Academic presentation

1. MIDDLE EAR IMPLANTS
DR VAISHNAVI SREERAM

3. INTRODUCTION
• Hearing aids are the principal means of hearing rehabilitation
• Yet ,they remain a tough sell to many who could potentially benefit from them due
to some non-ideal features of Hearing Aids, and due the problems with EAC, chronic
infections ,discomfort..
• To overcome the shortcomings of conventional HA, implantable hearing devices
were introduced.

5. Non-ideal features of conventional HA:
• Insufficient amplification(max:55-65dB for ITE)
• Acoustic feedback
• Spectral distortion
• Non linear/harmonic distortion
• Occlusion effects
• Appearance/visibility
• Lack of directionality

7. • Potential for improved sound clarity
• Bypass the EAC
• No use of speaker
• Transducer coupled to ossicular chain/inner ear fluid
• Rx of SNHL,mixed HL,middle ear malformations

8. BASIC DESIGN FEATURES:
Microphone processor transducer coupler
electromagnetic piezoelectric
no direct contact direct contact
smaller housing distortion free
eg:VSB eg :Carina

9. Partially implantable Fully implantable
• External microphone
• Speech processor
• Transmitter
• Internal receiving coil
• Mechanical driver
• Decreases the size of implanted
component
• Internal microphone, processor,
transmission coil
• Electromagnetic transducer in
contact with incus
• Reduces visibility
• Re-operate at 5 year interval

10. HISTORY
• WILSKA-first to use electromagnetic induction to stimulate the middle ear(1930s)
( Iron particles placed on TM, electromagnetic coil in EAC)
• Microphone in EAC to overcome pinna effect
• Transducer-electromagnetic/piezoelectric/hydro-acoustic transmission

11. CURRENT DEVICES
VIBRANT SOUNDBRIDGE(MED-EL, Innsbruck, Austria)
• AMEI with most clinical data
• Semi-implantable hearing device
• Developed by Symphonix, bought by MED-EL
• First FDA approved AMEI
• Treatment of conductive and mixed HL, moderate to severe
SNHL in adults and children
• Suitable for patients with hearing loss upto 70 dB

12. VSB..
• Parts : Internal surgically implanted part-VORP
External audio processor
• VORP: Receiving coil, conductor link, transducer
• Transducer-electromagnetic coil and a magnet to produce vibrations in the FMT,
which can be coupled to ossicles /round window
• Processor worn BTE contains microphone, audio processing electronics, magnet,
telemetry device,675 zinc battery.

15. DIRECT ACOUSTIC COCHLEAR
IMPLANT(COCHLEAR LTD,SYDNEY,AUSTRALIA)
• Initially called as Direct Acoustic Cochlear Stimulator and later Codacs
Investigational Device
• CE approved, but not FDA approved
• Treatment of profound mixed hearing loss
• It has an implantable electromagnetic transducer

16. • Transfers acoustic energy directly to the inner ear via a conventional stapes
prosthesis
• Stapes to be removed in total
• A second stapes prosthesis placed parallel to the first one into the oval window and
attached to the incus
• Audio processor worn externally behind the implanted ear

17. OTOLOGICS SEMI-IMPLANTABLE MIDDLE EAR TRANSDUCER(MET)
AND FULLY IMPLANTABLE CARINA
• (Otologics, Boulder, Colorado, USA, later Cochlear, Sydney, Australia)
• Fully implantable currently
• CE approved
• Semi-implantable MET :
• Button external audio processor-microphone, battery, signal processor transmitter
• Transducer drives an electromagnetic probe coupled to the body of incus
• Tip of probe-aluminium oxide, forms a fibrous connection with the incus body
• Ossicular chain left intact

18. MET..
• Fully implantable carina-
electromagnetic induction system –
subcutaneous microphone, battery,
electronic reciever connected to a
transducer
• No external components apart from a
charger and a remote control unit
• Mixed hearing loss with variety of
implantation sites(round window and
footplate) and aetiologies

19. FULLY IMPLANTABLE ENVOY ESTEEM
DEVICE
• Piezo-electric sensor placed on the incus
body,acting as an internal microphone
• Driver cemented to the stapes head
• Ossicular chain disarticulated and lenticular
process removed
• Sensor interface linked to the body of incus
• Treatment of mild to severe SNHL with
SDS>/=60
• CE (2006)and FDA(2010) approved.

