**2. Auditory system and otitis media**

Language plays an essential role in perceptual organization, including the reception and structuring of information, learning, and social interactions. Language

enables us to communicate with each other and acquire and transmit experience and knowledge. The development of speech and language requires a functional auditory system capable of detecting sound, paying attention, remembering, discriminating, and perceiving location. Any interruption to development will lead to significant functional impairments, not only in language but also in cognitive, intellectual, cultural, and social development [1, 2].

Central auditory processing (CAP) is defined as the efficiency and effectiveness with which the central auditory nervous system uses auditory information. It refers to the perceptual processing of auditory information and to the neurobiological activity underlying this processing that gives rise to electrophysiological auditory potentials [3, 4]. The efficient analysis and interpretation of normal auditory information involves several subprocesses and skills, and includes neural mechanisms underlying a range of auditory behaviors such as sound localization and lateralization; auditory discrimination; recognition of auditory patterns; temporal aspects of the hearing (integration, discrimination, resolution, temporal masking); auditory performance in the presence of competing acoustic signals (which includes dichotic listening); and decoding degraded acoustic signals [5, 6].

This whole process involves a complex system of neurons located in several stations of the auditory system. The initial analysis of the stimulus occurs in the peripheral auditory system, constituted by the external and middle ear, responsible for the capture, transduction, and processing of the sound stimulus. The stimulus arrives first at the cochlear nucleus and encephalic trunk, followed by the upper olivary complex, lateral lemniscus, inferior colliculus, and medial geniculate body, and finally reaches the primary area of auditory reception in the temporal lobe of each hemisphere. From the primary auditory cortex of each hemisphere, the signals travel to other regions of the brain-the association areas-both in the same hemisphere and in the opposite hemisphere. As the auditory information travels by ipsi- and contralateral routes, it undergoes increasingly complex levels of processing. This processing occurs both hierarchically and serially, as well as in parallel or overlapping. The result of combining serial and parallel processing makes the system highly efficient and redundant. In addition to ascending pathways, there are also descending pathways that can moderate the response to a received acoustic stimulus [7–8].

Central auditory processing disorder (CAPD) is a dysfunction of the central auditory nervous system that leads to hearing difficulties. It can lead to, or be associated with, changes in language, learning, cognition, or other communicative functions [3–5, 9]. In the pediatric population, there are several possible causes of the disorder, among them otitis media [10, 11].

Otitis media with effusion (OME) is a clinical entity characterized by the presence of effusion in the middle ear, without perforation of the tympanic membrane, but with an acute infection that lasts for a period of at least 3 months. The condition is common enough to be called an "occupational hazard of early childhood" [12] because about 90% of children have OM before school age and they develop, on average, four episodes of OM per year. OM may occur during an upper respiratory infection or occur spontaneously because of poor Eustachian tube function or an inflammatory response following a previous OM, most often between the ages of 6 months and 4 years [13, 14]. In the first year of life, 50% of children will experience OM, increasing to 60% by age 2. When primary school children aged 5–6 years were screened for OM, about 1 in 8 was found to have fluid in one or both ears [15] **Figure 1a**–**d**.

Most episodes of OM resolve spontaneously within 3 months, but about 30–40% of children have repeated OM episodes and 5–10% of episodes last 1 year [13]. At least 25% of OM episodes persist for 3 months and may be associated with hearing

**67**

**Figure 1**

*(a–d) Otitis media with effusion (OME)***.** *Personal collection.*

of sounds.

*Otitis Media, Behavioral and Electrophysiological Tests, and Auditory Rehabilitation*

loss which is usually noticed by parents or teachers as inattention, needing to ask

OM impairs sound transmission to the inner ear by reducing mobility of the tympanic membrane and ossicles, thereby reflecting acoustic energy back into the

Diagnosis is performed by otoscopy and confirmed by a basic audiological evaluation. Under otoscopy, a retracted, opaque tympanic membrane with reduced mobility is seen. In the vast majority of cases, a yellowish liquid line, sometimes with air bubbles, is visible through the tympanic membrane. In the audiological evaluation, the result can range from normal hearing to moderate conductive hearing loss (HL of 0–55 dB) [16]. The mean hearing loss associated with OM in children is 28 dB, while a lesser proportion (~20%) exceeds 35 dB, with a type B tympanometric curve characteristic of effusion. Auditory losses are characterized by being fluctuating, temporary, and asymmetrical [17]. The mild degree of loss is sufficient to impair certain auditory functions, and the fluctuating nature (which may change to periods of normal hearing) leads to variable stimulation of the central auditory nervous system. The effect is to make it difficult to perceive sounds, and leads to diffuse cognitive and linguistic abilities affecting both speech and the perception of phonemes; school performance also suffers [18]. In addition, the fluid in the middle ear can cause noise near the cochlea, producing a distorted perception

Depending on the clinical history and functional conditions of the child's middle

ear, treatment involves either clinical or surgical management. In small children with OME, the most common surgical procedure is tympanotomy with ventilation tube placement, which drains fluid from the middle ear and thus restores hearing. Diagnosis and treatment is essential, since in an acute episode of OM fluids can remain in the middle ear for 3–12 months; in 10–30% of children, the fluid remains for 2–3 months. Thus, a child who has had three to four OME episodes before the

*DOI: http://dx.doi.org/10.5772/intechopen.88800*

several times, disinterest, and poor school achievement.

ear canal instead of allowing it to pass freely to the cochlea.

### *Otitis Media, Behavioral and Electrophysiological Tests, and Auditory Rehabilitation DOI: http://dx.doi.org/10.5772/intechopen.88800*

loss which is usually noticed by parents or teachers as inattention, needing to ask several times, disinterest, and poor school achievement.

