Deafness

Question 1

What are the types of deafness? Define them.

Answer 1

Conductive: a problem conducting sound waves along the route through the outer ear, TM and middle ear

Sensorineural: the problem is in the inner ear, vestibulocochlear nerve or brain

Mixed

Question 2

What’s the normal threshold of hearing?

Answer 2

Can hear sounds as quiet as 0 - 20dB

Question 3

How is hearing loss categorised?

Answer 3

Quietest sound they can hear is:

Mild: 25-40dB

Moderate 40-70dB

Severe: 70-95dB

Profound: >95dB

Question 4

What are some causes of conductive hearing loss?

Answer 4

Occlusion: cerumen, foreign body, oedema

Glue ear

Infection: otitis externa, media

TM perforation

Growths: tumours, cysts, cholesteatoma

Otosclerosis
Myringosclerosis
TMJ syndrome

Question 5

What causes TM perforation?

Answer 5

Otitis media
Chronic otitis
Trauma: water, barotrauma
Surgery

Question 6

What is otosclerosis and how does it cause deafness?

What type of deafness does it cause?

Answer 6

Conductive

Abnormal bone deposition at base of stapes preventing normal ossicular vibration

Question 7

What is myringosclerosis and how does it cause deafness?

What type of deafness does it cause?

Answer 7

Conductive

Deposition of irregular white calcium patches on the TM

If it extends enough it can cause deafness

Question 8

What is TMJ syndrome and how does it cause deafness?

What type of deafness does it cause?

Answer 8

Conductive

Locking of jaw, pain in jaw and face

Hearing loss caused by spasms of muscles of inner ear
Self-limiting

Question 9

What are the clinical features of otosclerosis?

Pathophysiology?

Answer 9

Progressive bilateral conductive hearing loss
Tinnitus

Autosomal dominant

Abnormal bone deposition at the base of the stapes which affects conduction of sounds waves through the ossicles

Question 10

Management of otosclerosis?

Answer 10

Hearing aids

Stapedectomy or otomy

Question 11

What are the causes of sensorineural hearing loss?

Answer 11

Congenital:

Abnormal or absent cochlear hair cells, infections, hypoplastic nerves
Syndromes

Acquired:

Damage to V-C nerve (VIII)
Meniere’s disease
Presbycusis

Question 12

Which congenital infections cause deafness?

Answer 12

TORCH

Toxoplasmosis
Rubella
CMV
HIV, Herpes

Question 13

What congenital problems can cause deafness?

Answer 13

Abnormal or absent cochlear hair cells

Infections: rubella, toxoplasmosis

Hypoplastic nerves

Abnormal cochlea

Question 14

What is presbycusis?

Pathophysiology

Answer 14

Normal age-related progressive bilateral sensorineural hearing loss

Especially at high frequencies

Caused by cochlear and ganglion degeneration and vascular atrophy

Question 15

What are the clinical features of presbycusis?

Answer 15

Older age onset

Insidious high frequency hearing loss

Especially voiceless consonants

Question 16

Management of presbycusis?

Answer 16

Hearing aids

Assistive listening devices

Cochlear implants

Question 17

How does noise-induced hearing loss happen?

Answer 17

Overloading and damaging the sensorineural apparatus in the inner ear

Exposure to excessive noise causes a temporary shift in the stimulus threshold of the hair cells of inner ear

If this happens a lot then it becomes a permanent shift

Question 18

What is an acoustic neuroma?

Pathophysiology?

Answer 18

Tumour of the Schwann cells which myelinate the VIII nerve

Most are from the vestibular division rather than cochlear

Typically benign but can cause problems due to mass effect and pressure on local structures

Question 19

Presentation of acoustic neuroma?

Answer 19

Unilateral or asymmetrical hearing loss

Tinnitus

Insidious or acute onset

Impaired facial sensation or pain

Balance problems (often quite subtle)

Earache

Ataxia due to cerebellar compression

Raised ICP: headache, visual loss, decreased consciousness

Question 20

Investigations of acoustic neuroma?

Answer 20

Audiology

MRI

Question 21

Management of acoustic neuroma?

Answer 21

Depends on growth

Three options:

1. microsurgery
2. stereotactic radiosurgery
3. observation

Question 22

Define and describe tinnitus?

Answer 22

Hearing of sound when no external sound is present

Ringing, clicking, hissing, roaring

Interferes with concentration

Question 23

What causes tinnitus?

Answer 23

Noise induced hearing loss

Infections

Vasculitis

Meniere’s

Brain tumours

Emotional stress

Head injury

Earwax

Question 24

What two types of tinnitus are there? Give causes.

Answer 24

Subjective: no acoustic stimulus

• otological
• neurological
• infections: meningitis
• drugs
• TMJ syndrome

Objective: a noise is being generated in the head which is being heard

• pulsatile: blood movements
• muscular spasms
• spontaneous otoacoustic emissions

Question 25

What devices are available to help with hearing?

Answer 25

Hearing aid

Bone-anchored hearing aid

Cochlear implant

Question 26

How does a hearing aid work?

Answer 26

It amplifies sound

Question 27

How does a bone-anchored hearing aid work?

Answer 27

It uses bone conduction as a way to conduct sound if the usual route of conduction is broken

Bypasses external auditory canal and middle ear. Sound goes from bone to cochlea

Question 28

How does a cochlear implant work?

Answer 28

It stimulates the cells of the auditory spiral ganglion to produce a sense of sound

It directly stimulates the auditory nerve using electrical signals

Question 29

What ways are newborns’ hearing screened

Answer 29

Otoacoustic emissions (detects tiny cochlear sounds produced by movements of hair cells)

Audiological brainstem responses: measure brainwave activity in response to sounds

Question 30

How can childrens’ hearing be tested?

Answer 30

Distraction testing: makes noises behind and beside child and see if they turn their head

Visually reinforced audiometry: child turns head to sound stimulus and is rewarded by toy

Speech discrimination: child touches objects they are told to