Cranial Nerve Exam

By Dr. Julie Gilmour

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Demonstration

Prior to Exam

  • Hand hygiene, introduce self, informed consent, exposure & draping
  • Pituitary specific cranial nerve exam – nerves which run in close proximity to the pituitary gland (ie. optic chiasm and cavernous sinus)

CN 2

  • Assess visual acuity with Snellen Chart
    • At 20 feet (using corrective lenses).
    • Count fingers/light perception if cannot read top line on Snellen chart
  • Fundoscopic examination for signs of increased ICP
    • Optic disc pallor from pressure on optic nerve (most common)
    • Papilloedema – loss of optic disc margins and absence of retinal vein pulsations, exudates (late and uncommon presentation)
  • Visual field assessment by confrontation
    • Physicians head should be level with the patient’s head
    • Ptn stares at examiners nose. Test one eye at a time (cover the opposite one)
    • Use white or red (preferable as the colour field is smaller than for white) tipped pin – and brought inward in 4 quadrants of vision
      • Screening examination can be done with fingers (crude)
    • Ptn notifies examiner when they can see the object
    • Bitemporal hemianopia = lesion that affects inferior aspect of optic chiasm
      • Superior quadrantic defects are the earliest visual losses
  • Ishihara plates (if unable to read numbers – either abnormal optic nerve function or red-green colour blind)
  • Red Desaturation (ask colour of a red object)

CN 3, 4, 6

  • Pupil
    • Assess for response to light and accommodation
    • Assess for RAPD with swinging flashlight test
  • Assess EOM
    • Patient instructed to keep head still and follow physician’s finger with their eyes
    • Physician moves finger in a “H” pattern
      • Ask patient to report if they have any double vision
    • SO4, LR6 (the remaining are CN3 – SR, IR, IO, MR)
  • Eyelid
    • 3rd nerve palsy also includes ptosis and dilated pupil

CN V1 & V2

  • Corneal reflex
    • Afferent is V1, efferent is VII
  • Facial sensation in three divisions of the nerve
    • Dull pin & cotton wool
    • Ptn is instructed to say “yes” when they feel it touching them (eyes closed)

Completion of full CN examination

  • Assessment of CN 1, V3, 7-12
  • Physician should also perform screening neurological exam of the upper and lower limbs

References: Clinical Examination 6th ed: Talley & O’Connor, 2010.