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PM3A > (PM3A) ENT - Ear > Flashcards

(PM3A) ENT - Ear Flashcards

1
Q

What is the outer ear?

A

Filled with air

Composed of auricle (pinna) + auditory canal

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2
Q

What is the middle ear?

A

Air-filled

Comprises tympanic membrane (ear drum) + auditory ossicles

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3
Q

What are the auditory ossicles?

A

Chain of bones

(1) Malleus - hammer
(2) Incus - anvil
(3) Stapes - stirrup

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4
Q

What is the tympanic membrane?

A

Ear drum

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5
Q

What is the Eustachian tube?

A

Part of middle ear

Goes into respiratory system via nasopharynx

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6
Q

What is the inner ear?

A

Labyrinth

Fluid-filled

Consists of vestibular system + cochlea

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7
Q

What is the vestibular system?

A

Part of inner ear

3 semicircular canals + the vestibule

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8
Q

What is the cochlea?

A

Spiral-shaped series of 3 tubular canals

Contains organ of Corti (sound)

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9
Q

Where is the organ of Corti?

A

Inner ear (labyrinth)

Cochlea

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10
Q

What is the organ of Corti?

A

Found in cochlea in labyrinth (inner ear)

Organ of sound

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11
Q

What nerves are present in the inner ear?

A

(1) Vestibular nerve

(2) Cochlea nerve

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12
Q

What is the function of the outer ear?

A

To direct sound waves into auditory canal

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13
Q

What is the function of the middle ear?

A

(1) Amplified by tympanic membrane (ear drum)

(2) Sound waves must be converted into pressure waves in fluid in inner ear (cochlea)

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14
Q

What is the function of the inner ear (labyrinth)?

A

Cochlea - controls hearing

Vestibular system - controls balance

Both function by mechanical -> electrical signal transduction

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15
Q

What is the cochlea?

A

Part of the inner ear responsible for our ability to hear

Snail-shaped

Series of 3 ducts
- (1) Scala vestibuli - filled with perilymph
- (2) Scala tympani - filled with perilymph
- (3) Scala media - filled with endolymph + organ of corti

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16
Q

What are the sites of auditory transduction?

A

Organ of Corti (sound)

Inner + outer hair cells

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17
Q

What is the role of the inner hair cells in the organ of Corti?

A

Signalling to the brain via the cochlea nerve

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18
Q

What is the role of the outer hair cells in the organ of Corti?

A

Act as amplifiers

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19
Q

How do the hair cells of the organ of Corti transduce sound?

A

Bodies of the hair cells in contact with auditory (cochlea) nerve fibres

Cilia of the hair cells in contact with tectorial membrane

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20
Q

How do we hear?

A

(1) Vibration of basilar membrane activates inner + outer hair cells (sensory receptors) - caused by bending of cilia in contact with tectorial membrane

(2) Inner hair cells are depolarised

(3) Glutamate (excitatory neurotransmitter) released to activate afferent cochlear auditory nerves

Opposing this, when inner hair cells are hyperpolarised, the afferent cochlear auditory nerves are inhibited

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21
Q

How do we detect different frequencies of sound?

A

Basilar membrane in inner ear varies in width and stiffness along its length

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22
Q

What are stereocilia?

A

Cilia of inner hair cells

Largest is known as the kinocilium

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23
Q

What fluid do the stereocilia bathe in?

A

Endolymph

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24
Q

What fluid do the bodies of the hair cells bathe in?

A

Perilymph

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25
Q

Describe the properties of endolymph.

A

High potassium

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26
Q

Describe the properties of perilymph.

A

Low potassium

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27
Q

What is the potential difference of endolymph?

A

80mV

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28
Q

What is the potential difference of perilymph?

A

0mV

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29
Q

How do hair cells signal?

A

(1) Vibration of basilar membrane causes bending of stereocilia

(2) Bending of stereocilia towards kinocilium (largest stereocilia) mechanically opens ion channels

(3) Causes influx of potassium

(4) This causes depolarisation which leads to influx of calcium ions via voltage-gated calcium channels

(5) Leads to glutamate (excitatory neurotransmitter) release

(6) Activation of afferent cochlea nerve fibres

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30
Q

What happens if stereocilia are bent away from the kinocilium?