20. EMERGING TECHNOLOGIES
MAXUM HEARING IMPLANT (Ototronix, LLC, Texas, USA)
• SOUND TEC Direct Drive Hearing System(DDHS)
• FDA approved
• Semi-implantable device containing an electromagnetic transducer-external part in
the EAC
• Implanted part-magnet attached to the IS joint via a titanium alloy wire ring
• Placement –trans meatal approach
• Upgradation by Ototronix -self crimping Nitinol wire that obviates ISJ separation.

22. SEMI-IMPLANTABLE MIDDLE EAR ELECTROMAGNETIC HEARING DEVICE
• Magnet cemented to the incus body
• Titanium frame fixed to the temporal bone supports an implanted electromagnetic
coil
• Magnet and coil encased in titanium
• Human study has been proposed

23. PIEZOELECTRIC ROUND WINDOW IMPLANT WITH INFRARED OPTICAL SIGNAL
• Microtransducer placed on the round window
• It can receive power and signal transmitted through
an infrared optical transmitter located in the external unit
• Microphone, sound processor and battery placed in the ear canal
• Implanted endaurally without mastoidectomy
• Not yet tested in vivo

25. EARLENS TYMPANIC CONTACT TRANSDUCER
• A magnet placed in a silicone lens that sticks to the tympanic membrane by oil
induced surface tension
• A small induction coil placed in the ear canal

26. DEVICES NO LONGER AVAILABLE
SEMICIRCULAR CANAL PIEZOELECTRIC VIBRATOR
• Stimulates inner ear fluids directly by means of a lateral canal
fenestration ,bypassing the middle ear.
• Piezoelectric biomorph material(Welling and Barnes)-activate
auditory system via vibromechanical stimulation

27. UNIVERSITY OF BORDEAUX IMPLANTABLE PIEZOELECTRIC TRANSDUCER
• Piezoelectric biomorphic material with a short rod and platinum ball placed against
the round window
• No reports published regarding the application of this technology in vivo

28. RION PARTIALLY IMPLANTABLE HEARING AID
• Piezoelectric transducer connected to the head of stapes or footplate by a
hydroxyapatite coupling
• Transducer held in place by a fixing plate screwed to the temporal bone
• Was used in Japan but is no longer produced.

29. TOTALLY IMPLANTABLE COCHLEAR AMPLIFIER
• Developed by Implex
• First fully implantable middle ear device
• Ear canal subcutaneous microphone and piezoelectric transducer
• Problems with feedback necessitated disarticulation of the chain
• No longer in production
• The technology was purchased by cochlear to be implemented in cochlear implants

30. PATIENT SELECTION
CANDIDATES
• High frequency SNHL/Mixed HL
• Amplification with conventional HA/BAHA failed
• Failure due to acoustic feedback, occlusion effect, insufficient high frequency
amplification or wearing discomfort
• VSB,MET/Carina-can be used in patients below 18

31. • Candidates should not have any skin conditions preventing the attachment of
external device
• Relapsing SNHL after stapes surgery
• Medical fitness for anaesthesia and surgery
• Appropriately conselled for realistic expectations
• Audiological and otological conditions to be met

32. AUDIOLOGICAL
• Mild to severe SNHL
• In COHL/Mixed HL, aim is to overcome the residual sensorineural component
• Hearing loss should be ideally stable
• Codacs system for profound mixed HL like advanced otosclerosis

33. • Aided threshold for the present HA should be considered
• Tympanometry and acoustic reflexes to assess middle ear function
• Speech audiometry to assess retrocochlear loss
• Worse ear is selected for implantation

34. OTOLOGICAL
• Absence of retrocochlear or central involvement
• Middle ear inflammation should be controlled prior to implantation
• Assess the ear canal before surgery if external processor is worn in the EAC

