Neuro - CN

Question 1

Name the cranial nerves (CN I - XII)

Answer 1

• I olfactory
• II optic
• III oculomotor
• IV trochlear
• V trigeminal
• VI abducens
• VII facial
• VIII vestibulocochlear
• IX glossopharyngeal
• X vagus
• XI accessory
• XII hypoglossal

Question 2

Which are the visual cranial nerves?

Answer 2

• II optic
• III oculomotor
• IV trochlear
• VI abducens

Question 3

Which are the bulbar cranial nerves?

Answer 3

• IX glossopharngeal
• X vagus
• XII hypoglossal

Question 4

What is the exposure requried for a cranial nerve exam?

Answer 4

clavicle up

Question 5

what might be observed on general inspection during a cranial nerve exam?

Answer 5

• unilateral neck muscle wasting neck (XI)
• facial droop/asymmetry (VII)
• articulation of words (V, VII, X, XII)
• ptosis (III)
• strabismus e.g. ambylopia (III, IV, VI)
• abnormal/asymmetric pupils (II, III)

Question 6

How do you test CN II?

Answer 6

Inspection, AFRO

• Acuity
  
  1. distant vision - Snellen test
  2. near vision
  3. colour vision - Ishihara plates
• Fields
  
  1. inattention
  2. fields
  3. blind spots
• Reflexes
  
  1. accommodation
  2. direct & consensual
  3. swinging light - normal reaction = slight constriction, then slight dilation ​
• Ophthalmoscopy
  
  1. ‘to visualise optic disc’

Question 7

a) What is Horner’s syndrome?
b) What are the signs of Horner’s syndrome?

Answer 7

a) range of symptoms when sympathetic trunk is damaged
b) ipsilateral: miosis, partial ptosis, anhydrosis, enophthalmus

Question 8

How do you test CN I?

Answer 8

‘have you noticed any changes in your sense of smell?’

offer to test with UPen smell identification test

Question 9

How do you test CN III, VI, VI?

Answer 9

CN III = optic ; CN IV = trochlear ; CN VI = abducens

Inspect

1. H Test
2. saccades test
3. convergence test (bring finger towards nose, pupil shrinks)

Question 10

What is the pathology if there is

a) partial ptosis
b) complete ptosis

Answer 10

a) Horner’s syndrome
b) CN III lesion

Question 11

What are the afferent and efferent nerves for the accommodation reflex?

Answer 11

afferent = CN II

efferent = CN III

Question 12

What are the afferent and efferent nerves for the

a) direct pupillary reflex
b) consensual pupillary reflex

Answer 12

a) afferent = CN II ipsilateral ; efferent = CN III ipsilateral

b) afferent = CN II contralateral ; efferent = CN III ipsilateral

Question 13

What are the afferent and efferent nerves for the swinging light reflex?

Answer 13

????

Question 14

1. What is a Marcus-Gunn pupil?
2. What does a Marcus-Gunn pupil suggest?

Answer 14

1) when pupils dilate (to some degree) when a bright light is swung from the unaffected eye to the affected eye;
* as opposed to normal reaction = slight constriction, then slight dilation*
2) optic nerve lesion e.g. due to glaucoma, MS

Question 15

How do you test CN V?

Answer 15

inspect (wasting: masseter, temporalis, lateral pterygoids)

• sensory:
  
  • ‘any areas of pins and needles or numbness?’
  • sharp & dull sensation testing over 3 branches (temporal, maxillary and mandibular) ‘does it feel the same on both sides?’
• motor
  
  • from behind: clench jaw, feel masseters, temporalis & lateral pterygoids
• reflexes:
  
  • offer: corneal reflex
  • offer: jaw jerk reflex

Question 16

When testing CN V, what would you do if there are any sensory abnormalities found?

Answer 16

test the 3 branches again for:

• temp sensation: cold tuning fork
• light touch sensation: cotton wool

Question 17

What are the afferent and efferent nerves for the corneal reflex?

Answer 17

afferent = CN V: nasociliary branch of ophthalmic division

efferent = CN VII

Question 18

How do you test CN VII?

Answer 18

inspect

Motor:

• Raise eyebrows
• Scrunch up eyes + try to prise each open in turn with your thumbs
• Purse lips together + try to prise each open in turn with your thumbs
• Show teeth
• Puff out cheeks + try to push air out

Question 19

How does

a) UMN present when raising eyebrows (CN VII)?
b) LMN present when raising eyebrows (CN VII)?

Answer 19

a) forehead spared, bilateral eyebrow raise
b) unilateral eyebrow raise

Question 20

How do you test CN VIII?

Answer 20

‘any changes in hearing?’

• Crude hearing test: rub fingers in one ear
• Weber test -
  
  • 512Hz
  • forehead ‘which side is louder?’
• Rinnes test -
  
  • 512Hz
  • mastoid process ‘tell me when it stops’
  • by ear ‘can you hear it again?’

offer: vertigo tests e.g. Dill-Hallpike test

Question 21

What would be the results of Weber & Rinne’s in

a) sensorineural hearing loss
b) conductive hearing loss

Answer 21

Question 22

How do you test CN IX & X?

Answer 22

• Inspect: open mouth say, ahhh
  
  • look for palate symmetry (CN IX)
  • look for uvula deviation (CN X)
• Motor:
  
  1. speech - ‘say ahh & British constitution’
  2. cough
  3. swallow
• Reflex:
  
  • offer: gag reflex

Question 23

How do you test CN XI?

Answer 23

Inspect: SCM, trapezius wasting

Motor: against resistance - turn head & shrug shoulders

Question 24

How do you test CN XII?

Answer 24

‘have you noticed any changes/slurring in your speech?’

Inspect

• tongue wasting or fasciculations

Motor

• stick out tongue - deviation?
• against resist. press tongue inside cheek

Question 25

CHow could you complete your cranial nerve examination?

Answer 25

• Full Hx
• Upper & lower limb neuro examination
• fundoscopy (if hearing impaired)
• nerve conduction study
• CT head

Question 26

What is

a) bulbar palsy
b) pseudobulbar palsy

Answer 26

a) LMN lesion
b) UMN lesion

Question 27

How could you differentiate between bulbar palsy and pseudobulbar palsy?

Answer 27