Lesson 14 Tympanometry
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Identifies a measure of the dynamic compliance of the tympanic membrane (TM) and reflects the algebraic sum of the factors influencing middle ear performance.
Tympanometry answers what question?
Answers the question of "Should this patient be referred for medical follow-up?"
Measures the volume of the ear canal...positive and negative ranges...what are those ranges?
+200mm H2o to 0mm H2o to -200mm H2o.
Normal or 0mm H2o represents what
The TM is free to move, this neutral pressure status permits the maximum passage of acoustic energy through...
The peak on a tympanometer represents what?
The peak reflects the "point of maximum compliance" of the TM.
Maximum Compliance means....
the pressure exerted in the chamber matches the pressure level in the middle ear.
Maximum negative pressure means...
the TM is being pulled out into the canal and again, becomes stiffened by the combination of the shape and resistance of the TM itself.
Three observations to remember about tympanometry
1. Is not a hearing test. It is possible for a dead ear to produce a normal tympanogram.
2. Middle ear muscles (i.e., the stapedial reflex) in general, require acoustic stimulation (hearing) for activation of that activity, even under the most "normal" of middle ear conditions
3. The patient can be awake or asleep, and the results will be the same.
Type A Tympanogram & range of static compliance is....
"Normal" and the range of static compliance runs from .4cc to roughly 1.6cc
Type As & range of static compliance is...
"Shallow A" there is a stiffness somewhere through the transfer of energy.
Static compliance is ranging UP TO .4cc
What disorders are associated with a type As tympanogram?
Other possible causes could be a scar tissue or thickened epithelial tissue on the lateral margin of the TM
Type Ad and range of static compliance
"Deep A" Still has an intact TM as well as normal eustachean tube function.
Static compliance range falls ABOVE 1.6cc
Two most common causative, factors of Type Ad is...
1. Ossicular discontinuity, or an incomplete "chain" causing "flaccid" movement of the membrane.
2. A monomeric membrane, in which a recovering perforation produces a weak spot when the epithelial (or outer) layer grows back.
Type B tympanogram (shape)
Type B tympanogram can occur for number of reasons, those are....
1. Obstruction in the canal
2. Perforation of the TM
3. Middle Ear fluid
4. Misapplication of the probe tip
Type C tympanogram
Substantial negative pressure in the middle ear space.
Referred to as a retracted tympanic membrane.
Type C tympanogram can occur for what reasons...
retracted tympanic membrane
A Type A tympanogram with a "high peak" might require what adjustments on the hearing aid?
Reduction of output by 2-3 dB, b/c the transfer of energy through the middle ear mechanism is highly efficient and therefore more energy passes through.
A Type As tympanogram with a "shallow peak" might require what adjustments on the hearing aid?
Small addition to the output by 2-3 dB to allow for compensation for the additional stiffness of the system.
Lesson 14 Tympanometry
Unit 2 Lesson 14 Tympanometry