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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_4408_Библиотеки_им_академика_М_И_Перельмана
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35 Basic Imaging andNormal Temporal Bone Sections
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M. V. Goycoolea et al.
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35 Basic Imaging andNormal Temporal Bone Sections
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M. V. Goycoolea et al.
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35 Basic Imaging andNormal Temporal Bone Sections
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Evaluation andAuditory Rehabilitation
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inChronic Otitis Media (COM)
ByankaCagnacciBuzo, S.CatherineCatenacci,
andG.RaquelLevy
36
Chronic Otitis Media andits Eects
onHearing
Hearing loss is a major global public health problem,
occurring in both developed and developing countries,
with more than 466 million people affected worldwide [1].
The causes of hearing loss are varied, but one of the most
common is chronic ear infection, especially chronic otitis
media (COM). It is estimated that about 164 million cases
of hearing impairment may be due to COM.Global incidence rates are estimated at 5% for COM, of which 23%
are children [2].
COM is a chronic inammation of the middle ear with
discharge that drains into the ear canal through a perforation
in the tympanic membrane and often develops during early
childhood. As an after effect, the chronic perforations and
scarring of the tympanic membrane provoke hearing deterioration. In addition, the chronic state of inammation and discharge in the middle ear can lead to erosion of the middle ear
bones, worsening hearing loss. Because hearing loss is often
established in early childhood, it leads to difculties in language and speech development, together with associated
cognitive development. This again can result in impaired
social and emotional abilities, lower educational achievements, and restricted employment opportunities [3]. Because
of its long duration and greater severity compared to other
types of otitis media, and because most children need louder
B. C. Buzo (*)
Santa Casa de Sao Paulo School of Medical Science Hearing and
Speech Science Program, São Paulo, Brazil
Department of Research, Cochlear LATAM, Panamá City, Panamá
e-mail: bcagnacci@cochlear.com
S. CatherineCatenacci · G. RaquelLevy
Department of Otolaryngology, Clinica Universidad de Los Andes,
Santiago, Chile
e-mail: ccatenacci@clinicauandes.cl; rlevy@clinicauandes.cl
auditory stimuli than adults to function optimally, it is likely
that COM in children hinders cognitive and language
development.
During the inammatory process, COM frequently generates a conductive type of hearing loss. Moreover, the inammatory process of the middle ear can be detrimental to the
inner ear, as shown in histological and animal studies. During
the inammatory process, toxins can cause damage to the
round window membrane. This triggers the diffusion of toxins into the inner ear and uid leakage from the inner ear,
resulting in loss of cochlear function, leading to permanent
loss as will be discussed below [4].
Assessment ofHearing
The measurement of hearing is exemplied on a graphic
called an audiogram, in which the frequencies studied are
located on the horizontal axis and the intensity in decibels
HTL (hearing threshold level) on the vertical axis. The audiologist enters the symbols corresponding to the threshold
hearing of the patient in response of the sound stimuli that
are given through earphones (air conduction) or through the
bone vibrator (through the bone). The following audiogram
shows an audiological examination, in which its air and bone
thresholds are within normal limits (Fig.36.1).
Hearing loss that is reected in the audiogram in cases of
chronic otitis is generally classied as conductive hearing
loss, since it is the conductive or transmission system (external auditory canal, eardrum, and intratympanic bones) that is
affected. In some cases, there can also be a mixed hearing
loss, when, in addition to the eardrum-ossicular system,
there is also damage to the inner ear.
In cases of COM with conductive hearing loss, the audiogram shows an altered air conduction, i.e., outside the normal range while the bone conduction is within normal limits.
It is important to say that conductive hearing loss is charac-
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023
M. V. Goycoolea et al. (eds.), Textbook of Otitis Media, https://doi.org/10.1007/978-3-031-40949-3_36
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Fig. 36.1 Audiogram and symbols. Audiogram displaying the hearing
threshold levels within the normal ranges in accordance with WHO [1]
B. C. Buzo et al.
terized by a difference between air and bone thresholds
called air-bone GAP (Fig.36.2).
Hearing loss is classied by different grades. This classication is given by the average of the air conduction thresholds of 500, 1000, 2000, and 4000Hz, which we call PTA4
(pure tone average−4). Thus, conductive hearing loss can
be mild (PTA4 = 20 < 35 dB HL), moderate
(PTA4=35<50dB), until reaching its highest stage, which
is moderately severe (PTA4=50<65dB HL).
If recurrent infections continue, damage occurs at the
inner ear level. In these cases, the bone conduction deterioration begins to increase. Therefore, for air thresholds over
65dB HL, hearing loss should already be expected to be of
the mixed type, which is plotted in the audiograms below
(Fig.36.3).
When we talk about chronic otitis, we refer to a repetitive
process over time, a hearing loss that is installed and will probably increase if its cause is not stopped. As previously mentioned, this presents a very complicated scenario for children
in the language development stage, if they have long-standing
hearing loss. It is urgent to rehabilitate these patients’
hearing.
Fig. 36.2 (a) Conductive Hearing loss right ear. (b) Bilateral conductive hearing loss
ab
36 Evaluation andAuditory Rehabilitation inChronic Otitis Media (COM)
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Fig. 36.3 (a) Mixed hearing loss left ear, conductive hearing loss right ear. (b) Bilateral mixed hearing loss: severe in left ear and moderate in
right ear
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Thinking About Hearing Rehabilitation
means for hearing, which is the air conduction. The option
would be to use bone conduction. Rehabilitation using bone
The most logical reasoning for cases of conductive or mixed
hearing loss would be the adaptation of a conventional hearing aid. However, we must start with a practical question:
What effect can a conventional hearing aid produce in COM
cases? Let us remember that the hearing aid has a dome or
earmold that is placed in the external auditory canal of the
ear that seals it partially or even totally, to transmit the sound
toward the middle ear.
Auditory rehabilitation of patients with conductive or
mixed hearing loss due to chronic otitis media (COM) can be
challenging due to surgical sequelae with anatomical abnormalities and/or susceptibility to infections [5]. In daily clini-
conduction implants (BCI) has several advantages, as it
does not interfere with the local physiology and does not
increase the risk of infection. Additionally, it is particularly
effective in bypassing dysfunctional middle ear structures
and transmitting sound directly to the inner ear. A bone conduction hearing device does not block the ear canal and does
not require devices in the external auditory canal, making
COM patients highly qualied for the use of this
technology.
The ability of the cranial bone to conduct sound has been
exploited for a long time, and such sound transmission technology is now quite widespread as we shall see below [7].
cal practice, patients often nd that uid is leaking to their
external auditory canals when attempting to t a standard
hearing aid [6].
Sound Transmission by Bone Conduction
Consequently, people with chronic ear infections may
have difculty using traditional hearing aids if they experience uid drainage from the middle ear into the ear canal. In
these cases, this dome or earmold, which is located in the
external auditory canal, can become damp with middle ear
drainage, creating a humid space that facilitates the proliferation of germs and can lead to external and/or media otitis,
compromising the user’s hearing performance.
For that reason, it would be necessary to adapt sound
conduction devices that do not use the most conventional
We know that sound is not transmitted in a vacuum; it
requires a medium to propagate. This propagation involves a
transport of energy, in the form of mechanical waves that
spread through matter, in this case, bone.
These vibrations travel in the same direction in which
sound propagates. It is a longitudinal wave, which is transmitted in a straight line from the point of origin, and we
know that the speed of transmission of it is faster in solid
bodies than in less dense bodies.
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