Cranial Nerve Palsies (2)

Question 1

N.B. Marcus Gunn pupil – RAPD (defect)

Optic Neuritis:
What are the 2 types of it?

What does it present with?

How is it investigated?
→ What should be checked if bilateral presentation?

How is it managed?

Answer 1

➊ • Retrobulbar neuritis (inflammation behind eye) – Most common - Optic head looks normal
• Papillitis (inflammation of optic head) – Optic head looks inflamed

➋ Pain w/movement, visual loss, impaired colour vision

➌ • Screening tests - ANA, ANCA, ESR, Immunoglobulins, Syphilis, HIV
• MRI Brain and orbits w/contrast
• Visual evoked potentials
→ Anti-aquaporin4 for Neuromyelitis optica, which is often confused with MS

➍ 5 days 500mg PO Methylprednisolone

Question 2

CN 3 Palsy:
What is the structure of this nerve?

What are the ways in which this nerve can be affected?

What are the signs of a Surgical palsy?
→ What is the most common cause of this?

Answer 2

➊ Deep, extraocular muscle somatic efferents, and Superficial parasympathetic efferents

➋ • Medical e.g. ischaemia or diabetes - The deep, somatic efferents are mainly affected
• Surgical e.g. aneurysms or trauma - Superficial parasympathetics are mainly affected

➌ Non-pupil sparing:
• Early signs – Dilated pupil, Loss of accommodation
• Late signs – Ptosis, Ophthalmoplegia
→ PCOM aneurysm, Cavernous sinus thrombosis

N.B. Cavernous sinus thrombosis would also present with palsies of CNs 4, 5 (v1, 2), 6

Question 3

CN 4 Palsy:
How does it present?

What may patients do? Why?

CN 6 Palsy:
How does it present?

Answer 3

➊ • Unable to turn down and inwards (towards nose)
• Double vision

➋ May tilt head to the side opposite the affected eye to compensate and avoid double vision i.e. ocular torticollis

➌ • Unable to move affected eye laterally
• May result in double vision

Question 4

CN 7 Palsy:
How does its UMN type present?

How does its LMN type present?

What other symptoms will be present in a Bell’s palsy?
→ How is it managed?
→ What are the complications?

What is Ramsay-Hunt syndrome?
→ What other symptoms will be present with RHS?
→ How is it managed?

What do symptoms of CN7 and CN8 palsies indicate?
→ What can cause this?

Answer 4

➊ Incomplete weakness (More subtle), Forehead and eye sparing, Brisk jaw reflex

➋ Complete weakness, Not Forehead-sparing (Unable to lift eyebrow), Weak eye closure

➌ Dry eyes, altered taste sensation, hyperacusis
→ 50-60mg Prednisolone
→ Corneal ulceration (sclera constantly exposed to air, therefore at risk of ulceration) - will need artificial tear drops

➍ VZV (Shingles) affecting CN7
→ Severe ear pain, vestibular rash, taste dysfunction, hyperacusis
→ Aciclovir, Steroids, Analgesia

N.B. If the rash involves the tip of the nose, it’s called a positive Hutchinson’s sign (worrying sign). This indicatesthat the virus has affected the nasociliary nerve, which also innervates the eye, therefore could lead to vision loss if left untreated.

➎ A problem at the Cerebellopontine angle
→ Acoustic neuroma (Vest. shwanomma)