Cranial nerves examination

1. Dr. Abeer Abdulkareem

2. Neurological examination framework
The neurological examination can be complex and lengthy. The following is a
brief outline of an approach to a ‘full’ neurological examination.
• Inspection, mood, conscious level
• Speech and higher mental functions
• Cranial nerves II–XII
• Motor system
• Sensation
• Coordination
• Gait
• Other relevant examinations: Skull, spine, neck stiffness, ear drums.

3. The neurological exam should start with any clues that can be gleaned from
simply looking at, and engaging with, the patient.
• Do they use any walking aids or other forms of support?
• Any abnormal movements?
• Observe the gait as they approach the clinic room, if able.
• Any speech disturbance?
• What is their mood like? Ask the patient how they feel
What is the state or their clothing, hair, skin, and nails? Are they obviously depressed ?
Speech:
Dysarthria: A defect of articulation
Dysphonia: Defective volume
Dysphasia: This is a defect of language, not just speech, so reading and writing may also
be affected
General appearance

4. General inspection
Conscious level

6. Gather equipment
• Pen torch
• Snellen chart
• Ishihara plates
• Cotton wool
• Neuro-tip
• Tuning fork

7. General inspection
o General appearance
o Obvious facial asymmetries?
o Position of eyes – normal alignment/strabismus
o Ptosis (drooping of the upper eyelid)
o Abnormality of speech or voice – dysarthria

8. Cranial nerve I: olfactory
oNot routinely tested unless the patient complains of a loss of sense of smell (anosmia)
o“Have you noticed any recent change in your sense of smell?”
o Casual: take a nearby odorous object (e.g. coffee or chocolate) and ask the patient if
it smells normal.
o Formal: a series of identical bottles containing recognizable smells are used. The
patient is asked to identify them.
o Commonly used agents: coffee, vanilla, vinegar.
oTest each nostril separately and determine if any loss of smell is unilateral or
bilateral.

9. Cranial nerves II (optic) nerve
The examination of the II (optic) nerve for:
• Visual acuity.
• Visual fields.
• The pupils.

10. Cranial nerves II
Visual acuity.
Assessment of visual acuity using Snellen chart.
Color vision
Assess color vision using Ishihara charts
(unlikely to do this in an OSCE setting)

11. Visual fields
Sit directly facing the patient, approximately one meter away.
1. Ask the patient to cover their left eye with their left hand.
2. You should cover your right eye and be staring directly at the patient .
3. Ask the patient to look into your eye and not move their head or eyes.
4. Ask the patient to tell you when they can see your fingertip moving.
5. Position your fingertip at the outer border of one of the quadrants of your visual field.
6. Slowly bring your fingertip inwards, towards the center of your visual field until the
patient sees it.
7. Repeat this process for each quadrant – at 10 o’clock /2 o’clock / 4 o’clock / 8 o’clock.
8. Repeat the same assessment process on the other eye.

12. The pupils:
Inspect pupils
Size ,Shape and Symmetry
Relative Afferent pupillary defect (RAPD)
• Light shining into an eye will lead to constriction of the ipsilateral pupil,
the ‘direct’ reflex and constriction of the contralateral eye, the ‘consensual’
reflex.
Near reflex (accommodation reflex)
Looking at a near target activates the ‘near reflex’ which comprises
accommodation, convergence, and miosis.

13. Cranial nerves III, IV, and VI
The examination of the III (oculomotor), IV (trochlear), and VI (abducens)
Examining eye movements
1. Hold your finger about 30cm directly in front of the patient’s eyes and ask
them to look at it. Look at the eyes in the primary position for any deviation
or abnormal movements.
2. Ask the patient to keep their head still and follow your finger with their eyes.
3. Ask the patient to report any double vision.
4. Move your finger through the various axes of eye
movement (“H” shape).
5. Observe for restriction of eye movement
and note any nystagmus.

14. Cranial nerve V: trigeminal
Inspection
Inspect the patient’s face—wasting of the temporalis will show as
hollowing above the zygomatic arch.
Testing motor function
• Ask the patient to clench their teeth and feel both sides for the bulge
of the masseter and temporalis.
• Ask the patient to open their mouth wide—the jaw will deviate
towards the side of a V lesion.
• Again ask them to open their mouth but provide resistance
by holding their jaw closed with one of your hands.

15. Testing sensory function
• Distribution of the sensory branches of the trigeminal nerve.
V1 = ophthalmic, V2 = maxillary, V3 = mandibular.
• Assess light touch for each branch and ask the patient to say
‘yes’ if
they can feel it.
• Choose three spots to test on each side to make the examination
easy to remember—forehead, cheek, and mid-way along jaw.
• For each branch, compare left to right.
• Test pin-prick sensation at the same spots using a sterile pin.
• Temperature sensation is not routinely tested—consider only if
abnormalities in light touch or pin-prick are found. Use specimen
tubes or other small containers full of warm or cold water.

