Clinical and Pathological Aspects of the Auditory System

Question 1

Clinical evaluation of ear diseases

Answer 1

Outer ear / middle ear
- Pain, discharge, deafness, blocking, tinnitus

Inner ear:
- Deafness, tinnitus, communication problems

Balance symptoms:
- Vertigo

Question 2

Ear examination

Answer 2

Otoscopy
Voice tests / tuning fork tests
Hearing tests
Vestibular assessment
Functional evaluation

Question 3

Classification of hearing loss

Answer 3

Conductive hearing loss

• External ear problems (pinna/canal)
• Middle ear problems

Sensorineural hearing loss

• Inner ear problems (sensory)
• Nerve problem (neural)
• Brain problem (neural)

Mixed type of hearing loss

Question 4

Causes of hearing loss in adult (conductive) - External ear

Answer 4

External ear

• Pinna
• Ear canal (infection, wax)
• Tympanic membrane (perforations, chronic suppurative otitis media)

Microtia (Grades)

1: Small but almost normal
2: Some recognisable anatomy
3: Small rudiment of soft tissue and no ear canal
4: No external ear and no ear canal

Haematoma auris

Otitis Externa
- Itchiness, discharge, conchal skin changes, fungal/bacterial

Ear wax
- Treatment: softener / irrigation / instruments

Foreign body in ear

Question 5

Causes of hearing loss in adult (conductive) - Middle ear

Answer 5

Fluid (effusion, blood, CSF)
Solid (tumour, cholesteatoma)
Ossicular chain (discontinuation, fixation)

Chronic suppurative otitis media (infected vs. dry)

Otitis media with infusion

Question 6

Causes of hearing loss in adult (Sensorineural)

Answer 6

Bilateral

• Age-related
• Industrial noise-induced
• Ototoxic
• Asymmetrical bilateral hearing loss (weapon firing, head injury, Meniere’s, bilateral acoustic neuromas)

Unilateral

• Trauma
• Infections
• Acoustic neuroma

Question 7

Hearing screening

Answer 7

• 1:1000
• Early detection and intervention
• 6mo > 2yo > yo
• Universal screening
• Target screening (high risk group)

Otoacoustic emission (OAE) vs. Automated auditory brainstem response (ABR)
- Follow up diagnostic test for infants who failed initial hearing screening and rescreening

Question 8

Normal auditory brainstem response waveforms

Answer 8

1. CN8 - distal
2. CN8 - proximal
3. Cochlear nu.
4. Sup. olivary complex
5. Lat. lemniscus and inf. colloculus
   6 and 7. Med. geniculate body

Question 9

Early intervention of hearing problems

Answer 9

• Bilateral aiding / cochlear implantation (<2yo)
• Normal speech and development
• Goes to normal school

Question 10

Manaegment of paediatric hearing loss

Answer 10

• Bilateral hearing loss >40 dB affects speech development

Mild
- Observation / hearing aid / monitoring

Moderate to severe
- Hearing aids / implantable hearing aids / speech and language training

Severe to profound
- Cochlear / brainstem implants

Question 11

Assistive listening devices

Answer 11

• Vibration
• Flash light signal
• Amplification

Question 12

Hearing aids

Answer 12

• Completely in the canal (CIC)
• In the canal (ITC)
• In the ear (ITE)
• Behind the ear (BTE)
• Body worn hearing aid (BWHA)

How to choose HA?
Big device
- Louder amplification
- Less feedback
- More durable
- Longer battery life
- More conspicuous
Small device
- Less amplification (not for >severe hearing loss)
- More expensive
- Shorter battery life

Question 13

Operative treatment (implantable)

Answer 13

External ear (atresia)
- Bone anchored hearing aid (BAHA)

Middle ear

• Surgical reconstruction (ossiculoplasty)
• BAHA (percutaneous, transcutaneous)
• Vibrant sound bride (VSB); bone bridge (BB)

Cochlear
- Cochlear implant (CI)

Cochlear nerve
- Auditory brainstem implant (ABI)

Question 14

Bone anchored hearing aid (BAHA)

Answer 14

Indications
- Children >5yo
- Any patients using AC hearing aid with chronic discharging ear or discomfort because of otitis externa
- Previous radical mastoidectomy / large meatoplasty
=> Uncontrollable feedback

Contraindications

• Bone conduction thresholds worse than 45dB HL, speech discrimination score < 60%
• Uncooperative patients

Question 15

Cochlear implant (CI)

Answer 15

• Bilateral severe to profound hearing loss
• Bypasses outer, middle and inner ear, directly stimulates auditory n.

Indications for adults

• Bilateral severe or profound SNHL (>70dB)
• <70% aided speech perception score (open set sentence in the quiet)
• <40% aided speech perception score in ear to be implanated

Indications for children

• Bilateral profound SNHL (>90dB)
• No appreciable benefit with hearing aids
• For prelingual deafness, the younger the better