My baby, who is now almost 4 months old, is being followed due to suspected hearing loss. She has had 3 rounds of objective hearing testing using and .
The first test was made around 1 month, second around 2 months and third around 4 months. But the results have been surprisingly different each time.
At her first test, her right ear was around 25-30 and her left ear around 30–55 dB.
At her second test about a month later, her right ear appeared normal/almost normal (around <20–25 dB), while her left ear suddenly measured around 55–75 dB.
She has now had her third ABR/ASSR test, and strangely, the results have almost flipped. Her right ear, which previously appeared normal/almost normal, is now measuring around 60–80 dB, while her left ear has improved to around 35–50 dB.
We’re obviously continuing the evaluation with her doctors and audiologists - next time she will be sedated instead of just falling asleep on/off during the test, but we’re struggling to understand how objective tests like ABR/ASSR can fluctuate this much between appointments. And also very sad for our daughters future.
Have they performed a click on your daughter? This is required to rule out auditory neuropathy spectrum disorder which can result in very strange ABR results.
Have each of these tests been performed by the same audiologist using the same equipment?
Yes, they have performed that. The follows the results quite well for both ears.
It has been a new person performing the test each time. The two first times I believe it was with the same equipment, the third time it was in another room - the same test but I believe not the exact same equipment as the probably used what was in that room.
Which country are you based in? Was the click normal? Has there been any middle ear dysfunction during testing that might cause a fluctuating hearing loss?
From what I understood the click was not normal. At the last test the right ear ABR threshold was around 70 nHL (65 dB eHL), and the left around 60 dB nHL (55 dB eHL). The on the same day was 60–80 dB eHL on the right and 35–50 dB eHL on the left.
The middle ear testing was normal (1000 Hz showed type A curves bilaterally), so they don’t think middle ear dysfunction explains the current results. Bone-conduction ABR also showed no response at the maximum level tested (50 dB nHL).
What is confusing is that the right ear had previously tested normal/nearly normal on two occasions. At the previous test, for example, right click ABR was around 25 dB eHL and ASSR was around ≤20–25 dB eHL. The left ear has also varied between tests.
From what I understood the click ABR was not normal.
This is an indication that Auditory Neuropathy Spectrum Disorder () is possible which can explain a fluctuating sensorineural hearing loss. ANSD can have many potential causes and often results in poor synchronisation of auditory nerve firing which negatively impacts electrophysiological measures of hearing like and which depend on measuring synchronised repeatable response to sound.
Unaided cortical evoked auditory potentials (CAEPs) are the best way of estimating hearing thresholds with ANSD because these higher level responses are less dependent on a high level of synchronisation within the auditory system. Aided CAEPs can be used to measure benefit with and adjust hearing aids. CAEPs are done when the child is awake and relaxed.
If objective benefit using CAEPs is not clearly and reliably demonstrated with hearing aids in children with ANSD moving to cochlear implantation before 6 months of age provides the best language outcomes according to the population-based Longitudinal Outcomes of Childhood Hearing Impairment (LOCHI) study being conducted in Australia. They have the largest single cohort of children with ANSD diagnosed through newborn hearing in their study so much of what we know about ANSD in young children comes from this study.
If aided benefit is demonstrated, but speech and language development isn't progressing the research supports switching to quickly, as once delays set in they tend to only grow over time.
Children with ANSD can achieve good life outcomes with the right support, but every journey is unique to the individual child and their family and the diagnosis comes with many more uncertainties that are worked out over time that you don't get with many other types of congenital hearing loss. It also requires more intensive monitoring and testing due to the uncertainties that come with many cases of ANSD.
Having a clear plan of next steps including specific goals and accepting that not meeting these doesn't indicate failure but a need to change strategy can help deal with the uncertainty by giving you concrete things to observe and tasks to perform. If things go great and rapid progress is being made that's fantastic. If things aren't going great that is also helpful in informing the next steps.
I think the most important thing for the next testing is that they repeat the click-ABR using protocols designed to rule out or confirm ANSD. They should also be performing acoustic reflex testing. If ANSD cannot be ruled out, then they should be quickly switching to CAEP testing, which may involve referral to a different specialist center as not many places have the necessary equipment or expertise to perform this testing. As I don't have access to the results I cannot really comment as to whether sufficient information is already available for such a referral to be made, but if there was I would be making a referral now.
