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Year Two - Neurology System > Cranial Nerve Palsies > Flashcards

Cranial Nerve Palsies Flashcards

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1
Q

What are cranial nerve palsies?

A

They are defined as a lack of nerve function, which may cause partial weakness or complete paralysis of the areas severed by the affected nerve

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2
Q

What are the two functions of CN III?

A

It innervates four eye extra-ocular muscles to allow superior, inferior and medial eye movement

It innervates the sphincter papillae to produce pupil constriction and accommodation.

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3
Q

What are the eight causes of CN III palsy?

A

Diabetes Mellitus

Vasculitis (Temporal Arteritis, SLE)

Raised Intracranial Pressure

Posterior Communicating Artery Aneurysm

Cavernous Sinus Thrombosis

Weber’s Syndrome

Amyloid

Multiple Sclerosis

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4
Q

How is a raised intracranial pressure associated with CN III palsy?

A

It can cause herniation through the tentorium

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5
Q

What cause is indicated when CN III palsy is painful?

A

Posterior Communicating Artery Aneurysm

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6
Q

What are the five clinical features associated with CN III palsy?

A

Eye Deviation ‘Down & Out’

Superior Eyelid Ptosis

Pupil Dilatation

Pupillary Light Reflex Loss

Accommodation Loss

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7
Q

Why is ptosis a clinical feature of CN III palsy?

A

It results in paralysis of the levitator palpebrae superiosis muscle

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8
Q

Why do the eyes deviate down and out in CN III palsy?

A

This is due to the unopposed actions of the lateral rectus and superior oblique muscles

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9
Q

Why is pupil dilatation a clinical feature of CN III palsy?

A

This is due to interruption of the parasympathetic fibres to the sphincter pupillae, leaving the dilator pupillae unopposed

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10
Q

Why is accommodation loss a clinical feature of CN III palsy?

A

This is due to paralysis of the ciliary muscle

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11
Q

In CN III palsy, presenting with a large pupil, what is the most appropriate next step?

A

Urgent CT Brain

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12
Q

What is the general function of CN IV?

A

It innervates the superior oblique muscle to allow inferolateral eye movement

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13
Q

What are the four clinical features associated with CN IV palsy?

A

Vertical Diplopia

Torsional Diplopia

Eye Deviation ‘Upwards & Out’

Head Tilt

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14
Q

When does vertical diplopia occur in CN IV palsy?

A

When the patient reads a book or goes downstairs

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15
Q

What is vertical diplopia?

A

It results in defective downward gaze

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16
Q

What is torsional diplopia?

A

It results in the subjective tilting of objects

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17
Q

What are the two general functions of CN V?

A

It conveys facial sensation

It innervates the muscles of mastication

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18
Q

What are the five clinical features of CN V palsy?

A

Trigeminal Neuralgia

Corneal Reflex Loss

Facial Sensation Loss

Mastication Muscle Paralysis

Jaw Deviation

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19
Q

What side does the jaw deviate to in CN V?

A

It will deviate to the weakest side

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20
Q

What is the general function of CN VI?

A

It innervates the lateral rectus muscle to allow lateral eye movement

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21
Q

What is a cause of CN VI palsy?

A

Brain Metastases

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22
Q

What are the three clinical features of CN VI palsy?

A

Conjugate Lateral Gaze Disorder

Papilloedema

Internuclear Opthalmoplegia

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23
Q

What is another term for conjugate lateral gaze disorder?

A

Horizontal diplopia

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24
Q

What is conjugate lateral gaze disorder?

A

It is defined as defective abduction (medial deviation)

Specifically, when individuals look laterally in the direction of the affected eye, the affected eye will not be able to abduct

For example, in a lesion affecting the left eye, when looking to the left, the right eye will adduct and the left eye will remain in the middle as the muscle responsible for making it move laterally is not functioning

