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AUDE 5410 - Acquired Auditory-Vestibular Disorders > Disorders Affecting the Inner Ear > Flashcards

Disorders Affecting the Inner Ear Flashcards

1
Q

What is homeostasis?

A

The ability of an organism or a cell to maintain internal equilibrium by adjusting its physiological processes

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2
Q

What is inner ear homeostasis?

A

The process by which chemical equilibrium of inner ear fluids and tissues maintained

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3
Q

For proper inner ear function, is a tight control of ions and homeostasis required?

A

Yes

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4
Q

What are the functions of the inner ear that could be disrupted if not balanced?

A

Hair cell function
Regulation of extracellular endolymph and perilymph
Conduction of nerve impulses

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5
Q

What are the major ions involved in inner ear homeostasis?

A

Sodium
Potassium

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6
Q

What other ions also play a significant role in inner ear homeostasis?

A

Chloride
Calcium

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7
Q

Is ion homeostasis controlled by numerous ion channels and transporters in plasma membrane of cells, especially cells lining the scala media?

A

Yes

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8
Q

Is active transport of H2O across the cell membranes also needed?

A

Yes

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9
Q

Before sound is perceived, does it have to be converted to electrical impulses in the auditory nerve?

A

Yes
This process is mediated by the cilia of the inner ear hair cells

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10
Q

Does the sound-induced excitatory deflection of the stereocilia causes a mechanoelectrical transduction current to depolarize the hair cells and initiate action potentials?

A

Yes

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11
Q

Do endolymph and perilymph must maintain their specific ion concentrations for max sensitivity?

A

Yes

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12
Q

Are there several cochlear and vestibular disorders that are transient and recover spontaneously?

A

Yes

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13
Q

What are some of these temporary cochlear and vestibular disorders?

A

Sudden-onset hearing loss
Diuretic ototoxicity recovery after stopping drugs
Autoimmune labyrinthitis (transient symptoms)
Meniere’s disease (intermittent symptoms)

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14
Q

What is this temporary cochlear loss stemming from?

A

Not the hair cells or sensory nerves, because it comes back
Damage to homeostatic mechanism

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15
Q

What are symptoms of cochlear disorders?

A

Hearing loss (constant or fluctuating)
Difficulty with speech perception
Loudness recruitment (abnormal loudness growth)
Aural fullness
Tinnitus
Abnormal or excessive response to sound
Conditions that may be associated with psychological issues

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16
Q

What is the hearing loss associated with cochlear disorders?

A

Any severity
Always SNHL, unless superimposed with ME issue

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17
Q

What are some conditions that may be associated with psychological issues?

A

Hyperacusis - physical discomfort/pain when a sound is loud but would be tolerable to most people
Misophonia - intense emotional reactions to certain sounds that are not perceived as loud
Noise sensitivity - increased reactivity to sounds including general discomfort and annoyance in regards to loudness
Phonophobia - anticipatory fear of sound, can cause comorbid conditions (tinnitus) to worsen

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18
Q

What are the most common causes of SNHL?

A

Aging
Exposure to toxic levels of noise

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19
Q

What are some other causes of SNHL?

A

Genetic syndromic and non-syndromic SNHL
Ototoxicity
Infections of the inner ear
Autoimmune conditions that affect the inner ear

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20
Q

What are most infections of the inner ear caused by?

A

Viruses

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21
Q

Can bacteria also cause serious diseases?

A

Yes, such as meningitis

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22
Q

What are the two known kinds of viruses for the inner ear?

A

Ribonucleic acid (RNA) virus (covid 19 and flu)
Deoxyribonucleic acid (DNA) virus

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23
Q

What are RNA viruses?

A

Contain ribonucleic acid in their genome
High mutation rates compared to DNA viruses because RNA polymerases lack the proofreading ability

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24
Q

What are DNA viruses?

A

Contain deoxyribonucleic acid in their genome
More stable

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25
Q

What are some examples of DNA viruses?

