cranial nerves

Question 1

preparation

Answer 1

appropriate environment - chair for pt and you

snellen chart

pen torch

cotton wool

neuro-tip

512Hz tuning fork

glass of water

Question 2

introduction

Answer 2

WINDEC

wash

intro

name

DOB

explain

consent

Question 3

inspection

Answer 3

inspect pt - eyes, face, limbs and speech

inspect env - aids, prescriptions

look for asymmettry/abnormality

limbs - when walk into a room, fasiculations and posture

pt generally well

any walking aids

Question 4

describe olfactory nerve

Answer 4

sensory only - afferent to brain about odours

Question 5

how do you test olfactory

Answer 5

ask if they can smell something

ask if they have noticed any changes to smell

Question 6

optic nerve

Answer 6

sensory only

first inspect - pipil size and symettry, screening test - ask if they can see your whole face

Question 7

testing the optic nerve acuity

Answer 7

acuity - use sign behind you, check if usually have glasses/lenses - cover 1 eye and repeat with other

make sure you would be able to do the acuity (ie that the test is reasonable)

snellen chart - pt stand 6m from chart, cover 1 eye and read down the chart, record lowest line able to read with each eye

record as: distance/line on snellen test

test near vision by asking to read a line of a magazine

'’i would also like to test colour vision using ishihara plates’’

Question 8

test optic nerve field

Answer 8

compare with own visual field - sit 1m opposite pt at same level
ask them to look at your nose, ask if they can see your whole face and that its not blurry

1st test visual inattention - both eyes open, hold fists out laterally to each side - ask them to point at the fist that you’re opening/closing (inattention to 1 side = contralateral parietal lesion)

'’cover R eye with R hand’’ mirror pt

'’keep looking at my nose and tell me when you see my finger’’

move finger from periphery of field into centre

repeat for other quadrants and eye

(monocular field loss = retinal damage or ipsilateral optic nerve lesion, bitemporal hemaniopia = opyic chiasm compression, L/R homonymous hemianopia = contralateral optic tract/radiation lesion or occipital cortex of macular sparing)

Question 9

test blind spots as part of optic field

Answer 9

hold the red pin mid distance between yours and pts open eye (other eye closed)

check they can see it in the middle (central scotoma = optic nerve lesion)

check they can see it as red

now move it horizontally towards the periphery and get them to tell you when it disappears- map ach of their blind spots to yours

large blind spot = papilloedema

Question 10

nerves responsible for the pupillary reflex

Answer 10

optic afferent

oculomotor PNS fibre for pupil constriction

Question 11

examine the pupillary reflex

Answer 11

inspect pupil - any difference in size and symettry

dim lights

'’focus on sign behind me and put hand between eyes’’

'’im going to breifly shine a torch into your eyes’’ from about 45degrees

assess direct and consensual reflex (opp eye to shined in)

assess for relative afferent pupillary defect

Question 12

how do you assess for relative afferent pupil defect

Answer 12

swing torch between eyes

want to see constriction when light in both eyes

if you see dilation that is an inappropriate response - that eye is less sensitive to light = relative afferent papillary defect (partial optic nerve lesion on that side)

Question 13

effect of afferent defect to pupillary reflex

Answer 13

pupils are symettrical

when light is shined in affected eye - neither contract

optic nerve lesion

Question 14

effect of efferent defect to pupillary reflex

Answer 14

affected pupil is persistently dilated, while other is reactive to light being shined in either eye

CN3 lesion

Question 15

assess optic disk

Answer 15

'’i would also like to perform opthalmoscopy to visualise the optic disk’’

Question 16

additional tests for the optic nerve

Answer 16

colour vision

visual inattention/neglect - (look at neglect if suspecting a stroke)

blind spot

accomodation reflex

fundoscopy

Question 17

assess accomodation reflex

Answer 17

ask pt to focus on distant object and then ask them to focus on your finger close to their face

pupils shoudl constrict and eyes should converge

Question 18

nerves responsible for eye movement

Answer 18

cn3 - oculomotor

Cn4 - trochlear

cn 6 - abducens

motor only nerves

Question 19

nerve supply of lateral rectus

Answer 19

abducens cn 6

Question 20

nerve supply of superior oblique

Answer 20

trochlear cn4

Question 21

what muscles does oculomotor supply

Answer 21

all other eye muscles including levator palpebrae

Question 22

movement from SO

Answer 22

out, down and medially rotates

Question 23

movement of lateral rectus

Answer 23

abduction

Question 24

inspection of eye movement

Answer 24

ask if they have double vision, and to let you know if they experience any at any point

inspect eyelids and the position of eye - make sure they keep their head still

look for strabismus or ptosis (partial ptosis = horner’s, full = CN3 lesion)

follow finger with eye - 30cm from face - move finger in H pattern. Pause when they are looking laterally (nystagmus = cereballar lesion)

assess for opthomalplegia and/or nystagmus

if there is complex opthomalplegia - ask them to look straight up and to count down from 20 - fatigability = myasthenia

saccades test - ask pt to look between a central and peripheral target (eg your nose to index finger) in the horizontal plane and vertical plane - saccades are jerky movements

