Disorders of cranial nerves

Question 1

Aetiology of optic neuritis

Answer 1

demyelination of optic nerve

Question 2

Symptoms of optic neuritis

Answer 2

• Mono-ocular vision loss
• Pain on eye movement
• Reduced visual acuity
• Reduced colour vision
• Optic disc swollen

Question 3

Disorders affecting eye movement

Answer 3

• CN III, IV, VI palsy
• Supranuclear gaze palsy
• Nystagmus

Question 4

Different type of CN III Palsy and characteristic

Answer 4

-Microvascular :
Painless
Pupil saved
Due to diabetes/hypertension

-Compressive:
Painful
Pupil affected
Due to PCA aneurysm/ raised ICP

Question 5

Aetiology of CN VI palsy

Answer 5

• Idiopathic
• Meningitis
• Diabetes
• Raised ICP

Question 6

Aetiology of nystagmus

Answer 6

Congenital 
Cerebellar dysfunction 
Brainstem dysfunction 
Central vestibular dysfunction 
Serious visual impairment 
Toxins

Question 7

What is trigeminal neuralgia, what is it caused by and how is treated

Answer 7

Paraoxymal attacks of lacerating pain
Tend to occur in the middle aged/ elder
Due to 5th nerve compression in posterior loop- due to vascular loop
Can be treated with carbamazepine- surgical treatement if this doesn’t work

Question 8

Bell’s palsy

Answer 8

LMN palsy of CN VII
Develops suddenly: 24-72 hours
Unilateral facial weakness
Oftern proceeded by pain behind ear 
Risk of corneal damage 
Unilateral sagging of mouth 
Unilateral inability to close eye- Can lead to watery or dry eye. 
Difficulty speaking 
Drooling of saliva

Question 9

Vestibular neuronitis

Answer 9

• Sudden
• Vertigo
• Vomiting
• Gradual recovery

Question 10

Pseudobulbar palsy symptoms

Answer 10

UMN- BILATERAL
5, 7, 9-12

• Dysphagia
• Dysarthia: problems with speech
• Dysphonia
• exagerrated jaw jerk
• Brisk gag reflex
• Spastic immobile tongue
• No wasting/ fasciculations
• Emotional incontinence
• absent palate movement

Question 11

Bulbar palsy

Answer 11

LMN- CN IX-XII
Bilateral
-wasted, fasciculating tongue
-Spastic 
-dysarthria
-dysphonia
-dysphagia
-Absent gag reflex 
-absent palate movement

Question 12

CN reflexes

Answer 12

Pupillary
Afferent: CN II Efferent: CN III

Corneal :
Afferent: CN V Efferent: CN VII

Jaw jerk:
Afferent and efferent: CN V

Gag :
Afferent: CN IX Efferent: CN X

Question 13

Aetiology of Pseudobulbar Palsy

Answer 13

• Vascular lesions of both internal capsules
• Motor neurodegenerative: Motor Neuron Disease, MS
• Tumour

Question 14

Aetiology of bulbar palsy

Answer 14

• Polio
• Syphilis
• Tumour
• MND, MS
• Vascular lesion of the medulla
• Inflammatory conditions: myastenia gravis and Gullain bare

Question 15

Aetiology of dilation of the pupil

Answer 15

• Youth
• Dim lighting
• Excitement, anxiety
• Mydiatric- eye drops
• Amphetamine/ cocaine overdose
• Third nerve palsy
• Brain death

Question 16

Aetiology of constriction of the pupil

Answer 16

• Old age
• Bright light
• Myotic eye drops
• Opiate overdose
• Horner’s syndrome:

Question 17

What control are dilation and constriction of the pupil under

Answer 17

Dilation of Pupil

• Under control of the sympathetic pathway
• Any damage to the parasympathetic pathway can lead to XS dilation- FIXED

Constricted pupils

• Under control of parasympathetic pathway.
• Any damage to sympathetic pathway leads to constriction of pupils

Question 18

Treatment of Bells palsy

Answer 18

Corticosteroids: methylpredinosole

Aciclovar can help in some instances as thought to be associated with HIV.