A

Smallpox, herpes, and chickenpox

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26
Q

What is effected in the cochlea from these viruses?

A

Organ of corti is affected at basal turn (high freq SNHL)
Individual hair cells damaged or missing
Stria vascularis may become atrophied
Tectorial membrane appears shriveled
Complete collapse of Reissner’s membrane

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27
Q

Is rubella virus an RNA virus?

A

Yes

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28
Q

What is rubella virus?

A

Has adverse affects on fetus
Responsible for German measles
Greater affect on the auditory system if contracted when auditory system is developing (initial part of the 2nd trimester)

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29
Q

What can rubella lead to?

A

Congenital hearing loss
Congenital cataracts
Cardiovascular problems
Possible intellectual disability

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30
Q

Is paramyxovirus an RNA virus?

A

Yes

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31
Q

What is paramyxovirus?

A

Responsible for mumps
Inflammation of the parotid gland (salivary glands)
Can cause males to be infertile
Can cause permanent SNHL, typically unilateral

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32
Q

Is cytomegalovirus (CMV) a DNA virus?

A

Yes

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33
Q

What is CMV?

A

A common double-stranded DNA virus that belongs to the herpes virus family
Found in other mammals too
One of the most common viral diseases
Common all over north america

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34
Q

Does about 50 to 80% of the U.S. population carry CMV antibodies by age 35 to 40?

A

Yes

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35
Q

Can CMV result in decreased life expectancy?

A

Yes

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36
Q

Can CMV cause enlarged organs?

A

Yes

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37
Q

Can CMV result in a blueberry rash (reddish blue to magenta)?

A

Yes

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38
Q

Can CMV cause decreased immunity to the flu vaccine?

A

Yes
CMV has the most genes compared to any other known human virus (large genome)
Our immune system expends a lot of energy fighting this virus all life long

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39
Q

Is CMV the most common viral disease among newborns?

A

Yes
1 in 200 newborns has CMV
About 20% of newborns diagnosed with CMV will develop hearing loss
75% babies born with CMV can manifest delayed onset SNHL even as adults

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40
Q

How is CMV passed down to a fetus?

A

Through the placenta and is teratogenic to the fetus
nfected mothers may only exhibit symptoms of a common cold/mild ‘flu
In 2023, Minnesota became the first state to screen ALL newborns for CMV

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41
Q

What kind of hearing loss does CMV result in?

A

A progressive profound permanent SNHL with the final stage being reached by 3 to 5 years
Many of these children are CI candidates

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42
Q

Are newborns with CMV detected during NBHS?

A

No, due to late onset progressive loss

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43
Q

How can CMV show up in infants, older children, and adults?

A

Can be silent or symptoms may mimic common cold
Cause no permanent damage

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44
Q

What other neurological or other complications can CMV cause when it occurs in vitro?

A

Cardiovascular problems
Neurological problems
Blindness
Intellectual disability

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45
Q

Are infected newborns considered contagious?

A

Yes, can be passed to clinicians
Problem for pregnant clinicians

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46
Q

Can CMV also be transmitted through breastmilk?

A

Yes
But there is no evidence to suggest that it produces a SNHL past about 3 weeks of age

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47
Q

How is CMV diagnosed?

A

Urine polymerase chain reaction (gold standard)
Histologic examination
CT scan

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48
Q

What is urine polymerase chain reaction?

A

Laboratory technique for rapidly producing millions of copies of a specific DNA segment
Done to study things in greater detail

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49
Q

What is a histological examination for CMV?

A

Put saliva sample under microscope, look for specific inclusion bodies
Inclusion bodies are common in many virus infections

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50
Q

How does CMV show up on a CT?

A

Can show intracranial calcification

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51
Q

What is AIDS caused by?

A

The microbe human immunodeficiency virus (HIV)

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52
Q

Is HIV a retrovirus?

A

Yes

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53
Q

What are retroviruses?

