Cranial Nerve Examination (Upper CN – 1-4, 6)
UNILATERAL NERVE PALSIES
• Today I have been asked to check your cranial nerves. These are the nerves that supply your face and neck • Infection (HZV, CMV,
• Responsiveness + Orientated [“tell me how you got here today?”] syphilis, TB)
• Ischaemia – infarction
• Ptosis (drooping one/both eyelids = old age, 7th nerve palsy, Horner’s (ptosis + anhidrosis, myosis, anophthalmos)
GI • Raised ICP
• Proptosis / strabismus (misalignment/deviation of one/both eye)
• Trauma
• Facial asymmetry & facial drooping (salivation)
• Vascular (aneurysm)
• Obvious muscle wasting (Temporal)
• Alcohol wipe smell (test each nostril separately
o “Close eyes + cover one nose” “Describe to me what you smell”
CN I
o DDx (anosmia): Kallman URTI, smoking, ethmoid tumours, basal skull/frontal fracture, post pituitary surgery, congenital (eg. Kallmans syndrome),
meningioma of olfactory groove, infectious (meningitis)
• ENSURE YOU POSITION PATIENT AT EYE LEVEL!!
Acuity
• Cover one eye and read the smallest line you can
[snellan chart]
o If unable: ® “How many fingers” [CF] ® Hand movement [HM] ® Perception of Light (PL] ® NPL
• “Cover your own eye with one hand and then the other!”
• Cover your left eye with your left hand ® “look into my eye and say ‘yes’ when you see my finger moving”
• Repeat with coloured object (NARROWER visual field – cones located centrally in macula, rods peripheral)
Visual
Fields
(repeat other
eye)
CN 2
AFRO
CAP
Ishihara Plates:
• optic neuritis (loss of red, central scotoma, RAFD, unilateral vision loss + painful eye movements)
Colour vision
o DDx: MS, SLE, DM, sarcoidosis, Measles, mumps, syphillis, lyme disease
• Colour blindness: vit A deficiency / X-linked chromosome loss
• “Stare at point on the wall behind me ® now look at the red ball”
Accommodation
o Should see convergence of eyes
“Stare at a point behind me” ® Pen light from side and into eye slowly
• Check pupil size
Reflexes Pupil light reflex • Repeat x2 (see constriction in blinded eye (direct) and then the other (consensual))
(PEARL) Swing torch test
[Take glasses off]
[Check size, • If light shone on damaged eye (NO consensual response)
shape of pupil] • If light shone on bad eye ® good eye ® bad eye (appears to dilate)
• Bad eye = Marcus Gunn pupil is a relative afferent pupillary defect indicating a decreased pupillary
response to light in the affected eye
• Failure of accommodation ONLY è midbrain lesion or with cortical blindness.
Pathology • Absent light reflex ONLY è midbrain lesion (e.g. Argyll Robertson pupil of syphilis – accomodates but
does not react), a ciliary ganglion lesion (e.g. Adie’s pupil)
• Amsler grid è AMD
Definition Distribution vision Light reflex
Optic Disc Optic disc swelling due to None
Papilloedema Bilateral Huge blind spot
(Fundoscopy) raised ICP DDx: retinoblastoma,
*Say would do Inflammed or infarcted optic Scotoma ®
Optic neuritis Unilateral Reduced
nerve head blindness
• Do you have any double vision (diplopia) ?
