Causes of Deafness

Question 1

What are the most common causes of hearing loss?

Answer 1

• Ear wax
• Otitis media
• Otitis externa

Question 2

Age-related sensorineural hearing loss. Patients may describe difficulty following conversations

Audiometry shows bilateral high-frequency hearing loss

Answer 2

Presbycusis

Question 3

Autosomal dominant, replacement of normal bone by vascular spongy bone. Onset is usually at 20-40 years - features include:

• conductive deafness
• tinnitus
• tympanic membrane - 10% of patients may have a ‘flamingo tinge’, caused by hyperaemia
• positive family history

Answer 3

Otosclerosis

Question 4

• Peaks at 2 years of age
• Hearing loss is usually the presenting feature (glue ear is the commonest cause of conductive hearing loss and elective surgery in childhood)
• Secondary problems such as speech and language delay, behavioural or balance problems may also be seen

Answer 4

Glue ear

Also known as otitis media with effusion

Question 5

More common in middle-aged adults

• Recurrent episodes of vertigo, tinnitus and hearing loss (sensorineural). Vertigo is usually the prominent symptom
• A sensation of aural fullness or pressure is now recognised as being common
• Other features include nystagmus and a positive Romberg test
• Episodes last minutes to hours

Answer 5

Meniere’s disease

Question 6

What drugs cause hearing loss?

Answer 6

• Gentamicin
• Furosemide
• Aspirin
• Cytotoxic drugs

Question 7

A 45-year-old man presents with dizziness and right-sided hearing loss to his GP. Which one of the following tests would most likely indicate an acoustic neuroma?

• Jerky nystagmus
• Left homonymous hemianopia
• Tongue deviated to the left
• Fasciculation of the tongue
• Absent corneal reflex (not blinking)

Answer 7

Absent corneal reflex - 5th or 7th CN affected.

90% will have unilateral hearing loss. Often they will also have tinnitus. They will then also develop balance problems/vertigo as the tumour grows. (Balance portion of the 8th nerve is where the tumour arises).

Features can be predicted by the affected cranial nerves

• Cranial nerve VIII (Vestibulocochlear): hearing loss, vertigo, tinnitus
• Cranial nerve V (Trigeminal): absent corneal reflex
• Cranial nerve VII(Facial): facial palsy

Acoustic neuromas (a.k.a. Vestibular schwannomas)

Question 8

Answer 8

Question 9

What condition are bilateral neuromas seen in?

Answer 9

Neurofibromatosis Type 2

Question 10

Describe the corneal reflex with regards to cranial nerves.

Answer 10

The reflex is mediated by:

• Sensory - The nasociliary branch of the ophthalmic branch (V1) of the 5th cranial nerve (trigeminal nerve) sensing the stimulus on the cornea, lid, or conjunctiva (i.e. it is the afferent).
• Motor - The temporal and zygomatic branches of the 7th cranial nerve (Facial nerve) initiating the motor response (i.e. it is the efferent).
• Mediated by centre in the pons of brainstem.

Question 11

What are causes of tongue fasciculations and tongue deviation?

Answer 11

Tongue deviation - hypoglossal nerve lesion. Tongue deviates to the side of the lesion.

Tongue fasciculations - lower motor neuron injury or amyothropic lateral sclerosis.