7. Eustachian tube & cholesteatoma (lecture)

Question 1

how is the eustachian tube different in infants?

Answer 1

shorter and more horizontal

Question 2

what does a shorter and more horizontal eustachian tube in infants suggest?

Answer 2

1. easier passage for infection from the nasopharynx to middle ear
2. tube can block easier

Question 3

what can blockage of eustachian tube lead to?

Answer 3

compromising ventilation and drainage of middle ear, increasing risk of middle ear infection

Question 4

what are common complications of otitis media?

Answer 4

tympanic membrane perforation

facial nerve involvement (runs through middle ear - bulge)

Question 5

what are rare but potentially life-threatening complications of otitis media?

Answer 5

1. mastoiditis
2. intracranial complications:
   - meningitis
   - sigmoid sinus thrombosis (venous clot - drainage)
   - brain abscess

Question 6

what are important anatomical relations of the ear?

Answer 6

pharyngotympanic (auditory) tube
internal carotid artery (inferior to eustachian tube)
mastoid cells (inferior to EAM)
sigmoid sinus (inferior to mastoid cells, venous return)

Question 7

what is significant about mastoid cells in middle ear?

Answer 7

communicates with middle ear cavity

Question 8

why do mastoid air cells communicate with middle ear cavity?

Answer 8

mastoid air cells are involved in helping to equilibrate middle ear pressures

Question 9

what do mastoid air cells provide?

Answer 9

a potential route for middle ear infections to spread into the mastoid bone (where mastoid air cells are)

Question 10

how do patients with mastoiditis present?

Answer 10

ear bulge out - swollen mastoid air cells (around mastoid bone)

Question 11

what is the treatment for mastoiditis?

Answer 11

IV antibiotics (NOT oral)
may need surgery to drain pus from mastoid bone

Question 12

which nerve is the middle ear associated with in particular?

Answer 12

CN VII

facial nerve

Question 13

what is significant about the facial nerve and middle ear?

Answer 13

chorda tympani branch of CN VII runs through middle ear cavity
facial nerve may be involved in pathology involving the middle ear

Question 14

where does facial nerve through through?

Answer 14

posterior wall of middle ear cavity - can see prominence (bulge) of facial canal

Question 15

what does chorda tympani run very close to?

Answer 15

malleus
through the middle ear cavity
(branch of facial nerve)

Question 16

what is cholesteatoma?

Answer 16

painless otorrhea (ear discharge)

Question 17

what are causes of cholesteatoma?

Answer 17

usually secondary to chronic / recurring ear infections and blockage of ET

Question 18

what does cholesteatoma secondary to chronic / recurring ear infections create?

Answer 18

creates a sucking, negative pressure, drawing eardrum inwards
can lead to small pocket forming

Question 19

what happens if sucking negative pressure is created from cholesteatoma?

Answer 19

skin cells get trapped, collect and continue to grow in the small pocket within middle ear
(oma - tumour - benign swelling of skin cells)

Question 20

what can cholesteatoma lead to?

Answer 20

not malignant
but slowly grows and expands
eroding into structures e.g. ossicles, mastoid bone, cochlea

Question 21

what happens as the cholesteatoma grows?

Answer 21

at first erode and destroy structures in middle ear
in time may damage structures in inner ear
even erode into the bone of nearby skull and into brain

Question 22

how does the pocket in cholesteatoma form?

Answer 22

from negative pressure sucking tympanic membrane inwards - creating pace between tympanic membrane and malleus for skin cells to collect

Question 23

what is the negative pressure within cholesteatoma caused by?

Answer 23

blockage of eustachian tube

Question 24

what is a early cholesteatoma called?

Answer 24

cyst