7.1.3 Middle Ear Conditions

Question 1

Describe the middle ear

Answer 1

Air filled cavity between tympanic membrane and inner ear containing ossicles

Question 2

How are ossicles connected?

Answer 2

Synovial joints

Question 3

What is the function of ossicles?

Answer 3

Amplify and relay vibrations from the TM to the oval window of the cochlea (inner ear) stapes hits the oval window

Transmits vibration to waves in a fluid-medium

Question 4

What is the order of the ossicles from lateral to medial?

Answer 4

Malleus
Incus
Stapes

MIS

Question 5

What is the acoustic reflex?

Answer 5

Ossicle movement tampered by tensor tymapni and stapedius if there is excessive vibration due to loud noise

Protective

Question 6

What is otosclerosis?

Answer 6

Ossicles fused at articulations due to abnormal bone growth, partucularly between base plate of stapes and oval window

Sounds vibrations cannot be transmitted to cochlea effectively

Question 7

What is the cause of otosclerosis?

Answer 7

Genetic and environmental causes

Exact cause is unknown, viral or hereditary triggers?

One of the most common causes of acquired hearing loss in young adults

Patients present with gradual unilateral or bilateral Conductive hearing loss

Question 8

What happens if the ET/pharyngotympanic tube does not equilibrate pressure in the middle ear?

Answer 8

Mucus membranes of the middle ear continuously reabsorb air in the middle causing negative pressure

If there is no equilibration the tympanic membrane will become retracted and effusion will occur as there is no drainage of mucus or ventilation of the middle ear

Question 9

What is otitis media with effusion (glue ear)?

Answer 9

Not an actual infection but can predispose to

ET dysfunction, fluid and negative pressure in middle ear, decreases mobility of TM and ossicles, affects hearing

Question 10

How do you treat glue ear/otitis media with effusion?

Answer 10

Most resolve spontaneously in 2-3 months

If there is impeded speech & language development /persists for longer than 3 months can treat with grommets (tympanostomy tube), equilibrates pressures

Question 11

What is acute otitis media?

Answer 11

Acute middle ear infection, more common in infants/ children than adults

Question 12

Why is acute otitis media more common in infants?

Answer 12

ET is shorter and more horizontal, this means there is:
-Easier passage for infection from nasopharynx to middle ear
-Tube can block more easily, (lots of lymphatic tissue here can obstruct ET easily) compromising venitlation and drainage of middle ear

Question 13

What are some signs and symptoms of acute otitis media?

Answer 13

• Otalgia (infants may pull or tug at ear)
• Non-specific symptoms e.g. temperature
• Red +/- bulging TM and loss of normal landmarks

Question 14

What causes acute otitis media?

Answer 14

Mostly viral cause
Can be bacterial, streptococcus pneumoniae or haemophilus influenzae

Question 15

What are some complications of acute otitis media?

Answer 15

• Tympanic membrane perforation
• Facial nerve involvement Rare as there is close relationship to middle ear cavity, two intrapetrous branches run through middle ear cavity (chorda tympani and nerve to stapedius)

LIFE THREATENING COMPLICATIONS
* Mastoiditis
* Intracranial complications, meningitis, sigmoid sinus thrombosis (can invade petrous bone, sigmoid sinus directly below) and brain abcess

Question 16

Why can you get mastoiditis with ear infections?

Answer 16

Middle ear cavity communicates via mastoid antrum with mastoid air cells

Provides a potential route for middle ear infections to spread into mastoid bone

Question 17

Image just to see important anatomical relations of the ear

Answer 17