Hearing Loss

Question 1

What are the main types of hearing loss?

Answer 1

Sensorineural- cochlear or medial to this. Bone conduction and air conduction are equally reduced
Conductive- any pathology from the middle ear laterally. Bone conduction is in tact.
Mixed

Question 2

What are some causes of conductive hearing loss?

Answer 2

External canal obstruction- wax, pus, debris, foreign body, congenital abnormality
Drum perforation- trauma, barotrauma, infection
Problems with ossicular chain-(otosclerosis, infection, trauma)
Dysfunction of Eustachian tube- E.g. Middle effusion that can occur with nasopharyngeal carcinoma

Question 3

What are some causes of sensorineural deafness?

Answer 3

Ototoxic drugs (streptomycin, vancomycin, gentamycin, chloroquine, vinca alkaloids)
Post infective- meningitis, measles, flu, herpes, syphilis
Cochlear vascular disease
Trauma
Presbyacusis (loss with ageing)
Acoustic Neuroma
Multiple sclerosis
Brain metastases
If unilateral SNHL exclude dangerous conditions- acoustic neuroma (MRI), cholesteatoma, effusion from nasopharyngeal cancer

Question 4

What are some causes of acute conductive hearing loss?

Answer 4

Perforation of the ear drum
Foreign body
Trauma
Barotrauma
Infection- Otitis media/externa

Question 5

What are some causes of chronic conductive hearing loss?

Answer 5

Otosclerosis
Otitis media with effusion (Glue ear)
Cholesteatoma- erosive and destructive process (characteristic smelly discharge)

Question 6

What process is occurring in otosclerosis?

Answer 6

New bone is formed around the stapes foot plate which reduces the movement of the stapes and so leads to conductive hearing loss

Question 7

What is the cause of otosclerosis?

Answer 7

This condition is hereditary: Autosomal Dominant inheritance with incomplete penetrance
50% have a family history, 85% are bilateral

Question 8

When do symptoms of otosclerosis usually present?

Answer 8

Early adult life

Accelerated by pregnancy

Question 9

What other features might people with otosclerosis?

Answer 9

Tinnitus (in around 75%)

Vertigo- transient vertigo is common

Question 10

What is Schwartze’s sign? What condition is it seen in?

Answer 10

Schwartze’s sign is seen in otosclerosis
It is a pink tinge to the typanic membrane
It is also called Flemingo’s pink sign

Question 11

What unique feature is seen on pure tone audiometry bone conduction for otosclerosis?

Answer 11

Carhart’s Notch

A drop is seen at around 2,000Hz for bone conduction

Question 12

What is the treatment for otosclerosis?

Answer 12

Hearing aids
Surgery- stapedectomy or stapedotomy to replace the fixed stapes
Cochlear implant is another option if severe

Note- The stapes is the smallest bone in the body

Question 13

What is presbyacusis?

Answer 13

Sensorineural hearing loss that is age related, bilateral and seen at high frequency

Question 14

What might a person with presbyacusis describe?

Answer 14

Hearing is often reduced at higher frequencies
This therefore makes speech difficult to hear and a patient may describe people around them mumbling
Hearing is most problematic with background noise

Question 15

What is the treatment for presbyacusis?

Answer 15

Hearing aids

Cochlear implant

Question 16

What are some important things to investigate for if unilateral SNHL?

Answer 16

If unilateral SNHL exclude dangerous conditions- acoustic neuroma (MRI), cholesteatoma, effusion from nasopharyngeal cancer

Question 17

What is sudden onset SNHL defined as?

Answer 17

Loss of 30 or more dB in 3 continuous pure tone frequencies over 3 days

Question 18

Is sudden onset SNHL usually bilateral or unilateral?

Answer 18

Unilateral

Question 19

What should be done if a patient presents with new onset SNHL?

Answer 19

Immediate referral to a specialist for investigation

Question 20

What are some causes of sudden onset SNHL?

Answer 20

Noise exposure, ototoxic drugs (e.g. gentamycin), acoustic neuroma, mumps, MS, vasculopathy, TB).

If no cause found (~90%)- Idiopathic Sudden SNHL

Question 21

What is the treatment for idiopathic sudden SNHL?

Answer 21

Always refer sudden onset sensorineural hearing loss urgently

High dose steroids (presumed inflammatory cause)- Prednisolone

Question 22

What is an acoustic neuroma?

Answer 22

Subarachnoid tumour that is benign, slow growing and causes problems due to local pressure
Usually arise from the Schwamm cell layer of the vestibular nerve- also called a vestibular schwannoma

Question 23

What symptoms can an acoustic neuroma cause?

Answer 23

Unilateral tinnitus
Unilateral Sensorineural deafness- difficulty hearing speech
Raised ICP signs- papiloedema (blurring of vision), headaches, nausea, vomiting
Cranial nerve compression of:
V- Parasthesia/Numbness of face
CN IX- X- Dysphasia, Hoarse voice

Question 24

What investigations should be carried our if acoustic neuroma is suspected?

Answer 24

Request an MRI (with gadolinium contrast) for all those with unilateral tinnitus or SNHL

Question 25

What is noise induced hearing loss?

Answer 25

Exposure to loud noises causes damage to the inner ear resulting in hearing loss.

May be after a single exposure to a loud sound or after chronic exposure (often in occupations with loud noise- occupation NIHL)

Acoustic trauma can occur at sounds greater than 180 dB- rupture of ear drum or fracture of ossicles

Question 26

What are the symptoms of noise induced hearing loss?

Answer 26

Bilateral sensorineural hearing loss +/- tinnitus

Question 27

What is the management of noise-induced hearing loss?

Answer 27

Reduce the occupational exposures
Use ear defenders
Screen occupations at risk