Progressive Hearing Loss:
What We Know Now
When our daughter was four years old, she suddenly dropped between five and ten decibels of hearing across her audiogram. We thought she was just a busy four year old at first, but gradually saw that she didn’t hear as she used to hear with her aids. She was dropping speech sounds she had begun to master, but more critically, she was far more frustrated with her world. She had been at nearly a flat line of 80-85 decibels (dB), but now that line dipped to 90 - 100 dB. We heard for the first time the term..."progressive hearing loss." We had never thought to ask if her hearing loss would progress, as it already seemed “pretty darn deaf” to us. We found ourselves rethinking and re-evaluating all of our choices. In that instance, better equipment was one of the solutions. Later, at age seven, she informed us one day that she couldn’t hear a thing, and somehow she knew it was not a matter of fixing a hearing aid. I can't imagine what our daughter went through. Imagine being able to hear at a certain level one day, and then inexplicably that is all changed on the next day. It seemed to me at the time that nearly half of all families I met that year (with children who could lose more hearing) had experienced some level of progressive hearing loss during early childhood. I shared our story and the perspective of other families in the article “A Fork in the Road: Progressive Hearing Loss” (http://www.handsandvoices.org/articles/misc/prog_loss.html) quite a few years ago by now.
This past year, researcher Dr. Christie Yoshinago-Itano and her team learned more about progressive hearing loss and shared their findings recently at the national Early Hearing Detection and Intervention (EHDI) conference. We have had almost twenty years of newborn hearing screening and follow up information on children now, giving researchers more insight into progressive hearing loss. Before this study, we didn’t have a good answer to a parent’s question about whether or not their child might be at risk for progressive hearing loss. We have more information we can share with parents today through the information found in this longitudinal study.
Description of the study
The study involved children with bilateral hearing loss, including permanent conductive, sensorineural and mixed hearing losses, and all degrees of hearing loss between the ages of birth to 36 months who received early intervention services when the children were birth to 36 months of age. The study included children across all cognitive levels including children with additional disabilities, and all children in this particular study were from English-speaking homes. Data was collected on children from 1985 to 2011, from birth to age seven. This study did not include children with unilateral hearing loss or auditory neuropathy.
What is progressive hearing loss?
The term just means that hearing loss has increased at some or all frequencies. (“Why is it called “progressive?” asked my older son, “when her hearing is worse?” He thought progressive sounded like a good thing, and that severe sounded “worse” than profound, as well. I tend to agree.) A progressive loss doesn't necessarily mean that hearing continues to drop, as some children lose some range but then achieve a new stable level. Others continue to fluctuate in their hearing, including fluctuating up, as our daughter did. Some progressive losses are rapid, such as with LVAS or Enlarged Vestibular Aqueduct Syndrome, where a significant fall or bump on the head can change hearing. For purposes of this study, a progressive hearing loss (PHL) was defined as a drop of 15 or more dB in the better ear at two or more frequencies, or one or more frequencies testing at a drop of 20dB poorer than previously tested.
Who is at risk for progressive hearing loss? More than 400 syndromes are known to be related to hearing loss with many of these causing progressive losses. We know that certain medications, illnesses, and even noise exposure can increase a child’s chances of progressive loss. Children with unilateral hearing loss are at risk for progressive and/or bilateral loss, as well. See the sidebar for types of hearing loss or related conditions, or even medications and infections that are known to correlate with progressive hearing loss.
A word about feelings
The whole experience of having a sense that can be relied upon one day and is diminished the next is bound to create some frustration, fear, and sadness in the child, parents, and close friends and family. “I try to let parents know that while a progressive loss is difficult for them (and sometimes a nightmare for them) to try not to live in fear,” said Stephanie Olson, Family Consultant for Children’s Hospital Colorado and a deaf professional herself. “Be sure to praise and compliment your child on the good job they do in the sound booth. Kids don’t want to do “worse;” they want to do better and please their parents. That can’t always happen BUT they can do better on other things in the appointment. There is nothing worse than watching a child watch their parent cry because the hearing loss is worse.” It can be helpful to seek out new connections with other families and deaf/hard of hearing adults who have also had a progression or who have a similar level of hearing loss as your child now does. For an older child, writing a journal about their experience might be a good outlet, too. There is hope; there is adjustment; there is life beyond any audiogram.