A

Retroviruses rely on their enzyme reverse transcriptase to perform the reverse transcription of its genome from RNA into DNA (normal transcription is from DNA to RNA)
Embeds itself into the host’s cells
The virus then replicates as part of the infected cell’s DNA

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54
Q

Can people be HIV positive and not express any signs and symptoms?

A

Yes

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55
Q

Is HIV neurotropic?

A

Yes
It attacks the nervous system

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56
Q

Is HIV lymphotropic and immunotropic?

A

Yes
It attacks the lymph glands, both T and B cells, and the immune system

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57
Q

In populations at risk for HIV, should the condition be considered in all cases of sudden bilateral or unilateral HL?

A

Yes

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58
Q

What are some otologic signs and symptoms associated with AIDS?

A

OME with or without CHL; SNHL during later stages
Otalgia
Vertigo
Tinnitus
Aural fullness
Reduced OAEs (OHCs affected)
Delayed ABR interwave latencies (central effects)

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59
Q

Besides AIDS itself, what might the auditory symptoms be due to?

A

Ototoxic effects of the AIDS drugs
Recurrent/chronic OME and other opportunistic infections that attack the ear due to the suppressed immune system

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60
Q

Can HIV be transmitted through the placenta?

A

Yes

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61
Q

Is there a latent or dormant period for the AIDS virus in infants?

A

No
Can also have congenital or early-appearing encephalopathy that can damage the brain and CNS

62
Q

Is edema of the brain tissue present with pediatric AIDS?

A

Yes

63
Q

Is there a greater incidence of otitis media with poorer prognosis in children with AIDS?

A

Yes
Due to compromised immune system
Higher rate of recurrence of infection
Higher failure rate of response to treatment

64
Q

What is meningitis?

A

Inflammation of the meninges (duramater, arachnoid mater, and pia mater) surrounding the brain and spinal cord

65
Q

What is the etiology for meningitis?

A

Various viruses
Bacteria (haemophilus influenzae most common and pneumococcus pneumonia causes most cases of hearing loss post-meningitis)

66
Q

What are the two kinds of meningitis?

A

Primary and secondary

67
Q

What is primary meningitis?

A

Disease originates in the meninges

68
Q

What is secondary meningitis?

A

OME leading to mastoiditis/labyrinthitis and then meninges
Cholesteatoma that spreads to the meninges

69
Q

What are the initial symptoms of meningitis?

A

High fever
Neck rigidity
Malaise (blah)
Nausea/vomiting
In severe cases, coma and death

70
Q

What can severe cases of meningitis lead to?

A

Blindness
Paralysis due to damage of the motor centers of the brain
Hearing loss/deafness (one of the most significant causes of acquired SNHL, can cause permanent abnormal cochlear bone formation)
Vertigo and balance problems

71
Q

What is the treatment for meningitis?

A

Antibiotics
Mastoidectomy
Amplification or CI

72
Q

Why is a mastoidectomy done as treatment for meningitis?

A

If the infection is related to middle ear disease and is not resolved by antibiotics

73
Q

When can CIs be used for meningitis cases?

A

If severe to profound loss has occurred
Need to ensure there is enough space in the cochlea to place the implant because of abnormal bone growth
Bony growth in cochlea can continue after the CI and may compromise implant

74
Q

What is a perilymphatic fistula?

A

An abnormal connection (a tear or defect) in either or both the oval and round window that separate the air filled ME and the fluid filled perilymphatic space of the inner ear
Opening that shouldn’t be there

75
Q

What causes perilymphatic fistula?

A

Idiopathic
A history of straining or lifting; feeling the ear “pop”
Can occur during the early or late period following stapedectomy
Spontaneous PLF also discovered at the time of surgery for Meniere’s disease

76
Q

What are the 4 recognized patterns of symptoms for perilymphatic fistula?

A

Episodic vertigo without hearing loss
Hearing loss without vertigo
Symptoms maybe virtually indistinguishable from Meniere’s disease, i.e., tinnitus, SNHL, vertigo, aural fullness
Miscellaneous symptoms with disequilibrium but not episodic vertigo

77
Q

What is the diagnosis for perilymphatic fistula?

