Lecture 3.2: CNs (5%)

Question 1

1) How do you test the olfactory nerve?
2) What should you do after checking patency?
3) What is usually the result?
4) What is a good way to store materials for this test?

Answer 1

1) Present the patient with familiar but non caustic odors. (say, cinnamon + coffee)
2) Occlude one nostril and with the patients eyes closed present the smell
3) Normally they can at least perceive an odor, and will often get it right
4) Get a contact lens case and put a little of each substance in the two compartments. Spill-proof, small, and convenient

Question 2

What can cause abnormalities in olfactory nerve function? (6 things)

Answer 2

1) Chronic sinus conditions
2) Trauma
3) Smoking
4) Aging
5) Cocaine use
6) Parkinson disease

Question 3

1) What two things should you test to test CNII (optic)
2) What 3 conditions should be considered if there’s poor acuity?
3) What two things should you consider when the visual field is partially disrupted?

Answer 3

1) Test visual acuity as per HEENT exam and test Visual fields
2) Glaucoma, retinal emboli, optic neuritis
3) Consider nerve or optic tract lesions

Question 4

What 4 things should you test to test the oculomotor (CNIII) nerve?

Answer 4

1) Size and shape of pupils, comparing one side with the other
-Anisocoria = difference of more than 0.4 mm in diameter of one pupil compared to the other
2) Test pupillary reaction to light
3) Evaluate for ptosis
4) Evaluate EOM’s (external ocular muscles)
-CN III is involved in all but lateral deviation and inferior medial gaze

Question 5

1) What EOMs is CNIII (3) involved in?
2) Define anisocoria

Answer 5

1) All but lateral deviation and inferior medial gaze
2) A difference of more than 0.4 mm in diameter of one pupil compared to the other

Question 6

What two things should you test to evaluate CNs III, IV, VI (3, 4, 6)?

Answer 6

1) Evaluate the eye movements in all 6 cardinal directions
2) Evaluate for nystagmus, noting the direction of gaze in which it manifests (horizontal, vertical, rotary, or mixed)

Question 7

1) Binocular diplopia occurs in neuropathy of what 3 nerves?
2) When else may it occur?

Answer 7

1) 3, 4, and 6
2) In eye disorders from myasthenia gravis, trauma, thyroid ophthalmopathy

Question 8

What are the 4 directions of nystagmus?

Answer 8

Horizontal, vertical, rotary, or mixed

Question 9

1) How do you test the motor function of CNV?
2) What muscles are involved?
3) What should you suspect if there’s jaw deviation during opening?

Answer 9

1) Palpate muscles of mastication, having the patient clinch jaw or move to opposite sides
2) Masseter and lateral pterygoid
3) Weakness of that side

Question 10

A) How do you test the sensory function of CNV? What is the result when it’s affected?
B) What two things would follow up testing include?

Answer 10

A) Stroke forehead, cheeks, and lower face bilaterally, assessing for difference in sensation. Will be dulled on the affected side
-“Does it feel the same on both sides?”
B1) Semi-sharp object, testing ability to differentiate between sharp and dull sensation
B2) Ability to differentiate temperature with heated object

Question 11

1) Besides the motor test for CNV and the sensory CNV test, what else needs to be tested for that nerve?
2) Describe how this is done
3) What does a positive test indicate?

Answer 11

1) Corneal reflex (usually deferred)
2) Ask pt to look up and away and lightly touch cornea with cotton swab
3) Failure to blink both eyes indicates sensory deficit in CN V or motor deficit in CN VII

Question 12

What two things occur in acoustic neuroma?

Answer 12

Absent blinking AND sensorineural hearing loss

Question 13

1) What should you inspect for CN7?
2) What should you test for CN7?

Answer 13

1) Inspect face at rest and while speaking: assess muscle tone, looking for facial droop
2) Have patient do the following:
-Raise both eyebrows
-Make a happy face, frown
-Close both eyes tightly
-Try to open them
-Show both upper and lower teeth
-Puff out cheeks

Question 14

What is a crucial distinction to make when testing CN7? Explain why

Answer 14

1) Palsy of CN VII, called “Bells Palsy” will impair a patient’s ability to raise his/her eyebrows
2) A stroke will not: This is because these particular upper motor nerves are “double covered”

Question 15

What is palsy of CN7 called?

Answer 15

Bell’s palsy

Question 16

1) What is Chvostek Sign? What does it demonstrate?
2) How do you test it? What are you watching for?
3) What percent of patients have that reaction at baseline? What is it less specific than?

Answer 16

1) Hyperexcitability of the facial nerve; demonstrates hypocalcemia.
2) Tap pt’s face 2 inches ant. to external auditory meatus and watch pronounced twitch develop.
3) 10% of pts have this reaction at baseline; less specific than Trousseau’s, the BP cuff test

Question 17

1) How do you test CN8?
2) Once that test is done, how do you differentiate between the results?

Answer 17

1) Independently test hearing in each ear, either with whispered voice test or as described in HEENT
2) Use Webber and Rinne to differentiate between sensorineural and conductive hearing loss

Question 18

1) What do CN 9 and CN 10 do?
2) What happens if they don’t work? (2 things)

Answer 18

1) Together they raise the soft palate
2) Paralysis of the palate can cause:
-The voice to become nasal in quality.
-Dysphagia

Question 19

1) How do you test CNs 9 and 10?
2) What are the positive results?

Answer 19

1) Have patient say “ah” when examining oral pharynx
2)
-If there is unilateral nerve damage, the normal side will rise; the affected side will be pulled toward the normal side, along with the uvula
-Bilateral damage leads to no rise

Question 20

1) How should you test CN11? (3 ways) Describe results.

Answer 20

1) Assess shoulders for atrophy or fasciculations of the trapezius.
-In full paralysis, the shoulder droops and the scapula falls down and away (lateral)
2) Have patient shrug against resistance.
3) Have patient turn head to the side against resistance.

Question 21

1) What does CN12 do?
2) What should you assess?
3) What should you test directly?
4) What is the positive result of that test?
5) What should you do in a follow up test?

Answer 21

1) Causes the tongue to protrude.
2) The patient’s speech, which may be affected.
3) Have the patient stick out his or her tongue.
4) If the tongue deviates to the left, the LMN lesion is on the left side
5) In follow up test, have patient press on inner cheek as you resist the outside.