Cranial nerves

Question 1

How to test for RAPD?

Answer 1

Swinging torch test

RAPD aka Marcus Gunn pupil

Question 2

What is internuclear ophthalmoplegia? Where do you see it in?

Answer 2

INO - disorder of conjugate lateral gaze caused by lesion in medial longitudinal fasciculus

• causes failure of adduction of eye on affected side
• there is preservation of convergence of eyes

MS; stroke; lyme disease; tricyclic antidepressants

Question 3

What disease affects the motor function of facial muscles?

Answer 3

Bell’s palsy

Question 4

Causes of CN I palsy?

Answer 4

trauma
frontal lobe tumor
meningitis

Question 5

Causes of CN II palsy?

monocular blindness
bitemporal hemianopia
homonymous hemianopia

Answer 5

monocular blindness - MS; GCA
bitemporal hemianopia - pituitary adenoma; int carotid aneurysm
homonymous hemianopia - stroke; tumor; abscess

Question 6

Causes of CN III palsy?

partial/complete

Answer 6

partial (pupil sparing) - DM (why?)
- pial vessels perfusing parasympathetic fibres unaffected by diabetic microangiopathy, hence sparing the pupil

complete - PCA aneurysm; raised ICP w/ tentorial herniation

Question 7

Causes of CN IV palsy?

Answer 7

Orbit trauma

Question 8

Causes of CN V palsy?

Answer 8

idiopathic (trigeminal neuralgia)
acoustic neuroma
herpes zoster

Question 9

Causes of CN VI palsy?

Answer 9

skull fracture involvin petrous temporal bone
nasopharyngeal ca
raised ICP

Question 10

Causes of CN VII palsy?

LMN & UMN

Answer 10

LMN (affects forehead)

• Bells palsy
• malignant parotid tumor
• Herpes zoster (Ramsay Hunt)
• Sarcoid (often bilateral)

UMN (forehead sparing)
- stroke/tumor

Question 11

Causes of CN VIII palsy?

Answer 11

excessive noise
Meniere’s disease
Iatrogenic - furosemide; aminoglycoside antibiotics (gentamicin)

Question 12

Causes of CN IX/X/XI (bulbar) palsy?

LMN & UMN

Answer 12

LMN (bulbar palsy)

• MND
• diphtheria
• polio
• MGravis
• G-B syndrome
• syringobulbia

UMN (pseudobulbar palsy)

• MND
• bilateral strokes
• MS

Question 13

What are the general causes of cranial nerve palsies?

Answer 13

DM (microangiopathy of vasa nervorum)
Stroke
MS
tumor
sarcoidosis
SLE
vasculitis
lyme disease - bell's palsy

Question 14

What are the extra-ocular muscles?

Answer 14

CN III
- sup, inf, medial rectus
- inf oblique
CN IV
- sup oblique - SO4
CN VI
- lat rectus - LR6

Question 15

Rinne -ve in left ear, weber lateralise to left ear?

Answer 15

conductive loss in left ear

Question 16

Rinne -ve in left ear, weber lateralise to right ear?

Answer 16

complete sensorineural loss in left ear

Question 17

Rinne +ve in both ears, weber lateralise to left ear?

Answer 17

sensorineural loss in right ear

Question 18

What lesion is indicated in bulbar palsy?

Answer 18

LMN lesion

Question 19

What lesion is indicated in pseudobulbar palsy?

Answer 19

UMN lesion