The Middle Ear Disorders Flashcards
What is the purpose of the middle ear space?
It overcomes the impedance mismatch.
How does overcoming impedance mismatch occurs?
As sound transitions from an air-filled outer ear and middle ear to the fluid-filled cochlea, we will see a decrease in intensity. But since the size difference from our large TM to the small footplates of the stapes has the same amount of force being exerted on it, there’s going to be an increase the intensity
When does a 30dB drop occur?
When someone has missing ossicles and overcoming an impedance mismatch would not occur
What makes up the middle ear space?
- Malleus, Incus, Stapes
- Eustachian Tube
- Middle-ear cleft
- Cilia
What does the Eustachian Tube connect?
It connects the middle ear to the nasopharynx
What makes up the middle-ear cleft?
The eustachian tube + middle-ear
What is the middle-ear cleft lined with?
Mucous Membrane and Cilia
What’s the function of the cilia for the ME?
It has hairlike projections to help clean middle ear space
What does the cilia act like?
Cleaning conveyor-belt for the ME
For the Eustachian tube in adults, how is it positioned?
Downwards
For the Eustachian tube in children, how is it positioned?
What happens to their eustachian tube as they grow?
- It’s more horizontal
2. As their head grows, it will change and drop
What is the job of the eustachian tube?
It’s responsible for pressure equalization between outer and middle ear
For our eardrums, how should the pressure be?
Pressure should be the same behind the eardrum and in front of the eardrum
What allows our TM to move effectively?
If the pressure in front of and behind our eardrum is equal
Our eustachian tube is normally….
Closed
When does our eustachian tube open?
It opens when it realized the pressure behind our eardrum is not the same in front of ear drum
What are the natural ways our eustachian tube equalizes pressure?
- Yawning
2. Sneezing
What allows the equalization of the eustachian tube to happen effectively?
The angle of the eustachian tube
When the eustachian tube is horizontal, what occurs?
What does it mean for infections?
There isn’t good insertion of muscles to open and close the eustachian tube
We don’t have gravity on our side to drain the fluid from the eustachian tube
Is the mastoid part of the middle ear space?
Technically, no
How would you describe the mastoid?
As a “honeycomb” bone w/hundreds of air cells
What is the mastoid air cells lined with?
ONLY mucous membrane
What are two examples of non-auditory ME structures?
- Portion of facial nerve
2. Chorda tympani nerve
Why is it important to consider non-auditory ME structures?
IF things are going wrong with the ME space, anatomy needs to be considered to know that it’s not only hearing at stake
What are the muscles that exist in the ME?
- Stapedius Muscle
2. Tensor Tympani Muscle
Define the role of the stapedius muscle
Stapedius muscle contracts in the ME space when there’s sound.
Since the stapedius muscle contracts with sound, what happens when a loud sound is present?
The loud sound will tighten the ossicular chain and the loud sound wouldn’t get transferred
Which cranial nerve innervates the stapedius muscle?
Facial Nerve (CN VIII)
Which cranial nerve innervates the tensor tympani muscle?
Trigeminal Nerve (CN V)
When does the tensor tympani muscle tenses?
Only by tactile stimulation
When the stapedius muscle contracts it….
Attenuates low frequency sounds
With the stapedius muscle, stiffening of….
the ossicular chain decreases amplitude of vibration
What kind of hearing loss would one have if they have problems with the middle ear?
Conductive HL
What is the most common disorder of the middle ear?
Who experiences it more often?
Otitis Media
Kids
Define Otitis Media
Infection in the middle ear space
What the percentage & age of kids who had OM?
~70% of kids under the age of 2
Why is OM common in child?
Because of their horizontal Eustachian tube not being able to do the job it needs to do
When OM occurs, what travels and where does it go?
Organisms travel from the nasopharynx to eustachian tube to the ME space
What are the symptoms for OM?
Pain
Pressure
Hearing Loss
For OM, what determines the HL?
HL depends on severity of infection and the amount of fluid
What’s the typical order of treatment?
- Antibiotics
2. Surgical intervention if antibiotics isn’t working or if the OM is reoccurring
Is ME fluid snot?
No
What is middle ear fluid?
It’s the serum from the capillaries from the ME space
Describe the serum in the ME space
The serum that carries the blood cells through the capillaries get sucked out and gets into the ME space and leaves the blood cells behind in the capillaries
What allows the serum to get sucked out?
A vacuum effect is needed where (-) pressure is needed to get the pressure to what it should be because of the ET functionally effectively
For OM, when does a (-) pressure build up occur?
When the ET is not functionally effectively, negative pressure builds up in the ME space and the fluid that didn’t get sucked out gets infected
OM surgical intervention creates a….
Temporary eustachian tube (depending on case)
For OM Surgical Intervention, what are the steps?
- Myringotomy
2. Pressure-equalizing (PE) tubes
Define Myringotomy
It’s an incision in the TM and the infection gets sucked out
Define PE tubes
Are pressure-equalizing tube that gets put into the eardrum to hold open the incision that you made
Why is using a PE tube more effective?
Since our TM naturally heals and close on its own, we want to create a permanent hole that won’t close up
When a PE tube is put in, what’s being united?
The ME & OE space to ensure we’re always having equal pressure on both sides
What does the PE tube create?
An artificial eustachian tube in the eardrum not in the nasopharynx
What can untreated OM lead to?
Mastoiditis
Define mastoiditis?
Is when infection spreads from the middle ear to the mastoid
Why does having mastoiditis a problem?
Since the mastoid does not have cilia but air pockets, infection cannot naturally be cleaned out
What can untreated mastoiditis lead to?
Meningitis
From impact of having mastoiditis, what should we consider?
How close ear/mastoid is to the brain
For Mastoiditis, what are the symptoms?
Post-auricular swelling, pain, hearing loss
What’s the big difference between OM & Mastoiditis?
Post-auricular swelling
What’s the treatment for mastoidists?
- Antibiotics
2. And/or surgery to “scrape” out infection which also removes the bone
As Audiologist, why do we need to express the seriousness of these conditions?
- Potential SLP problems
- Temporarily/Permanent HL
- It can get worse
Define cholesteatoma
It’s a benign growth of skin in an abnormal location
For cholesteatoma, where can this aggressive growth occur?
- ME
- Eustachian tube
- Nasopharynx
- Brain cavity
What does cholesteatoma cause?
Erosion of ME structures
What are the symptoms of cholesteatoma?
- Fouls smelling otorrhea (drainage),
- Pressure,
- Hearing loss
For cholesteatoma, what’s the treatment used?
Surgery to remove all the cholesteatoma or quick re-growth
Define otosclerosis
It’s a bony growth in the middle ear on the ossicles
Which ossicle will otosclerosis occur on?
The stapes
What does otosclerosis cause?
A decrease/stop of vibration of ossicles
What does otosclerosis lead to?
Hearing loss
What type of cases are otosclerosis and what’s the percentage?
Hereditary & 70%
Who typically experiences otosclerosis?
Adults
Is otosclerosis progressive or regressive?
Progressive
What are the symptoms of otosclerosis?
- Hearing loss in the 2kHz notch for BC results
2. Tinnitus
For patients that has otosclerosis, what’s another name for the hearing loss at the 2kHz notch?
Carhart’s notch
What is the treatment for otosclerosis?
Surgery
Is surgery successful for those that has otosclerosis? Why?
No because bony growth may reoccur.
Why is a Carhart’s notch for a ME disorder surprising?
A middle ear disorder should be associated with a Conductive Hearing loss. But, since otosclerosis is occurring at the stapes on the oval window, the growth impacts the oval window and leads to a decrease of the BC threshold @ 2kHz
