Hearing Loss

Question 1

In what sequence is sound normally conducted through the ear?

Answer 1

Pinna
External auditory canal
Tympanic membrane
Malleus
Incus
Stapes
Oval window
Cochlea (cochlear fluid → basilar membrane)

Question 2

After conduction through the ear, what is the neural pathway that carries sound signals to the brain?

Answer 2

Basilar membrane vibration stimulates hair cells in the organ of Corti

Stimulates bipolar neurons in the spiral ganglion of the cochlear division of CN VIII

Cochlear nucleus

Superior olivary nucleus

Lateral lemniscus

Inferior colliculus

Temporal lobe

Remember: E COLI
(eighth CN, Cochlear nucleus, superior Olivary nucleus, Lateral lemniscus, Inferior colliculus)

Question 3

Give some examples of aetiology of conductive hearing loss

Answer 3

Impacted cerumen (ear wax)

Otosclerosis (new bone forms around stapes footplate, leading to fixation)

Otitis media

Congenital absence of external auditory canal

Glue ear (fluid in middle ear)

Haemotympanum (blood in middle ear)

Dislocation/erosion of ossicles

Question 4

Give some examples of aetiology of sensorineural hearing loss

Answer 4

Excessive noise exposure

Drugs (aminoglycosides like gentamicin; furosemide)

Mumps

Acoustic neuroma

Presbycusis (natural age-related)

Congenital (genetic or non-genetic)

Question 5

How does conductive hearing loss affect Weber and Rinne tests?

Answer 5

Weber’s: Localises to affected ear

Rinne’s: Abnormal (bone > air)

Question 6

What tests are used to assess hearing acuity?

Answer 6

Whispered voice

Tuning forks (Rinne’s and Weber’s)

Pure tone audiogram

Question 7

What frequency tuning fork is used for Rinne’s and Weber’s?

Answer 7

512 Hz

Question 8

What is a positive Rinne’s test?

Answer 8

Air conduction is better than bone conduction (this is normal)

Question 9

How is Rinne’s test performed?

Answer 9

Strike 512 Hz tuning fork

Hold firmly on mastoid process to test bone conduction

Then place beside the pinna to test air conduction

(Rinne’s positive is normal = AC > BC)

Question 10

To which ear does the sound localise in a positive Weber’s test?

Answer 10

To the unaffected ear in sensorineural hearing loss

To the affected ear in conductive hearing loss

Question 11

Interpret these results:

Weber’s: central (negative)

Rinne’s:

• L: +ve
• R: +ve

Answer 11

Normal

or

Bilateral sensorineural hearing loss

Question 12

Interpret these results:

Weber’s: Right

Rinne’s:

• L: +ve
• R: -ve

Answer 12

Right-sided conductive hearing loss, normal left ear

Question 13

Interpret these results:

Weber’s: Left

Rinne’s:

• L: +ve
• R: +ve

Answer 13

Right-sided sensorineural hearing loss, normal left ear

Question 14

How can you manage hearing loss due to otosclerosis?

Answer 14

Hearing aid

Surgery (to release the fixed stapes)

Cochlear implant, if severe

Question 15

How do you manage sudden onset sensorineural deafness?

Answer 15

Get an urgent ENT opinion

Question 16

How do you manage presbycusis?

Answer 16

Presbycusis = age-related hearing loss

Hearing aids are the usual treatment