How do you know when it is time to consider a cochlear implant? Well, the answer to that is constantly changing. When implants were first developed the only candidates were people with very profound hearing loss who had been hearing impaired since birth. People with better hearing and children were not initially candidates. As implants improved, implant criteria expanded. Children became candidates, adults with better hearing became candidates. Now, in the United States, the FDA rules permit children to be implanted at 12 months. Children between 12 and 24 months who have profound hearing losses are implant candidates, and adults with severe or profound hearing losses are as well.
Many clinicians working with people with hearing loss have thought about expanding the criteria for candidacy. We look at both children and adults with a severe hearing loss and see how they are struggling, and we look at people with profound hearing losses using cochlear implants who are having an easier time. So maybe people with severe hearing loss would do better with implants.
Degree of hearing loss
In the US, at least, we are still only implanting children with severe and profound hearing loss, except for special cases. There are some children with auditory neuropathy spectrum disorder who have hearing thresholds at low intensity levels, but who cannot understand speech because of the ANSD. Many of these children have been implanted and are doing well. There are other children with sloping hearing loss (good hearing in the low frequencies and poor hearing in the mid and high frequencies) who are really struggling because they cannot hear many consonants, which are critical for understanding speech. While these kids are clearly outside the standard criteria for implantation, many have been successfully implanted and are doing very well. So what should we be looking at?
Looking at speech perception
The really important question is, how is the child (or adult) hearing speech? Speech, after all, is the real goal. As I have discussed before, speech perception is critical. The ability to hear high frequencies is critical for perception of consonants (/s/, /sh/, /f/, /th/). So, what is good enough? I like to ask, “Would it be good enough on a math test?” If not, why would it be good enough on a speech perception test!!
What is good speech perception?
Excellent speech perception reveals scores of 90%-100%. Good speech perception reveals scores between 80%-89%. Fair speech perception is 70%-79% and poor speech perception is less than 70%. So if a child has speech perception poorer than 70%, we, as clinicians and parents, need to think that something is wrong and we need to do something about it. What exactly are we going to do? We need to change the technology. It may be as easy as changing hearing aid settings or implementing auditory therapy, but if that does not work, it may be time to consider a cochlear implant. With a cochlear implant we can expect much better access to sound, which should result in hearing more, understanding more, and greater ease of listening–all resulting in improved language and literacy.
Unfortunately, the way most clinical practices work, some audiologists dispense hearing aids and a different group of audiologists work in cochlear implants. As a result, hearing aid audiologists do not get to see how well cochlear implant patients do. When I was working in a CI Center, most of the patients who came in for evaluation told us that their hearing aid audiologist told them that they were not implant candidates but, in our opinion, they clearly were. Unfortunately, this means the responsibility falls on patients to do the research and determine if they are possible implant candidates and then seek out services. It is also the responsibility of everyone who works with children with hearing loss to be sure we keep up to date.