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aude 5410 aud-vestib disorders > Quiz 3 (Presbycusis) > Flashcards

Quiz 3 (Presbycusis) Flashcards

1
Q

what is presbycusis

A

age related HL
it is gradual, variable in age of onset & its progression rate
variable in how it progresses

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2
Q

what type of HL is seen in presbycusis

A

always SNHL because it is in teh inner ear and due to a lack of regeneration of the sensory system

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3
Q

two most common causes of HL

A

advanced age
noise exposure

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4
Q

presbycusis results from progressive loss of

A

EP, sensory cells, & other peripheral & central auditory system

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5
Q

results in a decline of auditory function

A

as inability to regenerate structures that cause audition

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6
Q

what was previously thought and now thought about etiology of ARHL

A

varied and not understood well
might be degenerative disase due to early start & noisey areas (city)

previously → cochlea was primary site & central involvement was secondary due to reduced sensory input

recently → CAS also has changes as a result of aging that is independent of peripheral involvement

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7
Q

incidence of ARHL

A

HL prevalence increases with age & is to increase as the US age continues to increase

WRS decline more rapidly in men & poorer in all aged men than women

socioeconomic & ethnic variations
African americans show lower incidence of HL in elderly population

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8
Q

Formula that leads to Presbycusis

A

genetics / (age + noise + ototoxic drugs)

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9
Q

why is there so much variation in HL in ARHL

A

because individual hearing relies on genetics

ototoxicity, noise, and age play a role on hl too

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10
Q

3 Variables that make it hard to study effects of pure aging on physiology & morphology

A

environmental noise exposure
drugs
genetics

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11
Q

accounts for variability seen among the elderly in hearing abilities

A

genetics

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12
Q

age-related HL is unique to aging & not a result of environmental factors (can contribute to HL)

A

true

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13
Q

where does high aerobic metabolism occur

A

in lateral wall of cochlea

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14
Q

why is high metabolism needed in cochlea

A

K+ maintenance bw endolymph & perilymph
EP generation

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15
Q

where is mechanical & metabolic damage the most common

A

basilar membrane at the basal turn of cochlea

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16
Q

ARHL is what type of HL

A

slowly progressive, sloping, HF SNHL

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17
Q

why is ARHL slowly progressive, sloping, HF SNHL

A

becuase damage is most common at the basilar membrane of the basal turn

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18
Q

presbycusis not related to environmental factors is just due to loss of cochlear hair cells

A

false
it is also caused by degenerative changes/pathologies of the lateral cochlear wall & not just the above

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19
Q

what are the three cochlear systems implicated in presbycusis

A

cochlear amplifier

power supply

transduction mechanism

20
Q

what is the pathophysiology seen at cochlear amplifier system in presbycusis

A

cochlear amplifier = OHCs

loss of this reduces sensitivity by ~ 40 to 50 dB HL

this active process amplify sound vibrations in cochlea and this relies on EP found in scala media (ENDOLYMPH)

21
Q

what is the cochlear battery

A

EP

22
Q

describe EP

A

extracellular resting potential with +80 to +100 mV

created from stria vascularis by the Na+/K+ pump and in turn provides energy for cochlear transduction = battery of the cochlea

23
Q

where is EP larger

A

at the base (also why we see HF HL with ARHL)

24
Q

1mv = _____dB gain in cochlear amplifier

A

~ 1 dB

25
Q

if EP drops by 30 mv, sensitivity to HF decreases by about ____ dB

A

30

26
Q

aging effects in the cochlea can be result of

A

deterioration of cochlear battery (EP) & not loss of hair cells

27
Q

how is research restoring EP

A

adding external battery by injecting current directly into scala media &/or regenerating the old batter by using stem cells to repopulate stria vascularis

these could recharge power supply to cochlear amplifier, regain some of HF sensitivity loss & reduce speech perception issues with aging

28
Q

what provides the power the OHCs need to function effectively

A

cochlear lateral wall, including stria vascularis

29
Q

what is the power supply of cochlea

A

cochlear lateral wall tissue including SV that generates EP

30
Q

what is the power supply dependent on

A

K+ recycling - actively putting it back into the endolymph after it is released into perilymph through supporting cells & fibrocytes that move it through gap junctions = generating EP

