What is everything based around the concept of?
Everything is based around the concept of measuring the change in response to a pure tone that is being delivered to the external canal
For clinical use, reflexes use ____Hz tone
226
What does tympanometry measure?
Admittance during the course of pressure manipulations
What does AR measure?
Admittance before [baseline] and following the presentation of an acoustic stimulus
What is the effect of the acoustic reflex?
The effect of the acoustic reflex is to produce a change in the admittance at the TM
What does the reflex activator do?
Creates a loud stimulus tone of different frequencies (500, 1K, 2K Hz)
Once we start testing for AR, are there pressure changes?
Once we start reflex testing there are no pressure changes done that will affect impedance
If an acoustic reflex happens, what does it travel down?
The facial nerve
WHat does the facial nerve innervate?
The stapedius muscle
What happens id the facial nerve is innervated?
It will pull on the stapes and stiffen everything up
Where does the reflex pathway cross over?
The level of the brainstem
Terminology of AR is based on the ____ ear
Stimulus
The right ear is bring stimulated and you are measuring the left ear
Right contra
The right ear is being stimulated and you are measuring the left ear
Right ipsi
The left ear is being stimulated and you are measuring the left ear
Left ipsi
The left ear is being stimulated and you are measuring the right ear
Left contra
What are the 6 steps for testing AR?
- Complete a tympanogram
- Set pressure to the point of the highest admittance value (peak) of the tymp
- Acoustic reflex option will measure very small admittance changes
- 0.02 ml/mmho will be a positive response
- Activate stim tone, either ipsi or contra
- Measure/monitor admittance changes in response to stim tone
What does acoustic reflex decay testing test for?
Retrocochlear involvement (stuff beyond the cochlea; some part of the neural system)
How does AR decay testing work?
- 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
Coming from the pyramidal eminence, the ____ inserts into the back part of the neck of the stapes
Stapedius tendon
Contraction of the stapedius muscle pulls the stapes in the ____ direction
Posterior
Explain the anatomy and physiology of the stapedius muscle and what happens?
- 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
What is needed for AR decay testing?
- Probe tone
- Stimulus
- Response from the ME
- Measured in mmho of admittance (YA): using a 226 Hz probe tone may get converted to ml
What are the parameters for AR decay testing?
- Threshold (where is the reflex getting triggered)
- Temporal characteristics (reflex has to have a certain timing pattern to call it a reflex)
- Amplitude (at least a 0.02 admittance change)
- Admittance: increase or decrease?
