Cranial Nerve Palsies

Question 1

What is this a presentation of?

Down and out appearance of one eye.

Answer 1

Cranial nerve III palsy (third nerve palsy)

Question 2

Why does a third nerve palsy appear down and out?

Answer 2

Unopposed action of the superior oblique and lateral rectus muscle not supplied by CN III.

Question 3

What is the difference between medical and surgical third nerve palsy?

Answer 3

1. Surgical - dilated and fixed pupil, parasympathetic fibres run on the outside.
2. Medical - normal pupil

Question 4

What are the causes of a third nerve palsy and how are they investigated?

Answer 4

1. Vascular disorders - DM, CVD, aneurysm of posterior communicating artery - CTA/MRA, routine bloods
2. SoL/tumour - CT/MRI
3. Inflammation, infection - temperature, ESR, CRP, ANA, ANCA, LP
4. Trauma
5. Demyelinating disease -MRI
6. CN III mimics like myasthenia gravis - anti-AChR Abs
7. Cavernous sinus thrombosis

Question 5

What is this a presentation of?

Problems looking down, eye appears slightly looking up, may be compensation with head tilting down, vertical diplopia.

Answer 5

Cranial nerve IV palsy

Question 6

What is this a presentation of?

Cannot abduct eye, horizontal diplopia.

Answer 6

Cranial nerve VI palsy

Question 7

What is this a presentation of?
Abrupt onset, complete unilateral facial weakness at 24-72 hours, ipsilateral numbness or pain around ear, decreased taste, hypersensitivity to sounds, unilateral mouth sagging/drooling, failure to close eye.

Answer 7

Bell’s palsy (CN VII)

Question 8

What can rule out a LMN pathology in Bell’s palsy?

Answer 8

Forehead sparing

Question 9

What are the causes of Bell’s palsy?

Answer 9

1. Idiopathic in 70%

2. Lyme disease, TB, HIV, Ramsay-Hunt syndrome (painful rash)

Question 10

How is suspected Bell’s palsy investigated?

Answer 10

1. ESR, glucose, VZV antibodies (Ramsay-Hunt syndrome), Borrelia antibodies in Lyme disease.
2. CT/MRI if suspect SoL/stroke/MS

Question 11

What is the management for Bell’s palsy?

Answer 11

1. Oral prednisolone 60mg for 5 days then wean off
2. Artificial tears/tape/eye patch to close eye at night
3. Usually full recovery in a few weeks

Question 12

What is this a presentation of?

Miosis, partial ptosis, anhidrosis.

Answer 12

Horner’s Syndrome

Question 13

What is the cause of Horner’s syndrome?

Answer 13

Due to interruption of facial sympathetic supply due to:

1. Vascular disease (carotid dissection, also thunderclap headache)
2. Pancoast tumour