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120 Disorders of the Auditory System
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means of special plastic snap. The boneconduction device is then positioned
on the head over the mastoid process
and sound is transmitted to the cochlea
through bone-conduction mechanisms.
It is ideal for infants and young children
who are not yet candidates for surgical
intervention. Patients must have a significant sensorineural reserve to be candidates for the placement of this type of
device, as well as for the implantation of
an osseointegrated device. For patients
who are candidates for an osseointegrated
device, the surgical implantation process
involves the placement of a metal implant
in the temporal bone to which a hearing
aid can be attached externally. Similar to
a bone-conduction hearing aid, an osseointegrated device directly conducts sound
through the temporal bone to the cochlea.
Case 4–1: Canal Atresia
and Stenosis
History
This 1-month-old female was referred for
an audiologic evaluation due to a failure
on her newborn hearing screening bilaterally. She was accompanied to her appointment by her mother who reported no significant family history or risk factors for
hearing loss. The patient’s birth history
was unremarkable; however, her mother
reported that her daughter had been evaluated previously by a pediatrician who
had diagnosed one definitive episode of
otitis media.
Audiology
Upon otoscopic examination, the tympanic membranes could not be visualized
in either ear; however, this was not due
to debris in the ear canal. Tympanograms
were attempted and yielded atypical findings. Results demonstrated flat tracings
with small equivalent ear canal volumes
bilaterally. While this could initially be
interpreted as an error in test administration (incorrect probe placement against
the canal wall), this finding actually supports the “ultimate” clinical diagnosis of
atresia and stenosis that was rendered
following completion of the infant’s audiologic, medical, and radiologic assessments. Due to the patient’s age, an ABR
test was performed (Figure 4–1A) during
her audiologic evaluation. Results for a
click-stimulus ABR yielded no identifiable
waveforms for the right ear and a threshold at 80 dB nHL (70 dB estimated hearing
level) for the left ear. An unmasked boneconduction response was obtained at 45
dB nHL (estimated hearing level 25 dB
HL). Frequency-specific ABR results could
not be obtained at the time of this evaluation as the patient awoke prior to test
completion. Due to the abnormal results
noted during her audiological evaluation,
the patient was referred to otolaryngology
for further evaluation.
Medical Examination
The patient presented with normal
appearing mastoids and pinnae; however, the tympanic membranes could
not be visualized during a routine otoscopic exam. Given the abnormal clinical exam, it was recommended that the
infant undergo an examination under the
microscope in the operating room along
with imaging studies. In addition, it was
recommended that the ABR be repeated
in the operating room for confirmation of
results. Once in the operating room, the
medical examination under the microscope confirmed what first appeared to
be bilateral canal atresia. The ABR was
repeated under sedation and results con-
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A
B
Figure 4–1. Auditory brainstem response results (A) and imaging results (B) for an infant with
canal atresia and stenosis (Case 4–1). The upper two waveforms in both figures are air-conduction
results, while the lower two waveforms on the left-hand figure are unmasked bone-conduction
results.
firmed the presence of a significant hearing loss bilaterally. Due to the presence of
significant ear canal compromise bilaterally, it was not possible to effectively mask
each ear independently; however, given
the click-evoked ABR test results suggesting a moderately severe hearing loss
in the left ear, a profound hearing loss in
the right ear, and a normal to near normal unmasked bone conduction threshold, coupled with the medical finding of
canal atresia on the left side and severe
stenosis on the right side, it is likely that
there is a significant conductive hearing
loss or component bilaterally. However, at
this time a definitive determination of the
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exact type, extent, and configuration of
hearing loss in each ear cannot be made.
A CT scan was also ordered to further evaluate the auditory structures (Figure 4–1B). Results from the CT procedure
demonstrated normal internal auditory
canals and a normal middle ear space
with all three ossicles appearing normal
in structure and size in both ears. The
cartilaginous external auditory canals
were patent bilaterally; however, they
appeared to terminate near the junction
of the bony external auditory canals. In
addition, both cochleae appeared normal.
The CT images revealed a complete osseous obstruction of the left external auditory canal at the bony canal, and severe
stenosis of the right external auditory
canal was observed.
Impression
External auditory canal atresia of a significant portion of the left ear canal and
severe canal stenosis of the right ear.
Audiologic Recommendations
and Management
Given the fact that the patient presented
with a maximum conductive hearing loss
in at least one ear and most likely in both
ears (see previous discussion) secondary to canal atresia (left ear) and stenosis (right ear), it was recommended that
the patient be fit with a softband boneanchored device. The patient’s mother
had a consultation with the audiologist
following medical clearance (see the following section) and the patient was fit
with the recommended softband device. It
was recommended that further frequencyspecific results for bone conduction be
obtained in order to maximize the device
fitting and patient outcomes.
