My baby failed the hearing screening so she is deaf, right?
This Ask the Expert article is a follow up to “Screening Newborns for Hearing Loss,” by Dr. Kirstin Chiasson. See that original article for a description of the newborn screening process, and for her amazing credentials.
Her follow up article, here, describes the next step if your baby “refers” on that newborn screen:
Guest Article by Dr. Kirstin Chiasson
Screening is a way to find babies who are at risk of hearing loss without doing a complete hearing test on every baby. Screenings only have two outcomes, a “pass” (low risk of hearing loss) or a “refer” (risk of hearing loss).
Hearing screenings are very accurate, but not 100% perfect.
There will be some babies who “referred” on the screening but who turn out to have normal hearing.
If you baby is “referred” based on their newborn hearing screening, you need to schedule a follow up hearing evaluation.
The goal of the first hearing evaluation appointment is to find out which babies referred on the hearing screening but have normal hearing, and which babies referred on the hearing screening and really have hearing loss.
How do you test my baby’s hearing? He can’t even sit up by himself!
Testing for hearing loss from the age of newborn to 6 months (or until the baby can hold his or her head up without help from mom or dad) is done by checking different parts of the hearing system anatomy, and determining if each part is working.
The hearing system is made up of the outer ear, the middle ear, the inner ear, and the hearing nerve.
The Outer and Middle Ear
The first part of the hearing system is the outer ear. The audiologist will use a magnified light (otoscope) to look into the ear canal. Looking “in the ear” allows the audiologist to determine if the ear canal and the ear drum (tympanic membrane) look normal.
There are three bones (ossicles) behind the ear drum that lead to the inner ear. [The audiologist cannot actually see these ossicles.]
However, the ossicles have to be able to vibrate so that sound can be carried from the air into the inner ear. A tympanometer is used to check the vibration of the ear drum and the three little bones. A small rubber tip is placed in the baby’s ear. A tone is played into the ear canal. A microphone reads how much of the tone bounces off the ear drum. This test evaluates the ability of sound to move from the ear canal to the inner ear. If there is a problem with the ear canal, the ear drum, or the three bones, there may be a hearing loss. This kind of hearing loss is called “conductive.” Conductive hearing loss can often be fixed by surgery.
Examples of Conductive Hearing Loss:
- An example of a conductive hearing loss can result from too much wax (cerumen) in the external ear canal.
- Another example results from fluid accumulation in the middle ear space, behind the ear drum – this is the typical temporary hearing loss common in children with recurrent or chronic ear infections.
The Inner Ear and Hearing Nerve
The outer and middle ear help the sound get from the air to the inner ear. The inner ear codes the sound for pitch and loudness. After the inner ear codes the sound, the hearing nerve sends the code up to the brain.
There are several different ways to check the inner ear and the hearing nerve.
Otoacoustic Emissions Testing (OAE)
When sound is played and is sent up to the brain, the brain tells the inner ear to listen more carefully. When the inner ear takes action and listens more carefully, a different sound, or echo, is actually created by the ear. This sound echo that is created by the ear is called an otoacoustic emission. OAE’s can be detected by very sensitive microphones.
Otoacoustic emissions testing is done by placing a small tip in the ear canal that has a speaker and a microphone. The speaker plays a tone or group of tones, and then the microphone measures the sound that the inner ear makes when it takes action to listen carefully. If we are able to record otoacoustic emissions, that tells us that the inner ear is probably coding sound the way it should.
Auditory Evoked Potential, or Auditory Brainstem Response (ABR)
The auditory evoked potential has many names and abbreviations. The most common is the auditory brainstem response, or ABR.
This test is like an EKG of the hearing signal as it moves through the hearing system to the brain. Small silver electrodes are taped behind the baby’s ears and on the baby’s forehead. A small speaker is placed in the baby’s ear and a clicking sound is played. When the hearing nerve fires it puts off electricity. The ABR is a measure of the electricity that the hearing nerve puts off each time a click is played to the ear. The audiologist will determine if the hearing nerve is responding to the click at a normal loudness.
If the inner ear or the hearing nerve is not working there may be a hearing loss. This type of hearing loss is called “sensorineural hearing loss,” and typically cannot be fixed with surgery. There are many potential causes of sensorineural hearing loss, all rare.
What Happens If My Baby Doesn’t Have a Normal Hearing Test?
If your baby does have hearing loss, your audiologist and otolaryngologist (ENT doc) will work with you and your family to make sure that your baby has as much access to communication as possible.
Note that sensorineural hearing loss can range from very mild – barely detectable – to profound deafness (rare). So don’t freak out if you are told that your baby has hearing loss. It will be difficult, but try to listen to the rest of what the audiologist and ENT doc are saying.
Your audiologist will help you assemble a team of professionals who are focused on your baby’s communication. The team will include an ear nose throat (ENT) doctor, a speech language pathologist, an early intervention specialist, your baby’s primary care doctor, and possibly a genetics or family counselor. Each member of the team will help you manage your child’s individual needs.
The genetics counselor can provide a good idea of whether your baby’s hearing loss is inherited and, if so, what the chances are that you may have other children with similar hearing loss.
The thing to remember is this: the goal is for your baby to grow up having normal ability to communicate, normal speech and language.
Special thanks to Dr. Chiasson for contributing. The next installment on this topic will review some of the most common misconceptions about hearing loss in children. Stay tuned.
Image Credit for Newborn Screening Pic: http://www.flickr.com/photos/blackdutchdoublelibra/
Review of “Newborn Hearing Screening” by A. M DeMichele, PhD, on eMedicine: http://emedicine.medscape.com/article/836646-overview
Hi, I’m Russell Faust, author of this medical education blog.
Let me know what topics are important to you and your child’s respiratory health. Join the conversation by leaving a comment / reply below, or email me any time.
Thanks for visiting, see you here later – we will be going into more detail on how to rid your children of allergies, rhinitis, sinusitis, and other chronic aero-digestive inflammatory disorders on this site.
If you are interested in these topics, please click here to subscribe to this blog (it’s FREE).
Be sure to type in your best email address (the one that you actually use). You will then receive an email with a “confirmation link” – click on that link to get weekly updates from this blog in your email.
It’s free, it’s convenient, it’s an easy way to stay up-t0-date on information to keep you and your family healthy. You can un-subscribe at any time.
Until next time, remember … you can pick your friends, and you can pick your nose, but you can’t pick your friend’s nose (unless you’re a boogor doctor ;~D)