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9 Basic Denition, Classication, andCharacteristics ofHearing Loss
179
9.3 Hearing Loss Configuration
The conguration of the hearing loss provides important information about the pathology causing the hearing impairment. It can be dened based on the following factors:
9.3.1 Pattern ofAudiogram
The pattern of an audiogram, or its shape, is named based on the frequency region
affected by hearing loss. Commonly recognized audiogram patterns include at,
sloping, rising, hearing loss, noise-notched hearing loss, and U-shaped (cookie
bite) hearing loss (Fig.9.9). The pattern of the audiogram can indicate not only
the frequency region in which the hearing difculty occurs but also the underlying
pathology causing the hearing loss. For example, Meniere’s disease often results
in signicant low-frequency hearing loss in its early stages. Otosclerosis and SCD
also have similar frequency congurations. On the other hand, tumors affecting
the auditory nerve typically cause signicant hearing loss in the higher
frequencies.
Fig. 9.9 Audiogram patterns
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A. M. Akşit and F. Akdaş
9.3.2 Progressive or Sudden Onset ofHearing Loss
Hearing loss can occur gradually or suddenly. Acquired hearing losses, such as
those caused by meningitis, measles, or trauma, may manifest abruptly. Some conditions cause a gradual increase in hearing loss over time, including age-related
hearing loss (presbycusis), use of ototoxic medications, and slowly developing
acoustic tumors.
Sudden hearing loss of unknown origin is called idiopathic sudden sensorineural
hearing loss (ISSNHL). Prompt intervention is critical in the management of this
group of hearing losses [12].
9.3.3 Unilateral or Bilateral Hearing Loss
Hearing loss may be unilateral or bilateral. Unilateral hearing loss may indicate a
cochlear pathology, while typical signs of retrocochlear pathologies and TWS, such
as LVA, include unilateral or asymmetric hearing loss, which warrants radiologic
evaluation [13].
9.3.4 Symmetric or Asymmetric Hearing Loss
Hearing loss may be symmetric or asymmetric. Asymmetric hearing loss may have
a cochlear origin, but the possibility of retrocochlear pathology suggests an extended
diagnostic investigation, as in the case of unilateral hearing loss.
9.3.5 Fluctuating or Stable Hearing Loss
Fluctuations in hearing loss can have various causes. Easily treatable factors, such
as cerumen impaction in the external ear canal, uid accumulation in the middle ear,
and Eustachian tube obstruction, can lead to uctuating hearing loss. Conditions
causing SNHL, such as Meniere’s disease, LVA, and perilymphatic stula, can also
cause uctuation in hearing thresholds. In addition, sudden SNHL, exposure to loud
sounds, and autoimmune hearing loss can cause uctuation in hearing [14].
9.4 Diagnostic Tests
The auditory process is completed by the conversion of acoustic energy into
mechanical energy in the middle ear, bioelectrical energy in the inner ear, and
neural networks in the cerebral cortex. As sound energy is transformed in the
external, middle, and inner ear, it is simultaneously amplied. Understanding
the energy changes during sound transmission and the amplication and
9 Basic Denition, Classication, andCharacteristics ofHearing Loss
inhibition methods used by the ear enhances the comprehension of the purpose
of diagnostic tests. Therefore, a brief description of diagnostic tests would be
benecial.
181
9.4.1 Pure Tone Threshold Testing
Pure-tone threshold testing is the cornerstone of audiologic assessment, providing
a comprehensive evaluation of the auditory process from the outer ear to the cerebral cortex. These tests not only determine the type and conguration of hearing
loss but also assess the diagnostic validity of additional assessments such as stapedial reex test, OAE test, and ABR.For example, the absence of OAE is considered an indicator of hearing loss. In the absence of OAE, the presence of an air/
bone threshold difference in pure tone tests suggests a conductive pathology,
whereas overlapping air/bone thresholds indicate a SNHL. Even if pure-tone
thresholds are within normal limits, the inability to record OAE may indicate otitis
media. A similar paradigm applies to ABR testing, where the absence of ABR
waves may indicate severe hearing loss. However, failure to record ABR waves in
the presence of mild hearing loss may lead to the consideration of ANSD or a retrocochlear pathology. Consequently, in the process of diagnostic assessments
employing objective tests, pure tone threshold testing plays a crucial role in the
evaluation.
