Introduction to the
Neurologic Examination
Focus on Cranial Nerves
Objective
1. Describe the components of a screening
Neurological Examination with an emphasis on
Cranial Nerves
“The Neurological Exam is
So Complicated!”
1. Because students find it hard to remember
what to do
2. Because students are not sure what they are
looking for
3. Because students do not know how to
describe what they find
G. Fuller
Dr. Heather MacLean
With practice the goal is to perform
a neurologic examination with…
• Strategic Efficiency!
• By
• Knowing what CAN be tested
• Having a systematic approach
• Following the localization clues on history and physical to
focus you exam where you will most likely yield findings
• Understanding how abnormal findings can lead you to the
lesion
Dr. Heather MacLean
Types of Examination
Complete
Virtually endless
Virtually impossible
Focused
Detailed, Specific,
to Test hypotheses
Screening
Efficient, Global view,
Somewhat Superficial
Dr. Heather MacLean
Eg: CN VII Screening
• When
• When you don’t particularly suspect a CN VII
lesion will be found
• Inspect face :
• Smile
• Raise eyebrows
Dr. Heather MacLean
Oh ya, I forgot to tell you... I
had right sided Bell’s palsy 2
months ago and it’s still not yet
back to normal
Dr. Heather MacLean
Eg: CN VII Focused
• When ?
• CN VII lesion suspected by history
• Facial weakness noted on screening
• Neighboring structures involved (CN 5 or 8)
• What tests ?
• Additional muscles: orbicularis oculi, orbicularis oris, platysma,
buccinator
• Consider salt/sweet taste test
• Test neighboring structures (CN 8, cerebellum, CN 5)
Dr. Heather MacLean
Eg: CN VII Complete
Special visceral frontalis,corrugator,
orbiculoris &ocul.
efferent
Buccin.,platysma
stapedius
inspect facial muscles
> 8 maneuvers
e.g. raise eyebrows
smile, frown,etc.
General visceral lacrimal gland
inspect eye
submandigular gland Schirmer test
efferent
Special visceral taste buds
anterior 2/3 tongue
afferent
test taste
salt, sugar, acetic a.
& quinine solutions
General somatic external ear
afferent
test light touch
in post ext. ear canal
Dr. Heather MacLean
The Neurologic Exam
1.
Mental status exam
2.
Cranial nerves
3.
Motor
4.
Coordination
5.
Sensory
6.
Reflexes
7.
Stance & Gait
8.
(“Extras”)
Dr. Heather MacLean
Focus On The Cranial Nerves
Origins of the Cranial Nerves
• CN I & II – cerebrum
• CN III & IV – from midbrain
4
• CN V-VIII – from pons
4
• CN IX-XII – from medulla
4
General Functions of the
Cranial Nerves
• 3 are purely sensory
• 5 are purely motor
• 4 are mixed
Individual Functions of the
Cranial Nerves
• I Smells
• II Sees
• IX Tastes, salivates,
swallows, monitors carotid
body and sinus
• III,IV,VI Moves eyeballs
around, constricts the pupil
and accommodates
• X Tastes, swallows, lifts
palate, talks, regulates
thoraco-abdominal organs
• V Chews and feels the face
• XI Turns head, lifts
shoulders
• VII Moves the face, tastes,
salivates, cries
• VIII Hears, balance
• XII Moves tongue
Blue: sensory nerve
Red: motor nerve
Black: mixed nerve
CN I Olfactory Nerve (Smell)
Rarely Tested unless is a complaint
Dr. Heather MacLean
CN II Optic Nerve (Vision)
• Visual acuity
• Snellen chart or
• Hand-held card (Rosenbaum)
• Visual fields
• Pupillary Responses
• Ophthalmoscopy
Dr. Heather MacLean
Visual Fields by Confrontation
Dr. Heather MacLean
Testing colour vision
Dr. Heather MacLean
Pupillary reflex testing
•
Afferent CN II
•
Efferent CN III
•
Eyes looking in the distance
• Are the pupils symmetric? Look for Anisocoria
• What size? Look for Miosis or Mydriasis
•
Use a bright light
• Test reactivity of the direct and consensual responses
• Perform a ‘swinging flashlight test’
•
Test accomodation
Dr. Heather MacLean
CN III, IV, VI
(Extraocular Movements)
• “6 is out , 4 is down & in , all the rest is 3”
Dr. Heather MacLean
Extraocular Movements
CN V Trigeminal Nerve
(Facial Sensation)
CN VII Facial Nerve
(Facial Movement)
Dr. Heather MacLean
CN VIII Vestibulocochlear
• Test auditory acuity (finger rub)
• If abnormal, or if CN 8 disorder suspected:
• Otoscopy
• Weber
• Rinne (Normally air conduction > bone conduction)
• Vestibular tests
• Dix-Hallpike test
Dr. Heather MacLean
Weber Test
• Conductive hearing loss
• Sound localizes to affected
ear
• Sensorineural hearing loss
• Sound localizes to nonaffected ear
CN IX & X
• Is there dysphonia?
• Assess palatal movement with phonation
• IF there is dysphagia, dysphonia, dysarthria of
palate:
• Test gag reflex
• Afferent IX
• Efferent X
Dr. Heather MacLean
CN XI Spinal Accessory
Nerve
• Two muscles:
• trapezius: shoulder shrug ; abduction of arm beyond 90
degrees
• sternocleidomastoid: turn chin to opposite shoulder
• REMEMBER:
• The left SCM turns the head to the right
• And vice versa
Dr. Heather MacLean
CN XII Hypoglossal
• Inspect tongue at rest
• atrophy, fasciculations
• Tongue protrusion
• deviation towards paretic side
Dr. Heather MacLean
Screening Exam of the CNs
1 : not tested
2 : VA, fundoscopy, finger counting fields (& simult)
3,4,6 : vertical & horizontal eye movements, pupils
5 : Fine touch on face
7 : show teeth, raise eyebrows
8 : acuity (finger rub)
9,10 : observe palatal movement
11 : turn head & shrug shoulders
12 : protrude tongue
Dr. Heather MacLean
I need a volunteer from the
audience
Dr. Heather MacLean