Medical Recommendations
and Management
The patient was medically cleared to be fit
with a softband device. While too young
to prescribe an exact course of medical
management for the outer ear conditions
identified, the patient will be closely monitored with appropriate medical recommendations and interventions to follow
in the future.
eustachian tuBe
dysfunction
Introduction
Eustachian tube anatomy and function is
vital as it connects the middle ear space
with the nasopharynx, and dysfunction
of this connection can lead to significant
otologic disease (Bluestone, 1998). The
middle ear opening to the Eustachian tube
is located in the anterior medial aspect of
the middle ear. The proximal one-third
of the tube passes through the petrous
portion of the temporal bone. The distal
two-thirds is primarily cartilaginous and
terminates in the superior-lateral aspect
of the nasopharynx. Redundant cartilage
of this tube protrudes into the nasopharynx and is referred to as the torus tubarius. Two muscles, the tensor veli palatini
and the levator veli palatini, which have
attachments to the palate, are responsible
for active dilation of the distal portion of
the Eustachian tube. Bluestone describes
the three physiologic functions of the
Eustachian tube as (1) ventilation of the
middle ear, (2) protection from the nasopharynx, and (3) clearance of secretions of
the middle ear.
The Eustachian tube is a dynamic
structure that is closed at rest but opens
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passively in response to changes in atmospheric pressure and actively in response
to activities such as sneezing, swallowing,
or yawning. The tube also can be opened
forcibly by autoinsufflation. If the tube
fails to open or becomes blocked, the air
within the middle ear is absorbed, creating a vacuum or a negative pressure condition. This negative pressure leads to
retraction of the tympanic membrane and
may lead ultimately to further disease of
the middle ear (e.g., otitis media). In some
individuals, the tube may be abnormally
patent (i.e., open), which is referred to as
a patulous Eustachian tube.
Symptoms
The symptoms of Eustachian tube dysfunction depend on the type of dysfunction present. Occlusion of the tube that
results in negative middle ear pressure
typically results in a sensation of pain
and pressure in the ear as the tympanic
membrane retracts. Patients also indicate difficulty in “popping” their ears
by autoinsufflation, and they may also
experience tinnitus and disequilibrium.
Chronic occlusion of the tube may lead to
the development of serous fluid collection
within the middle ear, a condition referred
to as otitis media with effusion. This effusion leads to a conductive hearing loss,
and the fluid may become infected, leading
to acute otitis media. Persistent effusion
with associated conductive hearing loss
may affect speech and language development in children (Dhooge, 2003).
Patients with patulous Eustachian
tubes experience autophony, which is the
perception of one’s own breathing and
speech as being excessively loud. This
perception of increased loudness of one’s
breathing and speech is due to the existence of a persistently patent or open tube.
Incidence and Prevalence
According to Bluestone (2004), Eustachian
tube dysfunction affects 70% to 90% of
children by the age of 2 years. He also
reported that Eustachian tube dysfunction is more common in children less than
5 years of age as well as in males, Native
Americans, and patients with lower socioeconomic status. In addition, Eustachian
tube dysfunction reportedly accounts for
more than 2 million adult medical visits
per year (McCoul et al., 2019).
Etiology and Pathology
Middle ear disease is extremely prevalent
in children and can be attributed primarily to a developing Eustachian tube. The
fundamental differences between pediatric and adult Eustachian tube anatomy
accounts for the increase in dysfunction
of this tube in children as compared to
adults. The Eustachian tube is shorter in
children and reaches adult size by 7 years
of age (Sadler-Kimes, Siegel, & Todhunter,
1989). In addition, the tube slopes approximately 10º from the horizontal plane of
the skull base in infants and young children compared with a 45° slope that is
noted in adults (Proctor, 1967). These differences can have a detrimental effect on
middle ear ventilation, protection, and
fluid clearance.
Obstruction of the tube may be due
to intrinsic inflammation within the nasal
cavity, the middle ear, or the tube itself.
Tobacco use, gastroesophageal reflux,
nasal polyps, allergic rhinitis, chronic
sinusitis, and upper respiratory infections
are common causes of this inflammation.
Functional obstruction can also occur in
children with cleft palate defects because
the peritubal muscles are unable to effectively open the distal portion of the Eusta-
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chian tube. Extrinsic obstruction of the
Eustachian tube may also result from the
presence of a mass within the nasopharynx, such as a nasopharyngeal carcinoma
or adenoid hypertrophy.
