Class 5 Quiz Flashcards
Acoustic immittance (tympanometry)
- a test to determine the function (impedance and compliance) of the tympanic membrane
- middle ear
3 measurements to look for when interpreting tympanometry:
- volume of the middle ear (estimated canal volume) (in mm)
- the peak pressure tip of the graph
- the measurement of movement of the tympanic membrane
Volume of the middle ear
- measured in mm (usually 1.5-2)
- important because if the eardrum is smaller than it should be, more wax or impaction
- if the volume is bigger look for perforation or a tube
Peak pressure of the tip of the graph
- should be -100 to +100
- measured in cubic centimeters
- important because there can be eustachian tube dysfunction and we need it to vibrate at its ultimate compliance level
- affects the transmission of sound and how readily it vibrates
Measurement of movement of the tympanic membrane
- measured in dekapascales-dPA
- no compliance could mean fluid or something behind the eardrum
- hypermobile compliance can mean not much
Normal Ranges for tympanogram for both children and adults child (3-10)
- Admittance/Compliance: .25-1.05
- dPA: 80-159
- Canal Volume (cm2): .3-.9
Normal Ranges for tympanogram for both children and adults adult (18+)
-Admittance/Compliance: .30-1.70
- dPA 51-114
- Canal Volume (cm2): .9-2.0
Type A Tympanogram
- normal (what we want to see)
- sensorineural hearing loss or normal (AC matches BC)
Type B Tympanogram
- flat tympanogram
- no measurement/movement
Type C Tympanogram
- have a positive and a negative
- can see if itll be positive or negative based on the pressure
- same compliance as a part A but peak will be different (outside of the box)
- common in someone who is just starting or getting over an ear infection
- Sometimes youll have no air-bone gap, but usually you get a conductive hearing loss
The box on a tympanogram
- clinical normal
Acoustic reflexes (ipsilateral and contralateral)
- the reflexive contraction of the middle ear muscles in response to sound stimulation
- can define middle-ear, cochlear, and 8th nerve disorders
- Frank Musiek
Small ear canal volume in an adult. Why?
- wax
- swimmers ear
Small ear canal volume in a child. Why?
- wax
- foreign object
Flat tympanogram with very small ear canal volume:
- full impaction
Flat tympanogram with normal ear canal volume and normal otoscopy:
- when there is fluid behind the eardrum
Flat tympanogram with large ear canal volume in both a child and adult:
- perforation
- tubes
Type C tympanogram clincial indication
- start or finish ear infection
- eustachian tube dysfunction
Type As tympanogram clinical indication
- ## stiff but correct peaking/pressurization
Type Ad tympanograms clinical indication
- soft sign for ossicular discontinuity
- hypermobile eardrum
Type B tympanogram clinical implication
- large volume/perforation
- lots of fluid
- impaction
When presented with a high intensity sound stimulus, the
stapedius and tensor tympani muscles contract
The stapedius stiffens the ossicular chain by pulling
the stapes of the middle ear away from the oval window of the inner ear
The tympani muscle stiffens the ossicular chain by loading the
Tympanic Membrane when it pulls the malleus in toward the middle ear
The contraction of the stapedius muscle stiffens the middle ear which
decreases middle-ear admittance (not allowing sound to go in) which can be measured by tympanometry
- PROTECTS HEARING AGINST LOUD SOUNDS
in normal hearing individuals
80dB is the pretty loud sound when contraction starts
Clinical Reasoning for Acoustic Reflex
- rule out malingering
- rule out acoustic neuroma
Acoustic reflexis are present in 85% of people
18-30 years old
Acoustic reflexis are present in 75% of
all people
