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Nicu Risk Factors For Hearing Loss
If any of the following indicators is present, the newborn/infant is at risk for hearing impairment:
- Birthweight < 1500 g
- APGAR (5 minute) 0-6
- Perinatal TORCHES infection – toxoplasmosis, rubella, cytomegalovirus (CMV), herpes, syphilis (CMV is especially important)
- Postnatal infections associated with hearing impairment, including bacterial meningitis
- Hyperbilirubinemia at serum levels indicating exchange
- Ototoxic medication dosage risk (e.g., double dose error - standard courses of aminoglycoside antibiotics with normal trough levels are no longer considered a significant risk indicator)
- Any condition requiring ECMO (extracorporeal membrane oxygenation)
- Mechanical ventilation > 5 days
- PPHN (persistent pulmonary hypertension) associated with mechanical ventilation
- Indicators of syndromes associated with hearing loss (eg Down, Goldenhar, CHARGE)
- Craniofacial anomalies (including dysmorphic pinna/canal, ear tags)
- Significant head trauma
- Family history of childhood permanent hearing impairment
- Syndromes associated with progressive hearing loss (e.g., neurofibromatosis, osteopetrosis, Usher)
- Neurodegenerative disorders (eg Hunter, Friedreich, Charcot-Marie-Tooth, etc.)
If systematic review for the above indicators is impractical, an alternative approach is to define newborns at risk by the following more global rules:
- Any baby born <= 34 weeks gestation is at risk.
- Any baby born > 34 weeks gestation and who has attended a Level III NICU for MORE THAN 48 hours is at risk, except for babies who have ONLY the following conditions: transient tachypnea of the newborn, transient hypoglycemia, or feeding difficulties.
- Any baby with a craniofacial anomaly (dysmorphic pinna/canal, ear tags) or any manifestation of a syndrome associated with hearing impairment.
- Any baby with a family history of permanent childhood hearing impairment.
If the latter approach is adopted, then clearly if knowledge of any one of the specific risk indicators is available for any individual child, it should set the child at risk regardless of the global rules.
MLH 2001-10-20 NICU risk summary
APPENDIX A
How To Conduct the Risk Assessment For Permanent Childhood Hearing Impairment (PCHI)
- Family History,
- Craniofacial Assessment
During the initial screening appointment, screeners will perform a ‘risk assessment’ to determine if the baby is at risk for Permanent Childhood Hearing Impairment (PCHI) and will therefore need to have hearing monitored periodically following the initial ‘pass’ of the hearing screening.
In this section, terminology will be used that may now be considered inappropriate by health professionals. It is included because the general public may use these terms, or recall their use in the past, which may be informative.
Two risk indicators for PCHI can be assessed during the screening appointment. One relates to family history and the other to anatomical features of the head. The first involves a few careful questions, the other a quick inspection of the baby's appearance. The overall risk assessment should not take more than about five minutes, and typically will take less time. Whatever can be done in five minute is sufficient.
There appears to be no strong reason whether the assessment of these risk indicators should be done before or after the actual hearing-screening test. Whatever comes naturally or seems the most convenient during the individual visit may be the best way.
Risk Indicator 1. Family history of permanent childhood hearing loss.
The mother, according to research, is the first choice to be asked about any family history of PCHI. If both parents are available and seem helpful, better information may be gained by asking both parents together.
Before questioning, the ground is prepared as follows:
"I'd like to talk for a minute about whether there's any history of childhood hearing problems in your family or the family of your baby's father. The reason is that if there IS a family history of certain kinds of hearing problems in childhood, it might be a good idea for us to check from time to time and make sure that <baby's name>'s hearing is fine. Even if we DO find a family history, the chance of <baby's name> having a problem is very, very small. So, is it OK with you to talk about family history?"
