2. Etiology of hearing loss in school-aged children

Moderate-to-profound degrees of hearing loss are targeted in our newborn screening programs; however, lesser degrees of loss are often not identified until school age. The late age of identification of mild hearing loss may contribute to our lack of knowledge about causative factors. That is, in some cases, a delay in identification of hearing loss may limit our ability to interpret etiologic evaluations reliably or may affect parental memory of possible illnesses or injuries that could account for the loss [5].

As discussed by Ross et al. [6], newborn screening programs are designed to identify hearing losses that are of moderate degree or greater. As such, the equipment and protocols used for newborn screening (e.g., otoacoustic emission (OAE)) are dedicated to identify impairment greater than approximately 40 dB HL. Moreover, a lot of factors appear after newborn screening:


#### 8. Ototoxic (damaging to the auditory system) drugs

neonatal or infancy but also in the subsequent years of the child's life. In this way, both

Timely intervention is an important component of Early Hearing Detection and Intervention (EHDI) screening program. In Poland, neonatal screening program (NHS) is carried out. The first projects were performed over 25 years ago [1]. The result of the Polish EHDI/NHS program shows that the prevalence of congenital hearing impairment ranges from 2 to 7 per 1000 births [2]. The National Institute on Deafness and Other Communication Disorders (NIDCD) adduces that 6–7/1000 children have permanent hearing loss in addition to the 3/1000 likely to be diagnosed in short period after birth [3]. From the official database of the National Health & Nutrition Evaluation Studies (NHANES) for screened children who are 6–19 years, it is indicated that approximated 3/1000 prevalence of permanent hearing loss in infants can be expected to

In years 2007–2016, the Institute of Physiology and Pathology of Hearing screened over million pupils from class I to VI primary school in Poland and approximately~ million children around the world [4]. This experience provided an opportunity to screen a significant number of school-age children and also created the international infrastructure for screening which makes

Moderate-to-profound degrees of hearing loss are targeted in our newborn screening programs; however, lesser degrees of loss are often not identified until school age. The late age of identification of mild hearing loss may contribute to our lack of knowledge about causative factors. That is, in some cases, a delay in identification of hearing loss may limit our ability to interpret etiologic evaluations reliably or may affect parental memory of possible illnesses or

As discussed by Ross et al. [6], newborn screening programs are designed to identify hearing losses that are of moderate degree or greater. As such, the equipment and protocols used for newborn screening (e.g., otoacoustic emission (OAE)) are dedicated to identify impairment greater than approximately 40 dB HL. Moreover, a lot of factors appear after newborn screening:

6. Viral/bacterial—mumps [13], otitis media with effusion [13]; meningitis, measles, chicken

congenital and acquired hearing defects can be detected.

114 An Excursus into Hearing Loss

increase to 9–10/1000 children in the school-age population.

it a suitable solution for place even in remote rural areas.

injuries that could account for the loss [5].

1. Genetic—connexin [7], mitochondrial [8]

4. Auditory neuropathy/dyssynchrony [11]

pox, influenza, encephalitis, rubella

3. Sudden idiopathic [10]

5. Noise inducted [12]

7. Head trauma

2. Enlarged vestibular aqueduct (EVA) syndrome [9]

2. Etiology of hearing loss in school-aged children

Acquired hearing loss is a hearing loss which appears after birth, at any time in one's life, as a result of a disease, a condition, or an injury. In fact, the most common cause of hearing loss in young children is otitis media. Fluctuating conductive hearing loss nearly always occurs with all types of otitis media [14]. Symptoms, severity, frequency, and length of the condition vary. At one extreme is a single short period of thin, clear, no infected fluid without any pain or fever but with a slight decrease in hearing ability. At the other extreme are repeated bouts with infection, thick "glue-like" fluid, and possible complications such as permanent hearing loss. Therefore, a hearing screening in school-age children is very important [15].

### 3. The impact of hearing loss on child's development

It is recommended that hearing loss in infants be identified, and when possible treated, prior to 6 months of age. This recommendation is based on studies that have shown that children identified with hearing loss prior to 6 months of age have a better chance of developing skills equivalent to their peers by the time they enter kindergarten.

Following the guidelines for hearing screening, hearing deficits in children can interfere with normal speech and language development, communication, and the ability to learn.

Failure to identify children with congenital or acquired hearing impairment can lead to lifelong consequences including deficits in speech and language abilities, cognition delays [16], poor academic performance [17], insufficient psychosocial skills, underemployment, and psychological distress [18].

