Teaching Handout – Neurology – Cranial Nerves
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Things worth knowing for finals in black. Thorough and optional things in grey. For interest sake only
Cranial nerves in order
I smell
Have you noticed any change in smell?
II vision
Can you cover your left eye. Can you read my badge? What colour is it? (repeat with right
eye, 2nd line of badge)
II fields
Test peripheral vision in each quadrant out, moving inward. Test for neglect.
II +III pupils
Test pupils – direct, consensual and RAPD
III, IV, VI
- Note any obvious misalignment. If so – Look straight at me, using a piece of paper, cover
Eye mvmts
each eye in turn to see if it corrects (strabismus) or not (palsy).
Pursuit and
- Keep your head still, follow my finger with your eyes. Horizontal movement R then L any
palsies
double vision? and repeat R and L, holding at extremities looking for nystagmus. Repeat with
vertical mvmt.
Saccades
Move finger to one side, face on the other. Look at my finger, now at my face
V sens
Close your eyes. Can you feel this cotton wool? Touch. Same or different? Test forehead
(ophthalmic), front cheekbone (maxillary), jaw (mandibular). Repeat with pinprick. (sharp or
dull?)
V Motor
Feel over TMJ. Clench your jaw.. Open your mouth, keep it open. Press shut.
VII
(mimic these actions) Raise your eyebrows. Squeeze your eyes shut, don’t let me open them
.Test both. Blow your cheeks out. Give me a smile. Show me your teeth. Squeeze your
mouth shut, don’t let me open it. Test both sides.
VIII
Whisper number into ear whilst rubbing fingers on opposite side.
Bulbar
IX, X, XII
XI
Finishing
Stick your tongue out, move it from side to side.
Stick your tongue right out, say aaah. Pentorch - uvula/palatal deviation
(if there is a glass of water) can you take a sip and hold it in your mouth, and swallow.
Can you shrug your shoulders. Turn your face to the left. Don’t let me push it back. Turn your
face to the right. Don’t let me push it back.
To finish my exam, I would like to formally assess sense of smell, visual acuity, blind spot,
hearing and perform fundoscopy.
If there is a lesion, offer to test cerebellar function as well. (Posterior circulation stroke
syndromes/ Multiple sclerosis)
Notes:
1. Testing eye movements in a ‘cross’ shape rather than an H shape should give you all the information
you need. Some people say that complex gaze palsies elicit diplopia only at extremes of the ‘H’. As
such, if you do get a palsy that isn’t obviously III or VI, it is reasonable to then test further with an H,
otherwise cross should be fine.
2. When testing for diplopia, I usually just start, and confirm the patient is following my instructions, and
then I ask about double vision 2nd time round.
3. In testing sensation, I have been taught (and found) that the most sensitive test of nerve dysfunction is
an alteration, rather than absence of sensation. When asking patients whether they can feel the cotton
wool/pin, they will often say ‘yes’, but not tell you that it does feel different. Hence ‘same or different’ for
cotton wool and ‘sharp or dull’ for pinprick. You get both the positive confirmation that they have felt the
stimulus, and the added information of it’s quality.
4. When testing pinprick, I usually preface with the instruction ‘this is a pin, it feels sharp but won’t break
the skin’. Does it feel sharp?
VI Nerve
Lateral rectus (and levator palpebrae)
Failure of abduction
Causes:
1. Brain stem lesion
Infarction
tumor
abscess
2. Compressive lesion in peripheral course
tumor
abscess
aneurysm (VI nerve runs along ICA)
3. Demyelination (MS)
4. Mononeuritis
5. False localising sign
CRN nuclei in the pons:
(like the Steps song…)
5,6,7,8
VI and III palsies can be false localising
signs in intracerebral herniation as the
brainstem is pushed downwards - the VI
nerve has the longest course and is
‘stretched’, and the III is compressed by the
herniating brain through the tentorium
Complex Opthalmoplegia
(Opthalmoplegia not consistent with a single cranial nerve lesion) Myasthenia
Gravis
Graves Disease (Thyroid)
Mitochondrial Cytopathies (eg. Kearns Sayre)
Fisher variant Guillain Barre
Retroorbital lesion / mass /carvernous sinus thrombosis