Cranial nerve lesions Flashcards
What cranial nerves can have lesions?
3-12 from brainstem
What are 3 conditions of cranial nerves?
- Bell’s palsy
- Trigeminal neuralgia
- Third nerve palsy
Define Bell’s palsy
Lower motor neuron weakness of cranial nerve VII (facial nerve) → acute peripheral facial palsy
What are causes of Bell’s palsy?
- idiopathic
- Thought to be related to inflammation and oedema of the facial nerve secondary to viral infection or autoimmunity
What are symptoms of Bell’s palsy?
- Presents with rapid onset (<72 Hours) of unilateral facial weakness
post-auricular/ear pain - Difficulty chewing
- incomplete eye closure
- drooling
- tingling in cheek/mouth
- hyperacusis - decrease in everyday sound tolerance
What are signs of Bell’s palsy?
- ocular dryness
- decreased taste
- Asymmetrical smile
- Drooping of the corner of the mouth
- Drooping of the eyebrow
Why might there be drooling and decreased taste in Bell’s palsy?
The facial nerve terminates within the parotid gland
How do you diagnose Bell’s palsy?
Clinical diagnosis - based on unilateral facial weakness, of rapid onset, without forehead sparing (with forehead sparing suspected UMN lesion)
What investigations would you do for Bell’s palsy?
- Bloods
- Neuroimaging, LP
- Consider HIV test
How do you treat Bell’s palsy?
- Management largely supportive, but prednisolone may be used in those presenting within 72 hours of onset
- antiviral treatment e.g acyclovir can be considered
- eye care - lubricating drops, taping eye when sleeping, sunglasses outdoors, referral to ophthalmology considered
Define third nerve palsy
A third nerve palsy refers to damage to the oculomotor nerve
What does the oculomotor nerve do?
→ Pupil: parasympathetic fibres run superficially within the nerve to cause pupil constriction
→ Eyelid: innervates the levator palpebrae superioris that elevates the eyelid
→ Extraocular muscles: innervates all the extraocular muscles except the superior oblique and lateral rectus muscle
What are the causes of third nerve palsy?
→Tumour
→Haemorrhage
→Ischaemia (stroke)
→meningitis
→aneurysm
→trauma
What are signs of third nerve palsy?
→ Ipsilateral ptosis with a down and out appearance
→ pupil dilation
→ loss of light reflex
→ Neck stiffness if there is subarachnoid haemorrhage or meningitis
What are symptoms of third nerve palsy?
→ Diplopia
→ Ptosis - drooping eyelid
→ pain
→ severe headache
→ Meningism - headache, neck stiffness, photophobia - subarachnoid haemorrhage/meningitis
