1
Q
Conductive hearing loss & its mechanisms
A
Mechanical disruption of the external
auditory canal or middle ear
Mechanisms:
1. Obstruction
2. Mass loading
3. Non-compliant structures
4. Discontinuity of structures
2
Q
Sensorineural hearing loss & its mechanisms
A
Deficit in the inner ear (sense) or central nervous system auditory pathway (neural)
Mechanisms:
1. Deterioration of cochlea – usually loss
of hair cells in Organ of Corti
3
Q
> ____% of childhood hearing impairment is thought to be hereditary
A
50
4
Q
Nonsyndromic vs. Syndromic hearing loss
A
- Nonsyndromic hearing loss: hearing loss is the only clinical abnormality
- Syndromic hearing loss: in which hearing loss is associated with anomalies in other organ systems
5
Q
_____: retinitis pigmentosa & hearing
loss
A
Usher syndrome
6
Q
______: pigmentary
abnormality (hair, skin, & nails) & hearing loss
A
Waardenburg syndrome
7
Q
____ → thyroid organification
defect & hearing loss
A
Pendred syndrome
8
Q
____ → renal disease & hearing loss
A
Alport syndrome
9
Q
_____ → prolonged
QT interval & hearing loss
A
Jervell & Lange Nielson syndrome
10
Q
Ototoxic Medications
A
- Aminoglycoside antibiotics: Gentamicin, Amikacin, Neomycin, Streptomycin
- Other antibiotics: Vancomycin, Erythromycin
- Antimalarials: Chloroquine, Quinine
- Platinum-based chemotherapy agents: Cisplatin, Carboplatin
- Loop diuretics: Furosemide, Torsemide
- Nonsteroidal anti-inflammatory drugs: Aspirin, Ketorolac, Ibuprofen
11
Q
Hearing Loss presentation
A
- Sudden, unexplained hearing loss
- Gradual painless hearing loss
- Bilateral or unilateral
- Deficits affecting high, low, or all
frequencies - Distorted sound (like “blown”
loudspeaker) - Ear fullness or pressure
- Ear feels numb or blocked
- May be associated with ear pain
- May also have Tinnitus or Vertigo
12
Q
T/F Remove impacted cerumen prior to
making a Dx of hearing loss
A
T
13
Q
Conductive hearing loss structures
A
- Involves auditory canal, tympanic membrane, & the ossicles
- Lesions in the auricle, external auditory canal, or middle ear
can cause conductive hearing loss - Often reversible
14
Q
Sensorineural hearing loss structures
A
- Involves cochlea and CN VIII
- Often permanent
15
Q
Weber test
A
- A 256 or 512 Hz tuning fork is placed on the mid forehead
- Sound should be perceived equally bilaterally
- Lateralization of sound = + test
16
Q
Rinne test
A
- Place the tuning fork against the mastoid process & count
- When the patient no longer hears the sound, note the number of seconds & rapidly
reposition the tuning fork 1-2 cm from the auditory canal, & count - The patient should indicate when sound is no longer heard
17
Q
Review weber/rinne results
A
:)
18
Q
Audiometry
A
- Most widely accepted diagnostic test for
hearing loss or concerns - Usually obtained in a sound-proof
environment - Demonstrates how loud sounds need to be at
different frequencies for you to hear them - “Audible threshold”
19
Q
Most widely accepted diagnostic test for hearing loss or concerns
A
Audiometry
20
Q
Tympanometry
A
Graph
* Relationship between air pressure in the canal and movement of
the tympanic membrane (TM)
* Provides volume measurement and pressure measurement
21
Q
Otosclerosis
A
Overgrowth of bone in the
inner ear
* Often stapes
22
Q
Otosclerosis etiology - 3 main theories
A
- Abnormal osteoclast & osteoblast activity of mature endochondral bone of the otic capsule
- Genetic: Inherited in an autosomal dominant pattern
with incomplete penetrance - Viral infection (likely measles)
- Endocrine factors (hormonal): Abnormalities in PTH & estrogen contribute to
abnormal bone turnover
23
Q
Otosclerosis clinical presentation
A
- Gradual conductive hearing loss beginning in young adulthood
- Typically speak quietly & report better hearing in noisy
environments, when voices tend to be raised - Tinnitus ~50% of patients
- Vertigo ~10% of patients
- Exam is normal
24
Q
Weber test in Otosclerosis
A
lateralizes
25
Otosclerosis Audiogram
Audiogram confirms either unilateral or
bilateral conductive hearing loss
* Conductive hearing loss (about 40-60 decibels
in lower frequencies & less in higher
frequencies) on audiometry, without tympanic
membrane abnormality
* Carhart notch at 2000 Hz
26
Tx for mild hearing loss
observation and/or hearing aids with routine hearing tests to determine if condition is progressing
* Florical
* Bisphosphonates
27
Aggressive Tx for hearing loss
stapedectomy with prosthesis (stapedoplasty)
* Most Successful
28
Otosclerosis Complications
* Progressive hearing loss
* Conductive at early stages of disease & progresses
to mixed or sensorineural hearing loss in later
stages of disease
* Severe conductive hearing loss can develop in
patients with obliterative otosclerosis
29
Most common cause of hearing loss in adults
