Physiology and Clinical Aspects of Hearing and Balance

Question 1

The middle ear transforms acoustic energy from the medium of air to the medium of fluid. How does the middle ear amplify the sound?

Answer 1

Ratio of tympanic membrane to stapes footplate is 17:1

Lever action of ossicular chain - pressure on stapes footplate to ratio on pressure is 1.3:1

Question 2

How does the organ of corti change in order to pick up lower frequency sounds?

Answer 2

Fibres on basillar membrane become larger

Question 3

What is the weber test?

Answer 3

Tuning fork test

Used to test lateralisation

Question 4

What is the Rinne test?

Answer 4

Used to determine loss of hearing in one ear.

It compares perception of sounds transmitted by air conduction to those transmitted by bone bone conduction via the mastoid.

Used to screen for conductive hearing loss

Question 5

What are the different types of audiometry?

Answer 5

Pure tone audiometry

Visual reinforcement audiometry

Play audiometry

Tympanometry

Question 6

What is pure tone audiometry?

Answer 6

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

Question 7

What is the effect of osteosclerosis on the ear?

Answer 7

Bone deposition in annular ligament, prevents sound being conducted to cochlea

Question 8

How does an audiogram show conductive loss?

Answer 8

There is a gap between bone conduction and air conduction seen on the graph

Question 9

What are the different forms of audiometry?

Answer 9

Pure tone audiometry

Visual reinforcement audiometry

Play audiometry

Tympanometry

Question 10

How does tympanometry work?

Answer 10

Tympanometry pushes air pressure into the ear canal, making the eardrum move back and forth. The test measures the mobility of the eardrum

Question 11

What graph is produced from tympanography?

Answer 11

Tympanogram

Question 12

What does tympanography tell you about the eardrum?

Answer 12

Tells you if the eardrum is stiff, perforated or if it moves too much. It can also assist in the detection of fluid in the middle ear and wax blocking of the ear canal.

Question 13

What does objective testing detect?

Makes use of autoacoustic emissions

Answer 13

Can detect blockage in the outer ear canal as well as the presence of the middle ear fluid and damage to the outer hair cells in the cochlea.

Question 14

How does objective testing work?

Answer 14

When the cochlea is stimulated by a sound, the inner ear gives off an almost inaudible sound called a Otoacoustic emissions (OAEs). 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.

Question 15

What information does the auditory brainstem response tell us?

Answer 15

Gives information about the inner ear and brain pathways for hearing.

Question 16

Who is auditory brainstem response recommended to?

Answer 16

Children or others who have a difficult time with conventional behavioural methods of hearing screening. Also used in newborn screening programmes.

Question 17

How does the auditory brainstem response test work?

Answer 17

Electrodes are pasted onto the patients head, these electrodes record brain wave activity in response to sound when the patient rests quietly or sleeps.

Question 18

What is management of hearing loss?

Answer 18

Surgery

Sound amplification

Direct stimulus of cochlear nerve cells

Intracochlear modification (for the future)

Question 19

What types of hearing aid are there?

Answer 19

Hearing aid

Open fit hearing aid

Bone anchored hearing aid (BAHA)

Middle ear implant

Cochlear implant

Question 20

What is the vestibulo-occular reflex?

Answer 20

The VOR stabilises gaze by moving eyes in order to compensate for head and body movement. This fixes image on retina for clear sight.

Question 21

What systems are involves in regulating body balance?

Answer 21

Question 22

What are clinical conditions of the inner ear that affect balance?

Answer 22

Benign Paroxysmal Positional Vertigo

Vestibular Neuritis

Meniere’s Disease

Question 23

What is the cause of benign paroxysmal positional vertigo?

Answer 23

Mechanism involves a small calcified otolith moving around loose in the inner ear

Question 24

What is the test and treatment for benign paroxysmal positional vertigo?

Answer 24

Diagnostic test: Dix - hallpike test results in nystagmus

Treatment: Epley manouvre

Question 25

What is vestibular neuritis?

Answer 25

Vestibular neuronitis, or neuritis, is an infection of the vestibular nerve in the inner ear. It causes the vestibular nerve to become inflamed, disrupting your sense of balance.

Question 26

What are the features of Ménière’s disease?

Answer 26

Ménière’s disease (MD) is a disorder of the inner ear that is characterized by episodes of feeling like the world is spinning(vertigo), ringing in the ears (tinnitus), hearing loss, and a fullness in the ear.

Question 27

Give an example of a clinical condition that affects balance

Answer 27

Migraine