Cranial nerves examination

Question 1

set up for cranial nerve examination

Answer 1

sitting in chair 1m away from you

Question 2

cranial nerve 1 testing

Answer 2

ask if any change in sense of taste/smell

Question 3

what is anosmia an early sign of?

Answer 3

parkinsons disease

Question 4

memory aid for 4 aspects of CN2 exam

Answer 4

AFRO

Acuity
Fields
Reflexes
Opthalmoscopy

Question 5

How to test visual acuity

Answer 5

formally: snellen chart from distance of 6m with eye covered up in turn

informal: ask patient to read word on name badge

Question 6

how to test visual fields neglect?

Answer 6

facing patient, ask them to look at your nose and keep head still

hold fingers approx 60cm apart and ask patient to point to the finger that moves

Question 7

what will happen if a person has visual fields neglect?

Answer 7

wiggle both fingers at the same time, a patient with neglect will only note one finger moving

Question 8

how to test peripheral visual fields informally

Answer 8

keep head still, eyes closed, wiggle finger from outside visual field towards centre, test all four quadrants

Question 9

how to formally assess peripheral visual fields

Answer 9

goldmann kinetic perimetry and Humphrey visual fields testing

Question 10

how to test visual reflexes?

Answer 10

make sure any ambient light is dim
check pupil size, shape, symmetry
direct reflex
consensual reflex
swinging light test

Question 11

first step in testing CN3,4, 6

Answer 11

ask patient to fixate on tip of pen held 50cm in front of their nose
-> inspect for ptosis, nystagmus, strabismus

Question 12

testing for diplopia CN 3,4,6

Answer 12

ask about diplopia in first position
H shape movement
ask them to tell you if they have any pain or double vision

Question 13

what do you do after doing the H test in CN3,4,6

Answer 13

smooth pursuit -> move your finger relatively rapidly from left to right and back again, pausing at the edges of the gaze

look for nystagmus

Question 14

CN5 testing

Answer 14

Sensation: ophthalmic, maxillary, mandibular with cotton wool

Motor: masseter and temporalis (chomp down)

Question 15

what are the CN5 reflexes?

Answer 15

corneal (afferent V1, efferent VII)
jaw-jerk (afferent V3, efferent: motor V)

Question 16

movements to ask for in CN7 testing

Answer 16

raise eyebrows
scrunch up eyes
puff out cheeks
show teeth

Question 17

CN8 testing

Answer 17

whisper a number in the patient’s ear in turn, ask them to repeat it

if hearing loss, offer:
- Rinne test
- Webers test
- Otoscopy
- Audiometry for formal assessment

Question 18

CN 9,10 testing

Answer 18

uvula deviation after getting them to say ‘arghhh’

Question 19

CN11 testing

Answer 19

Spinal accessory
-> ask to shrug shoulders and keep them there against resistance (trapezius)
-> ask patient to turn head and push back against examiners hand (sternocleidomastoid)

Question 20

CN12 testing

Answer 20

Inspect tongue at rest
-> wasting and fasciculations in MND
-> tongue deviation towards side of lesion in LMN pathology

Test power of tongue against each cheek

Question 21

clinical signs of complete unilateral CN3 palsy

Answer 21

ptosis
down and out eye
diplopia worst when looking up and out
fixed dilated pupil

Question 22

causes of a unilateral ptosis

Answer 22

Third nerve palsy
Horners syndrome
Myasthenia gravis

Question 23

causes of a bilateral ptosis

Answer 23

myasthenia gravis
neurosyphilis

Question 24

difference between a medical and surgical third nerve palsy

Answer 24

medical = pupil sparing and painless
surgical = pupil fixed and dilated

Question 25

causes of a third nerve palsy

Answer 25

compression from a posterior communicating artery aneurysm
vascular occlusion (e.g. atheroma or diabetes)
midbrain infarct / tumour
temporal lobe coning

Question 26

What is Horner’s syndrome

Answer 26

interruption to the sympathetic fibres supplying the face, resulting in a partial ptosis, anhidrosis and miosis

Question 27

how do you classify Horners syndrome causes?

Answer 27

according to site of lesion:

first order neurone = stroke / MS tumour

second order neurone = apical lung tumour, cervical rib, apical TB

third order neurone = internal carotid artery dissection / aneurysm

Question 28

what is the pathological process behind internuclear opthalmoplegia

Answer 28

lesion to the medial longitudinal fasciculus (connects CN 3,4 and 6)

Question 29

clinical signs seen with an internuclear opthalmoplegia

Answer 29

impaired adduction of ipsilateral eye
nystagmus in the abducting contralateral eye

Question 30

what is the neural pathway responsible for the pupillary light reaction

Answer 30

afferent: optic nerve
efferent: parasympathetic component of CN3 bilaterally

Question 31

what is the neural pathway responsible for accommodation reflex

Answer 31

afferent: frontal lobe
efferent: parasympathetic component of CN3

Question 32

what is an argyll-robertson pupil

Answer 32

small irregular pupil which is able to accommodate but does not react to light

Argyll-Robertson Pupil = ARP = Accommodation Reflex Preserved

Question 33

what is an afferent pupillary defect?

Answer 33

caused by a complete lesion to the optic nerve, anterior to the optic chiasm

results in an ipsilateral eye that is dilated and doesn’t constrict to light + contralateral lack of consensual reflex in other eye