ready for presentation on 27 sep 2012 Deptt of ENT, NMCH,Patna

1. Bone Conducting Hearing
Aid Solutions
Dr Zeeshan Ahmad Department of ENT,
M.S.(ENT,PGY1) NMCH,Patna.
27-09-2012

2. Hearing impairment is a common
occurence.
Most patients have abnormality of
cochlear function and can be treated by
use of conventional hearing aid.
However, a significant number have
conductive cause.
Many of these can also be treated by
conventional hearing aid but a proportion
do not tolerate mould or insert in ear
canal, so alternative means must be
considered.

3. What is Hearing aid?
A hearing aid is a battery-powered, electronic
device that makes listening easier for people
with a hearing loss. A hearing aid consists of a
microphone, an amplifier and a receiver. The
microphone picks up sounds in your acoustic
environment and turns them into electronic
signals. The amplifier selectively amplifies the
acoustic electronic signals. The receiver is a
very small speaker that changes the electric
signals back to sounds and delivers the sound to
the ear.

4. Consideration in using Hearing aids

6. History
1551- Bone conduction device consisting
of metal shaft or spear.
1670- Sir Samual Moreland, England
invented a large
speaking trumpet.
1892- first patent for electric hearing aid
in the U.S.
1912- first volume control for a hearing
aid.

7. History Contd….
1931- first electric hearing aid eyeglass
patent
1937- first wearable vacuum tube HA in
US
1953- first all-transistor hearing aid
1987- first commercially available
implantable hearing aid system.
1997- FDA approved BAHA®
Recently- Oticon implants

10. Basic Hearing Aid Structure

11. MECHANISM of BONE
CONDUCTION HEARING
Vibration of bone of skull is coupled to
soft tissues of ear canal. More when ear
canal is occluded.
Some of sound energy transmitted
directly to ossicular chain.
Alternate compression and expansion of
cochlear shell by vibratory forces on
bone.

12. The BAHA ®
BAHA® is the trade name
for bone anchored hearing
aid system available From
CochlearTM.

13. BAHA system is comprised of three
parts:
Titaniumfixture(3)
Connecting
abutment(4)
Detachable sound
processor(6)

14. How does it Work?
The processor
receives sound
through the abutment
and sends it to the
functioning cochlea
using the skull as a
pathway to bypass the
outer and middle ears

15. Candidates
Chronic otitis media Acoustic neuroma
Congenital aural Neurologic
atresia degenerative disease
Microtia Meniere’s disease
Cholesteatoma Viral infection
Middle ear Trauma
dysfunction or
disease

16. A photograph from NMCH OPD

17. Prerequisites
Mixed or conductive hearing loss
Bone conduction pure-tone average in the
indicated ear is greater than or equal to 45 dB
HL
Monosyllabic word discrimination score ≥ 60%
For single sided Deafness
For bilateral fittings – candidates must have
symmetrical bone conduction pure-tone
averages between ears
Age > 5 years

18. To anticipate a "high success rate"
with BAHA
Patients should have a PTA less than 45
dB, although improvements in hearing
should still be expected for a PTA of up to
60 dB.
(Hakansson B, Tjellstrom A, Carlsson P: Percutaneous vs. transcutaneous
transducers for hearing by direct bone conduction. Otolaryngol Head Neck
Surg 1990; 102:339-344.)

19. Operative Technique
A. Posterior-based skin flap is elevated
B. Flap is thinned until all hair follicles are removed from
the flap center
C. Soft tissues beneath and adjacent to the flap are excised
to create a smooth transition from surrounding tissue to
the thin central skin flap

20. Operative Technique
D. 3- to 4-mm hole is drilled in mastoid or retromastoid
cortex.
E and F, A countersink creates a recessed surface for
implant placement.

21. Operative Technique
G. The hole is tapped
H. Titanium screw is implanted
I. Titanium screw is tightened in place

22. Operative Technique
H/I. The titanium screw is tightened into place
K. The skin flap is replaced

23. Operative Technique
L/M. Metallic abutment for later attachment of the
vibrating external hearing aid is attached to the screw
N/O. A healing cap is placed to apply pressure to the skin
flap

24. Perioperative Complications with the
Bone-Anchored Hearing Aid
Loss of Skin Graft
Growth of skin graft over the abutment
Implant extrusion
Infection

25. The most important factor in
obtaining a trouble-free bone-
anchored hearing aid (BAHA) site is:
A. Having thin, immobile, hairless skin around the
abutment
B. Using a 4-mm fixture flange
C. Using a longer abutment – The longest
D. Performing surgery in two stages

26. To Prevent Loss of Skin Graft
Have thin, immobile, hairless skin around
the abutment - This allows for placement of
the fixture in a tissue bed that has minimal local
tissue reaction to the implant and thereby
minimizes chance of skin graft loss, infection or
extrusion
Ensure that the skin graft is firmly
attached to the underlying periosteum
Ensure that the fixture and skin
penetrating abutment are firmly secured

27. To prevent growth of skin graft
over the abutment
Use longest implant possible
Obtain adequate removal of surrounding
soft tissue
Approximate the surrounding skin edges
to the periosteum

28. To prevent implant extrusion
Allow patients with poor wound healing and
thin bones to have six months of
osseointegration
Fix any coagulopathies that the patient may
have pre-operatively
Maintain proper hemostasis to prevent
hematoma formation
Use a 4-mm fixture if there is bone still present
at the bottom after using a 4-mm drill guide
Patients with thin, brittle bone should have a
two stage surgery

29. To prevent infection

30. Other complications
Penetration of sigmoid sinus – Insert
bone wax or muscle plug
Brain abscess

31. OTICON PONTO HEARING AID

32. SOPHONO ALPHA 1 SYSTEM

33. THANK
YOU
for patient listening