What is Auditory Neuropathy Spectrum Disorder?
I’m so excited for scientific research to crack the code and be able to pinpoint the site of lesion for Auditory Neuropathy Spectrum Disorder (ANSD). We’re getting closer and starting to realize that certain genetic forms of ANSD are likely not going to resolve/improve (ANSD improves in a very very very very small % of patients). Between that and an MRI to determine if there is a thin or absent nerve we can give slightly better guidance about the plan of action.
Beyond that there can be a lot of gray area and questions marks. Starting early intervention right away is going to be the best thing you can do!
What is Auditory Neuropathy Spectrum Disorder?
Auditory Neuropathy Spectrum Disorder (ANSD) is one of the 4 types of hearing loss (conductive, sensorineural, mixed, and ANSD).
The outer hair cells of the cochlea are “working normally,” or (more accurately) “giving the appearance of working normally,” but there is a problem with how the cells are communicating with the hearing nerve, or how the hearing nerve is communicating to the brain, or somewhere else in this brain pathway that we haven’t exactly pinpointed yet.
Why is Auditory Neuropathy called a Spectrum Disorder?
Auditory Neuropathy Spectrum Disorder Diagnosis
Auditory Brainstem Response (ABR or BAER) Testing
Auditory Neuropathy Spectrum Disorder can be diagnosed in infants with Auditory Brainstem Response (ABR) testing.
High Intensity Click Testing for Cochlear Microphonic Reversal
In infants with ANSD the ABR Wave V (5) is absent or abnormal, but there is a cochlear microphonic reversal when comparing condensation and rarefaction of a high intensity (I use 90dB) click stimulus. Like OAEs this gives the appearance of a functioning cochlear, but does not tell us much about hearing levels or appropriate treatment.
Otoacoustic Emissions (OAEs)
Otoacoustic emissions (OAEs) is also an important part of a comprehensive audiologic/hearing evaluation for babies with ANSD. With ANSD OAEs can be present, reduced, or absent. They often are present at birth (giving the appearance of the outer hair cells working normally), but can diminish over time and become absent.
Present OAEs does not mean a child with ANSD has “hearing” that should be “preserved”
OAEs being present or absent does not help predict how much someone with ANSD hears, will hear, or what the treatment for their hearing loss should be.
Can ABR testing determine the level of hearing in someone with Auditory Neuropathy Spectrum Disorder?
Now comes the tricky part- I can figure out if an infant has ANSD, but an absent/abnormal ABR is how I diagnosed ANSD which means I can’t determine how much hearing loss someone with ANSD has from an ABR.
Levels of Hearing in People with ANSD
With ANSD you can have “normal hearing” (with difficulty understanding in noise), a profound hearing loss, anywhere in between, AND it can fluctuate 🤯.
How to determine what a baby with Auditory Neuropathy Spectrum Disorder hears
We figure out the degree of hearing loss by parent report (sometimes babies with ANSD don’t startle even to loud sounds due to profound hearing losses) and by using behavioral hearing tests which typically start when babies are 6 months old.
Related article: Meleca, J. et al. Outcomes of audiometric testing in children with auditory neuropathy spectrum disorder from the International Journal of Pediatric Otorhinolaryngology Vol 129, Feb 2020.
Treatment for Auditory Neuropathy Spectrum Disorder
The treatments for ANSD include early intervention, hearing technology like hearing aids and cochlear implants (a small # don’t need amplification), and close hearing monitoring.
Should babies with ANSD learn sign language?
Just like kids with profound hearing losses it’s a good idea to at least use some basic signs with kids with ANSD since you don’t know what kind of access to language they are getting when they’re babies. Lots of kids with ANSD are able to listen and speak using hearing aids and (more often) cochlear implants. Signing will never stop that or slow that down 🤗
Related post: How to Learn ASL as an Adult: Resources for Parents of Children with Hearing Loss
Do Cochlear Implants work in people with Auditory Neuropathy Spectrum Disorder?
Lots of people with ANSD do great with CIs, especially if they are implanted early, establish full time use quickly, and receive appropriate follow-up care.
What does Auditory Neuropathy Spectrum Disorder sound like?
Video with simulation of Auditory Neuropathy Spectrum Disorder
Read More Articles about Auditory Neuropathy Spectrum Disorder
Auditory synaptopathy, auditory neuropathy, and cochlear implantation
Evaluation and therapy outcome in children with auditory neuropathy spectrum disorder (ANSD)
Outcomes of audiometric testing in children with auditory neuropathy spectrum disorder