Transcript 6 Classifications of Presbycusis

Inner Ear Disorders
Lecture 14
Adults
Most common occurring causes of
SNHL
1. Noise
2. Presbycusis
3. Meniere’s disease
4. Immune Disease
5. Ototoxicity
6. Diabetes
Noise Induced HL
 Most common form of preventable HL
 Result from exposure to intense noise levels
 Permanent threshold shift (PTS)
 Temporary threshold shift (TTS) – recovers
within 16-48 hours
 Acoustic Trauma: impulsive sound
Noise Induced Hearing Loss
 More common in men with histories of noise
exposure
 Increasing incidence among children
 Site of pathology: basal end hair cellsprimarily OHC
http://www.neurophys.wisc.edu/~ychen/auditory/aud
iogram/audiogrammain.html
Symptoms of NIHL
 Tinnitus
 Difficulty understanding
in noise
 Difficulty understanding
speech
Audiometric Results
 Otoscopy:
 Tympanometry:
 Pure tone Air and Bone
 Maximal HL between 3000-6000 Hz – “Noise
Notch”
 OAE
 ABR
 Lowest Level for wave V
 IWI
Safe vs. Unsafe Sound Levels
 Noise levels measured in dB SPL
 Any loud noise over 85dB is considered
loud enough to cause NIHL.
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80 dB ….shouting.
110 dB….concert or sporting event.
111 dB…. iPod on full volume.
130 dB …an airplane taking off 100m away.
140 dB ….level at which noise causes pain
for most people
iPods
Percent of
Maximum Volume
•
•
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<= 40%
50%
60%
70%
80%
90%
100%
Time you can use
before Hearing
Loss WILL Occur
Equivalent Volume
dB
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•
•
•
•
•
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<= 73dB
81dB
87dB
92dB
98dB
106dB
111dB
•
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Unlimited
8 hours
4.5 hours
1.6 hours
23 minutes
4 minutes
1 minute
Metrics for Noise
oMax sound level is the highest sound level recorded over a
period of time
oAverage sound level is the average sound measured over a
period of time
oNoise dose is a percentage of the daily maximum permissible
exposure. 100% dose is equivalent to an 85 dBA time-weighted
average for 8 hours.
Noise Dose: 100%
Prevention of HL
 Walk Away
 Turn it down
 Use earplugs
 Educate students about NIHL
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OSHA NOISE guidelines
Duration
per Day,
hours
8
6
4.2
3
2
1.5
1
.5
.25
Sound
Level dBA
90
92
95
97
100
102
105
110
115
Education about Prevention of HL
 http://www.dangerousdecibels.org/
 http://www.cdc.gov/niosh/topics/noise/prevent
ion.html
Presbycusis
 The most common cause of
SNHL associated w/ aging
 Site of pathology: hair cell
damage in cochlea
 By 40-59 years, pure tone
thresholds show drop in
hearing in the high
frequencies
 By 60-80 years of age, the
lower frequencies become
affected
6 Types of Presbycusis
Schuknecht and Gacek 1993
1.
2.
3.
4.
5.
6.
Sensory
Neural
Strial
Cochlear Conductive
Mixed Presbycusis
Intermediate Presbycusis
Sensory Presbycusis
(*Otle, Schukneckt & Kerr, 1978)
 *Loss of inner and outer hair cells
 Loss of supporting cell structure; degeneration of the
Organ of Corti
 Differential diagnosis is difficult
 Aging vs acoustic trauma
 SNHL begins in high frequency range
 Possible mechanisms for intervention
 Susceptibility of hair
cells to aminoglycosides
 Genetics
Neural Presbycusis
(*Otto, Schukneckt & Kerr 1978)
 Loose 2,000 neurons per decade – S. Ganglion
less than 20,000 in adults 81-90 years of age
 *Loss of 50% of cochlear neurons, greater in
the elderly over 80 years of age = 15,000
from 30,000 as a young adult
 Most consistent pathological change in older ear
 Associated with poorer than expected word recognition
Stria Presbycusis
Function also
dependent on
capillary beds
 Atrophy of the stria vascularis
 Affects production of endolymph – important to
maintaining the electrochemical balance of inner
ear fluids (ion transport mechanism )
 Variable audiometric findings
Stria
Vascularis
Summary of Presbycusis
2 major age related structural changes
- Inner Ear
- Auditory Nerve
6 Classifications of Presbycusis affecting any or a
combination of:
- hair cells, supporting structures
- stria vascularis
- spiral ganglia, neurons
- nerve fibers of the 8th cranial nerve
Audiometric Results
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Otoscopy:
Tympanometry:
Pure tone Air and Bone
OAE
ABR
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Lowest Level for wave V
IWI
Endolymphatic Hydrops/Meniere’s
Disease
 1/1000 persons suffers MD
 Symptoms
 Sudden attacks of vertigo, tinnitus, vomiting
and Unilateral SNHL
 Onset 40-60 y/o
Endolymphatic Hydrops/Meniere’s
Disease
 Site of Pathology:
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Vestibular system
Malfunction of ES - overproduction of
endolymph in the inner ear
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causes increased pressure on hair cells
 Etiology: unknown, ES blockage, constriction
in blood vessels, migraine, autoimmune
reaction, genetic connection, viral infection
etc.
Endolymphatic Sac
ES – important for keeping fluid levels constant
Research ongoing to ID mechanisms that regulate
endolymph production
Endolymph Hydrops/ Meniere’s
Disease
 2 parts to the labyrinth: the bony and
membranous labyrinth.
