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Diagnostic Audiology > Lecture 5 > Flashcards

Lecture 5 Flashcards

1
Q

What is everything based around the concept of?

A

Everything is based around the concept of measuring the change in response to a pure tone that is being delivered to the external canal

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2
Q

For clinical use, reflexes use ____Hz tone

A

226

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3
Q

What does tympanometry measure?

A

Admittance during the course of pressure manipulations

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4
Q

What does AR measure?

A

Admittance before [baseline] and following the presentation of an acoustic stimulus

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5
Q

What is the effect of the acoustic reflex?

A

The effect of the acoustic reflex is to produce a change in the admittance at the TM

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6
Q

What does the reflex activator do?

A

Creates a loud stimulus tone of different frequencies (500, 1K, 2K Hz)

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7
Q

Once we start testing for AR, are there pressure changes?

A

Once we start reflex testing there are no pressure changes done that will affect impedance

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8
Q

If an acoustic reflex happens, what does it travel down?

A

The facial nerve

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9
Q

WHat does the facial nerve innervate?

A

The stapedius muscle

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10
Q

What happens id the facial nerve is innervated?

A

It will pull on the stapes and stiffen everything up

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11
Q

Where does the reflex pathway cross over?

A

The level of the brainstem

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12
Q

Terminology of AR is based on the ____ ear

A

Stimulus

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13
Q

The right ear is bring stimulated and you are measuring the left ear

A

Right contra

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14
Q

The right ear is being stimulated and you are measuring the left ear

A

Right ipsi

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15
Q

The left ear is being stimulated and you are measuring the left ear

A

Left ipsi

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16
Q

The left ear is being stimulated and you are measuring the right ear

A

Left contra

17
Q

What are the 6 steps for testing AR?

A
  1. Complete a tympanogram
  2. Set pressure to the point of the highest admittance value (peak) of the tymp
  3. Acoustic reflex option will measure very small admittance changes
  4. 0.02 ml/mmho will be a positive response
  5. Activate stim tone, either ipsi or contra
  6. Measure/monitor admittance changes in response to stim tone
18
Q

What does acoustic reflex decay testing test for?

A

Retrocochlear involvement (stuff beyond the cochlea; some part of the neural system)

19
Q

How does AR decay testing work?

A
  • Seeing if the muscle will hold for 10 seconds (if normal, the muscle should hold)
  • With a Retrocochlear lesion, the system cant hold a reflex for that long and it will decay over time
20
Q

Coming from the pyramidal eminence, the ____ inserts into the back part of the neck of the stapes

A

Stapedius tendon

21
Q

Contraction of the stapedius muscle pulls the stapes in the ____ direction

A

Posterior

22
Q

Explain the anatomy and physiology of the stapedius muscle and what happens?

A
  • When the stapedius muscle contracts, the stapes footplate moves/rocks laterally from the oval window
  • The ossicular chain gets stiffened
  • The tympanic membrane is moved slightly
  • These mechanical changes in the ME produce changes in the sound transmission characteristics of the ME
23
Q

What is needed for AR decay testing?

A
  1. Probe tone
  2. Stimulus
  3. Response from the ME
  4. Measured in mmho of admittance (YA): using a 226 Hz probe tone may get converted to ml
24
Q

What are the parameters for AR decay testing?

A
  1. Threshold (where is the reflex getting triggered)
  2. Temporal characteristics (reflex has to have a certain timing pattern to call it a reflex)
  3. Amplitude (at least a 0.02 admittance change)
  4. Admittance: increase or decrease?
25
Q

If you get an AR, the ____ is working fine

A

ME

26
Q

AR admittance change

A
  • At 226 Hz, a decrease in admittance of 0.02 mmho/ml or greater would constitute a reflex
  • The AR should be closely related to the stimulus in terms of latency and intensity
27
Q

Explain the AR schematic

A

A-B = Preactivator baseline (this should be stable)
B-C = delay from when you present a stim tone and when the flex shows up on your machine
D = Max amplitude
E = AR adapted to 90% amplitude
F = 50%

This is a positive AR decay test (some kind of retrocochlear disfunction)

28
Q

The AR should be closely related to the ____ in terms of latency and intensity

A

Stimulus

29
Q

What are 6 clinical uses of acoustic reflexes?

A
  1. Assessment of ME function (ossicular chain) – otosclerosis
  2. Assessment of VIIIth nerve integrity
  3. Assessment of VIIth nerve integrity
  4. Functional info about auditory brainstem structures
  5. Some information about hearing status
  6. Diagnostic marker of cochlear third-window lesion (semi-circular canal dehiscence)
    • Can have normal tymp and normal reflexes, but audiometry gives ABG
29
Q

Explain the areas of TM and AR and how they work together

A
  • Tympanometry is the ear drum area
  • AR is the very last structure of the ME
  • Combine the two and we get a very nice assessment of ME functoin
29
Q

What reflexes would you get if you had a neuroma on the right 8th N?

A

Right ipsi reflex is absent
Right contra reflex is absent
Left ipsi is present
Left contra is present

30
Q

What reflexes would you get if you had damage to the right facial N?

A

Right ipsi = absent
Right contra = present
Left ipsi = present
Left contra = absent

31
Q

Do these reflexes make sense?

A

Yes

32
Q

Do these reflexes make sense?

A

Yes

33
Q

Do these reflexes make sense? Explain

A
  • Right ME issue
  • Right contra are present and tell you that the left ME is fine
34
Q

Do these reflexes make sense?

A
  • If all AR are present and hearing is at 110 dB (that is not legit)
  • You can have normal hearing and absent reflexes
35
Q

What are the 4 theories of AR function?

A
  1. Protection theory (protection from louder sounds)
  2. Communication
  3. Labyrinthine pressure-regulation theory (ILP)
  4. No function at all
36
Q

Explain the communication theory

A
  1. Ossicular chain fixation theory (prevent the ossicles from distorting)
  2. Frequency selection theory (when the reflex activates it filters out some sounds and lets others pass through – band pass filter)
  3. Prevention of low frequency masking on the higher frequencies
37
Q

Explain the intra-labyrinthine pressure theory

A
  • Pressure chamber therapy alleviated/resolved symptoms of Meniere’s
  • Tenetomy of ME muscles alleviated symptoms of Meniere’s

Diagnostic Audiology (7 decks)

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