The Middle Ear Disorders Flashcards by Nkechi Nwagbara

What is the purpose of the middle ear space?

It overcomes the impedance mismatch.

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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

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When does a 30dB drop occur?

When someone has missing ossicles and overcoming an impedance mismatch would not occur

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What makes up the middle ear space?

Malleus, Incus, Stapes
Eustachian Tube
Middle-ear cleft
Cilia

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What does the Eustachian Tube connect?

It connects the middle ear to the nasopharynx

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What makes up the middle-ear cleft?

The eustachian tube + middle-ear

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What is the middle-ear cleft lined with?

Mucous Membrane and Cilia

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What’s the function of the cilia for the ME?

It has hairlike projections to help clean middle ear space

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What does the cilia act like?

Cleaning conveyor-belt for the ME

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For the Eustachian tube in adults, how is it positioned?

Downwards

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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

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What is the job of the eustachian tube?

It’s responsible for pressure equalization between outer and middle ear

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For our eardrums, how should the pressure be?

Pressure should be the same behind the eardrum and in front of the eardrum

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What allows our TM to move effectively?

If the pressure in front of and behind our eardrum is equal

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Our eustachian tube is normally….

Closed

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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

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What are the natural ways our eustachian tube equalizes pressure?

Yawning

2. Sneezing

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What allows the equalization of the eustachian tube to happen effectively?

The angle of the eustachian tube

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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

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Is the mastoid part of the middle ear space?

Technically, no

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How would you describe the mastoid?

As a “honeycomb” bone w/hundreds of air cells

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What is the mastoid air cells lined with?

ONLY mucous membrane

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What are two examples of non-auditory ME structures?

Portion of facial nerve

2. Chorda tympani nerve

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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

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What are the muscles that exist in the ME?

1. 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?

1. Antibiotics | 2. Surgical intervention if antibiotics isn't working or if the OM is reoccurring

Is ME fluid snot?

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?

1. 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?

1. 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?

1. Potential SLP problems 2. Temporarily/Permanent HL 3. 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?

1. ME 2. Eustachian tube 3. Nasopharynx 4. Brain cavity

What does cholesteatoma cause?

Erosion of ME structures

What are the symptoms of cholesteatoma?

1. Fouls smelling otorrhea (drainage), 2. Pressure, 3. 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?

1. 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