Patulous Eustachian tube has been
associated with extensive weight loss and
pregnancy, which may deplete peritubal
soft tissue mass or change tissue characteristics, respectively, allowing the tube
to abnormally remain open. In addition,
a neurologic insult, such as a stroke, and
degenerative neurologic disorders, such
as multiple sclerosis, may lead to muscle atrophy, allowing for abnormal tube
patency.
Site of Lesion
The site of pathology leading to Eustachian tube dysfunction may lie on multiple levels. The primary pathology may
reside within the nasal cavity as described
previously with either inflammation or a
mass effect obstruction. In addition, the
tube can be obstructed due to inflammation within the tube itself, or it functionally may not open due to peritubal muscle
dysfunction. Typically, the site of lesion
does not lie within the bony portion of the
Eustachian tube.
Audiology
Traditional audiologic evaluation typically
includes tympanometry to assess middle
ear function (see Chapter 3, “Audiologic,
Vestibular, and Radiologic Procedures”).
Tympanometry was first reported in the
assessment of Eustachian tube dysfunction in the late 1960s (Holmquist, 1969) and
has been an integral part of the evaluation
since that time (Leo, Piacentini, Incorvaia,
& Consonni, 2007). A number of tests can
be performed with tympanometric procedures to measure Eustachian tube function. These generally require acquiring
a baseline tympanogram, then creating
positive and/or negative pressure in the
ear canal and asking the patient to swallow several times. Following this procedure, the tympanogram is retraced and if
the peak pressure changes, the Eustachian
tube is functioning. If there is no change
in the peak pressure, the findings suggest
Eustachian tube dysfunction.
During tympanometric testing, individuals with patulous Eustachian tubes
often show oscillations that correspond
to the patient’s breathing patterns (inhalations and exhalations), with these oscillations becoming more notable with hard
breathing (see Fowler & Shanks, 2002, for
additional discussion).
When using regular tympanometry,
patients who present with Eustachian
tube dysfunction (exclusive of patulous
tubes) often present with either negative
pressure and/or reduced compliance. In
addition, a traditional audiologic evaluation including pure-tone threshold testing,
speech recognition thresholds, and speech
recognition testing is recommended to
determine if the Eustachian tube dysfunction has impaired the patient’s hearing
sensitivity and/or speech understanding.
If hearing loss is present, it will be either
conductive or mixed in nature (dependent
on whether or not a preexisting sensorineural loss is present).
Medical Examination
A thorough examination of the head and
neck is vital to diagnosing the etiology
of Eustachian tube dysfunction. Otoscopy with pneumatic insufflation is key
to determining the appearance of the
tympanic membrane, the presence of an
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effusion, and the compliance of the tympanic membrane. Rhinoscopy assists in
identifying nasal masses or inflammatory
conditions. A thorough evaluation of the
nasopharynx is mandatory and can be
accomplished by direct inspection with
a rigid or a flexible nasopharyngoscope.
A Valsalva test involves forced expiration
with a closed mouth and an occluded
nose while the tympanic membrane is
inspected. A tympanic membrane bulging laterally as the middle ear space is
filled with air indicates a patent Eustachian tube. A Politzer test involves inspection of the tympanic membrane while air
is injected into the nasopharynx as the
patient swallows. The tympanic membrane should respond in a manner similar
to the Valsalva test.
Radiographic evaluation with plain
film, lateral view X-ray of nasopharyngeal soft tissue may reveal adenoid hypertrophy or other nasopharyngeal masses.
Computed tomography (CT) and magnetic resonance imaging (MRI) can clearly
delineate skull base anatomy and pathology and is routinely utilized in evaluation
of masses of the nasopharynx.
or allergy immunotherapy. Obstruction,
whether intrinsic or extrinsic, that has
been refractory to medical management
typically is treated with myringotomy
and placement of a pressure equalization
(PE) tube (also referred to as a tympanostomy tube) in the tympanic membrane in
order to equalize the pressure between the
middle ear and the external environment,
thus bypassing the role of the Eustachian
tube in this function (Bluestone, 2004).
It should be noted that although Eustachian tube dysfunction is most common
in children, it is not uncommon for it to be
observed in adults.
Case 4–2: Eustachian
Tube Dysfunction
History
This 52-year-old male reported 6 weeks
of chronic aural fullness and pressure
with no noticeable hearing loss. He also
reported occasional tinnitus, which he
described as a “cracking” sound. No other
significant audiologic or otologic symptoms were reported.