The task is to get at the required information and to assess its reliability. The first question asked is
"Do you know if any of <baby's name>'s close relatives have had hearing problems or deafness in early childhood?" By 'close relatives', what is meant is any of the child's brothers or sisters, mother and father, aunts and uncles, maternal or paternal first cousins and grandparents. NO ONE ELSE MATTERS.
'Hearing problems' means any perception or memory of the affected family member having difficulty hearing for a period of years, or having a hearing aid as a child, or being considered or referred to as 'deaf' or 'hearing-impaired' or 'hard-of-hearing' or as having 'problems with his/her ears'.
'Early childhood' means that the problem probably started at age less than about ten years. There is no hard and fast limit, but it does not mean over 15 years.
A possible cause of confusion is that ear infections and other disorders affecting the middle ear (the space behind the eardrum) are common and often cause hearing loss but DO NOT lead to positive risk, because such hearing problems are rarely permanent.
Only permanent hearing loss indicates risk, so if there is any indication of an actual or possible hearing problem, the screener's task is to try and sort out whether the problem was likely to have been due to PCHI or to ear infections.
A strong clue about whether a hearing loss is or was permanent is the affected person having used a hearing aid. However, lack of knowledge about any hearing aid does not rule out PCHI. For example, many years ago some children with PCHI never got hearing aids. New devices such as cochlear implants are definite indicators of PCHI. Usually, if the word 'deaf' is or was used in reference to the affected child, it suggests PCHI, as does any indication of use of sign language or having attended a special school for the deaf.
Reports about hearing problems in more than one close family member increase the likelihood that there is positive risk of permanent hearing loss of genetic origin.
Clues that suggest that a 'hearing problem' or 'ear problem' may have been due to ear infections include recollection of pain, ear discharge, treatment with antibiotics and/or ear surgery to put in 'tubes' or 'grommets'. There may have been a 'no swimming' order. There may have been many episodes, because ear infections often recur in young children.
Remember that even children who have PCHI get ear infections. The question is whether any hearing problem reported is likely to have been EXCLUSIVELY due to ear infections.
To maximize the net benefit from screening, it is important to minimize parental anxiety throughout the processes of testing and risk indicator ascertainment. The screener should always remember that information is being volunteered by the parent(s), not extracted from them. They are not obliged to respond. They should be encouraged gently to do so, if willing, but they should on no account be pressed, especially if there is any indication of reluctance, anxiety or frustration. When in doubt, the parent should be reassured that the matter is not crucial and the screener should move on to the next activity.
Note that the baby may be adopted, or the father may not be known. In the case of adoption, the parents may know little about family history. If the father is unknown, the information will clearly be incomplete even if mom's history is clear and negative.
If there is a clear indication of PCHI, or if on balance it seems very likely that there is or was PCHI, the family history indicator is marked YES. If there is fairly clear recollection and no memory of any problem, AND the information base is complete (both maternal and paternal information known), the indicator is marked NO. In every other case, the indicator is marked UNKNOWN. It can be quite difficult to assess the reliability of the information, especially for the first few assessments. It may be helpful for the screener to think back about his or her own family, and imagine having said what the mother just said. Does it add up to being fairly sure that there was PCHI, or just raising a vague possibility?
There is much clinical experience indicating that for individual screeners, the speed, reliability and ease of determining the quality of the information will increase rapidly over time.
Risk Indicator 2. Craniofacial anomalies or stigmata
Certain unusual features of the face or head are associated with increased risk of PCHI. An example would be low-set ears, skin tags near the ear, eyes of a different color, a white forelock, etc. These kinds of anomalies are quite often associated with PCHI, as a result of genetic or environmental factors affecting common structures during early fetal development. Some of the anomalies may occur as part of a recognized syndrome (e.g., Down, Goldenhar, Pierre-Robin, Treacher-Collins, Turner, Waardenberg, etc).
The screener should carry out a brief and cursory inspection of the baby's head and neck, as the opportunity arises naturally. A detailed, deliberate inspection is not advisable, because anatomical characteristics may be a delicate issue with some parents. A brief check for obvious anomalies is all that is needed. This physical inspection is limited to what is immediately observable in the head and neck area. It will not be necessary for the screener to develop a detailed knowledge of craniofacial anomalies.
