cn exam

Question 1

PURE SENSORY

Answer 1

I – Olfactory
II – Optic
VIII – Vestibulo-cochlear

Question 2

PURE MOTOR

Answer 2

IV – Trochlear
VI – Abducens
XI – Accessory
XII – Hypoglossal

Question 3

MIXED NERVES

Answer 3

III – Occulomotor
V – Trigeminal
VII – Facial
IX – Glossopharyngeal
X - Vagus

Question 4

cn 1 test

Answer 4

rarely tested
each nostril tested sep (block the other) pt eye closed
easily identify smells
affected by local conditions eg chronic rhinitis
just mention

Question 4

cn 3,4,6 test

Answer 4

inspect eyelid- ptosis/drooping
insp pos of eyeball at rest & pres of squint/strabismus, invol mvnt/nystagmus
vol eye mvnt - instructed and pursuit- H
accom (cil m contr, eyes converge, pupil contr) and light refs

Question 4

cn 2 test

Answer 4

inspect pupil size, shape, symm, pos
1. distant- snellen chart, near- jaeger/newspaper
2. visual fields- periph- confrontation test, central- red pin head
3. papil light ref- direct and consensual
4. mention fundoscopy

Question 5

cn 5 test

Answer 5

light t and pain comparison bilat on 3 sesnory divs eyes closed
motor comp- clench teeth check strength and m bulk
ask to open mouth, move left right, open close against res
corneal ref
jaw jerk ref
mention gen sesns ant 2/3 of tongue

Question 6

cn 7 test

Answer 6

insp symm of face at rest and pres of naso lab folds
motor function- wrinkle forehead, shut eyes tightly against res, blow out cheeks, smile, show teeth notice deviation in mouth (test strength)
whistle test
mention taste on ant 2/3 tongue

Question 6

cn 8 test

Answer 6

whisper behind pt
rhinne test bilat and compare
weber test
test for nystagmus - vestib function

Question 7

cn 9,10 test

Answer 7

note voice, ask pt to swallow
open mouth and visualize uvula and soft pal at rest then say ah to det symm mvnt

mention gen sens post 1/3 tongue
mention gag ref

Question 7

cn 11 test

Answer 7

obs pt head, asym
trap and scm wasting
test trap - shrug against res
test scm - turn head side to side against res

Question 8

signs of brain stem injury

Answer 8

coma, irregular breathing, fixed dilated pupils, loss of occulovestibular reflexes

Question 8

cn 12 test

Answer 8

obs tongue for wating, asym, fascic,
obs active mvnt of tongue:
protruding note and dev
r - l test power again res of cheeks

Question 9

pupil light ref

Answer 9

Check direct light response (same side)
Check consensual response (opp side rxn)
Repeat with opposite eye
Best to do in dimmed light
Afferent limb is optic nerve, processing in superior colliculus (midbrain) and efferent limb is oculomotor nerve (CN III)

Edinger westphal nuc sends motor signals for reflex action through eff cn III

Question 10

confrontational test

Answer 10

Sit at arm’s length directly in front of the patient, with your head level with his
Patient to cover one eye and look directly at the examiner while examiner stretches out his right arm so that the hand is halfway between himself and the patient
Move the index finger in the outer part of each quadrant viz upper temporal, lower temporal, upper nasal, lower nasal fields
Patient to indicate if he sees the movement
Repeat for opposite eye
Also test patient with both eyes open – examiner’s hands outstretched – move index fingers and ask patient if one or both are moving

Question 11

menace test

Answer 11

rapid movement from side of visual field to see if pt blinds

Question 12

testing central fields

Answer 12

Patient to cover one eye and look directly at the examiner
Use a red or white pinhead and move slowly and stepwise into the central field in a diagonal direction from the four main directions, asking if the patient can see the pinhead as you move it centrally
Attempt to detect and map central field loss
Only a gross abnormality may be detected

Question 13

Fundoscopy

Answer 13

Note colour, shape and presence of swelling of the optic disc

Question 13

LR6 SO4 AR3

Answer 13

lat rectus - cn 6 abd
sup obliq - cn 4 troch

all the rest - cn 3 occ

Question 14

cn3 palsy (the ds)

Answer 14

drooping eyelid
down and out eye
pupil dial (ps of pupil ref)

Question 15

cn6 palsy

Answer 15

medial at rest
cannot abduct
(sup obliq issue)

Question 16

jaw jerk

Answer 16

tap on open jaw with patella hammer
normally absent
increased in pseudobulbar palsy

Question 17

hyperacusis

Answer 17

senstivity to sound because of cn vii issue with stapedius m

Question 18

corneal ref

Answer 18

touch pt cornea from the side and normal resp is
aff v1 and eff vii
blink reflex bilat

Question 19

umn vs lmn cn vii issue

Answer 19

umn- at level of brain stem
lmn- at level of nucl or below

frontalis m receives bilat umn hence preservation of forehead function in umn

umn lesion- forehead is spared but lower face on opp side is aff
lmn - Bells palsy

Question 20

Bells palsy

Answer 20

LMN palsy
Affects whole side of face ipsilaterally

Question 21

cn x dysphonia and hoarsness

Answer 21

laryngeal path due to rec lar n damage

Question 21

mention sens of post tongue and gag

Answer 21

test sens with spatula on post phar wall and tonsillar fossa
gently trigger gag ref

Question 21

Rinne Test

Answer 21

Check bone conduction by placing a vibrating tuning fork (256Hz) over the mastoid process.
Ask patient if he can hear this (bone conduction/ BC) and to report when the sound disappears.
Then move the tuning fork to in front of the ear to check air conduction (AC). This should be better than bone conduction.
Repeat for opposite ear.
Middle ear deafness/ bone conduction deafness – BC>AC
Neural deafness – AC>BC therefore wont be able to diag because of equal loss on ac and bc (problem of innner ear or auditory n)

Question 21

Weber Test

Answer 21

Place vibrating tuning fork over mid forehead. Ask patient to report in which ear the sound is heard or “all over”.
In Rt-sided neural deafness, sound will be localised to the left ear
In Rt-sided middle ear deafness, sound will be louder in the right ear

Question 22

webber test middle ear deafness

Answer 22

In Rt-sided middle ear deafness, sound will be louder in the right ear

Question 22

webber test neural deafness

Answer 22

In Rt-sided neural deafness, sound will be localised to the left ear