9.4.2 Speech Recognition Tests
Speech recognition threshold (SRT) is commonly used to monitor pure-tone air
conduction thresholds. The SRT is obtained at a value close to the average of the air
conduction thresholds at 500–1000Hz.
Another commonly used speech test is the Speech Recognition Score (SRS). The
purpose of the SRS test is to obtain information about the location of the pathology.
An unexpected decrease in SRS compared to hearing thresholds may be a sign of
retrocochlear pathology or ANSD.On the other hand, if the SRS is better than
expected based on air conduction thresholds, the cause of the hearing loss may be a
conductive pathology.
9.4.3 Tympanometric Tests
Tympanometry provides information about middle ear compliance and mobility
based on the frequency of the probe tone used during the measurement. While the
226Hz probe tone provides information about middle ear compliance, the 1000Hz
probe tone provides information about mobility. In addition, tympanometry is often
used to evaluate Eustachian tube function and perilymphatic stula.
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A. M. Akşit and F. Akdaş
9.4.4 Stapedial Reflex
The stapedial reex is the contraction of the stapedial muscle in response to highintensity sounds. High-intensity unilateral stimulation causes contraction of the
stapedial muscle in both ears. Also known as the acoustic reex, the stapedial
reex results from the reex arc formed by the cochlear nerve and the facial nerve.
To record the reex, there should be no transmission problems in the outer and
middle ear. Also, inner hair cells in cochlea and auditory and facial nerves should
be intact (outer hair cells in the cochlea do not interfere with the formation of the
stapedial reex). The reex decay test can also be used to assess auditory nerve
fatigue.
9.4.5 Otoacoustic Emission Test
OAE are sounds produced by outer hair cells in the cochlea. These sounds can be
recorded by a sensitive microphone in the outer ear canal [15]. The diagnostic signicance of OAE is that it records pre-nerve auditory potentials. OAE recording is
not possible in cases of cochlear pathology in which the outer hair cells are damaged. The presence of OAE in the presence of hearing loss indicates pathology
involving inner hair cells and/or the auditory nerve.
9.4.6 Auditory Brainstem Responses
The ABR test records the responses of the auditory pathways to acoustic stimuli. It
evaluates the synchronization of the auditory nerve. Diagnostic evaluation is based
on the duration and amplitude of ve consecutive peaks occurring within 10ms.
ABR is highly reliable and can be used to diagnose conductive pathology, cochlear
pathology, ANSD, and acoustic tumors.
The ABR criteria used to identify various pathologies are
• Conductive pathology: Prolongation of latencies of waves I, III, and V is
observed. However, the I–V wave interval remains within normal limits.
• Cochlear pathology: Latencies of waves I, III, and V are within normal limits.
However, if there is a high-frequency hearing loss, the latency of wave V may be
prolonged. ABR threshold is compatible with high-frequency air conduction
thresholds (especially 4kHz).
• ANSD: ABR waves are not observed even with high-intensity stimuli. Cochlear
microphonics are observed when condensation and rarefaction stimulation
modes are recorded consecutively at intensities greater than 70dB.
• Vestibular schwannoma/acoustic tumor: Evaluation is based on several criteria.
– Wave V may not be observed.
– Wave V may be observed, but:
Wave V latency and I–V wave interval are above normal.
9 Basic Denition, Classication, andCharacteristics ofHearing Loss
183
Between the two ears, wave V latency and I–V wave interval are greater
than normal.
Wave I to wave V (I/V) amplitude ratio is less than 1μV.
9.5 Audiological Test Battery forPathologies
The most reliable approach from a diagnostic standpoint is to subject the patient to
audiologic testing after a medical evaluation by an otolaryngologist. In addition,
careful documentation of the patient’s history and complaints will facilitate the
diagnosis.
Audiologic testing in adults usually begins with pure tone air and bone conduction thresholds, followed by speech and tympanometric testing. The data obtained
are reviewed and, if deemed necessary, further advanced diagnostic testing is performed. Figures9.10 and9.11 outline the stages of testing for common pathologies,
while Tables 9.2 and 9.3 show the differences in audiologic ndings observed in
common pathologies.