Audiologic Management
In most instances, Eustachian tube dysfunction is managed otologically. Audiologic
support for this is primarily diagnostic in
nature.
Medical Management
Management of Eustachian tube dysfunction depends on the etiology. Inflammatory conditions such as allergies or upper
respiratory infections are typically treated
medically with oral steroids, intranasal steroid sprays, antihistamines, and/
Audiology
Routine pure-tone testing revealed hearing thresholds within normal limits for
both ears and excellent word recognition
performance was noted bilaterally (Fig-
4–2). Tympanometry indicated normal
ure
volume and compliance bilaterally with
excessive negative pressure bilaterally.
Medical Examination
The patient presented with normal appearing mastoids, pinnae, ear canals, and tympanic membranes without evidence of
fluid, perforation, or retraction.
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Figure 4 –2. Pure-tone, speech audiometry, and tympanometry results for a 52-year-old male with
Eustachian tube dysfunction (Case 4–2).
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Impression
Bilateral Eustachian tube dysfunction.
Audiologic Recommendations
and Management
It was recommended that the patient follow up with an otolaryngologist, with subsequent audiologic follow-up as necessary.
Medical Recommendations
and Management
Following medical and audiologic evaluation, it was recommended that the patient
undergo a bilateral myringotomy and PE
tube placement under local anesthesia in
the office.
Additional Comments
The patient received significant benefit
from the bilateral PE tube placement,
with relief of his pressure and aural fullness symptoms noted posttube placement
bilaterally.
otitis media
Introduction
Otitis media refers to inflammation of the
middle ear and involves a broad range
of disease processes. This inflammation,
which is typically preceded by some form
of Eustachian tube dysfunction, is accompanied by a fluid collection (or effusion)
behind the tympanic membrane. In acute
otitis media, a purulent effusion develops
rapidly due to bacterial colonization and
is characterized by systemic symptoms.
This purulent effusion may resolve into a
serous effusion (a collection of fluid in the
middle ear space) before complete resolution occurs. The presence of a serous
effusion for more than 30 days, regardless
of etiology, is referred to as chronic otitis
media with effusion. The condition where
either three or more bouts of acute otitis
media occur within 6 months, or four or
more episodes of acute otitis media occur
in 1 year, is referred to as recurrent acute
otitis media. Chronic suppurative otitis
media refers to persistent inflammation
and disease of the middle ear with compromise of the tympanic membrane. Due
to the fact that it is often associated with
cholesteatoma, further discussion of this
chronic condition is reserved for the cholesteatoma section of this chapter.
Otitis media is ubiquitous and may
be due to a variety of etiologies. Infections, allergies, and environmental factors have all been found to contribute to
otitis media (Danishyar & Ashurst, 2019).
Common etiologies include, but are not
limited to, immunodeficiencies, anatomic
abnormalities, viral pathogens, passive
smoke exposure, and daycare attendance
(Bluestone, 2004). It has also been well
established that exposure to secondhand
smoke significantly increases the risk for
otitis media in children (Jones, Hassanien,
Cook, Britton, & Leonardi-Bee, 2012). Otitis media accounts for one of the most
common pediatric diagnoses made by primary care providers and results in a significant consumption of health care funds
annually (Bluestone, 2004).
Symptoms
Acute otitis media typically is accompanied by fever, otalgia, pressure, and irritability. These symptoms may be decreased
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or absent in older patients. Although
acute otitis media usually is responsive
to antimicrobial therapy, complications
that can occur include meningitis, labyrinthitis, petrositis, brain abscess, facial
paralysis, and coalescent mastoiditis. Any
evidence of mental status change in the
case of acute otitis media or of a failure
of symptoms to improve following appropriate medical treatment should raise the
suspicion of one of these complications.
The presence of an effusion also
causes a conductive hearing loss. In some
cases, chronic otitis media with effusion
may be completely asymptomatic with
the exception of a conductive hearing loss.
As small children are prone to this condition, they may be unable to adequately
describe their symptoms, particularly the
presence of a hearing loss. It therefore
falls on clinicians to look carefully at these
patients for any “hidden” symptoms.
Incidence and Prevalence
Otitis media can occur across the life span,
but is more common in children than
adults. Acute otitis media is extremely
prevalent. A recent study evaluating the
epidemiology of acute otitis media found
that by 1 year of age, 23% of children experience more than one episode, with this
rate increasing to 60% by 3 years of age
(Kaur, Morris, & Pichichero, 2017). This
middle ear condition is more common in
young children and occurs much less frequently in children over the age of 6 years
(O’Neill, Roberts, & Bradley Stevenson,
2006). The rates of acute otitis media are
higher in children with repeated exposure
to large numbers of other children, such as
in day care settings (Paradise et al., 1997).
