Early identification of childhood hearing loss through newborn hearing screening mitigates permanent speech, language, and developmental delays, but many children are lost to follow-up or develop postnatal hearing loss.
360 million people (approximately 5% of the world’s population) live with disabling hearing loss and nearly million of them are children. It is estimated that over 60% of such hearing loss could be avoided through preventive measures. In addition, children who have hearing loss can benefit greatly from early identification and appropriate interventions.
Disabling hearing loss in children is defined as hearing loss greater than 30 dB in the better-hearing ear.
The severity of the impact of hearing loss for a child depends on a number of factors:
Age of onset: Children develop language in the early years of life. The impact of hearing loss on the development of spoken language is greatest in those who are born with hearing loss or develop it soon after birth
Degree of hearing loss: Hearing loss may range from mild to profound. The greater the severity, the greater the impact .
Different degrees of hearing loss.
Age of identification and intervention:The sooner a child is identified as having hearing loss and the earlier he or she receives support, the greater the possibility of the child learning spoken language and the lower the likely adverse impact of the hearing loss . The Joint Committee on Infant Hearing recommends that all children with hearing loss should receive intervention by six months of age at the latest.
Environment: The overall living environment, including access to services, significantly influences the development of a child with hearing loss. Children with access to hearing technology, special education and sign language may be able to participate at school and in social activities
“Hard of hearing” is people with hearing loss ranging from mild to severe. sounds (such as speech) are heard but not clearly understood. Such people usually communicate through spoken language and may benefit from hearing amplification with hearing aids and cochlear implants . Deaf children are those with severe or profound hearing loss, which implies very little or no hearing. Hearing devices, such as cochlear implants, may help them to hear and learn speech.
The American Academy of Pediatrics Bright Futures EHDI prevention and health promotion program recommends formal hearing screening at age 4 years and a risk assessment for hearing loss at every well-child check between ages 1 and 4 years by asking parents about concerns for hearing loss to identify children who were lost to follow-up .
Timing of Hearing Loss
Congenital: identified in the neonatal period
Delayed- onset: identified after the neonatal period but attributed to etiologies present at birth
Acquired: occurs after the neonatal period and is attributed to etiologies not present at birth
Sensorineural hearing loss: due to injury or defect within the cochlea, cochlear nerve, or the brainstem pathways to the auditory cortex
Conductive hearing loss: due to injury or defect within the external or middle ear, including the external auditory canal, tympanic membrane, middle ear cavity, and ossicles Mixed hearing loss: combination of sensorineural and conductive types of hearing loss
Technology Used to Perform Screening
Otoacoustic Emissions (OAEs)
Sounds produced by outer hair cells in the cochlea in response to acoustic signals in the ear; this noninvasive test has different forms, known as transient evoked and distortion product OAE.
Auditory Brainstem Response (ABR)
A noninvasive test of the integrity of the auditory pathway from middle ear, to cochlea, to the vestibulocochlear nerve, and to brainstem, where the response is measured; the ABR can be used as a pass/fail test for screening or (softest sound) at which sounds are heard.
Automated Auditory Brainstem Response (AABR)
The hearing screening version of ABR for infants in the neonatal intensive care unit (NICU).
Protocols
Normal Newborn Nursery Hearing screening of full-term newborns usually involves the OAE.
If the infant does not pass the screen in one or both ears (termed as refer for diagnostic testing), then they may undergo a second screening at their primary care provider visitor the birth hospital before the age of 1month; a second screening refer should then cause the infant to undergo diagnostic ABR testing before the age of 3months. Neonatal Intensive Care Unit Hearing screening of infants from the NICU usually involves the AABR; a refer usually results in a transitory evoked otoacoustic emission test to rule out auditory neuropathy spectrum disorder and a diagnostic ABR before the age of 3 months (corrected for gestational prematurity).
Diagnosis of hearing disorders in early childhood
Diagnosis of hearing disorders in newborns and infants is generally a two-stage process. As described above, the current standard is UNHS, followed immediately by confirmatory diagnostic evaluation as appropriate.
Universal newborn hearing screening
The various studies on UNHS have either measured otoacoustic emissions (OAE) or performed automated auditory brainstem response (AABR) audiometry, or both. In two-stage screening, OAE measurement is followed by AABR audiometry.
