Session 7 - functional anatomy and disorders of the ear

Question 1

what is otalgia

Answer 1

ear pain. pain that originates within the ear is primary otalgia; pain that originates outside the ear is referred otalgia.
Typical sources of primary otalgia are external otitis, otitis media, mastoiditis, and auricular infections

Question 2

wihtin which bone of the skull do we find parts of the ear

Answer 2

petrous part of the temporal bone

Question 3

what parts make up the external ear

what is its function

Answer 3

pinna
external auditory meatus
lateral surface of tympanic membrane
collects, transmits, and focuses sound waves onto the tympanic membrane

Question 4

how does cauliflower ear occur

Answer 4

secondary to blunt injury to the pinns
accumulation of blood between cartilage and perichondrium
deprives the cartilage of its blood supply + pressure necrosis of
tissue
Prompt drainage of blood, measures to prevent re-accumulation and re-apposition of two layers are necessary
Untreated or poorly treated leads to fibrosis and new
asymmetrical cartilage development- ‘cauliflower
deformity’ of the ear

Question 5

why can ear infection affect the facial nerve and cause facial palsy

Answer 5

the facial nerve travels through the internal auditory meatus

Question 6

what is ramsey-hunt sydrome

Answer 6

is a herpes zoster oticus
where you get unilateral facial palsy
caused by the reactivation of the varicella zoster virus from the geniculate nucleus (nucleus if the facial nerve)

Question 7

in what way does the ear have to be positioned to examine it

Answer 7

straighten it by pulling it back and up as it has a sigmoid shape

Question 8

where are the gland that produce wax and hair found

Answer 8

outer part of ear canal (cartilaginous)

Question 9

how long is the external acoustic meatus

Answer 9

2.5cm

Question 10

what is ottitis externa

Answer 10

Inflammation of the external acoustic meatus usually caused by infection, sometimes due to allergy or irritation
Give ear drops/ steroids if infection
Swimmers ear- lots of water in ear predispose to this
More commonly seen in people with eczema

Question 11

how do you get a perforated tympanic membrane

Answer 11

Pressure has built up on the inside
Which can cause the tympanic membrane to perforate
Pus and exudate can leak out
Usually resolves itself
can also be due to poking the ear with things

Question 12

why might you get bulging of the tympanic membrane secondary to ottitis media

Answer 12

bulging due to increased pressure with the build up of immune cells

Question 13

what is the middle ear

and which bones are found here

Answer 13

tympanic cavity - the air filled cavity between the tympanic membrane and the inner ear
three ossicles- incus, malleus and stapes

Question 14

what do the ossicles do

Answer 14

Connected via synovial joints and relay vibrations from the tympanic membrane to the oval window of the cochlea (inner ear)
Transmitting vibration from an air medium to a fluid-medium

Question 15

what protects the ear from very loud noises

Answer 15

Movement is ‘tampered’ by two muscles tensor tympani and stapedius (faical nerve)
Muscles contract automatically if potentially excessive vibration due to loudnoise (protective; acoustic reflex)

Question 16

what is otosclerosis

Answer 16

Ossicles can become fused at articulations, in particular between base plate of stapes and oval window (otosclerosis)
Sound vibrations cannot be transmitted
Causes deafness
Patients develop gradual hearing loss

Question 17

why might you get hyperacusis

Answer 17

Can get hyperacoustis if they have facial nerve damage- lose ability to dampen loud noise
as the stapedius muscle which contracts when there is loud noise is innervated by the facial nerve

Question 18

why do we get a negative pressure in the middle ear

Answer 18

Mucous membrane of middle ear continuously reabsorbs air in middle ear causing negative pressure

Question 19

what is the function of the eustachian tube

Answer 19

Pharyngotympanic tube (Eustachian Tube) allows equilibration of pressure within middle ear cavity with that of the atmosphere. It also allows for ventilation of and drainage of mucus from the middle ear

Question 20

what is glue ear

Answer 20

otitis media with effusion
not an infection
Build up of fluid and negative pressure in middle ear due to Eustachian tube dysfunction: can predispose to infection
Decreases mobility of TM and ossicles- affecting hearing
Most resolve spontaneously in 2-3 months.. but some may persist

Question 21

if glue ear persists what has to be done

Answer 21

Require grommets (tympanostomy tube) to ventilate middle ear and equilibrate pressure

Question 22

why do we get the formation of a transudate in glue ear

Answer 22

cannot equilibrirate pressure in middle ear

negative pressure draws fluid out of mucosa

Question 23

how does the tympanic membrane look in glue ear

Answer 23

retracted and straw coloured
because of the negative pressure pulling the membrane towards the middle ear cavity
can also see a build up of fluid behind membrane giving straw colour

Question 24

what is acute otitis media

Answer 24

Acute middle ear infection
More common in infants, Otalgia (infants may pull or tug at the ear)
non-specific symptoms e.g. temperature
Red +/- bulging TM and loss of normal landmarks

