Hearing loss Flashcards
Conductive hearing loss & its mechanisms
Mechanical disruption of the external
auditory canal or middle ear
Mechanisms:
1. Obstruction
2. Mass loading
3. Non-compliant structures
4. Discontinuity of structures
Sensorineural hearing loss & its mechanisms
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
> ____% of childhood hearing impairment is thought to be hereditary
50
Nonsyndromic vs. Syndromic hearing loss
- 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
_____: retinitis pigmentosa & hearing
loss
Usher syndrome
______: pigmentary
abnormality (hair, skin, & nails) & hearing loss
Waardenburg syndrome
____ → thyroid organification
defect & hearing loss
Pendred syndrome
____ → renal disease & hearing loss
Alport syndrome
_____ → prolonged
QT interval & hearing loss
Jervell & Lange Nielson syndrome
Ototoxic Medications
- 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
Hearing Loss presentation
- 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
T/F Remove impacted cerumen prior to
making a Dx of hearing loss
T
Conductive hearing loss structures
- Involves auditory canal, tympanic membrane, & the ossicles
- Lesions in the auricle, external auditory canal, or middle ear
can cause conductive hearing loss - Often reversible
Sensorineural hearing loss structures
- Involves cochlea and CN VIII
- Often permanent
Weber test
- A 256 or 512 Hz tuning fork is placed on the mid forehead
- Sound should be perceived equally bilaterally
- Lateralization of sound = + test
Rinne test
- 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
Review weber/rinne results
:)
Audiometry
- 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”
Most widely accepted diagnostic test for hearing loss or concerns
Audiometry
Tympanometry
Graph
* Relationship between air pressure in the canal and movement of
the tympanic membrane (TM)
* Provides volume measurement and pressure measurement
Otosclerosis
Overgrowth of bone in the
inner ear
* Often stapes
Otosclerosis etiology - 3 main theories
- 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
Otosclerosis clinical presentation
- 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
Weber test in Otosclerosis
lateralizes
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
Tx for mild hearing loss
observation and/or hearing aids with routine hearing tests to determine if condition is progressing
* Florical
* Bisphosphonates
Aggressive Tx for hearing loss
stapedectomy with prosthesis (stapedoplasty)
* Most Successful
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
Most common cause of hearing loss in adults
Presbycusis
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
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
_____ is a diagnosis of exclusion
Presbycusis
Management of Presbycusis
- No cure
- ENT, audiology referral
- Amplification devices: hearing aids
- Lip reading:
- Assistive listening devices:
- Cochlear implants:
Acoustic Neuroma
Intracranial, extra-axial tumors arising from the
Schwann cell sheath investing either the vestibular or cochlear nerve
High dose ionizing radiation is the only known risk factor for _____
Acoustic Neuroma
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
Unilateral sensorineural hearing loss is ____
acoustic neuroma until proven otherwise
Diagnosis of Acoustic Neuroma
- Audiogram
- Gadolinium-enhanced MRI brain with attention to IACs
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
____ Americans risk noise-induced hearing
loss (NIHL)
5-10 million
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
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
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
Noise-Induced Hearing Loss management
- No cure
- Reduce or eliminate exposure to noise
- Control other factors (Smoking, DM, CVD)
Safe noise exposure limit
85 decibels for 8 hours a day
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
Sudden Sensorineural Hearing Loss
- Sensorineural hearing loss of 30dB or
greater over at least three contiguous
audiometric frequencies occurring within
a 72-hr period
Reported causes of Sudden Sensorineural Hearing Loss
- Infectious diseases (viral URI)
- Otologic disease
- Trauma
- Vascular or hematologic conditions
- Neoplasms (vestibular schwannoma)
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
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
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
Otologic emergency, until proven
otherwise
Sudden Sensorineural Hearing Loss