Epidemiology
The prevalence of permanent bilateral severe to profound hearing loss in newborns is1.1per 1000 newborns.1 to 2 per 1000 newborns have bilateral mild to moderate hearing loss or unilateral hearing loss of any degree
Early identification allows for early interventions with parent-child programs, with a benchmark of no later than 3 to 6 months of age established by the Joint Committee on Infant Hearing, including hearing aids and intensive speech-language therapy,leads to better outcomes, including earlier integration into general education (i.e., mainstream schooling).
In addition to identifying infants with profound bilateral hearing loss, the newborn hearing screening programs also identify infants with bilateral mild to moderate or unilateral hearing loss.
Etiology of hearing loss:
Genetic factors. These are responsible for nearly 40% of childhood hearing loss. Hearing loss is much more frequent in children born of a consanguineous marriage.
Infections:
Perinatal -Rubella or cytomegalovirus.
Childhood infections, such as meningitis, mumps and measles, can also cause hearing loss.
Ear infections – e.g. chronic suppurative otitis media (CSOM)OME, can also lead to life-threatening problems, such as meningitis and brain abscesses .
Perinatal conditions:
Conditions at the time of birth can also lead to hearing loss like, Prematurity, low birthweight, birth asphyxia, neonatal jaundice, congenital malformations of the ear and the auditory nerve
Noise Exposure to loud sounds: Short, high intensity sounds, such as fireworks and shooting, may cause permanent hearing loss. The noisy machinery in a neonatal intensive care unit can also contribute to hearing loss
Medicines: Medicines, such as those used in the treatment of neonatal infections, malaria, drug-resistant tuberculosis and cancers, can lead to permanent hearing loss (ototoxic medicines).
WHO estimates that about 60% of hearing loss is due to preventable causes:
Over 30% of childhood hearing loss is caused by infections, such as rubella, cytomegalovirus, mumps, meningitis, measles and chronic ear infections. Meningitis and rubella together are responsible for over 19% of childhood hearing loss. Most of these infections can be prevented by immunization and good hygiene. Ear infections and glue ear can be prevented through good ear care and general hygiene, and can be treated by prompt medical and surgical interventions.
Complications at birth, such as lack of oxygen, low birthweight, prematurity and jaundice, account for 17% of childhood hearing loss. Such complications can be prevented through improved maternal and child health practices.
Use of ototoxic medicines in pregnant women and children is responsible for 4% of childhood hearing loss, which could potentially be avoided.
The proportion of hearing loss due to preventable causes is much higher in middle- and lower-middle-income countries (75%) than in high-income areas (49%). The difference is probably explained by the overall higher occurrence of infections in the middle- and lower-middle-income countries and the better maternal and child health care in high-income countries.
Early identification helps
Early identification of hearing loss needs to be followed by timely and appropriate interventions, in order to minimize developmental delays and promote communication, education and social development. The choice of interventions depends on the degree and the cause of hearing loss. Otitis media can often be treated and reversed by medical or surgical means . Hearing loss due to other causes cannot be reversed. However, its impact can be reduced through timely use of various approaches .
· hearing devices, such as hearing aids, and cochlear or middle ear implants;
· hearing assistive technology, such as FM/radio systems and loop systems;
· therapy to develop spoken language, such as auditory-verbal therapy, cued speech and auditory-oral therapy.
· development of nonverbal communication, such as sign language.
Effects of hearing loss in children
Hearing loss is a well-known prominent risk for speech and language
developmental delay. The provision of hearing aids and
cochlear implants early in life has been demonstrated to help many
children attain near-normal speech and language trajectories, as
measured by growth curves using standardized language scores.
Hearing loss has also been found to affect a child’s quality of life,
particularly in the school and social domains, as well as behavior and
behavioral disorders.
Children may develop hearing loss at a later age. Regular preschool and school-based hearing screening can identify hearing loss soon after its onset, allowing its adverse impact to be limited .
For interventions to be effective, they should be appropriate, timely, family-centred and undertaken through an interdisciplinary approach, which includes audiological, medical, therapeutic and pedagogical services.
