Universal Newborn Hearing Screening Concept History Present Scenario And Hurdles
Concept: Hearing impairment is one of the most critical sensory impairments with significant social and psychological consequences. Failure to detect children with congenital or acquired hearing loss may result in lifelong deficits in speech and language acquisition, poor academic performance and personal-social and behavior problems The data on congenital disabilities indicate that hearing loss has a substantially high incidence with congenital hearing loss affecting 30 per 10,000 children Significant hearing loss is the most common disorder, occurring in 1 to 2 newborns per 1000 in the general population, and 24% to 46% of newborns admitted to neonatal intensive care unit
Concept: In this direction, the Universal newborn/infant hearing screening program has been initiated worldwide for early detection of hearing loss in young babies due to its high prevalence rates As per the recommendation of the WHO (2009),facilitating early hearing detection and intervention is crucial in the first month of life. The first 3 years of life is considered the most intensive and critical period for acquiring speech and language skills in newborns and infants, and accordingly, emphasis is laid on early detection programs like UNHS Without UNHS, infants with hearing loss are typically identified with an established language delay Hearing loss in infants : invisible disability
Concept: S ignificant expressive language deficit, noted well beyond one year of age, has been the primary diagnostic feature in young children with hearing loss. Thus, in unscreened children, as is the current situation in many countries, the average age at diagnosis is approximately 24 months . This will have a negative impact on intervention Without early intervention, children with hearing loss demonstrate predictable irreversible deficits in communication and psychosocial skills, cognition and literacy The impact on the child’s speech and language is directly proportional to the severity of hearing loss and the time delay in diagnosis and intervention
Concept: Thus hearing screening… Hearing screening applies to a large population with no apparent signs or symptoms of the target disorder. Screening program can be defined as a designed approach that separates disease group from clinically normal group. In any screening program there four sets of result can be expected when administered on target population. In case of hearing screening they are, true positive (presence of hearing loss), true negative (absence of hearing loss) false positive (though in the absence of hearing loss, screening instrument indicate presence of hearing loss), false negative (though in the presence of hearing loss, screening instrument indicate absence of hearing loss). Thus screening hearing test should have higher sensitivity (true positive) and specificity (true negative).
Universal Newborn Hearing Screening Concept History Present Scenario And Hurdles
History Historically, clinical screening for hearing loss in infants and young children was limited to observation of the behavioural response to a sound, such as a ringing bell, introduced out of direct vision of the child Later , behavioural observational audiometry (BOA) and high-risk register (HRR) (Northern & Downs, 1974) were included as part of the screening protocol. In order to improve the sensitivity and specificity of a screening protocol, and facilitate better identification of having hearing loss in newborns, various modifications in screening protocols have been introduced worldwide. A few of these modifications have been specific to the HRR criteria (JCIH, 2000,2007) inclusion of a two stage Otoacoustic emission screening along with automated auditory brainstem response (AABR) (2011); three-stage screening of Transient Evoked Otoacoustic Emission (TEOAE) & AABR ( 2015) HRR screening resulted in around 50% of congenital HL being undetected
Universal Newborn Hearing Screening Concept History Present Scenario Hurdles
Present Scenario The Joint Committee on Infant Hearing (JCIH 2000, 2019) recommends that all infants be screened no later than 1 month of age, diagnosed by 2 months of age, and enrolled in early intervention programs no later than 3 months of age. The basis for this recommendation is to maximize social, emotional, and linguistic outcomes for children who are deaf or hard of hearing The JCIH recommended a screening protocol with automated auditory brainstem response(AABR) and/or evoked otoacoustic emission (TEOAE) as they were reported to yield successful outcomes in the early detection of hearing loss ( Korres , et al., 2008). Further, studies also indicated that a two- stage screening with the use of TEOAE & AABR helped in reducing the false positive and referral rates (Iwasaki, et al., 2003 Tatli , et al., 2007).
