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Cranial Nerve Exam

Feb 07, 20245 min read

Introduction

  • Wash hands (and don PPE if needed)
  • Introduce yourself (name and role)
  • Confirm patient’s name and DOB
  • Explain what the examination involves
  • Gain consent to continue
  • Ask if patient in any pain before continuing

General Observation

  • Conscious level

  • Speech slurring

  • Facial asymmetry

  • Problem with eyelids

  • Obvious limb weakness

  • Walking aids

  • Hearing aids

  • Visual aids

Olfactory Nerve (1)

  • Have You Noticed Any Change in Smell?

Optic Nerve (2)

Have you ever had any problems with your vision or noticed any changes?

Do you wear glasses?

Snellen Test
  • Ensure that the patient is wearing glasses if normally does so
  • Ask patient to cover one eye
  • Ensure patient is correct distance (6m effective) away
  • Move closer (3m) if unable to read at 6m
Visual Fields
  • Ask patient to cover one eye
  • Ask patient to let you know when they can see the finger
  • Ensure the finger is in the mid line
  • Test 4 quadrants of field and repeat on other eye Could also perform visual inattention and blind spot test
Fundoscopy
  • Offer to do
  • Red reflex - absent may indicate cataract
  • Make sure your left eye is looking into their left eye to avoid complete face to face positioning!
  • Follow arteries towards the optic disc - they usually branch in a way to form arrow shapes that point towards the optic disc
  • Find 4 vessels and look in each quadrant
Check Pupil Size and Alignment
Check Pupillary Reflexes
  • Direct and consensual
  • Issues with direct reflex - CN2 lesion
  • Issues with consensual reflex - CN3 lesion
Accommodation
  • Move finger towards nose of patient and watch for eyes - both pupils should constrict as the eyes converge
Say You Would Assess Colour Using Ishihara Chart

Oculomotor (3), Trochlear (4) and Abducens (6)

H Finger Follow Test
  • Ask patient to follow finger for eyes
  • On lateral movement go a bit further than what the patient can do and watch for nystagmus
  • Eye cannot move in and down - CN4 lesion (superior oblique)
  • Eye cannot move laterally - CN6 lesion (lateral rectus)
  • Eye cannot move in other directions - CN3 lesions (other intraocular muscles)

Trigeminal (5)

Fine touch Sensation
  • Get some cotton wool
  • Give patient reference of what it will feel like somewhere other than their face
  • Tell them to say when they can feel it
  • Test all divisions of trigeminal on both sides
Course touch
  • Repeat with a neurotip instead of cotton wool
Assess Muscles of Mastication
  • Feel for temporalis & masseter muscles for atrophy
  • Ask for jaw to be open and for it to resist closing it
? Corneal reflex
  • Small touch on corneal with cotton to elicit blink
  • CN 5 afferent CN 7 efferent
? Jaw Jerk
  • Ask patient to relax jaw
  • Place finger on mentalis muscle and hit with tendon hammer
  • Exaggerated jerk is bad usually to side of lesion

Facial Nerve (7)

Facial Expression Assessment

Check for symmetry each time

  • Ask patient to raise eyebrows and don’t let me push them down - frontalis
  • Scrunch up eyes and don’t let me open them - orbicularis oculi
  • Smile and show teeth and then purse lips - orbicularis oris
  • Puff out cheek and don’t let me get any air out - buccinators

Vestibulocochlear (8)

Have You Been Hearing Sounds Louder than Usual?
Whispering Hearing Test

Explain to patient that you are going to go behind them and whisper a number and you want them to repeat what they heard

  • Assess at 15cm and 60cm
  • Test one ear at a time
  • Whisper a number and check patient response is the same
Rinne’s Test

To test whether bone conduction is louder than air conduction. Conduct test on both ears

  • Ask patient if they can hear the vibrating tuning fork help at the entrance to the ear canal.
  • Then place the vibrating fork on the mastoid process
  • Then ask which is loudest

In normal hearing the test is positive - and air conduction is louder than bone conduction

Weber’s Test

Used in conjunction with Rinne’s test to rule out unilateral deafness

  • Place tuning fork in the centre of the patient’s forehead and ask whether they can hear this equally on both sides or more on one side.
  • If its louder in one ear it could mean either an ipsilateral conductive hearing loss or contralateral sensorineural hearing loss

Glossopharyngeal (9)

  • Have you experienced any changes in taste?
? Gag reflex
  • Offer to do
  • Touch posterior pharynx on either side
  • CN 9 is afferent CN 10 is efferent

Vagus (10) and Hypoglossal (12)

While you have the light in your hand might as well assess other things that require it

  • Ask patient to open their mouth and say ahh - palate should rise equally (vagus) - uvula deviates away from lesions
  • Ask patient to stick out their tongue and move side to side (hypoglossal) - deviation towards lesion

Accessory Nerve (11)

Test Power of Shoulder Shrug and Neck Turning

Accessory supplies trapezius and sternocleidomastoid muscles

End Pieces

  • Peripheral nerve exam
  • MRI/CT head
  • LP

To Complete the Exam

  • Explain to the patient that the examination is now finished.
  • Thank the patient for their time.
  • Dispose of PPE appropriately and wash your hands.
  • Summarise your findings.

Graph View

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