Bone-anchored hearing device

The bone-anchored hearing device (BAHA) is a new implant system for children and adults who have conductive (middle ear) hearing loss who cannot be successfully fit with hearing aids. Recently this implant also received FDA approval for use in individuals with single-sided deafness. A short, relatively minor surgery is necessary to place the implanted portion of this system behind the ear. The implant is later coupled to an externally-worn speech processor which is removable and worn externally behind the ear.

How the BAHA works

The BAHA works by direct stimulation of the cochlea (inner ear) through a small, surgical implant placed within the skull behind the ear. This implant is made of titanium, a material that permits the patient's own bone to integrate within the implant itself. After the implant has become fully integrated, the patient is able to wear a small, high-fidelity sound processor that can be snapped on and off. This externally-worn processor transmits sounds to the internal implant which, in turn, causes vibrations that directly and efficiently stimulate the inner ear. As a result of this efficient stimulation, excellent hearing can be provided to people who do not have an ear canal and/or a normally functioning middle ear.

The majority of individuals who have conductive hearing loss can be fit with hearing aids or surgically treated via reconstruction of the middle ear structures that bring sound to the inner ear. Traditional hearing aids are referred to as air conduction aids because they transmit sound through air and, therefore, must be worn in the ear canal or attached to an ear mold placed within the canal.

Who are the best candidates for the BAHA?

However, there are individuals who are not good candidates for traditional surgery and cannot be successfully fit with air-conduction hearing aids. For example, many individuals born with a condition known as aural atresia (lack of development of the ear canal) are not candidates for reconstructive surgery, nor can they wear air conduction aids. Instead, they must wear a bone conduction hearing aid that is placed behind the ear, adjacent to the mastoid bone. Bone conduction hearing aids vibrate the skull in order to stimulate the inner ears. They provide distorted, poor quality sound and are uncomfortable to wear. The majority of people with aural atresia are excellent candidates for the BAHA.

In addition to children and adults with aural atresia, individuals who have chronic infection of the ear who cannot tolerate occlusion of the ear canal via a hearing aid, are also potential candidates for the BAHA. Single-sided deafness is the latest indication for the BAHA. The implant is placed behind the deaf ear. Vibrations from the implant's response to sound stimulate the opposite, normal-hearing inner ear. The BAHA has been shown to be more effective for single-sided deafness than a cross hearing aid. Children with single-sided deafness who are having difficulty in school, despite accommodations such as preferential seating or use of an FM system, may benefit from this implant.