16. Jaw jerk
• Explain to the patient what is about to happen
• Ask the patient to let their mouth hang loosely open.
• Place your finger horizontally across their chin and tap your finger
with a hammer.
• Feel and watch jaw movement.
• There should be a slight closure of the jaw but this varies widely in
normal people.

17. Corneal reflex
• Ask the patient to look up and away from you.
• Gently touch the cornea with a wisp of cotton wool
• Bring this in from the side so it cannot be seen
approaching.
• Watch both eyes. A blink is a normal response.

18. Cranial nerve VII: facial
Muscles of facial expression
• Look at the patient’s face at rest. Look for asymmetry in the nasolabial folds,
angles of the mouth, and forehead wrinkles.
• Ask the patient to raise their eyebrows (‘look up!’) and watch the forehead
wrinkle.
• Attempt to press their eyebrows down and note any weakness.
• Ask the patient to ‘close your eyes tightly’. Watch, then test against resistance
with your finger and thumb. ‘Don’t let me pull them apart.’
• Ask the patient to blow out their cheeks. Watch for air escaping on one side.
• Ask the patient to bare their teeth. ‘Show me your teeth!’ Look for asymmetry.
• Ask the patient to purse their lips. ‘Whistle for me!’ Look for asymmetry.

19. Taste
This is rarely tested outside specialist clinics.
• Each side is tested separately by using cotton buds dipped in the
solution of choice applied to each side of the tongue in turn. Be sure
to swill the mouth with distilled water between each taste sensation.
• Test: sweet, salty, bitter (quinine), and sour (vinegar).

21. Cranial nerve VIII: vestibulocochlear
Enquire first about symptoms—hearing loss/changes or balance
problems.
Begin by inspecting each ear.
Hearing
Test each ear separately. Cover one by pressing on the tragus.
Simple test of hearing
• Whisper a number into one ear and ask the patient to repeat it.
• Repeat with the other ear.
• Be careful to whisper at the same volume in each ear and at
the same distance (about 60cm).

22. Rinne’s test
• Tap a tuning fork and hold adjacent to the ear (air conduction).
• Then apply the base of the tuning fork to the mastoid process (bone conduction).
• Ask the patient which position sounds louder.
• Normal = air conduction > bone conduction = ‘Rinne’s positive’
• In neural deafness, Rinne’s test will remain positive
• In conductive deafness, the findings are reversed (bone > air).
Weber’s test
• Tap a tuning fork and hold the base against the vertex or forehead at the midline.
• Ask the patient if it sounds louder on one side.
• In neural deafness, the tone is heard better in the intact ear
• In conductive deafness, the tone is heard better in the affected ear.

23. Cranial nerves IX and X
Pharynx
• Ask the patient to open their mouth and inspect the uvula (use a tongue depressor
if necessary). Is it central or deviated to one side?
• Ask the patient to say ‘aah’. Watch the uvula. It should move upwards centrally.
Does it deviate to one side?
Gag reflex
This is unpleasant for the patient and should only be tested if a IX or X nerve lesion
is suspected (afferent signal = IX, efferent = X).
• With the patient’s mouth open wide, gently touch the posterior pharyngeal wall on
one side with a tongue depressor.
• Watch the uvula (it should lift up).
• Repeat on the opposite side.

24. Cranial nerve XI: accessory
• Applied anatomy
• Sensory: none
• Motor: sternocleidomastoids and upper part of trapezii
• Note that each cerebral hemisphere controls the ipsilateral
sternocleidomastoid and the contralateral trapezius.

25. Inspect the sternocleidomastoids.
Look for wasting, fasciculation, hypertrophy, and any abnormal head
position.
• Ask the patient to raise their shoulders and observe.
• Ask the patient to raise again, using your hands on their shoulders
to provide resistance.
• Ask the patient to turn their head to each side, first without and then
with resistance (use your hand on their cheek).
• Be sure to press against the patient’s cheek. Lateral pressure to the
jaw can cause pain and injury.

26. Cranial nerve XII: hypoglossal
Applied anatomy
Sensory: none
Motor: muscles of the tongue
Examination
• Ask the patient to open wide and inspect the tongue on the floor of the mouth.
Look for size and evidence of fasciculation.
• Ask the patient to protrude the tongue. Look for deviation or
abnormal movements.
• Ask the patient to move the tongue in and out repeatedly, then side to side.
• To test for weakness, place your finger on the patient’s cheek
and ask them to push against it from the inside using their tongue.