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Neurology > 13. Cranial Nerve Lesions > Flashcards

13. Cranial Nerve Lesions Flashcards

1
Q

Give some general causes of cranial nerve damage.

A

Polio
Guillian barre
MS
Tumour
Vasculitis
Stroke
Lupus
Syphilis
TB/fungal meningitis

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2
Q

What is CN1?

A

Olfactory nerve
- For smelling!

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3
Q

How can the olfactory nerve be damaged?

A

Trauma to cribriform plate

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4
Q

What does CN1 palsy present as?

A

Anosmia

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5
Q

Give 2 causes of anosmia caused by an olfactory nerve palsy.

A
  1. Respiratory tract infection
  2. Olfactory groove tumour
  3. Meningitis
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6
Q

What is CN 2?

A

Optic nerve
- For sight

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7
Q

Optic nerve vs optic tract?

A

Optic nerve is from the eye to the optic chiasm.
Optic tract is from the chiasm to the lateral geniculate body.

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8
Q

The right pupil constricts in response to light shone in the left eye, but when you shine the light on the right eye, neither eyes constrict.
Where is the problem?

A

CN2 - the optic nerve
- As the pupil is not detecting the light.

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9
Q

A left parietal lesion of the optic radiation causes what kind of vision deficit?

A

Quadrantanopia
of inferior right quadrant

PITS - parietal lesion = inf loss, temporal lesion = superior loss)

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10
Q

What is CN3?

A

Oculomotor nerve

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11
Q

What does CN3 innervate?

A

CN3 is the occulomotor nerve.

Motor – Innervates the majority of the extraocular muscles:
1. Levator palpebrae superioris (muscle of the eyelid)
2. Superior rectus
3. Inferior rectus
4. Medial rectus
5. Inferior oblique

Parasympathetic – Supplies the:
1. Sphincter pupillae of the eye
2. Ciliary muscles of the eye

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12
Q

If 1 pupil is not constricting to direct or consensual light stimulation to the other eye, where is the problem?

A

CN3 - the pupil is not constricting

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13
Q

What are the 3 main signs of a lesion to CN3?

A
  1. Ptosis - dropping eyelids
  2. Outward deviation (‘down and out’) - as there is function of the lateral rectus to look out (CN6), but not inferior oblique (CN3) to counteract it
  3. Dilated fixed pupil

Also:
- Pupil does not accomodate to light
- Absent pupillary light reflex

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14
Q

What is CN4?

A

Trochlear nerve

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15
Q

What does CN4 innervate?

A

CN4 = trochlear nerve
Innervates superior oblique - looks in and down

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16
Q

What does damage to CN4 result in?

A

Defective downward gaze - vertical diplopia
(diplopia on looking down e.g. walking downstairs)

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17
Q

What kind of visual symptoms would you get with a trochlear nerve lesion?

A

Diplopia on looking down and in

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18
Q

What is CNV?

A

Trigeminal nerve

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19
Q

What are the 3 branches of the trigeminal nerve?

A

V1 - opthalmic - forehead sensation
V2 - maxillary - cheeks sensation
V3 - mandibular - chewing + sensation on anterior 2/3 tongue

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20
Q

What are the functions of the trigeminal nerve?

A
  1. Facial sensation
  2. Muscles of mastication
  3. Tensor tympani (muscle within the middle ear)
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21
Q

How can the trigeminal nerve be damaged?

A
  1. Trigeminal neuralgia (pain but no sensory loss)
  2. Herpes zoster
  3. Nasopharyngeal carcinoma
  4. Acoustic neuroma (a type of non-cancerous (benign) brain tumour)
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22
Q

How may lesions to the trigeminal nerve cause?

A
  1. Trigeminal neuralgia
  2. Loss of corneal reflex
  3. Loss of facial sensation
  4. Paralysis of mastication muscles
  5. Deviation of jaw to weak side
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23
Q

What is CNVI?

A

Abducens nerve

24
Q

What does the CNVI innervate?

A

The lateral rectus muscle, thus the eyes will be adducted

25
Q

What do lesions to CNVI result in?

A

Defective adduction
- Horizontal diplopia

26
Q

Complete external opthalmoplegia is due to palsy of which nerves and what does it cause?

A

Palsy of the oculomotor, trochlear and abducens (III, IV and VI) nerves.

