Stroke examination: Cranial nerves

Question 1

How do you explain to a patient what a cranial nerve examination is, and what it involves?

Answer 1

An examination to assess how well your nerves from your brain to your head, eyes and face are working

Includes short tasks such as following a finger and making facial expressions

Question 2

In the cranial nerve examination, which cranial nerves are assessed?

Answer 2

2nd

3rd

4th

6th

7th

Question 3

What is the 2nd cranial nerve, and what does it control?

Answer 3

Optic nerve: Relaying sight back from the retina to the visual cortex in the occipital lobe

Question 4

What is the 3rd cranial nerve, and what does it control?

Answer 4

Oculomotor nerve: Carries command signals to 4 muscles that control eye movement (Medial rectus muscle,
Inferior rectus muscle, Superior rectus muscle, Inferior oblique muscle (moves the eye up and out)

Question 5

What is the 4th cranial nerve, and what does it control?

Answer 5

Trochlear nerve: Controls the movement of one of the eye muscles, the superior oblique muscle (moves the eye downwards diagonally, down and out, by moving top of eye towards nose)

Question 6

What is the 6th cranial nerve, and what does it control?

Answer 6

Abducens nerve: Controls the lateral rectus muscle of the eye (moves the eye outwards horizontally, away from the midline)

Question 7

What is the 7th cranial nerve, and what does it control?

Answer 7

Facial nerve: Contains the motor, sensory, and parasympathetic (secretomotor) nerve fibers, which provide innervation to many areas of the head and neck region

Question 8

Which 4 eye muscles are controlled by the CN III oculomotor nerve?

Answer 8

Medial rectus muscle: Moves eye inward towards nose vertically

Inferior rectus muscle: Moves eye downwards vertically

Superior rectus muscle: Move eye upwards vertically

Inferior oblique muscle: Move eye upwards diagonally (up and out), by rotating top of eye away from nose

Question 9

Which test do you do to assess the 2nd cranial nerve?

Answer 9

Visual fields test

Assesses your peripheral and central vision to detect areas of vision loss or damage

Question 10

In the visual fields test, what are main 2 abnormal findings to identify?

Answer 10

Homonymous hemianopia

Visual inattention

Question 11

What is homonymous hemianopia?

Answer 11

Visual field loss in the same halves of the visual field of each eye

Eg. Right HH: Visual field loss is on the right side in the right eye and on the right side in the left eye

Eg. Left HH: Visual field loss is on the left side in the right eye and on the left side in the left eye

Question 12

What is visual inattention?

Answer 12

Inability to process stimuli, which causes lack of attention/awareness of one side of space

So patient is not able to see or recognise what they are looking at due to lack of attention