Neuro - Cranial Nerves

Question 1

A 35yo pregnant woman presents with paralysis of the left side of her face that came on over 2/7. She also complains of mild ear pain but history + examination is otherwise normal.

What is the likely diagnosis? How would you investigate her?

Answer 1

Bell’s palsy

Clinical diagnosis but consider:

• Borrelia burgforferi serology if recent travel to Lyme disease-endemic area
• MRI head if ?neoplasm

Question 2

How would you treat someone presenting with Bell’s palsy?

Answer 2

1. PO PREDNISOLONE 60mg 5/7 (then taper down): if presenting within 72hrs of onset
2. eye protection: artifical tears + glasses during daytime, eye lubricants + tape shut at nighttime
3. VALACICLOVIR 5-7/7 if severe palsy/complete paralysis

Question 3

A person who was treated for a Bell’s palsy presents 4/12 later with no signs of improvement. What would you tell them?

Answer 3

MRI to rule out neoplasm (as onset of recovery nearly always occurs within 4-6/12)

Question 4

A 62yo man presents with a 1/7 Hx of painful right eye + ptosis. On examination, the right eye is in down + out position, with a dilated pupil that is unresponsive to light.

What is your differential? How would you investigate?

Answer 4

1. compression from posterior communicating artery aneurysm
2. subdural haematoma
3. RICP (e.g. benign or malignant space occupying lesions) causing uncal hernation

Dx: urgent CT/MRI brain

Question 5

How would differentiate between a medical and a surgical 3rd nerve palsy.

Answer 5

Medical: painless + pupil sparing

Surgical: pupil fixed + dilated, +/- pain

Question 6

What are the most common causes for medical 3rd nerve palsies?

Answer 6

Disruption to blood supply due to:

• DM
• HTN

Question 7

What is the differential for a unilateral ptosis?

Answer 7

1. 3rd nerve palsy (eye down + out)
2. Horner’s sundrome (anhydrosis + miosis)
3. myasthenia gravis
4. congenital

Question 8

A 70yo lady presents with paroxysms of shooting severe pain along her cheek + lateral nose. These are triggered by touching the area.

What is the likely diagnosis and how would you manage her?

Answer 8

Trigeminal neuralgia (clinical diagnosis)

Mx: CARBAMAZEPINE PO (or oxcarbazepine): increase dose gradually according to response

Question 9

What is internuclear ophthalmoplegia? How would it present?

Answer 9

Lesion to medial longitudinal fasciculus (neuronal fibres connecting CN III, IV and VI nuclei in brainstem to allow conjugate eye movement)

Features - dissociative conjugate gaze:

• impaired adduction of ipsilateral eye
• +/- nystagmus in abducting contralateral eye

Question 10

Suggest possible causes for internuclear ophthalmoplegia

Answer 10

1. MS
2. brainstem infarcts, tumours aneurysms
3. WErnicke’s encephalopathy
4. SLE
5. OD on phenytoin/TCAs/barbiturates