The Baha System for Unilateral Sensori-Neural Hearing Loss
Unilateral sensori-neural hearing loss, also known as single-sided deafness (SSD), is underestimated and often untreated in adults and children. Conventional treatment includes; use of contralateral routing of signal (CROS) air conduction hearing aids, or powerful ITE or BTE aids with transcranial routing of the signal from the deaf side to the normal ear.
Although CROS aids effectively deliver sound to the deaf ear, they also present disadvantages; such as the normal hearing ear s generally occluded with a microphone/transmitter, which potentially impacts that ear's natural hearing capabilities, and comfort may also be a factor. Patients report CROS aids are cumbersome and are dissatisfied with having to wear prosthetics on both ears, rather than just one. For these reasons many patients reject CROS aids. Studies have shown CROS aids are not typically utilized by children in the classroom. FM systems are generally considered more beneficial than CROS systems in educational settings Most children with SSD, are unfortunately, not offered any type of intervention except preferential seating, despite studies demonstrating that 30 percent of SSD children will repeat a grade level (Betz, et. al., 1986).
In August of 2002 the Food and Drug Administration (FDA) gave commercial market approval to Entific Medical Systems for use of the Baha System with SSD in candidates five years of age and older.
The Baha System is an implantable hearing system that uses direct bone conduction stimulation. In SSD patients the signal is transcranially routed to the normal cochlea via bone conduction. The result is a more natural sound quality experience, as compared to CROS aids, and the Baha System overcomes the head-shadow effect. The Baha System also eliminates the need for a device in the normal hearing ear.
To be considered a candidate for the Baha System, candidates must exhibit a profound, unilateral sensorineural hearing loss and an air conduction PTA of 20 dBHL or better in the contralateral ear. Clinical studies (Wazen, et. al., 2002) in SSD adults report they prefer the Baha System to CROS aids. Seventy percent report improvement in their quality of life with the Baha System, 88 percent have better performance with the Baha System when conversing with someone seated on their deaf side at a dinner table, and 88 percent report improved performance with the Baha System when speaking to one person in a group of people. These data suggest that SSD patients benefit with the Baha System in many different situations.