Cranial Nerve Palsies

Question 1

What does horizontal diplopia with esotropia or exotropia on cover test indicate?

Answer 1

A problem with the lateral rectus (LR) or medial rectus (MR) muscle

Question 2

What is esotropia?

Answer 2

Inward turning of the eye

Question 2

What is exotropia?

Answer 2

Outward turning of the eye

Question 3

What does vertical diplopia with hypertropia or hypotropia on cover test indicate?

Answer 3

A problem with superior oblique (SO), superior rectus (SR), inferior rectus (IR), or inferior oblique (IO) muscles

Question 4

What does a visible sclera in a position of gaze indicate?

Answer 4

Weakness of the corresponding extraocular muscle

Question 5

What causes the ‘down and out’ eye appearance in CN III palsy?

Answer 5

Unopposed action of lateral rectus and superior oblique muscles

Question 6

What additional signs occur in CN III palsy?

Answer 6

1. Ptosis = drooping eyelid
2. Pupil dilation = miosis loss

Question 7

What is the significance of a painful
CN III palsy?

Answer 7

Suggests an aneurysm — an emergency

Question 8

Which muscle does the trochlear nerve (CN IV) innervate?

Answer 8

Superior oblique muscle

Question 9

What are common causes of CN IV palsy?

Answer 9

1. Congenital decompensation
2. Microvascular issues
3. Tumour
4. Blunt head trauma

Question 10

How does CN IV palsy typically present?

Answer 10

1. Vertical diplopia is worse when looking down
2. Affected eye is elevated in primary gaze

Question 11

How do patients compensate for CN IV palsy?

Answer 11

1. Chin-down posture in bilateral palsy
2. Contralateral head tilt in unilateral palsy

Question 12

Which muscle does the abducens nerve (CN VI) innervate?

Answer 12

Lateral rectus muscle

Question 13

What are common causes of CN VI palsy?

Answer 13

1. Microvascular causes
2. Raised intracranial pressure
3. Tumour
4. Congenital
5. papilledema

Question 14

How does CN VI palsy present clinically?

Answer 14

1. Esotropia = Eye turns inwards
2. Horizontal diplopia is worse when looking toward the affected side

Question 15

Horizontal diplopia means what?

Answer 15

problem with muscles moving eyes side to side

Question 16

Vertical diplopia means what?

Answer 16

problem with muscles moving eyes up and down

Question 17

In CN IV palsy, what is the typical eye position in primary gaze?

Answer 17

The affected eye is elevated
= hypertropia

Question 17

A patient presents with sudden diplopia, ptosis, and a “down and out” eye. Which cranial nerve is affected?

Answer 17

Oculomotor nerve (CN III)

Question 18

What serious condition should be ruled out immediately with a painful CN III palsy?

Answer 18

Posterior communicating artery aneurysm

Question 19

How do patients typically compensate for a unilateral CN IV palsy?

Answer 19

By tilting their head to the opposite side

Question 20

Which cranial nerve palsy causes the eye to turn inward (esotropia) and diplopia worse on gaze to the affected side?

Answer 20

Abducens nerve (CN VI) palsy

Question 20

What does the cover test show in a patient with CN VI palsy?

Answer 20

Esotropia
= inward turning of the affected eye

Question 21

What type of diplopia occurs with CN IV palsy?

Answer 21

Vertical diplopia, worse when looking downward

Question 22

What is the typical eye position in CN III palsy?

Answer 22

Eye is “down and out” due to unopposed lateral rectus and superior oblique muscles

Question 23

Horizontal diplopia with exotropia (eye turns outwards) suggests what?

Answer 23

medial rectus (CN III) palsy

Question 24

Horizontal diplopia with esotropia (eye turns inwards) suggests what?

Answer 24

lateral rectus (CN VI) palsy

Question 25

Vertical diplopia with hypertropia or hypotropia suggests what?

Answer 25

involvement of superior oblique (CN IV) or other vertical muscles (CN III)

Question 26

You are examining a patient who complains of double vision. Whilst looking forward, the patient's left eye turns towards the nose. On looking to the patient's right, there is no obvious squint. However, on looking to the left, the patient cannot abduct the left eye, and double vision worsens. What is the most likely underlying problem?

Answer 26

Left 6th nerve palsy

Question 27

A 50-year-old man has a 2-month history of headaches with associated double vision. His headaches are worse upon waking and when coughing or straining, and has also had associated nausea and vomiting. He has a past medical history of atrial fibrillation and takes apixaban. On examination, there is right-sided defective eye abduction and horizontal diplopia. The other eye is unaffected. Both pupils are equal and reactive to light, his visual fields are intact, and the rest of the examination is unremarkable. What is the most likely underlying problem?

Answer 27

Right CN VI palsy

Question 28

A 64-year-old woman who reports vertical diplopia, in particular, whilst reading in bed at night. Which cranial nerve palsy would explain this?

Answer 28

Trochlear

Question 29

A 74-year-old man presents to the neurology outpatient clinic after noticing some eye changes. On examination, the following findings are noted: 1. Right eye fixed in a 'down and out' position 2. Right-sided ptosis 3. Dilated pupil in the right eye What cranial nerve is affected?

Answer 29

Ptosis - CN III