If any of the key characteristics is clearly apparent, the risk indicator is positive. Otherwise, it is considered unknown, because the physical examination is not exhaustive.
An important area in relation to this risk indicator is that of parental awareness, anxiety and sensitivity. A given anomaly may have many possible etiologies. Parents may or may not be aware of the anomaly or even of a syndrome, given that some syndromes can vary in their level of expression in the individual, and also that professional awareness of the significance of isolated anomalies may be limited. It is possible to code the risk indicator so that discussion of the issue need not arise inadvertently, but there are several concerns with masking the finding of an anomaly. It is conceivable, for example that the anomaly was not noticed previously and is important clinically. Also, the anomaly indicator may be the only thing that triggers a need for surveillance re-screening of hearing. Ideally the parents would be prepared for the re-screen, and at the time of scheduling the appointment, the parents would want to know why the test is necessary. Disclosure of a risk indicator at that time may be more problematic than doing it in an up-front manner.
One approach to this is to be quite overt in the logging of the indicator, and to mention the anomaly in a matter-of-fact way such as to minimize anxiety. The precise method will depend on the situation and be dictated by the judgement of the screener. In the case of an isolated anomaly such as moderately low-set ears, for example, the approach might be: "It looks to me as if <baby's name>'s ears might be a little bit lower down than usual. That's one of the things on my list so I'll make a note of it. What it means is that it would be a good idea for us to check from time to time…" Then, the various parental reactions and counseling options should be dealt with as considered appropriate by the screener.
Approaches to questions from parents about the significance of various anomalies will vary. The two most likely issues are on the one hand the syndromic possibilities and on the other the significance for hearing. If appropriate, the former might be best handled by suggesting that the finding be mentioned to the family doctor or pediatrician at the next visit. The hearing facet can be dealt with in the usual way with risk indicators, by minimizing the likelihood of anything being wrong but at the same time recommending that the child attend the check-up appointment when the call comes.
APPENDIX B
- COMMUNICATING WITH PARENTS
- SAMPLE QUESTIONS:
Before the screening:
- Why are you screening my baby’s hearing?
- What is a DPOAE screening test? How does it work?
- What is an AABR screening test? How does it work?
- What does it mean to "Pass" the screening?
- What does a "Refer" result mean?
After the screening:
- What can cause a "Refer" result?
- If baby "Passes" the screening, what is the next step?
- If baby "Passes" the screening, and there are risk factors, what happens next?
- If the result is "No Result" what does it mean?
- If there is a "Refer" result, what is the Stage 2 screen?
- If the result is "Refer" from Stage 2, the next step is an Audiology Assessment.
SUGGESTED ANSWERS:
Why are you screening my baby’s hearing?
The importance of acquiring communication skills early in life is well understood. Research has shown that delay in language development can have significant impact on cognitive, emotional and psychosocial development and that language development is a prime indicator of future academic success. Children born with permanent hearing loss or who acquire permanent hearing loss during the early years of life are at risk for delay in language development, if the hearing loss is not identified early. Further, it is well understood that the earlier the hearing loss is identified, and supports and services for communication development are provided, the better the acquisition of language skills.
Serious hearing loss is found in only six of every 1000 babies born in Canada. Some babies may develop hearing loss later in life from repeated ear infections, meningitis, head injury or other medical conditions. Sometimes babies lose their hearing and the reason in never known.
For babies in intensive care for a number of days after birth, 1 in 50 babies will have significant hearing loss. There is also a higher risk of late onset or progressive hearing loss for babies who graduate from NICU care.
What is a DPOAE test? How does it work?