Parents can expect a child who is used to a certain amount of hearing and was using it well to be more tired when those levels drop. Visual communication, listening breaks, reducing background noise, and making sure you get a child’s attention before sharing any conversation or a hug can be so helpful at a new baseline of hearing. Experienced professionals on your team can help you “see” what has changed, so you can adjust your communication style to better match your child’s new circumstances.
What was learned
For the 853 children in the study between 1985 and 2011, 768 had a stable hearing loss, and 85 had a progressive loss. Certainly more study needs to take place, but it was notable that looking across all ages, a smaller percentage of children had a progression of loss between birth and seven years of age in the mild to moderate range: 0 .9% with mild hearing loss, 4.3 % with moderate HL, and 12.3% in the moderate severe range.) As the hearing loss level becomes more moderate-severe-profound, the rate of hearing loss progression goes higher, with the highest percentage being almost 23% for children in the severe loss category and 15.9 in the profound loss range. Also notable was that more children experienced that progression between three and seven years of age than during the first three years of life. In the longitudinal study, 20.5% of children (in this birth cohort) had a progressive hearing loss between birth and seven years of age.
With more study, it might be possible for professionals to narrow down more information about whether a type of hearing loss is stable as opposed to fluctuating and/or progressive so that parents have a bigger picture about what lies ahead while making the choices for communication in the present. What we know now about progressive hearing loss is that it occurs more frequently that previously suspected, and that progression is more frequently documented between three and seven years of age. A conservative estimate is that 20% of families can expect some progression in a child’s hearing loss. Parents should know that this is a possibility for their child, depending on related factors. That little bit of knowledge may better inform parents in their decision making until those kids can take their place as the decision makers in their own lives.
Action list for parents:
- Use the six Ling sounds /m//oo/ /ah/ /ee//sh/and /s/; plus the additional /p/, /t/, /k/, /f/, /d/, /g/ sounds to check your child’s hearing regularly. This can give your audiologist valuable information.
- Compare audiograms to the first reliable test and to others over an extended period of time, instead of comparing just the two most recent audiograms.
- Ask questions of the audiologist. If the audiologist reports that it was a “good test” or that the child "really well," a parent might ask for clarification. Sometimes these comments are often interpreted by the parents to mean that the hearing has improved, when in fact in some instances the loss has actually progressed. The audiologist might be generally referring to the reliability of the test and the good cooperation of the child for the test itself, and not indicating that hearing is improved or stable. It’s always good to make sure we are on the same page in communicating.
- If you suspect a progressive hearing loss, do what you can to work through any potential feelings of grief or panic so you aren’t causing your child to feel unsettled. We can’t always be prepared for this, but there is a small person who is looking to us as his or her parent for guidance in how they themselves should react. Of course emotions are healthy and normal, but intense acting out of feelings by a parent can put the child in an awkward position of feeling the need to comfort or soothe the parent.
- Make the hearing tests a positive experience as much as possible. Plan something fun to reward all that hard work. Many children are highly tuned in to visual cues, so they’ll see marks being made on a paper and think they are failing. Maddie’s audiologist let her know that she has to write down everything, not just the “right” or “wrong” notes. I remind myself that I am not a fan of going to eye exams, since I am not good at them. (I should invite my daughter along to see that, actually.)
- Six month or even more frequent hearing tests may be recommended instead of the more typical annual exam. This is important in terms of both understanding what your child can hear unaided in the environment, as well as reprogramming hearing aids if that is a choice for your family.
- When considering hearing aids, consider the most flexible gain possible in the new aids.
- Know your child's audiogram and functional listening level in real life.
- Discuss the possibility of changes in hearing with an older child. Connecting to role models and peers can be so beneficial.
