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Head And Neck > Inner Ear Pathology And Physiology > Flashcards

Inner Ear Pathology And Physiology Flashcards

1
Q

What is the physiology of hearing in the outer and middle ear?

A

Sound enters the ear caught by the pinna, goes through the auditory canal and hits the tympanic membrane. This vibrates and sound pressure is transmitted through the ossicles, last one being the scapes.
The scapes vibrates against the membrane of ova window and transmits sound into the inner ear.

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2
Q

What does the middle ear do?

A

Transforms acoustic energy from the medium of air to fluid

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3
Q

What does the middle ear act as?

A

A sound amplifier

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4
Q

How does the middle ear act as a sound amplifier?

A

The area effect of the tympanic membrane- ration of TM to stapes footplate is 17:1
Lever action of ossicular chain- ratio of pressure on tapes to footplate to pressure on malleus is 1.3:1

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5
Q

What does otitis media cause?

A

Affects the movement of tympanic membrane. Causes conductive hearing loss

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6
Q

How does small perforation affect hearing?

A

Variable effect.
Main indication for repair is recurrent infection

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7
Q

How can subtotal perforation effect hearing?

A

If sensorineural function is maintained, the maximum hearing loss is in order of 60dB.
Even if whole drum is gone, some sound will go through hitting the ossicles and ova window

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8
Q

What is otosclerosis

A

Deposition of new bone where footplate of scapes fits into oval window

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9
Q

How does otosclerosis effect hearing?

A

Reduces movement of stapes footplate causing a conductive hearing loss

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10
Q

Describe the structure of the cochlea

A

A pressure wave flows up fron the vestibule from the piston of the stapes, through the helictotrema at the apex and down the scala tympani. The pressure differential deflects the basilar membrane of the scala media

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11
Q

What is the hearing mechanism of the cochlea?

A

Footplate of the stapes moves in and out of the oval window creating a traveling wave in the scala vestibule and scala tympani of the cochlea
This causes the movement of the basilar membrane and movement of the inner and outer hair cells in the organ of corti in relation to the tectorial membrane
The iliac of the hair cells are deflected and ion channel opens
Cations flow from the endolymoh into the hair cells
Depolorisation takes place and an impulse is sent up the cochlear nerve
Inner hair cells activate the afferent nerves
Outer hair cells modify the response of the inner hair cells

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12
Q

What is tonotopic arrangement?

A

For every frequency there is a specific place on the basilar membrane where the hair cells are maximally sensitive to that frequency

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13
Q

Where does the tonotopic arrangement continue to?

A

Through the auditory pathway up to the acoustic area of the temporal lobe

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14
Q

What can be used to assess hearing?

A

Clinical testing
Tuning fork test
Audiometry
Objective testing

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15
Q

What are the two different tuning fork tests?

A

Weber
Rinne

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16
Q

What is Webers test?

A

Compare the two ears
Fork in middle of forehead and sound radiates to both ears.
If equal hearing on both side= sound in middle
If sound loss in one ear - in conductive, sound work be louder in affected ear
- in senseroneural hearing loss, sound louder in unaffected ear

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17
Q

What is conductive hearing loss?

A

Something blocking the sound getting into the inner ear

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18
Q

What is sensory neural hearing loss?

A

Issue with cochlea or cochlear nerve or both

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19
Q

What is rinne test?

A

A test that compares loudness of perceived air conduction to bone conduction in one ear at a time

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20
Q

In Rinnes test, what would be seen in normal hearing function?

A

Sound louder at front of ear than back

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21
Q

In rinnes test, what would be heard in conductive hearing loss?

A

Louder on the bine at back than in front of ear

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22
Q

What are the different types of audiometry?

A

Pure tone audiometry
Visual reinforcement audiometry
Play audiometry
Tympanometry

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23
Q

What is different about tympanometry?

A

Don’t need a response from an individual

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24
Q

Wha can you measure for hearing?

A

Frequency and volume

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25
Q

What is pure tone audiometry?

A

Pure-tone air conduction hearing test determines the faintest tones a person can hear at selected pitches, from low to high. During this test, earphones are worn so that information can be obtained for search ear

26
Q

What is the air-bone gap?

A

Bone conduction perception is greater than air conduction perception

27
Q

What are OAEs?

A

Otoacoustic emissions are sounds given off by the inner ear when the cochlea is stimulated by a sound. When sound stimulates the cochlea, the outer hair cells vibrate. The vibration produces a nearly inaudible sound that echoes back into the middle ear. The sound can be measured with a small probe inserted into the ear canal.
People with normal hearing produce emissions. Those with hearing loss greater than 25-30 dB, do not produce these very soft sounds. The OAE test is often part of a newborn hearing screening programme.