A

Presentation of a symptom complex
High index of clinical suspicion
Dix Hallpike positional testing can result in nystagmus and vertigo

78
Q

What is the treatment for perilymphatic fistula?

A

Middle ear exploration (exploratory tympanotomy)
Surgical repair for obvious traumatic perilymph leak and sealing of the round or oval window
Patients cautioned against heavy lifting following repair surgery

79
Q

Repair of the perilymphatic fistula may result in what?

A

Improve/preserve hearing
Resolve vertigo/disequilibrium
Improve tinnitus symptoms

80
Q

Are humans particularly susceptible to noise induced hearing loss in the audible region?

A

Yes
Between 500 to 8000 Hz

81
Q

Does the A-weighted network follow the human audibility curve?

A

Yes, has the heaviest weight between 500 and 8000 Hz
Used in sound level meters

82
Q

Can damage to human hearing occur when subjected to an > 8-hour daily exposure of continuous sound at 85 dBA over a period of many years?

A

Yes

83
Q

Is noise induced hearing loss caused by both dose (level of noise) as well as duration (amount of time)?

A

Yes

84
Q

What is noise defined as?

A

Unwanted sound

85
Q

Is the ability of noise to cause a hearing loss related to its desirability or unpleasantness?

A

No
Classical music played loud enough and long enough can cause as much damage as a chainsaw

86
Q

Are high frequency sounds (up to 5000 Hz) more hazardous than low frequency sounds for NIHL?

A

Yes
Hearing protection devices also provide greater attenuation of high frequencies and less protection from low frequency sounds

87
Q

Are very narrow-band sounds (such as pure tones) more hazardous than broad-band sounds?

A

Yes
Concentrated and more damaging
Broad-band noise over a longer duration, however, can cause widespread cochlear damage

88
Q

What is the classic pattern for NIHL?

A

Noise notch

89
Q

What is a noise notch?

A

Greatest threshold shifts are noticed at the basal end of cochlea between the 3000 and 6000 Hz region in response to BBN
Peak loss is typically at 4000 and 6000 Hz, improving at 8000 Hz
All sound has to go through basal end
Noise is rarely narrow band

90
Q

Why is the noise notch vulnerable in the 3-6 kHz region?

A

Stronger mechanical forces due to cochlear geometry (more force generated at that area)
More tenuous blood supply of the cochlea (not as robust)
Just a hypothesis

91
Q

Where is the maximum damage from noise exposure?

A

About 1/2 an octave above the stimulating frequency
For e.g., a 1000 Hz exposure frequency would cause a hearing loss at 1500 Hz

92
Q

What is a threshold shift?

A

A change in hearing sensitivity from baseline

93
Q

What are the two types of noise-induced threshold shifts?

A

Noise-induced temporary threshold shift (TTS)
Noise-induced permanent threshold shift (PTS or NIPTS)

94
Q

What is a noise-induced temporary threshold shift (TTS)?

A

Reversible increase in auditory threshold following exposure to loud noise – swollen rootlets of stereocilia + hair cells

95
Q

When does most TTS resolve?

A

After about 15 minutes but can persist for about 14 hours

96
Q

What are the new findings about TTS?

A

Loud noise can result in hidden hearing loss (synaptopathy)
No permanent change to hearing thresholds
Damage to nerve or IHC
Residual problems

97
Q

What is PTS?

A

A persistent change in hearing sensitivity persisting after ~14 hours
Permanence is assumed if change still observed on a 30-day follow up hearing test – tip links break; fractured and detached stereocilia

98
Q

Does TTS and PTS vary with frequency, intensity, and temporal properties of the noise?

A

Yes

99
Q

Does initial noise exposure result in TTS?

A

Yes
Experienced as a dull or muffled sound quality
For example, at the end of a work shift or loud concert

100
Q

Does a daily dose of noise exposure cause TTS or PTS?