31
Q

describe K+ recycling during power supply in cochlea

A

top of OHCs has potential gradient of ~ 160 mV RP (+80mV endolymph and -80 mV in the body of the hair cells due to the resting potential of the hair cells), potential gradient causes constant flow of current from the scala media to inside of hair cells, potential changes produced by this flow of the electrical current is the cochlear microphonic

32
Q

what is a cochlear microphonic

A

potential gradient causes a flow of current from scala media to inside of hair cells and these potential changes that are produced by the flow of electrical current is CM

33
Q

what is transduction mechanism in cochlea

A

transduction of cochlear vibration to neural impulses

IHCs passively detect vibration that in turn excites the afferent nerve fibers of CN VIII fibers that are synapses at base of iHCs

these impulses are then sent to the brain

34
Q

what are common characteristics of presbycusis

A

HF SNHL sloping
speech perception issues espectially in noise & reverberation
recruitment

35
Q

what are the classification of presbycusis

A

Schuknecht’s & Killion & Fikret-Pasa

36
Q

why is classifying presbycusis in older adults important

A

improved differential diagnosis
changes to individualized intervention that leads to improved auditory function in older adults

37
Q

describe schuknech’t classificatioin of ARHL

A

based on postmortem eval of temporal bones
sensory presbycusis
primary loss of OHC & supporting cells

neural presbycusis
loss of afferent cochlear neurons

metabolic/strial presbycusis
loss of EP & atrophy of strial & lateral wall

mechanical presbycusis
stiffening of BM & organ of corti (no evidence)

38
Q

what is the primary goal of K &FP ARHL classification and what is it based on

A

develop a system which appropriate amplification based on other considerations than the pure-tone audiogram

develop a system which appropriate amplification based on other considerations than the pure-tone audiogram

39
Q

describe Killion & Fikret-Pasa classification of ARHL

A

type 1
mild - moderate SNHL (no worse than ~ 45 to 55 dB HL)
normal loudness sensation
findings consistent w/ loss of OHC fxn ONLY w/ normal IHC fxn

type 2
moderately severe HL (~ 6 dB HL)
presence of partial recruitment
assumed there is OHC loss WITH ICH loss
have issues w. speech intelligibility (especially in noise) even with the best HA’s because there is less info transmitted to the brain & fewer redundant speech cues are available

type 3
severe HL (~75 dB HL)
loudness & intelligibility are affected & recruitment is common
intelligibility becomes the primary concern
speech range that can be heard in noise is narrowed
these individuals do well when speech is presented close to UCLs
OHC, IHC & nerve fiber losses

40
Q

NIHL is anatomically characterized by

A

loss of hair cells (initially OHCs)
loss of supporting cells
secondary neural degeneration

41
Q

Presbycusis is anatomically characterized by

A

mostly degeneration of the stria vascularis and lateral cochlear wall
Compromised blood supply correlated with the extent of strial degeneration
Presence of mostly normal sensory cells except in the most basal and apical turns of the cochlea

42
Q

NIHL is physiologically characterized by

A

Threshold elevations of APs of the auditory nerve, ABR, and higher level evoked responses

The distinctive feature is loss of cochlear nonlinearities
for ex: OAEs

The endocochlear potential (EP) is generally unaffected in NIHL

Degeneration of the stria vascularis is not typical in NIHL

43
Q

Presbycusis is physiologically characterized by

A

Reduction of endocochlear potential (EP) → due to degeneration of the stria (the batter of the cochlea)

44
Q

ARHL is, therefore, a ___, ______, & _____ disorder

A

vascular, metabolic, and neural

45
Q

describe long term relationship of NIHL & ARHL

A

NIHL early can make ARHL worse and over time ARHL can flatten the noise notch

46
Q

what is hidden hearing loss

A

synaptopathy (auditory nerve damage) causes it
TTS can be indicative of immediate & irreversible damage to auditory n fibers & beginnings of HHL

loss of connection from the auditory nerve to the hair cells causes HL not seen on an audiogram

47
Q

may be significant contributor to classic complaint “I can hear but I can’t understand what people are saying”

A

HHL

aude 5410 aud-vestib disorders (18 decks)

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