Cranial Nerve Assessment

 

First Cranial Nerve – Olfactory:

  • ensure both nasal passages are patent
  • test nostrils separately by occluding the opposite side
  • Unilateral loss of smell without nasal disease suggests frontal lobe lesion

 

Second Cranial Nerve – Optic:

  • Test visual acuity
  • inspect the optic fundi ophalmoscopically
  • determine the visual fields by confrontation

 

Third, Firth and Sixth Cranial Nerves;

Occulomotor, Trochlear and Abducens

  • Test the pupillary reactions and extraocular movements
  • Identify ptosis and nystagmus

 

Fifth Cranial Nerve – Trigeminal

Motor:

  • while palpating the temporal and masseter muscles in turn, ask the patient to clench his teeth.
  • Note the strength of muscle contraction.

 

Sensory:

  • With the patient’s eyes closed, test the forehead, cheeks and jaw bilaterally for sensation of pain.
  • Use the blunt end of a safety-pin to test reliability and the sharp end to assess pain
  • if abnormalities are found, confirm this with a test of temperature sensation.
  • Use two test tubes filled with hot and cold water, upon touching these to the patient’s skin aske them to identify “hot” or “cold”
  • Test “light touch” using a fine wisp of cotton, ask the patient to respond whenever you touch his skin

 

The Corneal reflex:

  • ask the patient to look up
  • approach from the side and avoid eyelashes
  • touch the cornea and not the conjunctiva lightly with the cotton tip
  • The use of contact lenses may diminish or abolish the corneal reflex.
  • Note tearing and blinking

 

The Seventh Cranial Nerve – Facial:

  • Inspect the face both at rest and during conversation
  • note asymmetry
  • pay attention to the nasolabial folds and observe for tics or other abnormal movements.
  • Flattening of the nasolabial fold and drooping of the lower eyelid suggest facial weakness.

 

Ask the patient to:

  1. Raise his eyebrows
  2. Frown
  3. Close his eyes tightly so that you cannot open them – test his muscle strength by attempting to open them
  4. Show his teeth
  5. Smile
  6. Puff out his cheeks

 

Note the patient’s mouth will pull away from the paralyzed side while performing these facial expressions

Eighth Cranial Nerve – Acoustic

Assess hearing if hearing loss is present

  1. Test for lateralization
  2. Compare air and bone conduction

 

Ninth and Tenth Cranial Nerves – Glossopharyngeal Vagus

Ask the patient to say “ah” or yawn.

  • Observe the upward motion of the soft palate and uvula and the inward “curtain” movement of the posterior pharynx
  • identify asymmetry
  • stimulate the back of the throat and not the gag reflex
  • note any hoarseness of voice.

 

Palate and Uvula deviate away from the paralyzed side in a lsion of the vagus nerve.

Eleventh Cranial Nerve – Spinal Accessory.

  • Ask the patient to shrug his shoulders upward against your hand.
  • Note the strength and contraction of the trapezius muscles.
  • Ask the patient to turn his head to each side against your hand
  • Observe the contraction of the opposite sternomastoid and note the force of the movement against your hand.

 

Twelfth Cranial Nerve – Hypoglossal

  • Inspect the patient’s tongue as it lies in the flor of the mouth
  • note any fasciculations, fine twitching movements of the muscle bundles
  • Ask the patient to stick our his tongue
  • Note any asymmetry, deviation or atrophy
  • Ask the patient to stick out his tongue – note asymmetry, deviation or atrophy
  • Fasciculations and atrophy suggest lower motor neuron disease
  • The tongue wil deviate towards the paralyzed side.

Bates, Barbara. 1974. A Guide to Physical Examination. J.B. Lippincott Company, Toronto.

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