Acoustic Neuroma

Question 1

What is an acoustic neuroma?

Answer 1

Acoustic neuromas are benign tumours of the Schwann cells surrounding the auditory nerve (vestibulocochlear nerve) that innervates the inner ear.

They are also called vestibular schwannomas, as they originate from the Schwann cells. Schwann cells are found in the peripheral nervous system and provide the myelin sheath around neurones.

Question 2

Where do acoustic neuromas occurs?

Answer 2

They occur at the cerebellopontine angle and are sometimes referred to as cerebellopontine angle tumours.

Question 3

Are acoustic neuromas unilateral or bilateral?

Answer 3

Acoustic neuromas are usually unilateral.

Question 4

What is the significance of bilateral acoustic neuromas?

Answer 4

Bilateral acoustic neuromas are associated with neurofibromatosis type II.

Question 5

What are the clinical features of acoustic neuromas?

Answer 5

The typical patient is aged 40-60 years presenting with a gradual onset of:

• Unilateral sensorineural hearing loss (often the first symptom)
• Unilateral tinnitus
• Dizziness or imbalance
• A sensation of fullness in the ear

They can also be associated with a facial nerve palsy if the tumour grows large enough to compress the facial nerve.

Question 6

What investigations should be ordered for an acoustic neuroma?

Answer 6

• Audiogram
• MRI head
• CT head
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Question 7

What is the role of neuroimaging if an acoustic neuroma is suspected?

Answer 7

Brain imaging (MRI or CT) is used to establish the diagnosis and features of the tumour. MRI provides more detail than CT.

Question 8

How does an acoustic neuroma present on an audiogram?

Answer 8

Audiometry is used to assess hearing loss. There will be a sensorineural pattern of hearing loss.

Question 9

Briefly describe the management of an acoustic neuroma

Answer 9

ENT specialist management options include:

• Conservative management with monitoring may be used if there are no symptoms or treatment is inappropriate
• Surgery to remove the tumour (partial or total removal)
• Radiotherapy to reduce the growth

Question 10

What risks are associated with treating an acoustic neuroma?

Answer 10

Notable risks associated with treatment are:

• Vestibulocochlear nerve injury, with permanent hearing loss or dizziness
• Facial nerve injury, with facial weakness

Question 11

What differentials should be considered for an acoustic neuroma?

Answer 11

• Meningioma
• Epidermoid
• Facial nerve schwannoma
• Trigeminal schawannoma