A

(1) Closing of ion channels

(2) Leads to hair cell hyper polarisation

(3) Inhibition of afferent nerve fibres

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31
Q

How do the afferent cochlea nerve fibres signal to the brain?

A

(1) Synapses -> Brainstem

(2) Brainstem ->
- Different brain region, e.g. cortex for cochlea
- Different brain region, e.g. cerebellum and cranial nerves for vestibular system

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32
Q

What is the purpose of the vestibular system?

A

Maintenance of equilibrium/ balance

33
Q

How does the vestibular system maintain equilibrium/ balance?

A

Detection of angular/ linear accelerations of the head

34
Q

How is angular acceleration detected?

A

Vestibular system

Detected by semicircular canals
(1) Anterior (superior) in sagittal plane
(2) Posterior (inferior) in frontal plane
(3) Lateral (horizontal) in vertical axis

35
Q

How is linear acceleration or gravity detected?

A

Detected by otolithic organs

(1) Utricle - horizontal
(2) Saccule - vertical

36
Q

Where are the hair cells found in the semicircular canals?

A

In the ampullae

37
Q

What is the purpose of hair cells in the vestibular system?

A

Detection of movement of fluid to detect angular/ linear acceleration

38
Q

What happens following movement of the stereocilia in the vestibular system?

A

Downstream signalling to the brain of position/ movement

39
Q

What is otitis externa?

A

Outer ear inflammation

40
Q

What is otitis media?

A

Middle ear inflammation

41
Q

What is labrynthitis?

A

Inner ear inflammation

42
Q

What is vestibular neuronitis?

A

Inner ear inflammation

43
Q

Is ear wax build up considered a condition?

A

No

44
Q

What can ear wax build up cause?

A

Ear ache

Hearing loss

Difficulty upon examination

45
Q

How can an ear wax build up be treated?

A

Cerumenolytic products

3-5 days of ear drops to soften

Olive/ almond oil TDS/QDS

Can use sodium bicarbonate/ chloride ear drops

Avoid tool insertion into ear

46
Q

How can ear wax build up be prevented?

A

(1) Avoid compacting ear wax

(2) Use preventative ear drops

47
Q

What are some products which can be used to treat ear wax buildup, that are not recommended by NICE?

A

(1) Urea hydrogen Peroxide 5%

(2) Arachis oil

48
Q

What is otitis externa commonly caused by?

A

(1) Bacteria - e.g. P. aeruginosa/ S. aureus

(2) Fungi - e.g. Candida/ Aspergillus

49
Q

What are some symptoms of otitis externa?

A

Red + swollen

Scaly skin

Swelling (with central pus?) + pressure

Painful + itchy

Hearing loss

50
Q

What self-care advice can be given for localised otitis externa?

A

Keep clean + dry

Analgesia

Local heat

Usually self-limiting

51
Q

What treatment is available for acute diffuse otitis externa?

A

Acute diffuse:
(1) Corticosteroid ear drops/ astringents/ 2% acetic acid solution 3-4drops

(2) Topical antibiotics, e.g. neomycin sulfate

(3) Topical antifungal, e.g. 1% clotrimazole solution

(4) Anti-infective, e.g. clioquinol

52
Q

What is the treatment if otitis externa has spread beyond ear canal?

A

Regard as cellulitis

Oral flucloxacillin 500mg-1g 4 times a day for 5-7 days

(clarithromycin if penicillin intolerant)

53
Q

What is the treatment for chronic diffuse otitis externa?

A

Fungal: Anti-fungal agent, e.g. clotrimazole 1% solution

If ear drum (tympanic membrane) is perforated, aminoglycoside antibiotics (gentamicin + neomycin) are contraindicated

54
Q

Why are aminoglycoside antibiotics contraindicated in otitis externa with perforation of the ear drum (tympanic membrane)?

A

Can cause ototoxicity (hearing/ balance problems)

55
Q

What is contraindicated if a patient presenting with otitis externa has a perforated ear drum (tympanic membrane)?

A

Aminoglycoside antibiotics

e.g. gentamicin/ neomycin

56
Q

Name some examples of aminoglycoside antibiotics.

A

(1) Neomycin

(2) Gentamicin

57
Q

What causes otitis media?

