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
- while palpating the temporal and masseter muscles in turn, ask the patient to clench his teeth.
- Note the strength of muscle contraction.
- 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:
- Raise his eyebrows
- Close his eyes tightly so that you cannot open them – test his muscle strength by attempting to open them
- Show his teeth
- 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
- Test for lateralization
- 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.