 Membranous labyrinth is filled endolymph
 Increased production of endolymph alters
chemical balance of inner ear
Perilymph (Na)
Endolymph (K+)
Endolymph Hydrops/ Meniere’s
 If head moves> endolymph moves and sends
vestibular sensory info to the brain
 Increase in endolymph > the membranous
labyrinth dilates> vertigo > “endolymphatic
hydrops”
Meniere’s Disease
 Ménière's disease thought to be more than E.
Hydrops.
 Possible rupture of the membranous
labyrinth> endolymph mixes with perilymph.
 The mix of perilymph and endolymph is
thought to cause symptoms of Ménière's
disease
Treatment for Meniere’s
 No known cure > management of symptoms
 Acute
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Vasodialators, Corticosteroids – improve blood
flow to cochlea, anti-inflammatory effect
Anti vertigo medications
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Phenergen, dramamine ,antivert,valium
 Maintenance
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Diuretics
limit sodium in diet
Amplification
Vestibular rehabilitation Tx
Surgical Treatment
 Endolymphatic Sac Surgery – decompress
the sac/shunt insertion (not common today)
 Aggressive Tx approaches
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Labyrinthectomy – removal of vestibular
organ- causes total deafness in affected ear
Vestibular Neurectomy – partially sever the
affected nerve
 Current approach: Infusion of TM with
corticosteroids
Audiometric Findings
 Onset starts with unilateral LF SNHL
 Fluctuations in hearing and “Flattening” of
shape of audiogram as disease progresses
n
Audiometric Results
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Otoscopy:
Tympanometry:
Pure tone Air and Bone
OAE
ABR
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Lowest Level for wave V
IWI
Tests to assist with Differential
Diagnosis
 Auditory Brainstem Response (ABR) test
 Electronystagmography: ENG
 VEMPs
 MRI
Autoimmune inner ear disease (AIED)
 Inflammatory condition of the inner ear
 Inner ear proteins are recognized as foreign
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Primary process
Secondary to trauma or inflammation
 Occurs when the body's immune system
attacks cells in the inner ear that are mistaken
for a virus or bacteria
Symptoms & Incidence
 Incidence:
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<1% of the 28 million Americans with a HL
2/3 females, middle aged
 Sudden SNHL in one ear but becomes bilat
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progressing rapidly to second ear (<3 mos)
 Aural fullness
 Dizziness/vertigo
Theory and Symptoms of AIED
 Cochlea is devoid of immune cells
 Antibodies/ rogue T-cells (type of white blood
cell) that circulate around body to look for cell
abnormalities and infections
 T-cells essential for immunity
 Rogue T-cells cause inner ear damage
Treatment
 Drug therapy: steroids, prednisone and
methotrexate – (used in chemotherapy)
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If received early in disease, very helpful
Often results in severe to profound bilateral
SNHL
 Amplification
 Cochlear implant
Differential Testing
 ABR
 ENG
 Blood Tests
 Immunofluorescence
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labeling of antibodies with fluorescent dyes
 Audiometric Evaluations
Audiometric Results
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Otoscopy:
Tympanometry:
Pure tone Air and Bone
OAE
ABR
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Lowest Level for wave V
IWI
Ototoxicity
 Consider
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Sometimes the medicine is worse than the
disease
Sometimes there is no choice when presented
with life threatening conditions
 Toxicity is related to
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Dosage
Duration of administration
Common
ototoxic drugs
 Aminoglycosides antibiotics
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Treat infections
Gentamicin, kanamycin, neomycin,
streptomycin, tobramycin
 Antineoplastic drugs
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Treatment of cancer and tumors
Cisplatin,carboplatin, nitorgen mustard
Common ototoxic drugs
 Diuretics and loop diruetics
 Treatment of congestive heart failure,
pulmonary edema
 Lasix, bumetanide
 Salicylates
 Treatment of arthritis, rheumatic fever,
connective tissue disorders
 Aspirin
 Quinine
 Uncommon- Tx malaria
Common ototoxic drugs
 Environmental chemicals
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Arsenic
Mercury
Tin
Lead
Common Symptoms
 Impaired renal function
 Permanent SNHL – bilateral and mostly high
frequencies
 Tinnitus
 Can occur suddenly
 Speech recognition reduced
Main mechanism
 Free radicals form and anti-oxidant inhibition
result in HL
 Damages cells in cochlea
 Apoptosis – cell death
Audiometric Results
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Otoscopy:
Tympanometry:
Pure tone Air and Bone
OAE
ABR
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Lowest Level for wave V
IWI
Treatments
 Avoid or reduce doses of ototoxic agents as
possible
 Monitor hearing
 Substitute with a different agent
 SNHL – HA
Diabetes
 Elevated blood glucose levels affect inner ear
hair cells
 Progressive bilateral SNHL
 Often affects visual acuity
 Dual Sensory loss
Treatment
 Audiologic Monitoring
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Pure tone audiometry – esp in high freq
Speech audiometry – discrim may be very
poor when compared to pure tone thresholds
Otoacoustic emissions – most sensitive and
earliest detector of cochlear damage
Audiometric Results
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Otoscopy:
Tympanometry:
Pure tone Air and Bone
OAE
ABR
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Lowest Level for wave V
IWI
AMA Criteria for Medical Referral
 visible congenital, traumatic deformity
 history active drainage/bleeding from the ear
 sudden, rapidly progressive loss (90 days)
 acute/chronic dizziness
 unilateral loss of sudden, recent onset (90 days)
 ABG ≥ 15 dB @ 500, 1000, 2000 Hz
 significant cerumen accumulation, foreign body
 Ear pain or discomfort