Ataxic telangiectasia & Friedrich ataxia; Vestibular schwannomas (sometimes referred to as acoustic neuromas)

Question 1

Cerebellar hemisphere lesions cause [] (‘[] ataxia’)

Cerebellar vermis lesions cause [] ataxia

Answer 1

Cerebellar hemisphere lesions cause peripheral (‘finger-nose ataxia’)

Cerebellar vermis lesions cause gait ataxia

Question 2

Describe the clinical features of ataxic telangiectasia [4]

Answer 2

cerebellar ataxia
telangiectasia (spider angiomas)
IgA deficiency resulting in recurrent chest infections
10% risk of developing malignancy, lymphoma or leukaemia, but also non-lymphoid tumours

Question 3

Describe the differences betwen Freidrich’s ataxia and ataxic telangiectasia? [+]

Answer 3

FA:
- HOCM
- DM
- Onset at 10/15 yrs
- Optic atrophy
- Kyphoscoliosis

AT:
- Telangiectasia
- IgA deficiency –> recurrent chest infections
- Increased risk of leukaemia and lymphoma
- Onset at 1-5

NB: both autosomal recessive; cerebellar ataxia and onset in childhood

Question 4

Which is the most common early onset hereditary ataxias? [1]

Answer 4

Friedreich’s ataxia

Question 5

What are the two most common presenting features of Friredrich’s ataxia? [2]
Describe the neurological [4] and other [3] features of Friedrich’s ataxia

Answer 5

The typical age of onset is 10-15 years old. Gait ataxia and kyphoscoliosis are the most common presenting features.

Neurological features
* absent ankle jerks/extensor plantars
* cerebellar ataxia
* optic atrophy
* spinocerebellar tract degeneration

Other features
* hypertrophic obstructive cardiomyopathy (90%, most common cause of death)
* diabetes mellitus (10-20%)
* high-arched palate

Question 6

How do you confirm a dx of FA? [1]

Answer 6

Genetic testing:
- confirms a repeat of GAA

Question 7

Vestibular schwannomas (sometimes referred to as acoustic neuromas) account for approximately 5% of intracranial tumours and 90% of [] tumours.

Answer 7

Vestibular schwannomas (sometimes referred to as acoustic neuromas) account for approximately 5% of intracranial tumours and 90% of cerebellopontine angle tumours.

Question 8

Describe the classical history of vestibular schwannoma [4]

Answer 8

The classical history of vestibular schwannoma includes a combination of vertigo, hearing loss, tinnitus and an absent corneal reflex.

Question 9

Features can be predicted by the affected cranial nerves:
cranial nerve VIII: [3]
cranial nerve V: [1]
cranial nerve VII: [1]

Answer 9

Features can be predicted by the affected cranial nerves:
cranial nerve VIII
- vertigo, unilateral sensorineural hearing loss, unilateral tinnitus

cranial nerve V:
- absent corneal reflex

cranial nerve VII:
- facial palsy

NB: The effects on cranial nerves V and VII are due to compression once the tumour grows large enough

Question 10

Bilateral vestibular schwannomas are seen in [genetic disease]

Answer 10

Bilateral vestibular schwannomas are seen in neurofibromatosis type 2.

Question 11

Patients with a suspected vestibular schwannoma should be referred urgently to [].

Answer 11

Patients with a suspected vestibular schwannoma should be referred urgently to ENT. It should be noted though that the tumours are often slow growing, benign and often observed initially.

Question 12

What is the Ix of choice for vesitublar schwannoma? [2]

Answer 12

MRI of the cerebellopontine angle is the investigation of choice.

Audiometry is also important as only 5% of patients will have a normal audiogram.