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3a neurology > Cranial Nerve Lesions > Flashcards

Cranial Nerve Lesions Flashcards

1
Q

Which two extraocular muscle are NOT innervated by the oculomotor nerve

A

Lateral rectus
Superior oblique

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2
Q

What muscle is responsible for lifting the upper eyelid and what nerve innervates it

A
  • Levator palpebrae
  • Oculomotor
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3
Q

How does a 3rd nerve palsy present

A
  • Ptosis and squint
  • Fixed dilated, non-reactive pupil
  • Eye pulled down and out
  • Diplopia
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4
Q

How does a 3rd nerve palsy cause a dilated, non-reactive pupil

A

The oculomotor nerve carries parasympathetic fibres that innervate the circular muscles of the iris

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5
Q

What does a 3rd nerve palsy that spares the pupil suggest (2)

A

Microvascular cause
* DM
* HTN
* Ischaemia

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6
Q

Give 5 causes of third nerve palsy

A
  • diabetes mellitus
  • vasculitis e.g. temporal arteritis, SLE
  • raised ICP can cause a third nerve palsy due to uncal herniation
  • posterior communicating artery aneurysm (pain)
  • cavernous sinus thrombosis
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7
Q

What extraocular muscle does the trochlear nerve supply

A

Superior oblique

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8
Q

What are 3 functions of the superior obliques

A
  • Primary: Intorsion
  • Depression
  • Abduction
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9
Q

How does a trochlear nerve palsy present

A
  • Affected eye deviates upwards and slightly out
  • Affected eye elevates further as it moves medially
  • Vertical diplopia
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10
Q

What extraocular muscle does the abducens nerve supply

A

Lateral rectus

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11
Q

How does a 6th nerve palsy present

A
  • Affected eye turns inwards at primary position
  • Unable to abduct affected eye but can adduct
  • Horizontal diplopia when looking far away or in the direction of the affected eye
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12
Q

How may patients with a 4th nerve palsy compensate for vertical diplopia

A

Head tilt to better align the eyes and reduce the diplopia

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13
Q

4 ways a trigeminal nerve palsy may present

A
  • paralysis of chewing muscles
  • deviation of jaw to weak side
  • Loss of corneal reflex (afferent)
  • trigeminal neuralgia
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14
Q

5 ways a facial nerve palsy may present

A
  • Ipsilateral paralysis of face
  • Facial droop
  • increased sensitivity to sound
  • Loss of taste
  • loss of corneal reflex (efferent)
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15
Q

What does the facial nerve supply sensory innervation to

A

Anterior 2/3 of the tongue

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16
Q

Give 4 causes of bilateral facial nerve palsy

A
  • sarcoidosis
  • Guillain-Barre syndrome
  • Lyme disease
  • bilateral acoustic neuromas
17
Q

Give 5 causes of a unilateral facial nerve palsy

A
  • Bell’s palsy
  • Ramsay-Hunt syndrome (due to herpes zoster)
  • acoustic neuroma
  • parotid tumours
  • HIV
18
Q

How could you differentiate between a facial nerve palsy caused by an UMN lesions and a LMN lesion

A
  • UMN lesion ‘spares’ upper face i.e. forehead
  • LMN lesion affects all facial muscles
19
Q

3 ways a vestibulocochlear palsy may present

A
  • Hearing loss
  • Tinnitus
  • Loss of balance, vertigo
20
Q

Give 4 way a 9th/10th cranial nerve palsy may present

A
  • Difficulty swallowing
  • loss of gag reflex
  • Deviation of uvula away from the side of damaged nerve (vagus)
  • Hoarseness
21
Q

How does an accessory nerve palsy present

A

weakness turning head to contralateral side

22
Q

Give 3 ways a hypoglossal nerve palsy may present

A
  • Tongue fasciculations
  • Deviation to side of lesion when tongue is protruded
  • Ipsilateral tongue wasting
23
Q

What is bell’s palsy

A

unilateral, idiopathic, LMN facial nerve palsy

24
Q

Describe the epidemiology of bell’s palsy

A
  • peak incidence 20-40 years
  • more common in pregnant women
25
Q

Describe the features of Bell’s palsy

A
  • LMN facial nerve palsy -> forehead affected
  • altered taste
  • dry eyes
  • post-auricular pain
26
Q

How is Bell’s palsy managed

A
  • eye care: drops, lubricants and night time taping
  • oral prednisolone within 72 hours of onset
  • if the paralysis shows no sign of improvement after 3 weeks, refer urgently to ENT

3a neurology (16 decks)

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