28
Q

What is tympanometry?

A

Assists in the detection of fluid in the middle ear, perforation of the eardrum, or wax blocking the ear canal. Tympanometry pushes air pressure into the ear canal, making the eardrum move back and forth. The test measures the pressure within the middle ear and the mobility of the eardrum. Graphs are created, called tympanograms.

29
Q

What can tympanometry reveal?

A

Stiff eardrum
Hole in the eardrum
Eardrum that moves too much

30
Q

What is the management of hearing loss?

A

Surgery
Sound amplification
Direct stimulus of cochlear nerve cells

31
Q

What is a bone anchored hearing aid?

A

Osseous integrated screw into the skull
Microphone and amplifier clip onto an abutment or attached by magnet
Sound conducts through skull to cochlea

32
Q

What sensorineural threshold does BAHA require?

A

5dB or better

33
Q

Who uses BAHA?

A

Used by those whose anatomy makes use of conventional aid difficult e.g. persistent otitis externa, external canal atresia

34
Q

What is a cochlear implant?

A

A very strong hearing aid
Electrode placed inside cochlea

35
Q

Who uses a cochlear implant?

A

Those were profound hearing loss

36
Q

What is the balance part of the inner ear?

A

The vestibule

37
Q

What is the vestibule made up of?

A

2 otilist organs
-uricle
-saccule
3 semicircular canals
-connect to uricle
Blind ending part
-endolymphatic sac

38
Q

What is the sensory epithelium in cochlea?

A

Organ of corti

39
Q

What is the sensory epithelium in otolith organs?

A

Macula

40
Q

What are the ampullae of semi-circular canals?

A

Expanded areas at each end of the semicircular canals.
They contain the sensory organ- the crista

41
Q

What does the movement of crista cause?

A

Stimulus for the vestibulo-ocular reflex

42
Q

What does the vestibulo-ocular reflex cause?

A

Stabilises gaze by moving eyes in order to compensate for head and body movement, this fixes images on retina for clear sight

43
Q

What would a disorder in VOR cause?

A

Dizziness and vestibular problems

44
Q

What 3 main systems regulate balance?

A

Inner ear
Vision
Feet, hips, knees and ankles

45
Q

What’s does the inner ear help with in balance?

A

Rotation and gravity

46
Q

What does feet, hips, knees and angles help with in balance?

A

Pressure and Proprioception

47
Q

What happens if one balance system stop working?

A

It is manageable

48
Q

What happen if more than 1 balance system stops working?

A

There is a problem

49
Q

What are clinical conditions of inner ear that affect balance?

A

Benign paroxysmal postional vertigo
Vestibular neuritis
Ménière’s disease

50
Q

What happens in benign paroxysmal postional vertigo?

A

Loose otoconia move out of the uricle, into semicircular canals, most commonly the posterior
When moving te head, the otoconia move into the canal, stimulate the cristae and provoke vertigo and nystagmus

51
Q

What is the test for BPPV?

A

Dix - hallpike maneouvre

52
Q

What is the treatment for BPPV?

A

Epley maneouvre

53
Q

What is the initial clinical presentation of vestibular neuritis?

A

Acute onset of vertigo - nausea and vomiting
Rarely hearing loss nystagmus present if seen early enough

54
Q

What does the hitological evidence of vestibular neuritis show?

A

Viral damage of vestibular nerve rather than sensory cell labyrinth

55
Q

What may be the cause of hearing loss in vestibular neuritis?

A

Mumps, measles or infectious mononucleosis may be responsible

56
Q

What is the classic triad of Ménière’s disease?

A

Vertigo
Hearing loss- unilateral
Tinnitus

57
Q

What is the pathophysiology of Ménière’s disease?

A

Endolymohatic hydrops
- unknown cause or effect
- endolymph produced by stria vascularis
Hydrops drug to malabsorption of endolymph in endolymphatic duct and sac

58
Q

what is the vertigo like in Ménière’s disease?

A

Unpredictable
Severe
Last 30mins - 24 hours
May burn out

59
Q

What is hearing loss like in Ménière’s disease?

A

Unilaterlat at first
Sensorineural in nature
Initially removes
With time usually develop low tone sensorineural hearing loss

60
Q

What is a common clinical condition affecting balance?

A

Migraine

61
Q

What do migraines cause?

A

Episodic vertigo

62
Q

How are migraines managed ?

A

Lifestyle management and propohylacic medication

Head And Neck (9 decks)

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