Stage 1 screening is performed using a technology called Distortion Product Otoacoustic Emissions (DPOAE). Screening of hearing with DPOAE is usually quick, easy to do and reliable. It is completely objective. No behavioral response is needed from the baby, who ideally is tested asleep. Under good conditions, it takes less than two minutes to screen a baby, less than one minute per ear. The testing is done using a hand-held, automatic screening unit called the AudX. The test involves presenting sounds to the baby through a special probe that is gently inserted into the entrance of the ear canal. The normal inner ear actually generates tiny sounds in response to the stimulus, and these sounds are the otoacoustic emissions (OAE). A computer inside the screening unit distinguishes the OAE from ambient sound, which is always present in the baby's ear canal. Some ambient sound comes from the room where the test is done. Other sounds are generated if the baby or the probe moves during the test. The computer decides whether a real OAE is present, or just ambient sound, and then displays a 'pass' or 'refer' result.
What is an AABR screening test? How does it work?
The Auditory Brainstem Response is the response of a part of the brain (the brainstem) to sound. The ABR is a type of EEG which can be measured very early after birth. Screening of hearing with Automated ABR equipment is usually quick, easy to do and reliable. It is completely objective. No behavioral response is needed from the baby, who ideally is tested asleep. Under good conditions, it takes less than ten minutes to screen a baby. AABR screening is performed using a machine called an ABAER which consists of an automatic screening unit installed on a cart or on a table and a portable computer. Disposable skin electrodes are placed on the head and neck and soft sounds are presented to the baby through earphones. The ABAER computer extracts and interprets the EEG response to sound automatically. Typically, the test takes a total of 10 minutes or less.
What does it mean to "Pass" the screening?
‘Pass’ means that the computer detected a response to sound for all test frequencies at normal levels in both ears.
What does a "Refer" result mean?
‘Refer’ means that for any one of the test conditions (e.g. one frequency, one ear), a response could not be detected by the computer
What can cause a "Refer" result?
The most likely reason for not getting a pass result is that the baby’s activity level was too high or the ambient room noise was too loud. The ABR is a subtle response and can be hard to detect. Another possibility is that there was wax or debris in the ear canal, blocking the probe. Or the baby might have a cold, which may cause a small hearing loss. There are many reasons not to get a pass result, so the parents can be reassured. However, it is certainly desirable, and in the baby's best interests, that they attend for a follow-up check.
If baby "Passes" the screening, what is the next step?
The results of the hearing screening indicate that your baby is able to hear normally in both ears at this time. The hearing screening is the first step. But you should continue to pay attention to how your baby responds to sounds and speech, and to how your baby’s language and speech develop. If at any time you become concerned about your baby’s hearing, contact the infant hearing centre closest to you.
If baby "Passes" the screening, and there are risk factors, what happens next?
The results of the hearing screening indicate that your baby is able to hear normally in both ears at this time. Even if a baby passes the hearing screening, there may be factors that cause the baby to be at greater risk for developing hearing problems. Some of these factors are:
- The baby had to stay in the hospital for intensive care for a few days before coming home
- There is someone in the immediate family who had a hearing problem from early childhood
- The baby’s development is different than other babies, or has facial characteristics that are linked to the development of hearing loss.
- Because your baby has one of these factors, your baby will be re-screened periodically until reaching the age of 3 years.
If the result is "No Result" what does it mean?
"No Result" means that the screening test could not be completed for some equipment related reason. If the baby was too active and the noise levels are too high, the computer will not be able to recognize a response. There could be a problem with the probe, or probe fit, or with the computer software, although that would be rare. Whatever the reason, a "No Result" means that the screening will have to be repeated in order to determine whether the true result for that baby is "Pass" or "Refer".
If there is a "Refer" result, what is the Stage 2 screen?
