MedEd Cranial Nerves and Ophthalmology

Question 1

Main 3 CN conditions that could come up in OSCE

Answer 1

Bell’s palsy
Horner’s

Main nerves that show pathology - optic/oculomotor/facial/vestibulocochlear

Question 2

Differentials for CN exam

Answer 2

Diabetes 
MS
Tumours 
Sarcoid 
Vasculitis 
SLE
Syphilis

Question 3

Conjunctivitis symptoms

Answer 3

conjunctival hyperaemia - Red eye(s)
chemosis - oedema around eye 
crust and discharge (ESP BACTERIAL)
foreign body sensation 
photophobia

Question 4

Types of conjunctivitis

Answer 4

bacterial/viral/allergic

Question 5

What is puss made of

Answer 5

neutrophils - shows bacterial

Question 6

Bacterial vs Viral

Answer 6

unilateral
thick discharge
reduced vision
urethritis/vaginal discharge

viral - bilateral, watery, normal vision, signs of viral infection. - also lymphadenopathy, cough, runny nose.

Question 7

Allergic conjunctivitis

Answer 7

young adults
type 1 hypersensitivity
pollen/dust/chemical scents

Question 8

Cataracts. On exam?

Answer 8

lens becomes clouded –> reduced acuity
visual impairment, glare, halos around lights
painless

On exam - reduced red reflex.

Question 9

Glaucoma

Answer 9

Pressure on optic nerve

Peripehral vision goes first

Question 10

2 types of glaucoma

Answer 10

open and closed angle glaucoma - iris and canals of Schlemm
Open - drainage issue
Closed angle - iris and lens angle is too small

Question 11

Closed vs Open angle glaucoma

Answer 11

Closed angle:
Unilateral 
sudden onset 
severely painful 
N&V, cloudy cornea, HEADACHE, dilated pupil?

Question 12

Investigations for glaucoma

Answer 12

Slit lamp

Question 13

Pressure in eye

Answer 13

10-21 mmHg (measured with tonometry)

Question 14

Uveitis

Answer 14

anterior vs posterior
Anterior - autoimmune conditions, painful, ocular hyperaemia, blurry vision, increased larcimation and photophobia.

Posterioir - painless, can have dots in vision where you can’t see/floaters.

Question 15

What GI conditions could be linked to uveitis?

Answer 15

IBD - crohn’s, ulcerative colitis

Question 16

Visual field defects

Answer 16

Preciasmal - one eye only, ipsilateral
Chiasmal - bitemporal
Post chiasmal - homonymous,

Question 17

Prechiasmal causes of visual loss

Answer 17

ischaemia, TIA, inflammation like MS

Question 18

What if you blocked all nerves that cross over?

Answer 18

These are all the peripheral nerves -

Question 19

Top left of vision

Answer 19

right part of brain, further along tract botton

Question 20

Horner’s

Answer 20

ptosis - oculomotor
miosis
anhydrosis

Less sympathetic supply to the eye

Question 21

Differentials for Horner’s

Answer 21

carotid artery dissection
pancoast tumour
brainstem stroke/tumour

Question 22

Where does the nerve in Horner’s travel

Answer 22

brainstem –> neck –> clavicle –> back up to eye

Question 23

Investigations

Answer 23

CXR
CT head
MRI/MR angiography (for carotid dissection)

Question 24

What is mydriasis?

Answer 24

dilated pupil

Question 25

What is a down and out pupil with dilated pupil and ptosis?

Answer 25

OCULOMOTOR NERVE PALSY - parasympathetic is

Question 26

What are the medical and surgical causes of CN3 palsy

Answer 26

Medical - DM from inside out so you see ptosis first and down and out
Surgical - e.g. tumour. Parasymp is outside and compression affects this first so you get dilation first.

Question 27

Length dependance?

Answer 27

Long nerves affected first - peripheral neuropathy in diabetes ?

Question 28

4. Trochlear palsy ?

Answer 28

Up and in

Question 29

Abducens palsy?

Answer 29

Inability abduct - one eye will not move in one direction

Question 30

internuclear ophthalmoplegia

Answer 30

tract in brain allows the eyes to move together in a particular direction - MS in young/ stroke in old can damage this area and cause this

Question 31

Bell’s palsy

Answer 31

affects supply to movement of a side of the fact
LMN PROBLEM
facial nerve is damaged or inflammed

Question 32

Causes Bell’s palsy

Answer 32

Herpes simplex 1 virus or varicella zoster
Inflammation
Idiopathic

Question 33

Why would you get an eye patch for Bell’s Palsy?

Answer 33

Prevent corneal abrasions

Also give steroids - prednisolone

Question 34

Ramsay Hunt Syndrome

Answer 34

Type of Bell's DUE TO VARICELLA ZOSTER
Painful 
Rash - can be on tongue or in ear . Vesicular 
Other CNs can be affected 
Deafness and vertigo

Question 35

Forehead sparing - in Bell’s?

Answer 35

Forehead sparing - NO
No - LMN. Muscles unly have one LMN supplying them so if it is damaged then you lose all supply
Yes - UMN. Bilateral innervation of forehead in brain (prob due to evolution bc it would be bad to lose ability to close eye?). Other hemisphere can still supply the forehead if you have a stroke.

Question 36

Which tuning fork for hearing?

Answer 36

512 I hear you

Question 37

Weber’s

Answer 37

512Hz placed on forehead - shoudl be same on both sides

Infection in ear e.g. otitis media–> conductive problem = louder in affected ear.

Question 38

Rinne’s

Answer 38

POSITIVE RESULT IS GOOD - one of few
air conduction should be louder than bone conduction
So if sensorineural problem - still POSITVE - louder in air
In conductive problem - louder in bone

Question 39

Conductive hearing loss

Answer 39

External auditory canal - wax, foreign body, otitis media

Question 40

Sensorineural hearing loss

Answer 40

Inflammation
Tumour 
Ototoxic drugs - aminoglycoside antibiotics (gentomycin), aspirin overdose, loop diuretics 
Trauma 
Meniere's disease 

NEUROFIBROMATOSIS (type 2 causes hearing problems)

Question 41

Neurofibromatosis

Answer 41

Both types are autosomal dominant
Type 1 affects the body because you have one body - outgrowths of nerve tissue - feel weird when you squeeze them
Type 2 affects the ears because you have 2 - tumour inside damages nerves which damages the nerves causing hearing problems (to vestibular nerve)
Acoustic neuroma = vestibular Schwannoma