Our daughter received her first implant shortly after her first birthday back in 1999. Back then, implanting prior to 18 months of age was not common. She lost her hearing due to meningitis as a baby, and her right cochlea ossified (filled with bone) very quickly. Since we wanted to have her receive the implant, the doctors needed to move very quickly to insure a full insertion of the electrode array before her left cochlea ossified. The surgery was a success. Partly because of her prior hearing history, partly because of the early implantation and partly because of all the speech therapy we did with her, she did very well with the implant. Everyone was thrilled with her progress. But that does not mean she had equal access to sound that hearing people have. We were very aware of that, and did our best to give her better access to the language around her. She has no problem when she is with other D/deaf people who sign, and she has an FM system at school. Where she had the most difficulties was in noisy situations, such as the school hallway and the playground. We knew that the people who had gotten bilateral implants generally reported that the bilateral implants helped immensely in noise situations, and helped them in group discussion settings. But with her ossified right cochlea, bilateral success was a big question mark.
We talked it over, and since she was older, felt that she had to be involved in the decision this time around. She wanted to try, and in December 2008 the surgery was performed. Initially, the doctor said that he had gotten half of the electrodes in place, but subsequently, three of them were not able to be mapped. Out of 22 electrodes, she has 8 active. Between that and not having any stimulation on that side for 10 years, we knew that her progress would be slow. But the question still remained. Would she get any benefit from the right implant? The right side was activated in January, and her map stabilized in March. She had her six month mapping check up in early July.
No surprise that her right ear was still unable to understand any of the words in the booth test. With the ossification, and only having 8 active electrodes, she may never be able to use that ear alone to understand speech. Her left ear has 100% understanding in a quiet environment. The real question was how well would she do in noise. With both implants on, the doctor did the test several ways. With the background babble on the right side and the sentences she was supposed to repeat on her left side she tested 12% below normal hearing. When it was switched, and the babble was on her left (good) side, she tested at 13% below normal. When the babble and main voice were equalized, and both sounds were going to both ears (true bilateral hearing) she tested at only 6% below normal hearing.
The audiologist was thrilled with this outcome. She said that it showed that our daughter’s brain was really able to utilize her hearing in her right ear even though she couldn't understand anything in it alone. It also showed that the bilateral hearing was making a big difference when hearing in noise.
We had three things we wanted our daughter to achieve with bilateral hearing that she didn't have with her single implant. Better distance hearing, localization of sound, and better discrimination in noise. All three of those objectives have been achieved, and she has only had her right implant for 6 months. It would be icing on the cake if she could actually understand speech with her right implant alone, but even if that goal is never realized, she has benefited immensely from getting bilateral hearing, and we are thrilled with her progress.
K.L.