35. CLASSIFICATION BASED ON COUPLING
• Type A Vibroplasty: coupling of an AMEI to an intact ossicular chain in patients with
mild to moderate SNHL(umbo, incus, stapes head/footplate)
• VSB,MHI and CARINA
• Type B Vibroplasty: AMEI coupled to a remnant of ossicular chain(stapes/footplate)
• VSB mostly

36. • Type C Vibroplasty: coupling of the actuator on one of the middle ear window
membranes
• VSB
• Type D Vibroplasty: direct coupling of an AMEI to the inner ear fluid
• oval window is commonly used
• DACI system, VSB combined with a conventional stapes piston

37. SURGICAL CONSIDERATIONS
• Similar to cochlear implantation
• Retroauricular trans mastoidal access to the middle ear via facial recess
(VSB),atticus (Carina), round window niche (Codacs)
• Combined approach:(Carina, Esteem and Codacs) for joined placement with a
passive implant
• Implant bed drilled in the cortical temporal bone to accommodate the internal
reciever and conductor link

38. • Trans-meatal tympanotomy: MHI and EarLens
• -seperated coil and magnets
• Performance depends on the distance between the coil and magnets

39. • Posterior tympanotomy: (VSB) FMT placed and crimped over the long process of
incus
• Short process clip/stapes head, footplate, round window
• “Direct coupling of FMT onto the stapes footplate without the coupler is a reliable
procedure ,and is a good option for rehab in mixed HL in patients who have
undergone CW down mastoidectomy and in difficult RW vibroplasties”

40. • Retromeatal approach(Codacs): to assess the facial recess at the level of oval window
• MET/Carina device:
• Atticotomy to expose incus body and malleus head
• Laser to make a hole in the body of incus
• Transducer inserted into the mounting system, and probe tip aligned with the hole

41. • Anatomic limitations in the surgical procedure in regard to the dimensions of
antrum and attic
• Adequately estimated with HRCT Temporal bone and measurement of dura-meatal
distance
• Dura-meatal distance >8mm-implant placed safely
• If < 8mm,require surgical experience
• If< 5 mm, Carina is not advocated

42. Esteem system:
• Large facial recess opening
• Resection of chorda tympani
• Intra-op testing by laser doppler vibrometry to assess the mobility of incus and
stapes
• “The pathological status of middle ear and the skill of surgeon are as
important as the implant materials in the determination of surgical success”

43. COMPLICATIONS
• Damage to chorda tympani
• Dislocation of FMT(esp. in type2 vibroplasty)
• Extrusion of passive prosthesis
• Aural fullness(VSB)

44. • Tinnitus, deterioration of bone conduction,vertigo (Codacs)
• Device malfunction, failure(carina)
• Esteem- facial weakness, taste disturbance ,insufficient benefit, device malfunction

45. PATIENT REPORTED OUTCOME
MEASURES
• Improved quality of sound
• Elimination of occlusive effect
• Improved ability to lead an active lifestyle
• High fidelity due to direct ossicular stimulation
• Reduced distortion due to proximity of transducer to cochlea

46. AUDIOLOGY RESULTS
• Type A Vibroplasty (AMEIs in SNHL): AMEIs have a better functional gain compared
to conventional HA
• Type B,C,D Vibroplasty (AMEIs in mixed HL):
• Status of middle ear affects the performance
• Round window placement (type C) depends on the effectiveness of coupling

47. • Adequate coupling-20 dB hearing benefit
• Gain of 30-35 dB for coupling to stapes and 30-55 dB for coupling to RW
• Significant improvement in terms of functional gain, speech perception in noise and
word recognition scores noted with Codacs.

48. WHERE DO MEIS FIT??
Beyond hearing aids…
before cochlear implants..

49. REFERENCES
• SCOTTBROWN 8TH EDTN
• CUMMINGS 6TH EDTN
• COCHLEAR IMPLANTS AND OTHER IMPLANTABLE HEARING DEVICES
• BASICS OF AUDIOLOGY

50. THANK YOU