- Always be open and flexible about communication modes - let your child's personality, strengths and situation take a lead in the discussion.
Causes of Progressive Hearing Loss
Of the causes of hearing loss, we know that about half have a genetic cause, and about 30% of those have a syndrome related to the hearing loss, or roughly 15% of the time. These syndromes can be related to progressive hearing loss: Waardenburg, BOR, CHARGE, Stickler, Neurofibromatosis Types 1 and II, Usher, Pendred’s, Jervell-Lange-Nielsen, Cockayne, and Alstrom syndromes.
Non-syndrome related hearing loss can also be progressive, as in Connexin 26, Enlarged Vestibular Aqueduct Syndrome, and X linked hearing loss (attributed to 2-3% of children with hearing loss) and Alport syndrome.
Infections occurring at birth (congenital) or occurring later (acquired) can cause a progressive hearing loss. Intrauterine infections are the most common. TORCH is another, which is an acronym for a group of diseases that cause congenital conditions if there is exposure to the baby during pregnancy. These include toxoplasmosis, syphilis, mumps, HIV or parovirus B19, rubella, cytomegalovirus (CMV) or herpes simplex. Acquired infections can include bacterial meningitis, herpes simplex and herpes zoster among others. Neurodegenerative disorders, such as Hunter or Charcot-Marie-Tooth syndrome, are another risk for progressive hearing loss. Chemical exposure, viruses and strokes can cause other neurodegenerative disorders.
CMV can only be tested within a very short time after birth. Should all babies who refer on the hearing screening be tested for CMV and other infections, potentially reducing the severity of a potential hearing loss, if treated? That’s a current question being debated.
Autoimmune inner ear disease (AIED) is described as a progressive hearing loss and can occur as a result of immune-medicated diseases found in Cogan’s syndrome and other autoimmune pediatric disorders. AEID typically affects young children and is an uncommon symptom in childhood.
Late-onset or progressive hearing loss can be due to factors such as noise exposure or teratogens. Ototoxic (dangerous for the ear) drugs may be used in the neonatal period to fight infections. Ototoxic drugs generally, but do not always, cause permanent bilateral, symmetrical sensorineural hearing loss. Children may also experience vertigo, nausea and walking difficulties. Certainly illnesses requiring these medications can be life-threatening, and no one would suggest not prescribing them for children, but hearing should be assessed regularly if a child is receiving and of these known ototoxic treatments:
- The use of aminoglycoside antibiotics, such as kanamycin, neomycin, and gentamycin are commonly used antibiotics, however additional antibiotics such as vancomycin, amikacin, and tobramycine have also been noted to cause threshold shifts in hearing. Aminoglycosides are the most common and widely used antibiotics as they are efficient antibiotics and are available at a low cost Aminoglycosides are both ototoxic and nephrotoxic, or dangerous for kidneys.
- prolonged use of nonsteroidal analgesic anti-inflammatory drugs,
- chemotherapeutic drugs, containing platinum, such as cisplatin and carboplatin are some of the known ototoxic causes of hearing loss
- quinine and loop diuretics (Newton, 2001)
Additionally mitochondrial mutations (e.g. 1555A) responsible for variations of ribosomal RNA sequences may result with some individuals being more susceptible to hearing loss due to hypersensitivity to aminoglycosides
Noise: The American Academy of Pediatrics note that infant’s exposure to noise in the neonatal intensive care unit (NICU) may result in cochlea damage and may disrupt normal growth and development in premature children. Some evidence indicates that noise exposure and the use of ototoxic drugs such as Aminoglycosides are synergistic in producing auditory damage.
There is evidence that supports the association of hearing loss with perinatal problems and problems around the time of birth. Newborns with the following conditions or circumstances are particularly at risk for progressive hearing loss:
- persistent pulmonary hypertension (PPHN) associated with mechanical ventilation,
- low Apgar scores,
- low birth weight and
- persistent mechanical ventilation or oxygen treatment.
- A stay in the NICU due to coexisting risk factors of hearing loss (such as any of the above, i. e. medication, oxygen needs, noise, etc.)