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25
What is intranuclear ophthalmoplegia?
It refers to incoordination of eye movements
26
What are the four general functions of CN VII?
It innervates the muscles of facial expression It innervates the scalp It innervates the facial glands It conveys taste sensation
27
What are the four UMN causes of CN VII palsy?
Stroke Brain tumours Pseudobulbar palsy Motor neurone disease
28
What are the nine LMN causes of CN VII palsy?
Otitis media/externa HIV Lyme's disease Diabetes mellitus Sarcoidosis Multiple sclerosis Gullian barre syndrome Acoustic neuroma Parotid tumours
29
What are the four causes of bilateral CN VII palsy?
Sarcoidosis Guillain-Barre Syndrome Lyme's Disease Bilateral Acoustic Neuromas (Neurofibromatosis Type II)
30
What are the six clinical features associated with CN VII palsy?
Facial Paralysis Facial Weakness Corneal Reflex Loss Eye Dryness Ageusia Hyperacusis
31
What are the five types of facial paralysis associated with Bell's palsy?
Loss of forehead wrinkling Unable to lift eyebrows Unable to close eye Loss of nasolabial fold Dropping of corner of mouth
32
What muscle paralysis results in loss of forehead wrinkling?
Frontalis
33
What muscle paralysis results in drooping of the eyebrow?
Levitator palpebral superioris
34
What muscle paralysis results in permanent opening of the eye?
Orbicularis oculi
35
What muscle paralysis results in loss of the nasolabial fold?
Levitator labii superiorois
36
What muscle paralysis results in drooping of the corner of the mouth?
Oribularis oris
37
What is hyperacusis?
It s defined as features of everyday sounds seeming much louder than they should
38
What is ageusia?
It is defined as a decreased sensation of taste
39
What clinical feature is associated with an UMN lesion of CN VII?
The forehead will be spared, and the patient can move their forehead on the affected side
40
Why is the forehead spared in an UMN lesion?
This is due to the bihemispheric innervation of the facial nerve nuclei that send axons innervating the frontalis muscle, so that when one hemisphere is damaged the other can continue the function, but not for the lower half of the face
41
What clinical feature is associated with an LMN lesion of CN VII?
The forehead will not be spared, and the patient cannot move their forehead on the affected side
42
What is Bell's palsy?
It is defined as idiopathic facial nerve palsy, in which there is no known cause for the damage caused to the facial nerve
43
Is Bell's palsy - acute or chronic?
Acute
44
Is Bell's palsy - unilateral or bilateral?
Unilateral
45
Is Bell's palsy - UMN or LMN?
LMN
46
Which age group tends to be affected by Bell's palsy?
30 - 45 years old
47
What are the four risk factors of Bell's palsy?
HSV Infection Diabetes Pregnancy Hypertension
48
What are the three additional clinical features of Bell's palsy?
Bell's phenomenon Synkinesis Crocodile tears
49
What is Bell's phenomenon?
It refers to the movement of the eyeballs in an upward direction when the eyelids are forcefully closed
50
What synkinesis?
It occurs when when the damaged axons regrow, however target the wrong muscle This results in involuntary movement occurring at the same time as a voluntary movement, such as when someone blinks, the corner of their mouth will move upwards at the same time
51
What is another term for crocodile tears?
Autonomic synkinesis
52
What is crocodile tears?
This occurs when the axons of the salivary glands regrow to the lacrimal gland This results in the production of tears whenever someone is hungry or smells food
53
What are the two treatments for Bell's palsy?
Prednisolone Lubricating Eye Drops
54
What dose of prednisolone is given when Bell's palsy is detected within 72 hours of onset?
We administer oral prednisolone 50mg/d for ten days OR We administer oral prednisolone 60mg/d for five days, followed by a five day reducing regime of 10mg a day
55
Why do we administer Bell's palsy patients lubricating eye drops?
In order to prevent the affected cornea from drying out and becoming damaged
56
How else do we protect the cornea in Bell's palsy patients?
We advise these patients to cover the affected eye at night
57
What do we do if Bell's palsy patients develop eye pain?
A referral to ophthalmology is required to investigate for exposure keratopathy
58
What is the most appropriate next step in cases where Bell's palsy shows no improvement after 3 weeks of treatment?
An urgent referral to ENT
59
What is Ramsay Hunt syndrome?
It is defined as facial nerve palsy caused by the herpes zoster virus (HSV)
60
Is Ramsay Hunt syndrome - unilateral or bilateral?
Unilateral
61
Is Ramsay Hunt syndrome - UMN or LMN?
LMN
62
What additional clinical feature is associated with Ramsay Hunt syndrome?
A painful and tender vesicular rash in the ear canal, pinna and around the ear on the affected side This rash can extend to the anterior two thirds of the tongue and hard palate
63
What are the three pharmacological treatment options of Ramsay Hunt syndrome?
Prednisolone Aciclovir Lubricating Eye Drops
64
What is the first line management option of Ramsay Hunt syndrome?
Oral aciclovir for 7 days AND Oral prednisolone for 5 days
65
What is the general function of CN VIII?
To allow hearing and balance
66
What are the four clinical features associated with CN VIII palsy?
Hearing Loss Vertigo Nystagmus Acoustic Neuromas
67
What are acoustic neuromas?
They are Schwann cell tumours of the cochlear nerve
68
What are the three general functions of CN IX?
It innervates the parotid gland to allows salivation and swallowing It mediates input from the carotid body/sinus It conveys taste sensation from the posterior third of the tongue
69
What are the two clinical features associated with CN IX?
Carotid Sinus Hyperreflexia Gag Reflex Loss
70
What are the four general functions of CN X?
It allows phonation It allows swallowing It conveys taste sensation from the epiglottis and palate It transmits visceral sensation
71
What are the two clinical features associated with CN X palsy?
Uvula Deviation Gag Reflex Loss
72
What side does the uvula deviate to in CN X palsy?
It will deviate away from the site of lesion
73
What is the general function of CN XI?
It innervates the sternocleidomastoid and trapezius muscles to allow head and shoulder movement
74
What are the two clinical features of CN XI palsy?
Head Movement Weakness Shoulder Movement Weakness
75
What side does head/shoulder weakness occur on in CN XI palsy?
Contralateral side to lesion
76
What is the general function of CN XII?
It innervates the intrinsic and extrinsic muscles of tongue to allow tongue movement
77
What is the clinical feature associated with CN XII palsy?
Tongue deviation

Year Two - Neurology System (25 decks)

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