Present Scenario JCIH in its most recent revision, it expanded the target hearing loss as permanent bilateral, unilateral sensory, or permanent conductive hearing loss to include neural hearing loss (e.g., Auditory Neuropathy Spectrum Disorder [ANSD]). It also established separate screening & rescreening protocols for well baby & neonatal intensive care units (NICU), specifying that babies in the NICU for 5 days or more should be screened with Automated Auditory Brainstem Response (A-ABR) technology.
Present Scenario Both AABR and OAE techniques are portable, inexpensive, automated and reproducible Otoacoustic emissions (OAE) Principle: Transient evoked otoacoustic emissions (TEOAEs) are frequency-dispersive responses arising within the cochlea. Since OAE evaluates hearing from the middle ear to the outer hair cells of the inner ear, it is used to screen for sensorineural hearing loss (SNHL) but cannot detect auditory neuropathy (AN). Technique: The OAE screener consists of small microphone that is placed in the ear canal of the infant. The screener sends stimuli in form of clicks or tones and also receives the reflected sound from the cochlea. The device measures the signal-to-noise ratio to make sure that recordings are accurate.
Present Scenario Automated Auditory Brainstem Response (AABR) Principle: It is an electro-physiologic measurement that is used to assess auditory function from the eighth nerve to the primary auditory cortex of the brain in response to a click stimulus. The AABR method produces a simple ‘pass’ or ‘fail ’ result without requiring interpretation. It is important to note the difference between AABR and ABR; ABR being a diagnostic test which provides quantitative data ( e.g , waveforms) that must be interpreted by a trained audiologist, thereby determining the degree and the site of the hearing loss. Technique: AABR equipment measures the surface signals by placing electrodes on the forehead and the mastoid, and on the nape of the neck. Most commercially available devices effectively screen infants younger than 6 months.
Two-step screening A two-step screening means that if any ear fails the first screen, a repeat screening should be done on both ears within a specified time frame . The repeat screening in such cases should be done prior to discharge of the infant from the hospital Two-step screening: What is the evidence? A large community-based trial showed that a 2-step screening approach (OAEs followed by ABR for those who failed the first test) 4 yielded a sensitivity of 0.92 and specificity of 0.98 Present Scenario
Well infants 1 st screen OAE Clinical follow up 2 nd screen AABR or OAE Conventional ABR Clinical follow up
Well infants 1 st screen AABR Clinical follow up 2 nd screen AABR only Conventional ABR Clinical follow up
infants with HRR 1 st screen AABR Periodic follow up Referral directly to audiologist Detailed diagnostic evaluation
Universal Newborn Hearing Screening Concept History Present Scenario Hurdles
Hurdles Loss to follow-up and loss to documentation . Although loss to follow-up has improved from almost 50% in 2006 to 35.3% in 2011, state EHDI programs continue to work diligently to reduce this percentage So, healthcare providers that involved in UNHS program must provide more counselling to the caregivers in order to avoid loss to follow up for hearing examination Ensuring correct identification of the primary care provider before discharge from the birthing hospital. Acquiring a second contact phone number before discharge. Scripting the message given to families when an infant does not pass the initial screening test. Scheduling a follow-up appointment (rescreening or diagnostic) before the family leaves the hospital and stressing its importance to the family. Calling the family to verify the follow-up appointment Solution
Hurdles 2. The shortage of professionals with skills and expertise in pediatrics and hearing loss, continue to work on education and training within their respective professional communities. Invite more applicants in hospitals , primary care clinics etc Solution
Hurdles 3. Lack of knowledge about importance of early intervention among medical professionals the ultimate challenges was to persuade pediatricians regarding the importance of applying newborn hearing screening test in children without any risk factors Make the professional aware about 50% missing case and its consequences Solution
Hurdles 4. Timely referral for diagnosis of and intervention for suspected hearing loss in infants and children. Barriers include the lack of support in rural areas, finances of the parents, cultural and linguistic obstacles, etc 5. The lack of uniform performance and national standards for the calibration of OAE or A-ABR instrumentation. 6. The inability of state tracking systems to follow individual infants with suspected or confirmed hearing loss through the EHDI program. 7. there is also a challenge in societies with a lower socioeconomic status , included not attending to the re-screening date, deficiency of information of caregivers around the indications and the impacts of hearing impairment
Hurdles 8. On the other hand, the challenges facing hearing screening in newborns in developing countries are great. Finding the resources to implement solutions for the detection and treatment of newborns is a major problem. Most developing have a high birth rate with heavily dense populations. Hearing impairment prevalence rate in the newborns is estimated to be higher in developing countries considering the relatively higher rate of exposure to risk factors Standardizing screening and intervention programs remains an important goal to establish national newborn hearing screening programs in developing countries. Also, it needs to consider the local culture and be acquainted with local resource limitations and strengths.