Approximately 2.2 million episodes of
otitis media with effusion are diagnosed
annually in the United States (Rosenfeld
et al., 2016).
Otitis media with effusion typically
presents in children less than 6 years of
age and may be secondary to upper respiratory infections or acute otitis media
(Rovers, Schilder, Zielhuis, & Rosenfeld,
2004). The rate of middle ear effusion is
reported to be higher in pediatric patients
in an ICU setting than in other settings
(Derkay, Bluestone, Thompson, & Kardatske, 1989), and the overall incidence of
chronic otitis media with effusion in children is reported to range from 15% to 20%
(Zielhuis, Rach, van den Bosch, & van den
Broek, 1990).
Etiology and Pathology
An upper respiratory viral infection commonly occurs in conjunction with acute
otitis media and results in a breakdown of
the protection that the nasal mucosa provides against bacterial infection (Henderson et al., 1982). The primary cause of otitis media is Eustachian tube dysfunction.
When bacteria are allowed to colonize
the middle ear space, otitis media occurs.
The most common bacterial pathogens
are Streptococcus pneumoniae, Haemophilus
influenzae, and Moraxella catarrhalis (Blue-
stone, Stephenson, & Martin, 1992). Conditions that impair immune system function, such as diabetes or HIV, can increase
the risk of infection. Anatomic abnormalities of the Eustachian tube secondary to
craniofacial conditions such as cleft palate also increase risk of acute otitis media.
Tobacco smoke exposure, adenoid hypertrophy, lower socioeconomic status, and
group day care attendance are additional
risk factors. Finally, chronic infectious or
inflammatory granulomatous diseases,
such as tuberculosis or Wegener’s granu-
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lomatosis, can induce exudation of fluid
from the middle ear mucosa and lead to
the development of otitis media (da Costa
& Polanski, 2015).
Site of Lesion
Otitis media, by definition, is located primarily in the middle ear; however, as previously described, its etiology depends on
Eustachian tube dysfunction as bacteria
typically migrate or reflux into the middle
ear from the nasopharynx. Due to the confluent relationship between the middle
ear and the mastoid, an effusion that fills
the middle ear typically extends into the
mastoid as well. Therefore, patients with
serous otitis media or acute otitis media
will often be found to have fluid in their
mastoid air cells as well as their middle
ears on CT scans. In the situation of acute
otitis media, increasing middle ear pressure due to accumulating purulent effusion can lead to perforation of the tympanic membrane and drainage of pus into
the external auditory canal (Bluestone &
Klein, 2003).
Audiology
presenting with negative pressure and/or
reduced compliance. As the disease progresses, tympanograms typically change
from a negative pressure peak early on
to a flat tympanometric configuration
(little to no compliance) with significant
fluid accumulation in the middle ear at
advanced stages of the disease. The audiologic evaluation typically reveals a conductive or mixed hearing loss (depending
if a preexisting sensorineural loss is present). Although in the early stages of development of otitis media (i.e., when Type C
tympanograms are observed), hearing
thresholds may fall within normal limits.
The configuration of the hearing loss, if
one is noted, is usually rising (i.e., poorer
hearing thresholds in the low frequencies
when compared to the high frequencies).
This ascending contour is often noted at
the beginning of the disease process as
the tympanic membrane and the ossicular
chain increase in stiffness with decreasing middle ear pressure. As the fluid in
the middle ear accumulates over time, a
mass effect may result, and the configuration flattens as the high frequencies also
are compromised. The degree of hearing
loss is usually in the mild range (20 to 40
dB HL), but it can fluctuate considerably
(Jerger & Jerger, 1981).
In cases of otitis media, the audiologic
evaluation is an integral part of the entire
medical workup. The audiologic examination for the patient with otitis media typically includes tympanometry and routine
audiologic evaluation appropriate to the
patient’s age (Aithal, Aithal, & Pulotu,
1995). Tympanometry, although first introduced by Metz in the mid-1940s (Metz,
1946), truly began its clinical integration
in the early 1970s. Tympanometry allows
for objective evaluation of the middle ear
status with most patients with otitis media
Medical Examination
Pneumatic otoscopy is key to the diagnosis of otitis media. In acute otitis media,
the tympanic membrane appears red and
bulging; however, the purulent middle
ear effusion behind the eardrum may not
be easily visualized due to thickening of
the tympanic membrane. Chronic otitis
media with effusion is characterized by
a clear, honey-colored fluid in the middle
ear. A thorough examination of the upper
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