Disorders of the Cranial Nerves

Question 1

Name and function of CN I

Answer 1

Olfactory nerve

Olfaction

Question 2

Name and function of CN II

Answer 2

Optic nerve

Vision

Question 3

Name and function of CN III

Answer 3

Oculomotor nerve

Control of eye muscle activity, pupillary constriction

Question 4

Name and function of CN IV

Answer 4

Trochlear nerve

Control of eye muscle activity

Question 5

Name and function of CN V

Answer 5

Trigeminal nerve
Ordinary sensation
Control of muscles of mastication

Question 6

Name and function of CN VI

Answer 6

Abducens nerve

Control of eye muscle activity

Question 7

Name and function of CN VII

Answer 7

Facial nerve 
Taste 
Control of muscles of facial expression 
Lacrimation 
Salivation

Question 8

Name and function of CN VIII

Answer 8

Vestibulocochlear nerve
Hearing and balance
Ordinary sensation from ear

Question 9

Name and function of CN IX

Answer 9

Glossopharyngeal nerve
Taste
Ordinary sensation from ear
Salivation

Question 10

Name and function of CN X

Answer 10

Vagus nerve
Taste
Control of muscles of larynx and pharynx
Parasympathetic innervation beyond the diaphragm

Question 11

Name and function of CN XI

Answer 11

Accessory nerve

Control of sternocleidomastoid and trapezius muscle

Question 12

Name and function of CN XII

Answer 12

Hypoglossal nerve

Control of tongue muscles

Question 13

Testing sense of smell would assess the function of what cranial nerve?

Answer 13

Olfactory

Question 14

How to assess optic nerve function

Answer 14

Visual acuity 
Visual fields
Pupillary reactions
Fundoscopy 
Colour vision

Question 15

How to assess oculomotor, trochlear and abducens nerves function

Answer 15

Assess for ptosis
Pupils of equal size
Pupillary reaction
Eye movements - vertical and horizontal

Question 16

How to assess trigeminal nerve function

Answer 16

Assess sensation in ophthalmic, maxillary and mandibular divisions
Power of muscles of mastication
Corneal reflex
Jaw jerk

Question 17

How to assess facial nerve function

Answer 17

Assess muscles of facial expression (raise eyebrows, bear teeth etc.)
Corneal reflex
Taste

Question 18

How to assess vestibulocochlear nerve function

Answer 18

Rinne’s and Weber’s tests to assess hearing

Dix-Hallpike manouvre and Unterberger’s test to assess vestibular function

Question 19

How to assess glossopharyngeal and vagus nerve function

Answer 19

Movement of palate
Gag reflex
Quality of speech
Quality of cough

Question 20

How to assess accessory nerve function

Answer 20

Head turning and shoulder shrug (sternocleidomastoid and trapezius function)

Question 21

How to assess hypoglossal nerve function

Answer 21

Appearance, movement and power of tongue

Question 22

Fibres tested by pupillary light reaction

Answer 22

CN II afferent fibres

CN III efferent fibres

Question 23

Fibres tested by corneal reflex

Answer 23

CN V afferent fibres

CN VII efferent fibres

Question 24

Fibres tested by jaw jerk

Answer 24

CN V afferent and efferent fibres

Question 25

Fibres tested by gag reflex

Answer 25

CN IX afferent | CN X efferent

Question 26

Causes of dilated pupils

Answer 26

``` Youth Dim lighting Anxiety/excitement Mydriatic eye drops Amphetamine use Third nerve palsy Brain death ```

Question 27

Causes of small pupils

Answer 27

``` Old age Bright light Miotic eye drops Opiate overdose Horner's syndrome ```

Question 28

Examples of eye movement disorders

Answer 28

``` Isolated third nerve palsy Isolated fourth nerve palsy Isolated sixth nerve palsy Combination of isolated third, fourth and sixth nerve palsies Supranuclear gaze palsy Nystagmus ```

Question 29

Microvascular causes of isolated third nerve palsy

Answer 29

Diabetes Hypertension (painless, pupil spared)

Question 30

Compressive causes of isolated third nerve palsy

Answer 30

Posterior communicating artery aneurysm Raised ICP (painful, pupil affected)

Question 31

Causes of isolated sixth nerve palsy

Answer 31

Idiopathic Diabetes Meningitis Raised ICP

Question 32

Causes of nystagmus

Answer 32

``` Congenital Serious visual impairment Peripheral vestibular problem Central vestibular/brainstem disease Cerebellar disease Toxins ```

Question 33

Clinical features of trigeminal neuralgia

Answer 33

Paroxysmal attacks of lancinating (piercing/stabbing) pain

Question 34

Cause of trigeminal neuralgia

Answer 34

Vascular loop - compression of fifth nerve in the posterior fossa

Question 35

Treatment of trigeminal neuralgia

Answer 35

Carbamazepine | Surgery if medication resistant

Question 36

Presentation of Bell's palsy

Answer 36

Idiopathic facial nerve palsy Unilateral facial weakness May be preceded by pain behind the ear Eye closure affected

Question 37

Treatment of Bell's palsy

Answer 37

steroids

Question 38

Presentation of vestibular neuronitis

Answer 38

Sudden onset, disabling vertigo, vomiting

Question 39

What is dysarthria

Answer 39

Disordered articulation and slurring of speech

Question 40

What is dysphagia

Answer 40

Difficulty swallowing

Question 41

Cause of bulbar palsy

Answer 41

``` Bilateral lower motor neurone lesions affecting CN IX-XII e.g. Motor neurone disease Polio Malignancy Vascular lesions of medulla Syphilis ```

Question 42

Clinical features of bulbar palsy

Answer 42

Wasted, fasciculated tongue Dysarthria Dysphonia Dysphagia

Question 43

Causes of pseudobulbar palsy

Answer 43

Bilateral upper motor neurone lesions e.g. vascular lesions in both internal capsules

Question 44

Clinical features of pseudobulbar palsy

Answer 44

``` Spastic, immobile tongue Dysarthria Dysphonia Dysphagia Brisk jaw reflex Brisk gag reflex ```