This document discusses middle ear implants as an alternative to conventional hearing aids. It describes the structure of middle ear implants, which differ from hearing aids in that they convert electrical signals to mechanical vibrations via a transducer coupled directly to the ossicular chain. The document outlines current implant devices including the Vibrant Soundbridge, Otologics middle ear transducer, and Esteem hearing implant. It notes that initial trials have demonstrated the safety and efficacy of these devices, with medium-term data suggesting maintained benefit and high patient satisfaction over time.

1. Middle ear implants
Prepared by :
Dr . Sayf M. Dehaies
M.B.Ch.B SHO ORL-HNS

2. Scott-Brown's Otorhinolaryngology, Head and
Neck Surgery
7th edition
Richard M irving MD FRCS (ORl-HNS)
Consultant in Neurotology
University Hospital Birmingham NHS Trust and
Diana Princess of Wales (Birmingham Children's) Hospital; and
Honorary Senior Lecturer
University of Birmingham
Birmingham, UK
Andrew Scott FRCS (ORL-HNS)
The Royal Shrewsbury Hospital
Shrewsbury, UK

3. Middle ear implants
These are a type of hearing aid with potential benefit over the
conventional one .
Its superior to the conventional hearing aid in the following point :
• Better sound quality , no occlusion effects ,no acoustic feedback.
• More comfortable
• Better cosmoses
• No wax blocking or recurrent OE.
they are not beyond the reach of the conventional hearing aid. i.e. the
patient should be able to hear by the conventional hearing aid but
complaining about the sound quality or comfort or cosmoses ….

4. The current device are most suitable for mild to sever SNHL ,
recently the sound bridge device approved for use in conductive or
mixed losses in combination with passive middle ear prostheses.
ME function should be normal , any ME inflammation should
controlled prior to surgery.
There should be absence of retro-chochlear or central involvement.
The patient should not have any skin condition that prevent the
attachment of any external part.

5. structure
The conventional hearing aid consist from:
• Microphone : receive the sound energy.
• Amplifier or processor unit ( digital or analouge )
• Transmitter or speaker : transmit the sound energy through the normal
auditory pathway of TM & ossicles to the ME.
Middle ear implants differ only in the 3rd part i.e it not
convert the electrical energy from the amplifier to acoustic
energy but to mechanical energy through the TRANSDUCER _
then the mechanical energy is coupled directly or indirectly
to the ossicular chain

6. • Piezoelectric transducer : the piezoelectric
crystal is capable of converting the alternating
voltage from the electrical sound signal from
the amplifier to mechanical vibrating force
that is coupled directly to the ossicular chain.
• Electromagnetic transducer : contain a coil
which convert the electrical signal from
amplifier to electromagnetic signal which will
vibrate ferromagnetic unit coupled directly to
the ossicular chain – so the transducer is not
in direct contact with the ossicular chain.
There are
2 type of
transducer
:

7. Current device :
Vibrant sound bridge :
• developed by Symphonix and currently by Med-El
• is an active semi-implantable electromagnetic hearing device.
• It consists of an internal, surgically implanted part - the vibrating
ossicular prosthesis (VORP) - and an external audio processor.
• The VORP is made up of a receiving coil, conductor link and
transducer.
• The transducer have small electromagnetic coil and enclosed
magnet to produce vibrations in this floating mass transducer, which
is coupled to the long process of the incus.

9. • The approach for implanting the Vibrant Soundbridge is similar to that for a
cochlear implant and the siting of the transducer shares similar demands
to stapes surgery
• Different incisions are used
1. extended endaural,
2. postaural or
3. extended postaural
• cortical mastoidectomy is done and then a posterior tympanotomy Which
should be large enough to take a 3-mm diamond burr to ensure sufficient
space to site the transducer.
• An implant bed is drilled in the squamous temporal bone to accommodate
the internal receiver and conductor link.
• The floating mass transducer is placed in the middle ear via the posterior
tympanotomy with its attachment clip around the long process of the incus
using the special forming forceps provided with the implant.
• there is concern about crimping the clip to the long process of the incus. If
the clip is crimped too tightly there is a potential for necrosis of the long
process of the incus, and if it is too loose the implant may fail.

11. Otologics™ middle ear transducer
fully implantable device,
The device consists of a subcutaneous microphone and an
electronic receiver connected to a transducer.
The transducer drives a probe coupled to the body of the incus.
The tip of the probe is made of aluminium oxide and this forms
a fibrous connection with the laser-made hole in the incus body.
The ossicular chain is left intact.
The Otologics MET ossicular stimulator is currently under FDA-
approved clinical trial in the United States.

12. Esteem®-Hearing Implant™
fully implantable piezoelectric device currently under FDA trial .
The device comprises a piezoelectric sensor on the incus body and driver
cemented to the stapes head.
Implantation of the device require disarticulation of the ossicular chain with
removal of the lenticular process of the incus.
DEVICES NOT CURRENTLY AVAILABLE
• Soundtec® Direct Drive Hearing System
• Rion partially implantable hearing aid
• Totally implantable cochlear amplifier

13. The initial trail have establish the safety &
efficacy of these device.
Medium term date ( 10 years ) are now available
& suggest that the benefit is well maintained
over time & the patient satisfaction is high.