MIDDLE EAR IMPLANT Detailed POWERPOINT PRESENTATION

Middle ear implants represent a type of hearing aid that has a potentially widespread application to patients with mild to severe hearing loss
The main purpose to develop these devices has come from patient dissatisfaction with conventional amplification aids relating to performance
sound quality , occlusion effects band acoustic feedback , discomfort
social stigma and cosmetic implications
wax blocking bthe receiver
recurrent otitis externa
Implantable hearing aid differ from conventional hearing aids in that they are partially or totally implanted and directly couple acoustic energy to the ossicular chain or cochlea
in exchange for the added surgical risk and cost associacted with implantation , they offer several potential advantages over conventional hearing aids including
Increased gain and dynamic range
reduced feedback , reduced maintenance
Improved appearance
freedom from ear canal occlusion.

1. MIDDLE EAR IMPLANT , INDICATION AND CONTRAINDICATION

2. INTRODUCTION Middle ear implants represent a type of hearing aid that has a potentially widespread application to patients with mild to severe hearing loss The main purpose to develop these devices has come from patient dissatisfaction with conventional amplification aids relating to performance sound quality , occlusion effects band acoustic feedback , discomfort social stigma and cosmetic implications wax blocking bthe receiver recurrent otitis externa

3. Implantable hearing aid differ from conventional hearing aids in that they are partially or totally implanted and directly couple acoustic energy to the ossicular chain or cochlea in exchange for the added surgical risk and cost associacted with implantation , they offer several potential advantages over conventional hearing aids including Increased gain and dynamic range reduced feedback , reduced maintenance Improved appearance freedom from ear canal occlusion.

4. Wilska is credicted with being the first to use electromagnetic induction to stimulate the middle ear

5. BASIC PRINCIPLE ELECTROMAGNETIC; ELECTROMAGNETIC transducers generate a magnetic field using a wire coil carrying a current that encodes the microphone output. This magnetic field induces motion of a nearby magnet , which can either be separate from the coil and attached alone to the ossicles or integrated with coil to become a vibrating compound mass affixed to the ossicles

6. PIEZOELECTRIC this devices move ossicles using a piezoelectric crystal that bends or lengthens in time with changes in a signal voltage applied across it . Piezoelectric ossicular actuators yield greater power and less distortion than electromagnetic devices, but requires precise placement to ensure proper compressive force between the actuator and the ossicles it contacts.

7. TOTAL VERSUS PARTIALLY IMPLANTABLE HEARING DEVICES Partially implantable devices consist of an external microphone and speech processor connected to a transmitter with an external coil that transmit electric energy transcutaneously to the internal device Battery powered system is contained within the external device ( decreases the size of the implanted component ). The internal device consists of an internal receiving coil , which provides electric energy to the mechanical driver connected to the ossicular chain

8. Fully implantable system house all of the above mentioned component within the implanted portion of the device , including the battery pack Because of the finite life if the rechargeable batteries : requires reoperation at approx. 5 year interval to exchange the battery More complex and bulky

9. VIBRANT SOUNDBRIDGE Partially implantable active middle ear device that uses electromagnetic energy to mechanically drive the ossicular chain Two components : External component – audio processor secured magnetically to the scalp Internal component – implanted vibrating ossicular prosthesis ( VORP) attached to a floating mass transducer The FMT is coupled to the ossicular chain with an attachment clip to serve as an electromagnet transducer

10. Sound detected by audio processor microphone is processed and relayed across the skin to the internal receiver of the VORP . Electrical signals are then relayed from the VORP to the FMT , which in turn generates vibration from the oscillating magnet within an electromagnetic filed drive the ossicular chain

11. MIDDLE EAR TRANSDUCER AND CARINA Is an electromagnetic middle ear hearing aid Originally , semi-implantable MET has been replaced by fully implantable CARINA

12. Via a postauricular incision, a well is drilled to house the implant body and then a limited mastoidectomy is performed to expose the incus body and malleus head A laser is used to make a small pit in a posterosuperior incus body , and then

13. ESTEEM – HEARING IMPLANT ( ENVOY MEDICAL CORP.) Is a fully implantable piezoelectric device One especially notable design feature of the ESTEEM is its use of the tympanic membrane and malleus as a microphone diaphragm

14. DRAWBACK: Implantation of the esteem requires partial removal of the incus to prevent feedback from the actuator to the sensor. This results in a maximal CHL in the event of device failure or removal , unless an ossiculoplasty is performed the internal battery must be replaced approximately every 5 years, and this requires repeated surgeries

15. DIRECT ACOUSTIC COCHLEAR IMPLANT It consist of an implantable electromagnetic transducer and external audio processor Indicated in profound hearing loss

16. SEMI IMPLANTABLE MIDDLE EAR ELECTROMAGNETIC HEARING DEVICE ( SIMEHD) A magnet is cemented to the body of the incus There is an implantable electromagnetic coil that is supported by a titanium frame which is fixed to the temporal bone .

17. PIEZOELECTRIC ROUND WINDOW IMPLANT WITH INFRARED OPTICAL SIGNAL Combinationof an infra- red technology with piezoelectrics system A microtransducer is placed on the round window , this can receive power and signal transmission through an infrared optical transmitter located in an external unit This system is implanted endaurally without mastoidectomy .

18. INDICATION Patient selection – ideal candidate High frequency sensorineural or mixed hearing loss , in which amplification with conventional hearing aid has failed Absent of skin infection condition that will prevent attachment of the external component of the implant Patient should be medically fit for surgery and anesthesia

19. Audiological considerations Current devices are mostly suitable for mild to severe SNHL hearing loss should be stable or gradually progressive The ear which is severly affected is first selected for the implant.

20. Otological considerations Absence of retrocochlear or central involvement in hearing loss no middle ear inflammation the external auditory canal ( EAC) must be assessed if suitable for an external processor or is fit to hold the processor .

21. CONTRAINDICATION History of significant eustachian tube dysfunction , active middle ear disease Prior ossiculoplasty or stapes surgery Meniere disease or inner ear disease with fluctuating hearing loss Retrocochlear pathology Disabled tinnitus Anticipated need for MRI in the future Bleeding disorder