Strategies for prevention and care
A. Strengthening relevant programmes and organizations
· Strengthen immunization programmes , to prevent many of the infections that lead to hearing loss, such as congenital rubella, meningitis, mumps and measles. Potentially, over 19% of childhood hearing loss could be avoided through immunization against rubella and meningitis.
· Strengthen maternal and child health programmes to prevent low birthweight, prematurity, birth asphyxia, congenital cytomegalovirus infection, and neonatal jaundice.
Action: improve maternal and neonatal care through
1. improved nutrition,
2. awareness of hygienic practices,
3. promotion of safe birth,
4. prompt management of neonatal infections and jaundice
· Strengthen organizations of people with hearing loss, parents and family support groups.
B. Implementation of screening and intervention programmes
Implement newborn and infant hearing screening with tracking, and initiate appropriate interventions to identify and treat children with congenital or early-onset hearing loss . A newborn hearing screening programme should follow a family-centred approach, in which families are empowered to make decisions for their children .
Action: put early intervention programmes in place and implement newborn hearing screening programmes (based on physiological methods) that focus on:
· appropriate interventions, ideally initiated before 6 months of age;
· family support, including guidance and counselling of parents;
· hearing rehabilitation through hearing aids and cochlear implants;
· suitable therapy and communication options.
· Implement school-based hearing screening with the aim of identifying, referring and managing common ear diseases and hearing loss.
Action: integrate ear and hearing screening in school health programmes and develop links for provision of suitable medical, surgical and rehabilitative care.
C. Training:
· Train primary-level physicians and health care workers about the relevance of ear diseases, the need for early intervention to address hearing loss and the available treatment options. This would allow provision of accessible services and facilitate referral for management of ear diseases and hearing loss.
· Train otologists, audiology professionals, other medical professionals (such as nurses), therapists and teachers to provide the required care and services. This is an important step in addressing ear and hearing problems.
D. Technologies Making appropriate accessible:
Make hearing devices accessible. Advances in the field of hearing aids and cochlear implants have considerably improved the available options for people with hearing loss. Despite this, only a fraction of those who need these devices have access to them. Particularly in developing countries, there are several significant barriers to access to hearing aids for people with hearing loss. A major barrier is the cost of hearing aids, batteries and maintenance. There is also a scarcity of health care professionals able to fit, maintain and repair devices. Transportation costs and travel time to a health centre may be prohibitive for many people with hearing loss, especially in rural areas . Technological advances, such as solar-powered or self-fitting hearing aids, may help to overcome some of these significant barriers in the future.
Action: develop sustainable initiatives for affordable fitting and maintenance of hearing devices, and provide ongoing support for people using these devices.
Make communication and education accessible . A deaf child benefits greatly from early introduction to language. This may be in the form of rehabilitation for verbal communication (such as auditory-verbal and auditory-oral therapy). Policy-makers should also promote alternative means of communication, including sign language, total communication, bilingual/bicultural (bi-bi) teaching, cued speech and lipreading approaches . Use of loop and FM systems in classrooms and public places, as well as provision of captions on audiovisual media, are important for improving accessibility of communication for people with hearing .
E. Regulation and monitoring:
Regulate and monitor the use of ototoxic medicines, in order to minimize the dangers posed by their indiscriminate use . Where their use is unavoidable, regular audiological monitoring will help identify hearing loss at an early stage.
Regulate and monitor noise levels in the community, especially at recreational venues and sports arenas. The addition of safety features to personal audio systems can help to reduce the risk of hearing loss associated with their use .
F. Raising awareness:
Raise awareness about healthy ear care practices that can reduce ear infections . For instance, avoiding insertion or instillation of any substance into the ear can help to decrease ear problems. Ensuring that children with ear pain are not treated with home remedies and consult a medical practitioner can prevent chronic ear infections and the associated hearing loss.
Raise awareness about the dangers of loud sounds by educating children at an early age about the risks associated with high volumes, especially in a recreational context (firecrackers, loud music, use of headphones, noisy games) . This can help to modify behaviour patterns and promote safe listening, which in turn can prevent the development of noise-induced hearing loss during childhood and adolescence or later in life.
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