Hearing loss

Question 1

What tests can be performed on clinical exammination to distinguish between conductive and sensorineural hearing loss ?

Answer 1

Rinne’s and Weber’s test

Question 2

Describe how to perform rinnes test and what information it provides

Answer 2

Rinne’s test:

• Tuning fork is placed over the mastoid process until the sound is no longer heard, followed by repositioning just over external acoustic meatus
• ‘positive test’ = air conduction (AC) > bone conduction (BC) (this is normal)
• ‘negative test’: if BC > AC this indicates conductive deafness

Question 3

Describe how to perform weber’s test and what information it provides

Answer 3

Webers test:

• Tuning fork is placed in the middle of the forehead equidistant from the patient’s ears & the patient is then asked which side is loudest
• In unilateral sensorineural deafness, sound is localised to the unaffected side
• In unilateral conductive deafness, sound is localised to the affected side

Question 4

Which test should be performed first - rinnes or webers?

Answer 4

Rinnes - because this allows you to indentify if there is conductive hearing loss initially and then if not you can determine if webers localises to one side that the hearing loss must be SNHL e.g. pos rinnes but webers localises to the right and the patient complains of left sided HL then it is likely left sided SNHL

Question 5

What is generally the first test to do to assess hearing loss ?

Answer 5

Pure tone Audiometry (PTA)

Question 6

What do the following symbols stand for on an audiogram graph?:

• O
• X
• Triangle
• The red colour of the lines and symbols
• The blue colour of the lines and symbols

Answer 6

• Red = Right side
• Blue = Left side
• O = Air conduction Right side
• X = Air conduction Left side
• Triangle = Bone conduction Left and Right sides

Question 7

Below what level of hearing is considering hearing loss on an audiogram?

Answer 7

Anything below 20dB, anything above is considered normal

Question 8

What is done during an audiogram to ensure that the results of the ear being tested is not due to the non-test ear helping out ?

Answer 8

Masking

This is where a narrow band noise centred around the test frequency is introduced into the non-test ear. This noise “occupies or distracts” the non-test ear and allows the test ear to respond the pure tones at the true threshold

Question 9

What are the 3 main types of hearing loss ?

Answer 9

• Sensorineural
• Conductive
• Mixed

Question 10

Define what sensorineural hearing loss is

Answer 10

It is the result of permanent (once damage occurs to the hair cells they cant be repaired) damage to the hair cells in the chochlea

Question 11

What are some of the pathological causes of sensorineural hearing loss ?

Answer 11

• Regular and prolonged exposure to loud sounds.
• Ototoxic drugs
• Certain infectious diseases, including Rubella
• Complications at birth
• Benign tumours on the auditory nerve
• Genetic predisposition

Question 12

Define what presbycusis is

Answer 12

It is normal damage to the chochlea resulting in age-related hearing loss

Question 13

Describe the appearance of sensorineural hearing loss on a audiogram graph

Answer 13

There is no difference between air and bone conduction and the graph shows a downward slope

Question 14

Define what conductive hearing loss is

Answer 14

It is hearing loss due to sound not being able to pass freely in the inner ear

Question 15

What are some of the causes of conductive hearing loss ?

Answer 15

• Ear infections
• Middle ear fluid (Glue ear)
• Perforated ear drums
• Possibility of surgical interventions

Usually due to abnormalities in the outer or middle ear impeding the flow of sound to the inner ear

Question 16

Describe the appearance of conductive hearing loss on audiogram graphs

Answer 16

• Audiogram shows a significant difference between air and bone conduction
• With the bone conduction being in the normal ranges and air conduction showing the hearing loss (not in the normal ranges)

Question 17

Define what mixed hearing loss is

Answer 17

It is a combination of conductive and sensorineural hearing loss, which means there is damage in both the outer or middle ear and in the inner ear.

Question 18

What are the causes of mixed hearing loss ?

Answer 18

• Genetic factors
• Birth defects
• Diseases
• Infections
• Tumours or masses
• Head injuries

These are all possible causes of both conudctive and sensorineural hearing loss

Question 19

Describe the appearance of mixed hearing loss on an audiogram

Answer 19

There is a significant gap between air and bone conduction thresholds but bone conduction thresholds are not all within normal limits and drop down to the lower air conduction at points on the graph

Question 20

What is tympanometry used for ?

Answer 20

• Used to test the condition of the middle ear by creating variations of pressure in the ear canal
• It permits a distinction between sensorineural and conductive hearing loss

Question 21

What test is tympanometry used inconjunction with to test hearing loss?

Answer 21

PTA - pure tone audiometry

Question 22

What is tympanometry usefull in diagnosing (hint these cause the hearing loss but talking about specifically the condition or disease)?

Answer 22

• Otitis Media by demonstrating the presence of middle ear fluid
• A Tympanic Membrane Perforation by showing a large ear canal volume

Question 23

What are the 3 main types of tympanograms?

Answer 23

• Type A
• Type B
• Type C

Question 24

What does a type A tympanogram show ?

Answer 24

Shows normal eardrum movement

Question 25

What do type B tympanograms show ?

Answer 25

• Abnormal eardrum movement - something is restricting movement of the eardrum
• Due to mainly fluid behind the ear
• The graph is flat

Question 26

What do type C tympanograms show ?

Answer 26

• The graph is shifted to the left - due to negative pressure in the middle ear
• Usually due to developing or resolving otitis media