Causing complete paralysis of the eye.

27
Q

What is CN7?

A

Facial nerve - facial expression

28
Q

What are the functions of the facial nerve (CNVII)?

A
  1. Muscles of facial expression
  2. Taste - anterior 2/3 of the tongue
  3. Salivation + lacrimation
29
Q

What are the parasympathetic functions of the facial nerve?

A
  1. Lacrimation
  2. Salivation
30
Q

What are the causes of facial nerve dysfunction?

A
  1. Bells palsy
  2. Temporal bone fracture
  3. Herpes zoster
31
Q

What do lesions to the facial nerve result in?

A
  1. Flaccid paralysis of upper + lower face
  2. Loss of corneal reflex
  3. Loss of taste
  4. Hyperacusis (AKA noise sensitivity - when everyday sounds seem much louder to you than they should)
32
Q

What is CN8?

A

Vestibulocochlear - hearing and balance

33
Q

What are the functions of CN8?

A
  1. Hearing
  2. Balance
34
Q

Aminoglycosides cause damage to which nerve?

A

Vestibulocochlear CN 8

35
Q

What do lesions to CN8 present as?

A
  1. Hearing impairment
  2. Vertigo and lack of balance
36
Q

What is CN9?

A

Glossopharyngeal nerve

37
Q

What are the functions of CN9?

A
  1. Taste - posterior 1/3 of tongue.
  2. Parasympathetic -> Provides parasympathetic innervation to the parotid salivary gland.
  3. Sensory -> Innervates the stylopharyngeus muscle of the pharynx.
  4. Swallowing.
38
Q

Which cranial nerves innervate the tongue?

A
  1. CNVII Facial nerve -> for taste -> anterior 2/3 of tongue
  2. CNIX Glossopharyngeal nerve -> for taste -> posterior 1/3 of tongue
  3. CNV Trigeminal nerve -> sensation
  4. CNXII Hypoglossa nerve -> motor
  5. CNX Vagus nerve -> supplies the 1 muscle, the palatoglossus muscle
39
Q

How do lesions in CNIX Glossopharyngeal nerve present?

A
  1. Gag reflex issues
  2. Swallowing issues
  3. Vocal issues
  4. Hypersensitive carotid sinus reflex
40
Q

How can you test the CNIX Glossopharngeal nerve?

A

Gag reflex

41
Q

What is CNX?

A

Vagus nerve

42
Q

What are the functions of CNX Vagus nerve?

A
  1. Sensory and motor to pharynx and larynx
  2. Phonation - production and utterance of speech sounds
  3. Swallowing
  4. Parasympathetic to GI tract and viscera
43
Q

How do lesions in CNX Vagus nerve present as?

A
  1. Uvual deviates from side of lesion
  2. Loss of gag reflex
44
Q

What is CNXI?

A

Accessory nerve

45
Q

Which cranial nerve innervates the accessory muscles?

A

CN 11 Accessory nerve

46
Q

What is the function of the CNXI Accessory nerve?

A

Controls the movement of certain neck muscles

47
Q

Which 2 muscles does the accessory nerve innervate?

A
  1. Sternocleidomastoid muscle
  2. Trapezius muscle
48
Q

How can you test the accessory nerve?

A

Ask patient to shrug their shoulders or turn head

49
Q

What is CNXII?

A

Hypoglossal nerve

50
Q

What does CNXII innervate?

A

Intrinsic and extrinsic muscles of the tongue

51
Q

What is the functions of CNXII?

A

Controls muscles that move the tongue

52
Q

How do lesions in CNXII present as?

A

Tongue deviates towards side of lesion

53
Q

How can you test CN12?

A

CN 12 is hypoglossal.
Ask patient to stick tongue out, it will deviate to weak side.

54
Q

Why do lesions of the glossopharyngeal and vagus appear together?

A

They both leave the skull through the jugular foramen.

55
Q

A patient is struggling to turn their head to the right - they think they have slept on it in a weird position.
What nerve could have been damaged?

A

Left hand side accessory nerve

56
Q

You ask a patient to stick their tongue out and it immediately deviates to the right and is very stiff to move.
What do you suspect?

A

UMN lesion affecting the right hypoglossal nerve

Neurology (20 decks)

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