Classroom is an auditory verbal environment where precise transmission and reception of speech is critical for effective learning to occur [19]. For instance, being able to hear all sounds is fundamental when learning to read. The behavioral effects of hearing impairment are frequently subtle and look similar to those of children who experience attention-deficit disorders, learning disabilities, language, and cognitive delays. Commonly cited behaviors include the following [20]: difficulty attending to spoken or other auditory information; often requests repetition; tired easily when listening; gives not suitable answer; avoids contacts with peers; difficulty with reading skills and written language; and easily frustrated. Children with mild unilateral hearing impairment can cause difficulties in sound-source location and problem with speech perception in background noise. In addition, problem associated with the loss of binaural summation and sound localization is delays in speech-language development and school achievements. Lack of binaural hearing may decrease accidental learning due to background noise interferes with overheard speech. Therefore, only such early identification results in early intervention via hearing aids, cochlear implants, and various assistive listening devices. The intervention allows for speech and language development and academic achievements to remain on target.

What is important, there are many factors that affect the speech and language acquisition, academic achievements of each child. Level of hearing loss (mild, moderate, severe, or profound) based on the pure-tone threshold does not predict handicap or success in school. Some children have severe hearing loss; however, their speech is comprehensible and they get good grades. But on the other hand, other children with mild hearing loss and lack of family support exhibit considerable academic failure. Therefore, any hearing impairment, no matter how mild, needs to be assessed in order to assert confidently attention to any barrier of learning.

Conduction analyses show that this questionnaire from all of the children identified only with permanent severe-to-profound hearing loss. This tool showed low sensitivity of 44% and specificity of 87%. Researchers recommended the questionnaire for use in healthcare settings. To conclude, all questionnaires were designed as a tool to identify children with hearing problems so that appropriate treatment and/or intervention could be provided; there were differences in the extent of hearing loss being targeted by the questionnaire. The purpose of population-based hearing screening is to identify those who need further testing from those who do not, with a minimum of false positives (failing the questionnaire when hearing is

Hearing Screening around the World http://dx.doi.org/10.5772/intechopen.73535 117

Physiologic test specifically measures outer hair cell response to presentation of a click stimulus (transient evoked OAEs). The test is that acoustic signals generated from within the cochlea travel in a reverse direction through the middle-ear space and tympanic membrane out of the ear. OAEs use a tiny, flexible plug that is inserted into the baby's ear. Sounds are sent through the plug. A microphone in the plug records the otoacoustic emissions (responses) of the normal ear in reaction to the sounds. There are no emissions in a baby with hearing loss. This test is painless

1. Advantages: quick time test; ear-specific results; not dependent on whether patient is asleep

2. Limitations: infant or child must be relatively inactive during the test; not a comprehensive test of hearing, because it does not assess cortical processing of sound; OAEs are very

Auditory brainstem responses (ABR) are measures of electrical events generated within the auditory brainstem pathway. These ABRs are used to assess brainstem function at different levels of the auditory pathway and are typically evoked by rapid multi-frequency clicks or chirps. Small metal discs with thin electrodes (wires) are placed on the baby's scalp, and then send signals to a computer to record the results. One objective physiologic means of screening hearing is the automated ABR. This instrument measures cochlear response in the 1- to 4-kHz range with a broadband click stimulus in the ear. While the baby sleeps, clicking sounds are

sensitive to middle-ear effusions and cerumen or vernix in the ear canal

made through tiny earphones in the baby's ears. As in OAEs, this test is painless.

1. Advantages: ear-specific results; responses not dependent on patient cooperation

2. Limitations: infant or child must remain quiet during the test (sedation is often required); not a comprehensive test of hearing, because it does not assess cortical processing of sound

normal) and false negatives (passing the questionnaire when hearing loss exists).

4.2. Evoked otoacoustic emission

or awake

3. Average time: 10-min test

3. Average time: 15-min test

4.3. Automated auditory brainstem response

and usually takes just a few minutes, while the baby sleeps.

Children with unilateral hearing loss (UHL) appear to have an increased rate of grade failures, need for additional educational assistance, and perceived behavioral issues in the classroom. Possible risk factors include lower cognitive ability, right-ear hearing loss, and severe-to-profound hearing loss. Speech and language development may be delayed in some children with UHL, but it is unclear if children "catch up" as they grow older.