Question 25

why are children more likely to get an ear infection

Answer 25

Pharyngotympanic tube is shorter and more horizontal in infants
In infants therefore easier passage for infection from the nasopharynx to the middle ear
tube can block more easily, compromising ventilation and drainage of middle ear, increasing risk of middle ear infection

Question 26

what are some complications of Acute Otitis Media

Answer 26

Tympanic membrane perforation
Facial nerve involvement
Rarer but potentially life-threatening complications include
– Mastoiditis
– Intracranial complications
     • Meningitis
     • Sigmoid sinus thrombosis
     • Brain abscess

Question 27

how can you get meningitis from an ear infection

Answer 27

the middle ear cavity communicates with air filled cavities in the mastoid process via mastoid antrum (mastoid air cells)
if infection spreads into mastoid air cells it spread into venous structures close by or the brain itself causing meningitis

Question 28

what is mastoiditis and how does it present

Answer 28

Middle ear cavity communicates via mastoid antrum with mastoid air cells.
Provides a potential route for middle ear infections to
spread into the mastoid bone (mastoid air cells)
Infection in mastoid air cells has pushed the ear forward
Ear needs to be drained

Question 29

which branch of the facial nerve runs through the middle ear cavity

Answer 29

chorda tympani

Question 30

what is a cholesteatoma

Answer 30

Abnormal skin growth (sac or cyst of skin cells) growing into into middle ear, behind the tympanic membrane - ear drum retracted due to negative pressure
Rare, but should not be missed!
Causes painless, often smelly otorrhea (ear discharge) +/- hearing loss
But also potentially more serious neurological complications
Usually secondary to chronic ET dysfunction or chronic/recurring ear
infections
Not malignant but slowly grows and expands, eroding into structures e.g. ossicles, mastoid bone, cochlea

Question 31

what is the function of the cochlea

Answer 31

the cochlea converts vibrations into an electrical signal (action potential) that is perceived as sound
it is a fluid filled tube
Movements at the oval
window set up movements of the fluid in the cochlea.
Waves of fluid cause
movement of special sensory cells (stereocilia) within the cochlear duct which generate action potentials in CN VIII - vestibulocochlear nerve

Question 32

what does the vestibular apparatus do

Answer 32

maintains our sense of position and balance

Question 33

what is sensorineural hearing loss

Answer 33

pathology involving the inner ear structures or CNVIII
A sensorineural hearing loss is defined as damage to the hair cells in the cochlea (this is the sensory hearing organ) or damage to the neural pathways of hearing (nerves).

Question 34

how do we hear

Answer 34

Auricle and external auditory canal focuses and funnels sound waves towards tympanic membrane which vibrates

Vibration of the ossicles (stapes at the oval window) sets up vibrations/movement in
cochlear fluid

Sensed by stereocilia (nerve cells) in the cochlear duct (part called the spiral organ of Corti)

Movement of the stereocilia in organ of Corti trigger action potentials in cochlear part of CN VIII

Primary auditory cortex (make sense of the input)

Question 35

what is the vestibular apparatus

Answer 35

Vestibular apparatus includes the semicircular ducts, the saccule and
utricle: these are a fluid filled series of channels and sacs that respond to position and rotation and maintain our sense of balance

Question 36

what is menineres disease

Answer 36

This is a disorder of the inner ear caused by a change in fluid volume in the labyrinth
symtoms include vertigo tinnitus and fluctuating hearing loss
acute attacks

Question 37

what is Benign paroxysmal positional vertigo

Answer 37

causes short episodes of intense dizziness (vertigo) when you move your head in certain directions. Vertigo is the sensation that you or your surroundings are moving. Benign paroxysmal positional vertigo is thought to be caused by tiny solid fragments (otoconia) in the inner ear labyrinth

Question 38

what is labyrinthitis

Answer 38

an inner ear infection which cause the labyrinth to become inflamed affecting your hearing and balance
symptoms include vertigo
feeling or being sick
some hearing loss

Question 39

which tests are performed to differentiate between sensorineural and conductive hearing loss

Answer 39

Rhine’s test and Weber’s test

Question 40

how do you perform a rhines (conduction)test

Answer 40

tap tunning fork, get it to ring and place the base of the tinning fork over mastoid
and then pace it in front of ear
and ask the patient which was louder
in a normal ear should be loudest when placed in front of ear as conduction in air should be greater than conduction in bone
in sensorineural loss it will also be louder in air than bone
but in conductive hearing loss the sound will be louder in bone than air as ambient noise is blocks the sound in air but the bone still conducts

Question 41

how do you perform a weber’s (localisation) test

Answer 41

ring tuning fork
place base of tuning fork on midline of head
see which ear the sound is louder in
if the sound is the same in both ears it is normal
if the sound is louder in the normal ear it is senorineural hearing loss
if it is louder in the affected ear it is conductive hearing loss

Question 42

What are some causes of sensorineural hearing loss

Answer 42

presbyacusis - old age
meniere’s disease
acoustic neuroma
ototoxic medications

Question 43

what are some causes of conductive hearing loss

Answer 43

pathology involving the external or middle ear
wax
otitis media
glue ear
otosclerosis