Disorders of Cranial Nerves

Question 1

How is the first cranial nerve tested?

Answer 1

Smell- unilateral or bilateral loss

Question 2

How is the second cranial nerve tested?

Answer 2

Optic- visual acuity, visual fields, pupillary reactions, fundoscopy and colour vision

Question 3

How are the third, fourth and sixth cranial nerves tested?

Answer 3

Evidence of ptosis?
Pupils of equal size?
Pupillary reactions
Eye movements

Question 4

How is the fifth cranial nerve tested?

Answer 4

Sensation in the ophthalmic, maxillary and mandibular divisions
Power in the muscles of mastication
Corneal reflex
Jaw jerk reflex

Question 5

How is the seventh cranial nerve tested?

Answer 5

Muscles of facial expression
Corneal reflex
Taste

Question 6

How is the eighth cranial nerve tested?

Answer 6

Hearing using Rinne’s and Weber’s tests

Vestibular function using Dix-Hallpike manoevre and Untenberger’s test

Question 7

How are the ninth and tenth cranial nerves tested?

Answer 7

Movement of the palate
Gag reflex
Quality of speech
Quality of cough

Question 8

How is the eleventh cranial nerve tested?

Answer 8

Head turning

Shoulder shrugging

Question 9

How is the twelfth cranial nerve tested?

Answer 9

Appearance, movement and power of the tongue

Question 10

What is the afferent and efferent supply of the pupillary light reflex?

Answer 10

Afferent- second cranial nerve

Efferent- third cranial nerve

Question 11

What is the afferent and efferent supply of the corneal reflex?

Answer 11

Afferent- fifth cranial nerve

Efferent- seventh cranial nerve

Question 12

What is the afferent and efferent supply of the jaw jerk reflex?

Answer 12

Afferent- fifth cranial nerve

Efferent- fifth cranial nerve

Question 13

What is the afferent and efferent supply of the gag reflex?

Answer 13

Afferent- ninth cranial nerve

Efferent- tenth cranial nerve

Question 14

Where are the nuclei of the third and fourth cranial nerves found?

Answer 14

In the midbrain

Question 15

Where are the nuclei of the fifth, sixth and seventh cranial nerves found?

Answer 15

In the pons

Question 16

Where is the nuclei of the eighth cranial nerve found?

Answer 16

Lies at the pontomedullary junction

Question 17

Where are the nuclei of the ninth, tenth, eleventh and twelfth cranial nerves found?

Answer 17

Lie in the medulla

Question 18

Where can cranial nerves be damaged?

Answer 18

Within the brain
Crossing the sub-arachnoid space
Outside the skull

Question 19

What are the symptoms of optic neuritis?

Answer 19

Monocular visual loss
Pain on eye movement
Reduced visual acuity
Reduced colour vision
Optic disc may be swollen

Question 20

What are the causes of dilated pupils?

Answer 20

Youth
Dim lighting
Anxiety, excitement
"Mydriatic" eye drops
Amphetamine, cocaine overdose
Third nerve palsy 
Brain death

Question 21

What are the causes of constricted pupils?

Answer 21

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

Question 22

What is the difference between microvascular and compressive isolated third nerve palsies?

Answer 22

Microvascular- caused by diabetes or hypertension. Painless and pupil spared
Compressive- caused by posterior communicating artery aneurysm or raised ICP. Painful and affects pupil

Question 23

What are the causes of isolated sixth nerve palsy?

Answer 23

Idiopathic
Diabetes
Meningitis
Raised intracranial pressure

Question 24

What are the causes of nystagmus?

Answer 24

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

Question 25

What are the characteristics of trigeminal neuralgia?

Answer 25

Paroxysmal attacks of lancinating pain Triggers Middle age and older Caused by vascular loop

Question 26

How is trigeminal neuralgia treated?

Answer 26

Medically with carbamazepine | Surgical options if medication resistat

Question 27

What are the characterstics of Bell's palsy and how is it treated?

Answer 27

``` Unilateral facial weakness Lower motor neurone type Often preceded by pain behind ear Eye closure affected Risk of corneal damage Treated with steroids ```

Question 28

What are the symptoms of vestibular neuronitis?

Answer 28

Sudden onset Disabling vertigo Vomiting Gradual recovery

Question 29

What are the signs and symptoms of pseudobulbar palsy and what lesions cause it?

Answer 29

``` Caused by bilateral UMN lesions Dysarthria Dysphonia Dysphagia Spastic, immobile tongue Brisk jaw jerk Brisk gag reflex ```

Question 30

What are the signs and symptoms of bulbar palsy and what lesions cause it?

Answer 30

``` Caused by bilateral LMN lesions affecting CNIX-XII Wasted, fasciculating tongue Dysarthria Dysphonia Dysphagia ```