Parents usually want to know the results of the test right away. If there is a pass in both ears, there is usually no problem. If one or both ears give a refer result, then it is important to reassure the parent(s) that all this means is that a more detailed hearing check-up would be a good idea, preferably within a few weeks. The word 'fail' is never used in connection with a screening result, because it alarms parents unnecessarily and because it does not capture the true significance of not recording an OAE. If the test is done properly, less than about 5% of well babies will fail it. If the baby does indeed fail, what it means is that there is an increased risk of a hearing problem, but not that there is a hearing problem. The odds are that a baby who fails the screen will have normal hearing, but virtually ALL babies who DO have hearing loss will fail. Leading authorities on hearing health consider the false-positive rate for this test to be a perfectly acceptable price to pay for the ability to detect all babies with hearing problems. This test is much more reliable than any possible test based on observing the baby's behavior. Behavioral screening tests are no longer recommended.
The fact that the screening test is obviously not behavioral means that in the event of a refer result it can be emphasized that this initial screening test does not actually measure true hearing. It measures 'echoes that come out of the baby's ear, and is a good test but certainly not perfect'.
The follow-up check is a stage 2 screen using a more advanced test, the AABR (automated auditory brainstem response), that measures the baby's brainwaves (EEG). The AABR test is also quick, painless and automatic, and is best done on a sleeping baby. It is more accurate than the DPOAE test, and the equipment is MUCH more expensive. It usually takes about 15 minutes, in a quiet baby. Most babies will pass this Stage 2 screen.
If the result is "Refer" from Stage 2, the next step is an Audiology Assessment.
If a baby doesn’t pass the screen, the parents should be informed in a low-key manner that there will be a follow-up contact for an audiology assessment within a few weeks, to be done at a time convenient to them and provided the general health of the baby is satisfactory. The parents should be reassured that the pre-discharge test does NOT mean that the baby is deaf. There are many possible causes of screening failure, such as fluid in the middle ear that will resolve naturally in some cases or with medical management. Most infants who fail the pre-discharge screen will turn out to have normal hearing. However, the 'refer' screening result does indicate increased risk and it should be indicated that a hearing check-up would be a good idea after the acute-care stage is passed.
The Next Step:
An audiology assessment is another step in checking your baby’s hearing. It includes a number of tests to get a complete picture of how your baby hears. The assessment will be completed by an audiologist, a health care professional who specializes in hearing.
How is the Assessment Done?
While your baby is sleeping, special equipment is used to play soft sounds through earphones specially made for testing babies’ hearing. Your baby’s responses to sound are electronically recorded through the earpieces or through little wires attached by sticky pads on the head. Because more tests are done, an audiology assessment takes longer than the screening. It is possible you may be at the office for an hour, and may have to return for a second visit.
IHP Screener Updates and Bulletins
OAE Screener Software Update
The AuDX OAE screener software has been updated as of December 15, 2002. Most screeners should have been updated by January 2003. The new software allows for a faster screening with improved results. 1500 Hz has been dropped from the protocol as it was not resistant to noise and did not add much information to the results.
The new AuDX software works a little differently than the previous version.
In addition to some transparent changes to the noise rejection, etc. you will notice that you can get a very quick 'refer' result after only one frequency is tested - this may happen because our criteria for a 'pass' is now different. The AuDX will test at only 3 frequencies - 4000, 3000, and 2000 and the baby must pass at all three frequencies in order to have a 'pass' result. If there is a refer at the first frequency (4000 Hz), the test will stop then and a 'refer result will appear immediately. Previously you would have had to wait for the test to scroll through several frequencies. Since our 'pass' criteria is now 3/3, a refer at any one frequency will cause a 'refer' result.
AABR Patient Cable Bulletin
This bulletin applies to personnel screening with the ABaer Automated ABR equipment only. It does not apply to the AuDX OAE screener.
Apparently, some screening personnel are having problems with excessive and intermittent interference problems with their ABaer, which are loaded on carts. The problems can occur when the blue patient cable is looped around the isolation transformer (the power source) or when it is tangled with other cords. Please pass on the importance of having the patient cord stretched out from the box to the baby without having it coiled or looped around any other electrical sources because that will cause some of these interference problems.