A

Eustachian tube become inflamed/ blocked, traps fluid in middle ear

Common in young children

Common following viral respiratory tract infection

Typically caused by viruses

58
Q

What are some symptoms of otitis media?

A

(1) Sudden onset of otalgia (ear ache)
(2) Fever
(3) Hearing loss
(4) Vomiting/ discharge when more severe

59
Q

What is the considerations for treatment for otitis media?

A

Usually self-limiting (3-7 days)

(1) Analgesia
(2) Antibiotics often not needed
(3) Can give backup Rx for worsening of symptoms
(4) ABx considered when patient is systemically unwell or high risk of complications or <2yrs old

60
Q

What is the first line treatment for otitis media?

A

5-7 days oral amoxicillin

400mg tds

Clarithromycin/ erythromycin if amoxicillin not tolerated (penicillin allergy)

Erythromycin is preferred alternative

61
Q

What often defines chronic otitis media?

A

(1) Perforated ear drum - tympanic membrane
(2) Referral to ENT specialist

62
Q

What is the treatment for chronic otitis media?

A

Antibiotic ear drops, e.g. topical quinolones

Refer to ENT specialist

63
Q

What is labrynthitis?

A

Inflammation of inner ear (labyrinth)

64
Q

What vestibular neuritis?

A

Inflammation of vestibular nerve

65
Q

What are some conditions of the inner ear?

A

(1) Vestibular neuritis
(2) Labyrinthitis

66
Q

What causes inner ear infections?

A

Commonly viral infections

Can be linked with stress + ototoxicity

Rarely bacterial infection

67
Q

What are some symptoms of inner ear conditions?

A

(1) Dizziness/ vertigo

(2) Balance disorder

(3) Tinnitus

(4) Hearing loss (labyrinthitis ONLY)

68
Q

What is the treatment for inner ear conditions?

A

Self-care + rest

Prochloperazine for vertigo + nausea

Antihistamines, e.g. cinnarizine/ cyclizine

Corticosteroids for inflammation (not recommended by NICE)

Antivirals usually not recommended

Antibiotics IF bacterial

69
Q

What is normally not recommended for inner ear condition treatment?

A

(1) Corticosteroids
(2) Antivirals
(3) Benzodiazepines

70
Q

What is hearing loss?

A

Temporary/ permanent

Can be mild/ moderate/ severe/ profound

One/ both ears

Either sensorineural/ conductive

71
Q

What is sensorineural hearing loss?

A

Damage to hair cells of cochlea/ auditory nerve

Permanent

Hair cells cannot regenerate

72
Q

What is conductive hearing loss?

A

Inhibition of sound transmission from outer to inner ear

e.g. blockage

Permanent/ temporary

73
Q

What are some different causes of hearing loss?

A

(1) Genetic

(2) Noise-induced (loud noises damage hair cells)

(3) Age-related (gradual damage to hair cells)

(4) Otosclerosis (bony growths in ear, conductive loss)

74
Q

What are some causes of sudden hearing loss?

A

(1) Ototoxic drugs (damage inner ear)

(2) Infections (e.g. viral Rubella, measles, mumps, or bacterial meningitis

(3) Trauma/ injury (infection/ noise)

(4) Meniere’s disease (changes in fluid pressure in inner ear - endolymph)

75
Q

Name some drugs associated with ototoxicity.

A

BASICALLY, noemycin, furesomide, cisplatin

(1) Analgesics/ antipyretics - not so severe

(2) Aminoglycosides (neomycin in particular)

(3) Macrolide ABx - may be reversible

(4) Glycopeptide ABx - not so severe

(5) Antineoplastics (cisplatin in particular)

(6) Loop diuretics (furosemide)

76
Q

What are hearing aids?

A

Behind ear/ in ear/ in canal

Used for conductive/ sensorineural hearing loss

Amplifies sounds to aid hearing

77
Q

What are ear implants?

A

Bone-anchored hearing aids, e.g. cochlea implants, auditory brainstem implants, middle ear implants

78
Q

What are cochlea implants?

A

For more severe sensorineural hearing loss (damage/ loss of hair cells)

For more profound deafness

Directly stimulate cochlea nerve

Bypass damaged upstream signalling to nerve

PM3A (36 decks)

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