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As printed in Hearing Health, volume 20:3,
Fall 2004
By Richard A. Roberts, Ph.D., FAAA
Although alternatives for managing hearing loss are
more plentiful and sophisticated than ever, many people
remain who do not benefit from standard medical intervention
nor do they perform well with conventional hearing aids.
For some, the BAHA® system fills the bill.
A one-of-a-kind treatment option, the BAHA system works
through direct conduction of sound energy via the skull
bone to a functioning cochlea in the inner ear, bypassing
the outer and middle ear. Developed in Sweden and available
abroad since the late 1970s, the implantable system
received clearance from the Food and Drug Administration
(FDA) in 1996 for use in adults and in 1999 for children
aged five and older. In 2002, it was cleared by the
FDA for individuals with unilateral severe-to-profound
sensorineural hearing loss (SNHL), also called Single
Sided Deafness (SSD). And the BAHA® Softband, which
does not have an implantable component, is available
for children under five.
The versatility of the BAHA system technology enables
hearing healthcare professionals to offer this unique
solution in an expanding variety of cases. Because it
does not have an in-the-ear component, the BAHA system
may be the only alternative for people who have a missing
ear canal, chronic outer or middle ear infection or
another condition that keeps them from wearing a traditional
hearing aid. It works well for people with conductive
hearing loss, usually due to impaired function of the
middle ear. It also works well in cases where moderate
SNHL is mixed with a middle ear condition. And for people
with SSD, the BAHA system is a real breakthrough.
Hearing technology based on bone conduction is a concept
that is far from new. According to the American Academy
of Otolaryngology-Head and Neck Surgery, bone conduction
devices have been tested since the 16th century, all
seeking a way to transfer sound to the inner ear by
vibrations in the bones of the skull.
The BAHA system takes bone conduction a step further
by including a titanium implant that is placed in the
mastoid area of the skull behind the ear. This provides
effective sound transmission by bypassing hair and skin
tissue and allowing vibrations to pass directly into
the bone.
The surgical procedure required to place the implant
is minor, usually consisting of one step in adults and
performed on an outpatient basis. During the first three
months after surgery, the implant forms a permanent
functional bond with living bone tissue through a process
called osseointegration.
When osseointegration is complete, the individual
receives a small sound processor that snaps easily onto
a tiny portion of the implant that remains outside of
the skin. The processor collects sound waves and the
BAHA system user begins to hear and understand natural
sound immediately as it is received via direct bone
conduction. People with mixed or conductive hearing
loss can benefit from unilateral or bilateral fittings
of the BAHA system.
For the littlest users, the BAHA Softband uses an
adjustable elastic headband to hold the sound processor
comfortably in place against the skin. This alternative
allows children to benefit from indirect bone-conducted
sound until they are old enough to receive the complete
system.
Individuals with SSD receive a unilateral fitting that
transmits vibrations to the functioning inner ear on
the opposite side. For them, the BAHA system represents
an effective alternative to what has traditionally been
the only treatment available, CROS (contralateral routing
of signal) hearing aids that rely on technology that
delivers amplified sound to an earmold in the opposite
ear.
In a 2003 comparison study conducted by John Niparko,
M.D., Kenneth Cox, M.D., and Lawrence Lustig, M.D.,
the BAHA system consistently yielded greater perceived
benefit than CROS aids among people with SSD. Findings
also indicated that the BAHA system enhances speech
understanding in these cases.
Available for all users of the BAHA system, a line
of accessories enhances sound quality in a variety of
listening environments. An audio adapter allows direct
input from personal stereos, televisions, etc. A directional
mic improves the ability to understand one-on-one or
small group conversations in noisy settings. A telecoil
unit improves sound quality and speech understanding
in public facilities equipped with assistive listening
systems and when used with personal loop systems at
home. And a Microlink BAHA FM unit receives signals
from Phonak FM transmitters often used in school settings.
Ultimately, the value of any technology is its ability
to make life easier and better. Experiences of thousands
of users worldwide suggest the BAHA system is indeed
a valuable tool for successfully treating hearing loss.
Megan Myers is the public relations
associate for Entific Medical Systems USA, a subsidiary
of the manufacturer and distributor of the BAHA system.
She has authored several articles about the product
and is the primary liaison between Entific and BAHA
system users in the U.S.
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