Visual Acuity in Children with Hearing and Vestibular LossKristen Janky, Au.D., Ph.D., CCC-A, Vestibular Audiologist
The vestibular system is responsible for decoding any sort of movements, so head movements, when you’re walking, and just sort of keeping the body balanced. But the primary responsibility is keeping vision steady during any type of head movement.
A lot of effects of vestibular loss have been measured in adults and very few have been measured in children. So we are looking at how well children who have vestibular loss can see when their head is stable and when their head is in motion.
Typically we see vestibular loss more often in children who have greater degrees of hearing loss which is why we are studying children with cochlear implants because they have a large degree of hearing loss which is necessitating the cochlear implant.
There are actually three different tests that we do. One is called the video head impulse test and that is where the subjects will wear very tight fitting goggles and we stand behind them and move their head very rapidly.
Then we do something called the vestibular evoked myogenic potential and that’s where we put electrodes on the neck, under the eyes and then they listen to loud clicking sounds while they either look up or lift their head.
The then the last test is going to be the rotary chair test where they sit in a chair in a darkened booth and the chair just rotates back and forth. All those tests look at the vestibular system in a different way and let us know if it is functioning or not.
After we determine whether they have vestibular loss or not then we put them through a functional assessment first of all just looking at how well he can maintain his balance. The purpose of that is to see whether vestibular loss disrupts balance, does it disrupt walking, does it disrupt your ability to do more than one thing at a time. And then the last thing is looking at how that affects how well you can see.
So we were asking him to watch visual targets while he was sitting still and then watching visual targets while he moved his head back and forth to see if there is disruptions in how well he can see.
The overall goal is to determine whether or not we should be paying attention to the vestibular system particularly in kids with hearing loss. So much rehabilitation is directed towards the hearing part which addresses speech and language concerns but there is some research that is showing that we need to be paying attention to vestibular side of things because disruptions in the way that we see during head movement can potentially affect academic performance.
We are hoping that it generates awareness for one assessing for vestibular loss in children and the second thing then is to get children enrolled in vestibular rehab programs. Our research then will eventually look at outcomes of whether rehabilitation corrects some of the abnormalities we see with vestibular loss.
In addition to hearing loss, children with cochlear implants may also have vestibular loss, which can result in gross motor developmental delay and reduced visual acuity. This project examines how often vestibular loss occurs in children with cochlear implants, and the relationship between vestibular loss severity and functional decrements. These results are expected to influence the identification and habilitation of vestibular loss in children with hearing loss.