A

PTS

101
Q

Are both TTS and PTS accompanied by tinnitus?

A

Yes
Temporary tinnitus after noise exposure may be a useful warning that PTS will occur if exposure continues without use of hearing protection devices (HPDs)

102
Q

Is injury to the ME from noise rare?

A

Yes
Occurs only with extremely high levels of noise

103
Q

What noise level can result in TM perf?

A

At or greater than 165 dB SPL

104
Q

What noise level can result in an ossicular chain injury?

A

At or greater than 190 dB SPL

105
Q

Can TM perfs be used as a sign of possible concussion in human victims of bomb blasts?

A

Yes
If the TM is perforated, more likely that the person has sustained a concussion from the blast

106
Q

Can exposure to loud noise result in tinnitus?

A

Yes

107
Q

What structure is most susceptible to noise in the cochlea?

A

OHCs
Initially, stereocilia lose their stiffness and, therefore, their ability to vibrate in response to sound
The result is a reversible hearing loss or TTS
After repeated hazardous levels of exposure, permanent damage occurs to stereocilia
Hair cell death ensues with PTS

108
Q

T/F: The more intense and prolonged the exposure, the greater the degree of hair cell loss

A

True
Eventually, IHCs and auditory nerve fibers are also damaged/lost

109
Q

Can noise levels that cause NIHL cause vestibular system injury?

A

Doubtful

110
Q

Can acoustic trauma (different category of noise exposure) cause vestibular system injury?

A

Yes
Most patients present with a history of noise trauma and balance symptoms
For e.g., dizziness and vertigo

111
Q

Can acoustic trauma patients also have coincidental causes for their vestibular problems?

A

Yes

112
Q

Is clinical history crucial for diagnosing NIHL?

A

Yes

113
Q

Should you do a medical examination to rule out NIHL from other causes of HL?

A

Yes

114
Q

Is NIHL usually symmetrical?

A

Yes
But asymmetries of 15 dB HL of greater are not uncommon
Left sided hearing loss with right-handed shooting of weapons
Other causes of asymmetric SNHL (e.g., vestibular schwannoma) should be ruled out

115
Q

Is profound SNHL rare in purely NIHL?

A

Yes

116
Q

In NIHL, are low frequency thresholds are rarely worse than 40 dB HL?

A

Yes

117
Q

In NIHL, are high frequency thresholds are rarely worse than 75 dB HL?

A

Yes

118
Q

Can cessation of noise exposure cause a slower progression of the hearing loss?

A

Yes

119
Q

Is most NIHL symmetric?

A

Yes especially if caused by occupational or recreational noise exposure

120
Q

Can asymmetry be greater in the high frequencies (3000 to 6000 Hz)?

A

Yes, especially with long-gun firearm use because of the head shadow

121
Q

When presbycusis meets NIHL, does the HL flatten?

A

Yes

122
Q

What is the treatment for NIHL?

A

No effective treatment

123
Q

What is the best management for NIHL?

A

Prevention
Environmental controls to reduce noise in the work-place
Use of hearing protection devices to minimize the level of noise exposure
For e.g., earmuffs and ear plugs
Musician earplugs, which can attenuate environmental noise by 15 to 25 dB but allow speech/music to be heard

124
Q

Should you use appropriate amplification when a permanent hearing loss occurs?

A

Yes, to prevent it from worsening

125
Q

Are the uses of anti-oxidants and other chemicals used to protect against NIHL?

A

Currently being investigated

126
Q

Is acoustic trauma distinct from other forms of NIHL?

A

Yes
It is a sudden permanent hearing loss from a single event or exposure without intervening TTS

127
Q

What is most acoustic trauma caused by?

A

Impulse noise (sudden, short duration very loud sounds)
Bombs/improvised explosive devices (IEDs)
Firearms and other weapons
Industrial blasts

128
Q

What kind of injury does acoustic trauma cause?

