Cranial Nerve Examination

Cranial Nerves

Examination

Introduction

• Introduction, correct patient, consent, wash hands (WINDEC), any pain

• Adequate exposure

• End of the bed inspection

CN I-XII

• CN I - Any change to sense of smell (vanilla essence is rarely used)

• CN II (Eyes)

  • Visual acuity- ask about glassses, offer- Snellen chart + one eye at a time; with glasses on ask to tell the time of the clock (colour- Ishihara plates)

  • Visual fields - both eyes, left & right eye - central & peripheral 

  • Pupillary response to light- direct & indirect, RAPD- pupil dilates with light (CN II, III)

  • Offer fundoscopy (shouldn't have to do it)

• CN III, IV, VI- eye movements

  • Draw H,

  • Finger-palm: vertical/ horizontal

  • Accommodation response (look into distance then finger close)

• CN V

  • Fine touch V1, V2, V3; (near midline to avoid cervical nerves)

  • Jaw open- don't let me close mouth

  • Jaw Reflex- abnormal to close, normal: no response

• CN VII

  • Eye brows to ceiling, close eyes (attempt to open)

  • Puff cheeks, show teeth, purse lips (don't let me open mouth)

• CN VIII

  • Hearing b/l- whisper number + rub fingers together & ask to repeat

• CN IX, X

  • Open mouth, say arh- palatal movements

  • Cough

• CN XI

  • Neck rotation + resistance

  • Shrug shoulders + resistance

• CN XII

  • Tongue in mouth + movements

Functions not assessed: 

• Corneal reflex (V, VII)

• Gag reflex (IX, X)

• Sensation to pain and temperature

• Speech

Conclusion

Thank patient, help to re-dress, wash hands.

Cranial Nerve Functions

• CN 1- Olfactory: sensory- smell

• CN 2- Optic: Visual acuity (visual fields), pupillary sensory response

• CN 3- Oculomotor: motor eyelids, pupil constriction, eye muscles- inferior oblique; medial, superior and inferior rectus

• CN 4- Trochlear: motor- superior oblique

• CN 5- Trigeminal: sensation of face; motor- mastication

• CN 6- Abducens: motor- lateral rectus

• CN 7- facial: motor movements of face V1, V2, V3, anterior 2/3rd of tongue

• CN 8- vestibulo-cochlear: hearing & balance

• CN 9- glossopharngeal: posterior 1/3rd tongue, swallowing

• CN 10- Vagus: parasympathetic autonomic control of heart, lungs, 

• CN 11- accessory: motor- head and shoulder

• CN 12- hypoglossal: motor- tongue 

Signs

• RAPD- optic neuritis, glaucoma, macular degeneration, infection e.g. herpes

Conditions

• Oculomotor Nerve Palsy (Cranial Nerve III)- unilateral affected eye, fixed in down and out; ptosis +- mihydrosis

• Trochlear Cranial Nerve IV Palsy- inability to move affected eye inferior at ADDuction, head tilted

• Abducens Cranial Nerve VI Palsy- inability to ABDuct affected eye

• Bell's palsy: unilateral paralysis of all 3 segments of face

Complex Ophthalmoplegia

Multiple eye signs not fitting into one cranial nerve:

• Vasculitis, Lyme disease, Meningitis, Sarcoidosis

• Thyroid eye disease

• Myasthenia Gravis

• Myotonic Dystrophy

• Miller Fisher Syndrome

• Ophthalmoplegic Migraine- painful mononeuropathy that self resolves