature • Sprinzl, G.M. & Wolf-Magele, A. Department of Otorhinolaryngology, Karl Landsteiner Private University, St. Poelten, Austria • Accepted for publication 8 June 2015 Clin. Otolaryngol. 2016, 41, 131– 143
  • 41. INTRODUCTION • Sound conducted to cochlea through the bone stimulates the cochlea in 3 ways: 1. Compressional/Distortional BC: • Vibration energy -> Compression & Expansion oth cochlear shell -> Fluid movement. 2. Inertial BC: • Vibration energy sets skull into vibration. • Ossicles lag behind and don’t move due to inertia -> Sets up a relative motion between the footplate and the cochlear fluid. 3. Osseotympanic BC: • Vibrating skull causes vibration of column of air in the EAC which is partially transferred to tympanic membrane.
  • 42. • Bone conduction hearing aid (BCHA) treatment has become the standard of care for patients suffering with Conductive and mixed losses 1. Congenital causes such as atresia or microtia 2. Acquired causes such as chronic otitis media or 3. Ossicular pathology 4. Chronic discharging ear (such as chronic suppurative 5. Otitis media (CSOM) or recurrent otitis externa) ( 6. Inability to wear a hearing aid following radical Mastoid surgery 7. Unilateral mixed hearing loss.
  • 43.  Single-sided deafness – sensorineural or conductive 1. Trauma resulting in hearing loss. 2. Unsuitable ear canal for a conventional hearing aid, e.g. i. In a radical mastoid cavity ii. An extremely narrow ear canal iii. ‘Blind sac’ ear canal closure iv. Lateral temporal bone resection v. Extensive cranial base surgery.
  • 44. BCHDs will not be commissioned for: • patients with a bone disease that is unable to support an implant • patients who have a sensitivity or allergy to the materials used • patients with physical, emotional or psychological disorders that, despite suitable treatment and support,would interfere with surgery or the ability to allow suitable rehabilitation such that significant benefit would be unlikely.
  • 45. Transcutaneous vs Percutaneous
  • 46. • BC sensitivity is fairly similar between percutaneous and transcutaneous modes of transmission for frequencies below 1 kHz. • There would be an expected 5–15 dB improvement in efficiency with percutaneous systems when a BC transducer is directly attached to the skull at higher frequencies.
  • 47. Skin-drive BCDs • Vibrations are transmitted through the skin, which is kept intact. • In conventional skin-drive BCDs, all components are kept outside the skin, while the passive transcutaneous skin-drive BCDs contain implanted magnet(s).
  • 48. 1. Conventional skin-drive BCD • It is attached with a soft headband (softband), a steel spring headband, or with spectacles for glasses. • BAHAs are sometimes used with a softband/headband instead of a titanium screw, thus behaving as a conventional skin-drive device.
  • 49. • The use of BAHA on a softband (elastic fabric) or headband (diadem type) is a valuable method of hearing rehabilitation in children who are too young for implantation, and it is the gold standard for preoperative assessment.
  • 50. • The recently introduced Sound Arc (manufactured by Cochlear) and the adhesive skin attachment ADHEAR (manufactured by MED-EL) Sound Arc
  • 51. In the mouth • Ludwig van Beethoven, the well-known 18th century composer who was completely deaf, was the first person to use bone conduction. • It has been theorized that Beethoven discovered a way to hear the sound of his piano through his jawbone by putting a rod between his teeth and touching his piano with this rod. • This was the first proof that sound can also reach our brain by making use of the bones in our skull.
  • 52. • Soundbite • It utilizes a behind-the-ear (BTE) transmitter that is connected to a microphone placed in the ear canal of the hearing-impaired ear. • The BTE module sends a signal to a custom made in- the-mouth (ITM) transducer that couples the buccal surface of the maxillary molars to a piezoelectric bone stimulator capable of conducting sound.
  • 53. • It offers advantages over traditional osseointegrated devices in that it does not require surgical placement. • Acoustic feedback is the most commonly reported problem with the Sound-Bite, and this is minimized with proper fitting.
  • 54. 2. Passive transcutaneous skin-drive BCDs • Sophono® device • BC hearing thresholds should be ≤45 dB or in the case of SSD,≤20 dB in the contralateral (‘good’) hearing ear. • It uses a retention magnet system where two magnets are implanted in the temporal bone, and fixated by small titanium screws, and the sound processor is attached on the outside of the skin by magnetic attraction force.
  • 55. • The vibrations of the transducer are transmitted through the soft tissues, and the skin is most often thinned to 4–5 mm thickness (only in adults). • In order to overcome skin problems related to high skin pressure, the Sophono® Alpha 1 uses a larger contact area than is used in conventional BCDs.
  • 56. Travelling of vibrations • Skin will conduct sound (Force) and in certain frequencies skin will even amplify sound (Force) • The size of the baseplate in contact with the skin is important for maximum transfer of power to the bone
  • 57. • Baha® Attract device • The magnet on the inside of the intact skin is attached to the skull bone with a screw, and the Baha® sound processor is attached to a magnet plate on the skin via a soft pad to equalize the force distribution over the attachment surface.
  • 58. Direct-drive BCDs • The vibrations are transmitted directly to the bone via a screw or a flat surface attachment. • Divided into percutaneous and active transcutaneous devices.
  • 59. OSSEOINTEGRATION • It combines the concept of osseointegration and bone conduction transmission to aid hearing. • Osseointegration refers to the direct structural and functional connection between ordered living bone and the surface of a load- carrying implant. • It was found in the 1950s by Professor Branemark that implanted titanium would fuse with human bone in harmony and become part of the bone, instead of giving rise to a foreign body reaction. • Tjellstron was the pioneer in utilizing the concept of osseointegration in hearing implants and established the use of BAHA in 1977.
  • 60. 1. Percutaneous direct-drive BCD • BAHA • BAHAs are mainly indicated for conductive and mixed hearing loss as well as for single-sided deafness (SSD), and are used both on adults and on children • surgery not be undertaken prior to age 2–3 years. • This was to allow the skull to reach a minimum thickness and conditions to be suitable to fit the fixture and allow osseointegration.
  • 61. INDICATIONS 1. Patient using a conventional BC hearing aid 2. Conventional AC hearing aid user with a. chronic otorrhea b. chronic otitis media/externa c. uncontrollable feedback due to a radical mastoidectomy or a large meatoplasty. 3. Otosclerosis, tympanosclerosis, canal atresia with a contraindication to repair, eg, a. only hearing ear b. combination with 2a-c. 4. SSD with better ear BC PTA better than 45db HL and SDS >60% 5.Mixed hearing loss
  • 62. Components of BAHA 71 2 1 Titanium implant placed in the bone just behind the ear Abutment which coupled with the fixture and act as a connector to the speech processor1 2 3 3 External sound processor which connects to the implant
  • 63. • The titanium fixture is implanted in the skull bone of the patient and attached to a percutaneous abutment and sound processor. • The sound processor will convert sound energy to vibration, transmitted via the abutment and the titanium fixture and then the skull, directly to the functioning cochlea via bon
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