Fig. 9.10 Audiological test scheme for conductive hearing loss
Table 9.2 Audiological conguration commonly seen in low-frequency hearing loss pathologies
Pathology
Meniere Otosklerosis SSCD
Audiological
nding
Air/bone gap
Speech
recognition score
Tympanogram Type A Type As Type A
Stapedius reex (+)
Progress Progressive Progressive Stable
(−)
Compatible with
hearing loss
(+) (+)
Better compared
to hearing loss
(−)
Better compared
to hearing loss
(+)
184
A. M. Akşit and F. Akdaş
b
Depends
b
(−) (−)
Depends
*
Large vestibular
aqueduct synd. Schwannoma Neurobromatosis 2
(+)
Compatible with
hearing loss
Compatible with
hearing loss
Compatible with
hearing loss
(−)
Asymmetric Unilateral Asymmetric
c
shaped
Symmetric HFHL Asymmetric, V
a
Pathology
Presbycusis Ototoxicity Acoustic trauma
(−) (−) (−)
Depends
Air/bone gap
Speech
recognition score
Audiological
Table 9.3 Common audiological ndings in high-frequency hearing loss pathologies
nding
Tympanogram Type A Type A Type A Type A Type A Type A
Stapedius reex (+) (+) (+) (+) Depends
Conguration Symmetric
HFHL
Visible at 250 and 500Hz
Depends on the size and location of tumor
Depends on the site of pathology
*
Depends on the noise source
a
b
c
9 Basic Denition, Classication, andCharacteristics ofHearing Loss
Fig. 9.11 Audiological test scheme for unilateral and asymmetric high frequency
9.6 Reporting Audiological Findings
185
Clear reporting of audiologic ndings is critical to the diagnostic process. Therefore,
it is important to know the normative values for all audiologic ndings and to
describe them according to these norms. However, because the interpretation of test
results is the responsibility of the otolaryngologist, the audiologic report should
avoid absolute certainty. However, when reporting audiologic test results, highlighting particularly critical ndings with diagnostic signicance may facilitate the otolaryngologist’s pathologic evaluation. An example of an audiogram and a report
highlighting critical ndings is shown in Fig.9.12.
186
a
A. M. Akşit and F. Akdaş
b
Fig. 9.12 (a and b) Example of an audiogram and a report with a detailed explanation
9.7 Conclusion
Hearing loss can be classied by degree, conguration, and type. The primary goal
of these classications is to identify the underlying pathology causing the hearing
loss. It is important to note that no single audiologic test can provide sufcient
information to make a pathologic diagnosis. The basic tests used in audiologic evaluations are designed to assess the function of different regions within the auditory
pathways. Therefore, a comprehensive interpretation of test results is essential for
an accurate diagnosis.
9 Basic Denition, Classication, andCharacteristics ofHearing Loss
187
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Otologic History Taking andBasic
Examination Techniques
SerdalCelik, SekibUmihanic, MahmutTayyarKalcioglu,
andSuatOzbilen
10.1 Introduction
An otologic examination is an important clinical procedure used to assess the wellbeing of the ear, hearing and balance system and to identify potential problems.
Hearing plays a critical role in vital functions such as communication and balance,
so it is important to monitor and evaluate the health of the ear. In otologic conditions, many disorders can be diagnosed with a detailed history and physical examination. It is, therefore, important to listen carefully to the patient’s complaints and
history, remembering that even the smallest detail can be crucial to the diagnosis.
There are many techniques and instruments used in the physical examination. With
the help of advancing technology, there have been developments in examination
tools and techniques over the years. However, although the advanced examination
tools we use are invaluable, the importance of the examinations that have been used
for many years is too great to be ignored. This section discusses ear examination
methods, history taking, and basic physical examination techniques.
10
S. Celik (*) · M. T. Kalcioglu
Faculty of Medicine, Department of Otorhinolaryngology, Istanbul Medeniyet University,
Istanbul, Turkey
Goztepe Prof Dr Suleyman Yalcin City Hospital, ENT Clinic, Istanbul, Turkey
S. Umihanic
Clinic for Ear, Nose and Throat Disease,Head and Neck Surgery,
University Clinical Center Tuzla, Tuzla, Bosnia and Herzegovina
S. Ozbilen
Faculty of Medicine, Department of Otorhinolaryngology, Gazi University, Ankara, Turkey
© The Author(s), under exclusive license to Springer Nature
Switzerland AG 2024
M. T. Kalcioglu et al. (eds.), Otology Updates, Comprehensive ENT,
https://doi.org/10.1007/978-3-031-76173-7_10
189