CRANIAL NERVES II-XII

Ever wondered what is tested when they say "cranial nerves II-XII are intact"?

Nervous: Cranial Nerves Exam

1. Setup

2. I: Olfactory

3. II: Optic

4. III-IV-VI: extraoculars

5. V: Trigeminal

6. VII: Facial

7. VIII: Vestibulocochlear

8. IX-X: Glossopharyngeal, Vagus

9. XI: Accessory

10. XII: Hypoglossal

Setup

• Patient sitting over edge of bed.

CN I: Olfactory

• Usually not tested.
• Rash, deformity of nose.
• Test each nostril with essence bottles of coffee, vanilla, peppermint.

CN II: Optic

• With patient wearing glasses, test each eye separately on eye chart/ card using an eye cover.
• Examine visual fields by confrontation by wiggling fingers 1 foot from pt's ears, asking which they see move.
  • Keep examiner's head level with patient's head.
• If poor visual acuity, map fields using fingers and a quadrant-covering card.
• Look into fundi.
• For more detail, See Eye Exam.

CN III, IV, VI: Oculomotor, Trochlear, Abducens

• Look at pupils: shape, relative size, ptosis.
• Shine light in from the side to gauge pupil's light reaction.
  • Assess both direct and consensual responses.
  • Assess afferent pupillary defect by moving light in arc from pupil to pupil. unne). Optionally: as do arc test, have pt place a flat hand extending vertically from his face, between his eyes, to act as a blinder so light can only go into one eye at a time.
• "Follow finger with eyes without moving head": test the 6 cardinal points in an H pattern.
  • Look for failure of movement, nystagmus [pause to check it during upward/ lateral gaze].
• Convergence by moving finger towards bridge of pt's nose.
• Test accommodation by pt looking into distance, then a hat pin 30cm from nose.
• If MG suspected: pt. gazes upward at Dr's finger to show worsening ptosis.

CN V: Trigeminal

• Corneal reflex: patient looks up and away.
  • Touch cotton wool to other side.
  • Look for blink in both eyes, ask if can sense it.
  • Repeat other side [tests V sensory, VII motor].
• Facial sensation: sterile sharp item on forehead, cheek, jaw.
  • Repeat with dull object. Ask to report sharp or dull.
  • If abnormal, then temperature [heated/ water-cooled tuning fork], light touch [cotton].
• Motor: pt opens mouth, clenches teeth (pterygoids).
  • Palpate temporal, masseter muscles as they clench.
• Test jaw jerk:
• Dr's finger on tip of jaw.
• Grip patellar hammer halfway up shaft and tap Dr's finger lightly.
• Usually nothing happens, or just a slight closure.
• If increased closure, think UMNL, esp pseudobulbar palsy.

CN VII: Facial

• Inspect facial droop or asymmetry.
• Facial expression muscles: pt looks up and wrinkles forehead.
  • Examine wrinkling loss.
  • Feel muscle strength by pushing down on each side [UMNL preserved because of bilateral innervation].
• Pt shuts eyes tightly: compare each side.
• Pt grins: compare nasolabial grooves.
• Also: frown, show teeth, puff out cheeks.
• Corneal reflex already done. See CN V.

CN VIII: Vestibulocochlear (Hearing, Vestibular rarely)

• Dr's hands arms length by each ear of pt.
  • Rub one hand's fingers with noise on one side, other hand noiselessly.
  • Ask pt. which ear they hear you rubbing.
  • Repeat with louder intensity, watching for abnormality.
• Weber's test: Lateralization
  • 512/ 1024 Hz [256 if deaf] vibrating fork on top of patients head/ forehead.
  • "Where do you hear sound coming from?"
  • Normal reply is midline.
• Rinne's test: Air vs. Bone Conduction
  • 512/ 1024 Hz [256 if deaf] vibrating fork on mastoid behind ear. Ask when stop hearing it.
  • When stop hearing it, move to the patients ear so can hear it.
  • Normal: air conduction [ear] better than bone conduction [mastoid].
• If indicated, look at external auditory canals, eardrums.

CN IX, X: Glossopharyngeal, Vagus

• Voice: hoarse or nasal.
• Pt. swallows, coughs (bovine cough: recurrent laryngeal).
• Examine palate for uvular displacement. (unilateral lesion: uvula drawn to normal side).
• Pt says "Ah": symmetrical soft palate movement.
• Gag reflex [sensory IX, motor X]:
  • Stimulate back of throat each side.
  • Normal to gag each time.

CN XI: Accessory

• From behind, examine for trapezius atrophy, asymmetry.
• Pt. shrugs shoulders (trapezius).
• Pt. turns head against resistance: watch, palpate SCM on opposite side.

CN XII: Hypoglossal

• Listen to articulation.
• Inspect tongue in mouth for wasting, fasciculations.
• Protrude tongue: unilateral deviates to affected side.