I should also note, that poor synchronization of auditory nerve firing leading to fluctuating hearing also prevents the language areas of the brain from developing as they don't have a consistent input signal for the pattern recognition required for learning language to take place. So even if a child with may appear to respond to soft sounds it doesn't mean their hearing is sufficient for language development. More intensive language development monitoring, especially early language is required to track progress.
Do you guys use ? I find international differences interesting. We primarily use for infant assessment. I wonder why the difference.
In the last year our protocol has changed to include genetic testing for otoferlin in which case those babies are getting gene treatment, the other ANSD babies wait to six months for behavioral assessment before determining first steps for amplification. I suppose it hasn't changed in that they were always getting genetic testing, it's just been expedited and waited for in advance of other options.
In the last year our ANSD protocol has changed to include genetic testing for otoferlin in which case those babies are getting gene treatment, three other ANSD babies wait to six months for behavioral assessment before determining first steps for amplification.
We're not using here. With confirmed diagnostics shifts straight to unaided CAEPs, aiding measured thresholds if any and if aided CAEPs aren't providing audibility of modified speech phones across the speech spectrum even with fully optimized devices the children were going directly to cochlear implantation before 6 months of age. I'm not sure what is happening re: otoferlin testing and gene therapies down under.
It looks like the gene therapy treatment can still be performed following cochlear implantation so I suspect that the standard treatment course will proceed until regulatory approval is given for the gene therapy. Cochlear implants can be removed if necessary. At present only a small number of Australian children have taken part in trials. The results have been mixed. One child had measurable hearing but it was still severe to profound and this degree of loss on average does better with a anyway. For other children in a global phase 1/2 trial the results were more promising with a number slowly developing normal or near normal hearing.
From what I understand there are some not responding well to the gene therapy. They are not yet sure why. For the others the results so far are positive. This may vary as there are several therapeutics being trialed by different companies. Some Australians have opted to pay to have the therapy in the US where the therapeutic is currently free from the manufacturer but the medical costs of the procedure are not free.
When is removed isn't there often still damage to residual hearing?
When CI is removed isn't there often still damage to residual hearing?
With there is often no hearing that is useful for speech and language development prior to insertion, so this isn't as much of a concern. There is a fixed neurodevelopmental window for speech and language development and you need to optimize for this. There is a significant risk that gene therapy could fail or not provide much benefit and you lose time that you cannot get back for early speech development.
Whether a CI gets removed with gene therapy success is also another question that needs answering. It may be safer to leave it in place.
There is prelingual and postlingual period in childhood. It is very important to perceive speech cues during prelingual period.
This is so important that sometimes it is necessary to decide to have a cochlear implant early, otherwise there is a risk that the child will never fully develop language skills, which may indirectly translate into intellectual and social development as well as living comforts in negative way.
There is prelingual and postlingual period in childhood.
The specific term is "critical period" for speech and language development rather than "post-lingual" as language development continues throughout adolescence.
The critical period is is a time-fixed neurodevelopmental period. The fundamentals of language development occur during this window and when it is ends it is significantly more difficult --> almost impossible to acquire certain skills.
This critical period includes windows for the development of specific auditory: linguistic skills which is why it is considered so important for cochlear implantation to occur prior to six months of age as after this there will be delays in early language development that push out subsequent language milestones. If too many are pushed out beyond the end of the critical period children may never catch up.
This is why hearing loss in young children is treated very seriously and in many cases as an emergency that needs urgent attention. The critical period may seem long, but there is a lot that needs to happen within it.
Language is the foundation of cognition and communication so it is critical that a child learn some form of language during this time. If an auditory:oral path isn't possible due to technology access or failure of technology sign language should be used.
The specific term is "critical period" for speech and language development rather than "post-lingual" as language development continues throughout adolescence.
I agree that term "critical period" is more adequate than "prelingual" to emphasise its crucial role to neural development. Language matters.
Thanks, that explanation is more for the OP than anyone else as this discussion has veered away from their child but it is still very relevant to them.
Poland