Question 25

assessing nystagmus

Answer 25

is it one eye or both

cover one eye and see if it disappears

see if images separate vertically or horizontally

most jerk nystagmus - slow move away and fast is the corrective movement

fast is the direction of the nystagmus

Question 26

assess the trigeminal nerve sensation

Answer 26

facial sensation

ask if pt has any pins and needles or numbness

demonstrate sensation modality on sternum - use neurotip

'’close your eyes and say yes each time you feel me touching you’’

V1 - forehead

V2 - cheek

V3 - chin

'’does it feel the same on both sides’’

Question 27

test the trigeminal nerve muscles

Answer 27

muscles of mastication

inspect for temporalis/masseter wasting

place fungers underneath the zygomatic arch laterally and ask pt to clench teeth - assess masseter muscle contraction

place fingers under chin - ‘‘open your mouth against my fingers’’ - assess lateral pterygoid muscles

Question 28

test reflexes of trigeminal nerve

Answer 28

jaw jerk - place funger under chin and hammer under jaw

corneal reflex - cotton on cornea and see if they produce tears

Question 29

test facial nerve

Answer 29

taste - have you noticed any change in taste (facial nerve control taste for anterior 2/3 of tongue)

are you troubled by loud noises - stapedius muscle in inner ear is controlled by facial (motor)

facial expression - check for asymettry, demonstrate to the patient what you want them to do

• inspection - forehead wrinkles, nasolabial folds and angles of mouth
• raise your eyebrows - frontalis muscle
• scrunch up your eyes and dont let me open them - orbicular oculi
• purse lips
• puff out your cheeks - orbicularis oris
• do a big smile - levator anguli oris and zygomaticus major

Question 30

test vestibulocochlear nerve

Answer 30

have you noticed any changes in your hearing

do gross assessment of hearing - repeat the numbers that i am going to whisper into your ears (start peripherally and move towards their ear). stroke the tragus/exclude auditoy meatus of one ear - repeat on other side

rinne test

weber test

i would also consider performing vertigo tests such as walking on the spot and Dix-Hallpike test

Question 31

what is weber test

Answer 31

vestibulocochlear

dde before Rinne

place heel of tuning fork in centre of pts forehead

do you hear the sound more on L or R or just in middle of head

normal -hear equally on both sides

louder on effected side of conductive problem

louder on normal side if sensinoral problme

Rinne’s test can confirm which

Question 32

what is the rinne test

Answer 32

vestibulocochlear nerve

place heel of vibrating tuning fork on mastoid process - this is sound 1, when sound stops

place prongs of vibrating tuning fork at external auditory meatus - this is sound 2, should be able to ehar it again

'’which was louder sound 1 or 2’’

repeat for other ear

rinne +ve (which is normal) - air conduction = louder

if bone louder might be conductive hearing loss

Question 33

test glossopharyngeal

Answer 33

sensory - posterior 1/3 tongue

say ahh - test for palate raise symettrically - deviates away from lesion

motor - elevation of pharynx swallowing

'’have you noticed any issues with swallowing or changes to your voice or cough’’

tested with vagus

'’i would also test for gag reflex’’

Question 34

test vagus

Answer 34

open mouth and say ‘ahh’

inspection - soft palate should raise symettrically

please cough

take small sip of water

gag reflex

tested with glossopharyngeal

Question 35

test accessory nerve

Answer 35

inspect muscles for wasting

shrug shoulders against resistance - trapezius

turn your head and resist me - SCM (when turning head to R - testing for L SCM)

Question 36

test hypoglossal

Answer 36

extrinsic tongue muscles

please open mouth

inspect for wasting and fasiculations - LMN lesion ie bulbar palsy)

stick tongue straight out - observe for any deviation towards lesion

move tongue from side to side - check strength by resisting tongue pressed into cheek

Question 37

to complete

Answer 37

thank pt

'’i would do full upper and lower limb neuro exam’’

summarise and suggest further investigations