CRANIAL NERVES

Question 0

GI CN exam?

Answer 0

Ptosis
Proptosis
Facial asymmetry
Scars

Question 1

What is the rule of 4’s?

Answer 1

4 CNs in medulla, pons and midbrain.

4 motor nuclei medially - III, IV, VI, XII

Question 2

Test CN I?

Causes of anosmia?

Answer 2

Have you noticed any change to your sense of smell?

Bilateral: URTI, smoking/age, ethmoid tumour, meningitis

Unilateral: head trauma without fracture, early meningioma

Question 3

What would cause a bitemporal hemianopia?

Answer 3

Optic chiasm lesion.

Question 4

What would cause a homonymous hemianopia?

Answer 4

Optic tract lesion

Question 5

What would you test for CN II?

Answer 5

Visual attention
Visual acuity
Visual fields
Ophthalmoscopy

Question 6

What would you test for CN III?

Answer 6

Inspect pupil: size, symmetry 
Accommodation reflex
Light reflex - direct and consensual 
Relative Afferent pupillary defect 
Eye movements - comment on Diplopia and nystagmus

Question 7

If there was a CN III lesion, what would you see?

Answer 7

Ptosis 
Divergent strabismus (down and out) 
Dilated pupils with no reflex constriction

Question 8

Testing CN V?

Answer 8

Sensory (sharp or blunt)

• frontal
• maxillary
• Mandibular

Motor

• massatter
• temporalis

Corneal reflex
Jaw jerk

Question 9

Testing CN VII?

Answer 9

Wrinkle forehead (frontalis)
Scrunch eyes (obicularis oculi)
Clench their teeth (obicularis oris)
Puff their cheeks out (buccinator)

Question 10

How to distinguish between UMNL and LMNL with CN VII?

Answer 10

Forehead sparing in upper motor neuron lesion

Question 11

How do you test CN VIII?

Answer 11

If hearing aid, take it out.

Inspect pinna for scars

Whisper 66 and 100 into different ears.

Then do rinnes and webers test.

Question 12

What conductive hearing loss findings on rinnes or webers?

Answer 12

Rinnes - BC > AC

Webers - localises to abnormal ear (makes it louder)

Question 13

Sensorineural hearing loss findings?

Answer 13

Air conduction is better than bone

Localizes to normal ear

Question 14

Testing CN IX, X?

Answer 14

Say ahh: inspect soft palate and uvula

Gag reflex: absence is only significant if unilateral

Question 15

CN XII test?

Answer 15

Stick your tongue out and wave it.

Look for signs of wasting or fasciculations.

Question 16

CN XI?

Answer 16

Shrug your shoulders (trapezius)

Turn your head to the side (SCM)

Question 17

What is INO? What is it due to?

Answer 17

Inter nuclear opthalmoplegia.

Dysfunction to the medial longitudinal fasciculus (carries tracts to oculomotor nucleus).

If bilateral -> ms
Unilateral -> stroke

Question 18

What is “medical” oculomotor nerve palsy?

Answer 18

DM, MS, b12 causing peripheral neuropathy. Affects lesions centrally then moves out.

Parasympathetic nerve fibres that affect pupillary size are found on outside.

Therefore pupil is preserved early on.

Medical = “pupil sparing”

Question 19

What is a surgical CN3 palsy?

Answer 19

Usually a tumour compressing on outside fibres causing pupil constriction first.