BAHA: An Overview

By Bonnie O'Leary

Editor: The Bone Anchored Hearing Aid (BAHA) is a treatment for conductive and mixed hearing loss. Here's Bonnie O'Leary's report on the BAHA Workshop at the 2009 HLAA National Convention.

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This session about the Bone Anchored Hearing Aid, or the Baha(r) system, was a presentation of the National Center for Childhood Deafness and Family Communication: Vanderbilt Bill Wilkerson Center. The speakers were Dr. David Haynes, MD, Andrea Hedley Williams, AuD, and Kristina Rigsby, AuD.

The Baha System has been well recognized for treating conductive and mixed hearing losses since 1977. It is a prosthesis, and it is the only implanted hearing treatment that works through direct bone conduction. It is composed of three parts: a titanium implant, an external abutment, and a detachable sound processor. Bone conduction can be accomplished by conducting sound to the inner ear through the bones of the skull, or through the skull bone bypassing the outer and middle ear and stimulating the cochlea.

Direct bone conduction works independently of the ear canal and middle ear. Its direct transmission gives clear and natural sound. Preoperative testing is possible, the surgery is safe and straightforward, the wearing comfort level is high, and the outcome is predictable.

Osseointegration

When titanium is left undisturbed in bone, it forms an initial bond which will strengthen over time. The term "osseointegration" comes from "os" meaning "bone" and "integro" meaning "renew." It is the process by which living bone tissue bonds with titanium. This is important because the integration needs to be in place before the external processor can be attached.

Surgical and Healing Process

The Baha System is outpatient surgery and relatively non-invasive. The implant is connected to an abutment that will protrude through the skin. A small, hair-free, possibly numb area will remain around the abutment. The dressing and pressure bandage should be in place for one to two weeks following surgery, and it should take about three months for the osseointegration before the external sound processor is fitted for adults. The procedure is different from very young children. The first stage of the process involves drilling holes for the fixture, placing a sleeper receptor under the skin and allowing the skull to continue to thicken. After osseointegration, which can take six to eight months, the "post" is attached during a second surgery.

FDA Clearance

The Baha System was cleared to treat mixed and conductive hearing loss in 1996. In 1999, it was cleared for pediatric use in children age five and older. The Baha System was cleared for bilateral fittings in 2001, and in 2002, the Baha Softband was introduced for children under the age of five. In 2002, the Baha System was cleared for use in patients with unilateral sensorineural hearing loss, also known as single sided deafness (SSD).

Who Is a Candidate?

Persons who could benefit from the Baha system have mixed and conductive hearing loss. They can suffer from chronic otitis media which is an infection or inflammation of the middle ear; they can be born with congenital atresia which is the absence of an external ear canal; they can have cholesteatoma, which is an abnormal skin growth in the middle ear behind the eardrum; they can have middle ear dysfunction or disease, or external otitis. Also, individuals who have acoustic neuroma or have had a labyrinthectomy, can benefit from the Baha.

Studies show that the sound quality of the Baha System is significantly better than hearing aids due to reduced gain, less distortion and fewer feedback issues.

For very young children, the Softband provides excellent audibility compared to conventional hearing aids. It also allows accurate pre-operative testing and evaluation and gives good access to sound while waiting for the implant.

Care and Maintenance

The sound processor can be worn during all waking hours, but it is not waterproof, so it must be removed prior to bathing, showering, or engaging in water activities. The sound processor should never be exposed to extreme heat or cold. It is recommended that the sound processor be removed during contact sports to avoid damage. A safety line is provided to keep from losing the sound processor during physical activity.

Models Available

The current Baha System models are the Divino, the Intenso, and the Compact. There are also accessories available to Baha System users. The Audio Adapter protects the wearer from power surges when connected to external equipment such as personal stereos, MP3, TV, Hi Fi systems, FM and IR systems. And the MicroLink FM Receiver, developed by Phonak, enables wearers to use their Baha System with the Phonak FM transmitters.

To learn more about the Vanderbilt Bill Wilkerson Center, visit www.mc.vanderbilt.edu

For more about the Baha: http://tinyurl.com/ctgql4

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