Cranial Nerve Exams

Question 1

List all the cranial nerve exams.

Answer 1

Refer to Notion.

Question 2

What can cause a loss of smell?

Answer 2

1. Kallmann’s syndrome - impaired development of olfactory bulbs and tracts
2. Parkinson’s disease - neurodegeneration of olfactory bulbs and tracts

Question 3

How do you test for pupillary light reflex?

Answer 3

1. Dim lights, ask patient to look far away. This allows pupils to dilate
2. Shine light in one eye from the side, and observe for direct + consensual miosis
3. Repeat with the other eye

Question 4

How do you test for pupillary accommodation reflex?

Answer 4

1. Dim lights, ask patient to look far away. This allows pupils to dilate
2. Hold a pen 15cm in front of patient’s eyes, and ask them to switch focus to that near object
3. Near triad should be observed - miosis, convergence, (and implied lens accommodation)

Question 5

How do you test for eye movements?

Answer 5

Use a pin to test in a H-movement

Question 6

What structures are usually damaged in visual acuity defects?

Answer 6

Anterior to optic chiasm (e.g. cornea, lens)

Question 7

What structures are usually damaged in visual field defects?

Answer 7

Posterior to optic chiasm (e.g. optic nerves)

Question 8

What does it mean if direct eye does not constrict but the consensual eye does upon illumination?

Answer 8

Afferent / Efferent nerve lesion in direct eye

Question 9

What does it mean if direct eye constricts but the consensual eye does not upon illumination?

Answer 9

Efferent nerve lesion in consensual eye

Question 10

What does it mean if pupils do not undergo miosis?

Answer 10

Defect in nerves / muscles that cause miosis

Question 11

What does it mean if pupils don’t converge?

Answer 11

Medial rectus muscle / oculomotor nerve defect

Question 12

What do each of the eye muscles do?

Answer 12

SR - upwards movement, intorsion

IR - downwards movement, extorsion

MR - inward movement

LR - outward movement

SO - intorsion, outward movement, downward movement in medial position

IO - extorsion, outward movement, upward movement in medial position

Question 13

What innervates the extraocular muscles?

Answer 13

CN III for most, except:

• SO (CN IV)
• LR (CN VI)

Question 14

How do you test for facial sensation of the trigeminal nerve?

Answer 14

1. “Can you chew?”
2. “Can you feel anything over your face when your eyes are closed?”
3. Gently touch the cornea with a soft material from the side while the patient stares straight ahead; they should blink

Question 15

If the lower side of the face is affected, what is the lesion pattern?

Answer 15

• UMN (hemisphere / brainstem)
• Upper face’s LMN receives innervation from both hemispheres (redundancy), but lower face’s LMN only receives innervation from contralateral hemisphere

Question 16

If both the upper and lower side of the face was affected, what is the lesion pattern?

Answer 16

• LMN (CN VII)

Question 17

If the direct eye does not blink, but the consensual eye does, where is the lesion?

Answer 17

CN VII

Question 18

If both eyes do not blink, where is the lesion?

Answer 18

• Brainstem
• CN V1

Question 19

What cranial nerves can be affected by cerebellopontine angle lesions?

Answer 19

CN VII and VIII

Question 20

How do you test for general hearing?

Answer 20

1. Rustle hand in non-tested ear
2. Speak with your other hand over your mouth
3. See if they can hear

Question 21

When do you use Rinne and Weber tests?

Answer 21

To differentiate between conductive and sensorineural deafness

Question 22

How does Rinne’s test work?

Answer 22

1. Hold tuning fork near ear
2. Hold tuning fork against mastoid bone
3. Compare

Question 23

How does Weber’s test work?

Answer 23

1. Hold tuning fork on crown of head
2. Compare L/R ears

Question 24

In conductive hearing loss, what would the Rinne and Weber test results be?

Answer 24

R - bone > air conduction
W - conduction louder on abnormal side

Question 25

In sensorineural hearing loss, what would the Rinne and Weber test results be?

Answer 25

R - air > bone conduction, but still soft in both W - conduction is louder on normal side

Question 26

What is an abnormal palate exam result?

Answer 26

Uvula pulled to one side

Question 27

How do you test CN XI?

Answer 27

1. Ask patient to turn head against resistance to test the contralateral SCM 2. Ask patient to shrug shoulders against resistance to test trapezius

Question 28

How do you test CN XII?

Answer 28

1. Check patient's tongue for atrophy, fasciculations, deviations (will deviate to side of lesion due to weakness) 2. Ask patient to move tongue side-to-side (weakness on side of lesion) 3. Ask patient to push tongue against inner cheek against resistance (weakness on side of lesion)