A

Direct mechanical injury to the cochlea with or without perf

129
Q

What sound intensity causes acoustic trauma?

A

165 to 190 dB SPL
Can rupture or produce hemorrhage of the TM
Disrupt or fracture the ossicular chain

130
Q

Can impact noise greater than or equal to 140 dB SPL peak pressure result in PTS?

A

Yes

131
Q

What are some signs and symptoms of acoustic trauma?

A

Visible TM perforation/hemorrhage on otoscopy
Audiometric results following acoustic trauma are similar to NIHL (noise notch at 3000 to 6000 Hz)
Type Ad tymp with absent ARTs if ossicular disarticulation (which can result in a mixed hearing loss)

132
Q

Are there a variety of hearing configurations possible with acoustic trauma?

A

Yes
High frequency sloping configuration
Flat configuration (more common)

133
Q

Can hearing loss from acoustic trauma improve over a 4 to 6 month period?

A

Yes

134
Q

May surgery be required to repair TM and ossicles if they are damaged from acoustic trauma?

A

Yes

135
Q

What are blast injuries caused by?

A

Indirect impact from a pressure wave generated by an explosion that causes an instant rise in pressure, creating a blast wave that starts at the site of the explosion and travels outward

136
Q

When do blast waves occur?

A

When the compression of air in front of the pressure wave heats and accelerates air molecules, leading to a sudden increase in overpressure and temperature, which are transmitted into the surrounding environment as a propagating shock wave known as the blast wave

137
Q

What is the most susceptible organ to primary blast injury?

A

The ear

138
Q

What can blast injuries damage in the ear?

A

The entire auditory system, resulting in TM perforation, ossicular disarticulation, tinnitus, otalgia, hearing loss, and/or vertigo

139
Q

Are otologic injuries often missed for blast injuries?

A

Yes
Highest priority is directed toward diagnosis and treatment of life-threatening injuries

140
Q

What is the intracellular potential of hair cells?

A

-80 mV
The high K+ concentration in the endolymph creates a +80 mV endocohlear potential (EP) that couples with a -80 mV hair cell intracellular potential to create a differential potential of +160 mV

141
Q

What is the endocochlear potential in the vestibular system?

A

About 5 to 10 mV
Resulting in a much smaller total potential difference

142
Q

What are the two ways that hair cells are diplaced?

A

Shearing movement of the tectorial membrane (outer hair cells) or
Motion of the endolymphatic fluid (inner hair cells)

143
Q

Does potassium flow down the electrical gradient into the cell from the endolymph, and then out the base of the cell into the perilymph?

A

Yes

144
Q

What happens when the two fluids in the inner ear are allowed to mix?

A

Transduction is compromised
Resulting in hearing loss or vestibular dysfunction
Happens in Meniere’s disease when the membranous labyrinth ruptures

145
Q

What is responsible for the endocochlear potential?

A

Tight junction of the vascular endothelial cells and basal stria cells
Limit intercellular leakage

146
Q

Will any cochlear disorder that disrupts the strial cell layers, channels, transporters, or gap or tight junctions reduce the endocochlear potential and result in hearing loss?

A

Yes

147
Q

What hearing loss results from increased potassium transport in the endolymph or increased endolymph production?

A

Endolymphatic hydrops (meniere’s)

148
Q

What hearing loss results from decreased potassium transport in the endolymph or decreased endolymph production?

A

Endolymphatic xerosis (JLNS and connexin)

149
Q

Do the majority of genetic disorders cause a permanent hearing loss due to impaired ion transport to the inner ear?

A

Yes

150
Q

Is endolymphatic xerosis believed to be the most common genetic hearing loss in humans?

A

Yes

151
Q

What do the connexin genes do?

A

Abnormalities in connexin gap junctions proteins

152
Q

What do the JLNS genes result in?

A

They are responsible for producing proteins that make up the potassium channels on the apical stria

AUDE 5410 - Acquired Auditory-Vestibular Disorders (11 decks)

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