• Pursuit Movements (tracking) ® smooth conjugate movement
CN 3 • Saccades “Look left then right” “up and down”
Eye movements o hypometric OR hypermetric/overshoot saccades
[Draw large H ] • Horizontal Nystagmus (MS or vascular lesion) 3 D’s -CN3 palsy:
o Vestibular lesion = nystagmus away from side of lesion Dilated pupils
Reflex types: Diplopia (down and out)
o Cerebellar lesion = nystagmus to side of lesion Divergent squint
1) pursuit
2) saccades • Vertical Nystagmus
CN 4 3) convergence o Midbrain lesion, floor of 4th ventricle
4)VOR o EtOH, phenytoin
Conjugate Gaze Palsy
LR6 = abduction
• Supranuclear palsies – bilateral vertical and horizontal gaze palsy
SO4 = depressor BUT reflex movement intact
in eye adduction
• PSP = Loss of vertical ® then horizontal gaze ® bilateral fixed
(head tilt away
unequal eyes but reflex eye movements intact
from lesion
CN 6 • Parinaud’s syndrome (Pseudo–Argyll-Robert)= Involuntary upward
dev of eyes + loss of vertical gaze = pinealoma, MS, vascular To exclude a CNIV lesion in context of 3rd nerve palsy, tilt head
• One and a half syndrome = horizontal gaze palsy + impaired to same side as the lesion à the affected eye will intort if
adduction CNIV intact)
, Cranial Nerve Examination (Lower CN – 5, 7-12)
“This is what the cotton wool/pin feels like” [Both sides of Head ® cheek ® jaw]
• Is it cold/hot or sharp/dull AND
• did it feel the same on both sides of the face?
Examine
Sensory division facial
of trigeminal sensation
V1 = ophthalmic [close
(sup. orbital) patients’
V2 = mandibular eyes]
(foramen
rotundum)
Dermatomes of the head and Facial sensation V, test all three Herpes zoster distribution of
neck divisions on each side the maxillary nerve
*Corneal Lightly touch cornea (not the conjunctiva) with cottonwool brought to the eye from side
reflex [Not
done] • No sensation = corneal ulceration / ACOUSTIC NERUOMA ( NO CN7 TO BLINK)
• (clench your teeth for me + relax): Feel for temporalis and masseter muscle wasting?
CN 5
Muscles of • (ask patient to bite down on wooden tongue depressor with molars): muscle strength
Motor division of mastication
trigeminal • (open your mouth – don’t let me close it): pterygoid muscle
V2 = maxillary • Jaw deviates to affected side
(foramen ovale)
Jaw Jerk Or • “Relax your jaw down slightly for me ® just going to tap tip of your chin/jaw lightly”
Masseter o è exaggerated jaw jerk = UMN lesion above pons [pseudobulbar palsy]
Reflex
Practise point:
The tongue and jaw
never lie ® always
point to side of lesion!
NB: schwannoma from CNVIII can compress adjacent CNV and CNVII nerves, brainstem and cerebellum
• Frontalis (temporal) = “Raise your eyebrows and don’t me push them down “è NO wrinkle (UMN lesion –
FOREHEAD SPARING)
• OBICULARIS OCULI (ZYGOMATIC) “Close eyes TIGHTLY as you can and don’t let me open them” è Bell’s LMN
Facial movements palsy: upward movement of the eyeball and incomplete closure of the eyelid
• BUCCINATOR (BUCCAL) “Puff cheeks and don’t let me push them in” è asymmetry (LMN lesion)
• ZYGOMATIC MUSCLE (ZYG + BUCCAL) “Smile and show me your teeth” è facial paralysis (cortical lesion)
• CERVICAL Platysma + occipitalis
Q “Any change in • CNVII (chorda tympani) has sensory fibres for taste from anterior 2/3 of tongue ® fibres reach brain via CNV
taste” • Unilateral loss of taste: middle-ear lesions involving the chorda tympani (CN7) or lingual nerve (CNV)
Q “Any change in • Stapedius supplied by VII è controls stapes è hyperacusis when damaged
hearing”
Central causes (pons, medulla, upper
cervical cord) = FOREHEAD SPARING
Ø vascular lesion,
CN 7 Ø tumour,
Ø syringobulbia.
Peripheral causes
Ø aneurysm, tumour,
Ø chronic meningitis.
Ø Trigeminal ganglion causes include
trigeminal neuroma, meningioma
fracture