OM impairs sound transmission to the inner ear by reducing mobility of the tympanic membrane and ossicles, thereby reflecting acoustic energy back into the ear canal instead of allowing it to pass freely to the cochlea.

Diagnosis is performed by otoscopy and confirmed by a basic audiological evaluation. Under otoscopy, a retracted, opaque tympanic membrane with reduced mobility is seen. In the vast majority of cases, a yellowish liquid line, sometimes with air bubbles, is visible through the tympanic membrane. In the audiological evaluation, the result can range from normal hearing to moderate conductive hearing loss (HL of 0–55 dB) [16]. The mean hearing loss associated with OM in children is 28 dB, while a lesser proportion (~20%) exceeds 35 dB, with a type B tympanometric curve characteristic of effusion. Auditory losses are characterized by being fluctuating, temporary, and asymmetrical [17]. The mild degree of loss is sufficient to impair certain auditory functions, and the fluctuating nature (which may change to periods of normal hearing) leads to variable stimulation of the central auditory nervous system. The effect is to make it difficult to perceive sounds, and leads to diffuse cognitive and linguistic abilities affecting both speech and the perception of phonemes; school performance also suffers [18]. In addition, the fluid in the middle ear can cause noise near the cochlea, producing a distorted perception of sounds.

Depending on the clinical history and functional conditions of the child's middle ear, treatment involves either clinical or surgical management. In small children with OME, the most common surgical procedure is tympanotomy with ventilation tube placement, which drains fluid from the middle ear and thus restores hearing. Diagnosis and treatment is essential, since in an acute episode of OM fluids can remain in the middle ear for 3–12 months; in 10–30% of children, the fluid remains for 2–3 months. Thus, a child who has had three to four OME episodes before the

**Figure 1** *(a–d) Otitis media with effusion (OME)***.** *Personal collection.*

*The Human Auditory System - Basic Features and Updates on Audiological Diagnosis and Therapy*

enables us to communicate with each other and acquire and transmit experience and knowledge. The development of speech and language requires a functional auditory system capable of detecting sound, paying attention, remembering, discriminating, and perceiving location. Any interruption to development will lead to significant functional impairments, not only in language but also in cognitive,

Central auditory processing (CAP) is defined as the efficiency and effectiveness with which the central auditory nervous system uses auditory information. It refers to the perceptual processing of auditory information and to the neurobiological activity underlying this processing that gives rise to electrophysiological auditory potentials [3, 4]. The efficient analysis and interpretation of normal auditory information involves several subprocesses and skills, and includes neural mechanisms underlying a range of auditory behaviors such as sound localization and lateralization; auditory discrimination; recognition of auditory patterns; temporal aspects of the hearing (integration, discrimination, resolution, temporal masking); auditory performance in the presence of competing acoustic signals (which includes dichotic

This whole process involves a complex system of neurons located in several stations of the auditory system. The initial analysis of the stimulus occurs in the peripheral auditory system, constituted by the external and middle ear, responsible for the capture, transduction, and processing of the sound stimulus. The stimulus arrives first at the cochlear nucleus and encephalic trunk, followed by the upper olivary complex, lateral lemniscus, inferior colliculus, and medial geniculate body, and finally reaches the primary area of auditory reception in the temporal lobe of each hemisphere. From the primary auditory cortex of each hemisphere, the signals travel to other regions of the brain-the association areas-both in the same hemisphere and in the opposite hemisphere. As the auditory information travels by ipsi- and contralateral routes, it undergoes increasingly complex levels of processing. This processing occurs both hierarchically and serially, as well as in parallel or overlapping. The result of combining serial and parallel processing makes the system highly efficient and redundant. In addition to ascending pathways, there are also descending pathways that can moderate the response to a received acoustic

Central auditory processing disorder (CAPD) is a dysfunction of the central auditory nervous system that leads to hearing difficulties. It can lead to, or be associated with, changes in language, learning, cognition, or other communicative functions [3–5, 9]. In the pediatric population, there are several possible causes of

Otitis media with effusion (OME) is a clinical entity characterized by the presence of effusion in the middle ear, without perforation of the tympanic membrane, but with an acute infection that lasts for a period of at least 3 months. The condition is common enough to be called an "occupational hazard of early childhood" [12] because about 90% of children have OM before school age and they develop, on average, four episodes of OM per year. OM may occur during an upper respiratory infection or occur spontaneously because of poor Eustachian tube function or an inflammatory response following a previous OM, most often between the ages of 6 months and 4 years [13, 14]. In the first year of life, 50% of children will experience OM, increasing to 60% by age 2. When primary school children aged 5–6 years were screened for OM, about 1 in 8 was found to have fluid in one or both ears [15]

Most episodes of OM resolve spontaneously within 3 months, but about 30–40% of children have repeated OM episodes and 5–10% of episodes last 1 year [13]. At least 25% of OM episodes persist for 3 months and may be associated with hearing

intellectual, cultural, and social development [1, 2].

listening); and decoding degraded acoustic signals [5, 6].

the disorder, among them otitis media [10, 11].

**66**

**Figure 1a**–**d**.

stimulus [7–8].

age of three can have had 12 months of conductive hearing loss, which is a third of the period considered critical for development and learning [19]. The periods of auditory deprivation during the active periods of OME over the first years of life can delay the maturation of the structures in the CANS and consequently impair auditory abilities associated with central auditory processing.

Therefore, evaluation of auditory processing is fundamental in children with a history of otitis media in order to allow diagnosis, intervention, and guidance.