Newborn hearing screening in India
India faces the challenge of a very large population and a high annual birth rate Moreover, 75% of the population live in rural areas and over 50% of births occur at home and are frequently attended by a trained birth attendant. In India, although Newborn screening programs have been initiated, it is not widely spread across the country due to inadequate professionals in the field of Speech and Hearing. However, India also has a well-developed health care delivery system, right down to the grassroots/village level, and a well-established immunization programme
In 2006, India launched the National Programme for Prevention and Control of Deafness. (NPPCD) Currently running in over 60 districts of the country Aim : to identify babies with bilateral severe-profound hearing losses by 6 months of age & initiate rehabilitation by 9 months of age Under this programme, the following two-part protocol for infant hearing screening is being implemented:
Institution-based screening – to screen every baby born in a hospital or admitted soon after birth using OAE. Those who fail the test are re-tested after 1 month . Those who fail the second screening are referred for ABR testing at the tertiary-level centres 2. Community-based screening to screen babies who are not born in hospitals. Such screening is carried out using a brief questionnaire & behavioural testing. The screening is performed when the baby attends for immunization at 6 weeks of age & onwards. A trained health care worker at the subcentre administers immunization & conducts the hearing screening. The protocol is repeated at every immunization. Any baby failing the screening is referred for formal OAE screening to the district hospital, and if they fail OAE they are then sent for ABR testing.
The programme includes: training of existing human resources using standardized training programs & other materials provision of the equipment required for behavioral testing & for OAE at the respective centers provision of suitable audiological personnel for diagnosis & for rehabilitation at the district hospitals creating awareness of the importance of detecting childhood hearing loss amongst parents and the general population through the use of posters, flipcharts, fliers, handouts and other suitable materials provision of a referral slip to aid patient compliance and simplify the visiting process.
Once an individual is identified as hearing impaired, they are referred for hearing aid fitting and for suitable therapy at the district hospital. Identified problems include the need for patients/parents to make repeated visits and to visit different centres . In addition, even though OAE is provided at all centres , there is a shortage of centres where ABR is done . There is also a shortage of audiological personnel and a heavy burden placed on health care workers.
As a part of the newborn screening programs, various protocols have been evaluated in our country. In one such reported study (Vignesh et al., 2015), a two – stage protocol with DPOAE and AABR was found to significantly reduce referral rates of newborns in newborn screening programs. Further, they also stated that AABR reduces the false positive responses resulting in increasing the efficiency of a screening program. Similarly, another study was carried out using a three stage protocol including High risk register, TEOAE and Screening ABR ( Savithri et al., 2015). It was concluded that rescreening using TEOAE significantly reduces the false positive response and referral rate for ABR. Attempts to improve the efficacy of the NBS protocol continue across the country.
The Department of Prevention of Communication Disorders (POCD) at the All India Institute of Speech and Hearing (AIISH), Mysore is actively involved in carrying out various extension activities such as screening, diagnostic and rehabilitation services for communication disorders. As a part of secondary prevention, the institute is extensively involved in newborn screening program for communication disorders.