Presbycusis
30
4 theories of etiology in Presbycusis
* Sensory presbycusis: Epithelial atrophy with loss of sensory hair
cells & supporting cells in the organ of Corti
* Neural presbycusis: Atrophy of nerve cells in the cochlea & central
neural pathways; ~2100 neurons are lost every decade (of 35,000
total)
* Metabolic presbycusis: Atrophy of the stria vascularis
* Mechanical presbycusis: Results from thickening & secondary stiffening of the basilar membrane of the cochlea
31
Clinical presentation of presbycusis
* Sensorineural hearing loss usually occurs first with high-
frequency sounds & progresses to lower tones
* Difficulty understanding rapidly spoken language, vocabulary
that is less familiar or more complex, & speech within a noisy,
distracting environment
* Localizing sound becomes difficult
32
_____ is a diagnosis of exclusion
Presbycusis
33
Management of Presbycusis
* No cure
* ENT, audiology referral
* Amplification devices: hearing aids
* Lip reading:
* Assistive listening devices:
* Cochlear implants:
34
Acoustic Neuroma
Intracranial, extra-axial tumors arising from the
Schwann cell sheath investing either the vestibular or cochlear nerve
35
High dose ionizing radiation is the only known risk factor for _____
Acoustic Neuroma
36
Clinical Presentation of Acoustic Neuroma
* Unilateral hearing loss is the most common
symptom
* 50-60% of patients experience headache at
the time of diagnosis
* 25% of patients report facial numbness
* Unilateral sensorineural hearing loss is an
acoustic neuroma until proven otherwise
37
Unilateral sensorineural hearing loss is ____
acoustic neuroma until proven otherwise
38
Diagnosis of Acoustic Neuroma
* Audiogram
* Gadolinium-enhanced MRI brain with attention to IACs
39
Acoustic Neuroma Management
* Refer to neurotology for surgical excision of the tumor: Treatment of choice for tumor eradication
* Stereotactic radiation therapy: Stops tumor growth
* Serial observation
40
____ Americans risk noise-induced hearing
loss (NIHL)
5-10 million
41
Noise-Induced Hearing Loss Etiology
* Several minutes after exposure to noise:
* Edema of the stria vascularis appears, & may persist for several days
* The cochlea also becomes inflamed in response to acoustic trauma
Outer hair cells are more susceptible to noise exposure than inner
hair cells → ↓ stiffness of the stereocilia of outer hair cells
* Severe exposure → injury from a loss of adjacent supporting cells to
complete disruption of the organ of Corti, which may be permanent
42
Clinical Presentation of NIHL
* History of long-term exposure (10+ years)
* With hearing loss in the high frequencies, the patient is unlikely to report difficulty in quiet conversational situations
* Trouble understanding speech when significant background noise is present
* May progress to difficulty understanding high-pitched voices (women, children)-even in quiet conversational situations
43
Noise-Induced Hearing Loss diagnosis
* Audiometry
* Sensorineural hearing loss
* Almost always bilateral
* Loss is greater with frequencies 3000-6000 Hz, less with 500-2000 Hz
44
Noise-Induced Hearing Loss management
* No cure
* Reduce or eliminate exposure to noise
* Control other factors (Smoking, DM, CVD)
45
Safe noise exposure limit
85 decibels for 8 hours a day
46
Earphones usage adjustments
* 70% of max vol. should be limited to <4.6 hrs/day
* 80% of max. volume, limit to less <1.2 hrs/day
47
Sudden Sensorineural Hearing Loss
* Sensorineural hearing loss of 30dB or
greater over at least three contiguous
audiometric frequencies occurring within
a 72-hr period
48
Reported causes of Sudden Sensorineural Hearing Loss
* Infectious diseases (viral URI)
* Otologic disease
* Trauma
* Vascular or hematologic conditions
* Neoplasms (vestibular schwannoma)
49
Sudden Sensorineural Hearing Loss presentation
* Usually in 1 ear (< 5% of cases BL)
* Mild to severe-profound
* Can affect high, low, or all frequencies
* Sound may be distorted (like "blown
loudspeaker”)
* Ear fullness or pressure
50
Sudden Sensorineural Hearing Loss Diagnosis
* Weber & Rinne
* Audiogram
* Evaluate for alternative diagnoses suggested
by symptoms such as: bilateral sudden
hearing loss, recurrent episodes of sudden
hearing loss, or focal neurologic findings
* Consider MRI to identify: Stroke, acoustic
neuroma, multiple sclerosis
* Labs to evaluate autoimmune disorders,
syphilis, HIV, West Nile, cat scratch
51
Sudden Sensorineural Hearing Loss Management
* Treat specific causes
* Idiopathic sudden sensorineural hearing
loss
* Oral corticosteroids tapered over 10-14
days if within 2 weeks of onset
* Intratympanic dexamethasone injections
* Antiviral
52
Otologic emergency, until proven
otherwise
Sudden Sensorineural Hearing Loss
EENT Exam 2
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