MedEd Cranial Nerves and Ophthalmology Flashcards
Main 3 CN conditions that could come up in OSCE
Bell’s palsy
Horner’s
Main nerves that show pathology - optic/oculomotor/facial/vestibulocochlear
Differentials for CN exam
Diabetes MS Tumours Sarcoid Vasculitis SLE Syphilis
Conjunctivitis symptoms
conjunctival hyperaemia - Red eye(s) chemosis - oedema around eye crust and discharge (ESP BACTERIAL) foreign body sensation photophobia
Types of conjunctivitis
bacterial/viral/allergic
What is puss made of
neutrophils - shows bacterial
Bacterial vs Viral
unilateral
thick discharge
reduced vision
urethritis/vaginal discharge
viral - bilateral, watery, normal vision, signs of viral infection. - also lymphadenopathy, cough, runny nose.
Allergic conjunctivitis
young adults
type 1 hypersensitivity
pollen/dust/chemical scents
Cataracts. On exam?
lens becomes clouded –> reduced acuity
visual impairment, glare, halos around lights
painless
On exam - reduced red reflex.
Glaucoma
Pressure on optic nerve
Peripehral vision goes first
2 types of glaucoma
open and closed angle glaucoma - iris and canals of Schlemm
Open - drainage issue
Closed angle - iris and lens angle is too small
Closed vs Open angle glaucoma
Closed angle: Unilateral sudden onset severely painful N&V, cloudy cornea, HEADACHE, dilated pupil?
Investigations for glaucoma
Slit lamp
Pressure in eye
10-21 mmHg (measured with tonometry)
Uveitis
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.
What GI conditions could be linked to uveitis?
IBD - crohn’s, ulcerative colitis
Visual field defects
Preciasmal - one eye only, ipsilateral
Chiasmal - bitemporal
Post chiasmal - homonymous,
Prechiasmal causes of visual loss
ischaemia, TIA, inflammation like MS
What if you blocked all nerves that cross over?
These are all the peripheral nerves -
Top left of vision
right part of brain, further along tract botton
Horner’s
ptosis - oculomotor
miosis
anhydrosis
Less sympathetic supply to the eye
Differentials for Horner’s
carotid artery dissection
pancoast tumour
brainstem stroke/tumour
Where does the nerve in Horner’s travel
brainstem –> neck –> clavicle –> back up to eye
Investigations
CXR
CT head
MRI/MR angiography (for carotid dissection)
What is mydriasis?
dilated pupil
What is a down and out pupil with dilated pupil and ptosis?
OCULOMOTOR NERVE PALSY - parasympathetic is
What are the medical and surgical causes of CN3 palsy
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.
Length dependance?
Long nerves affected first - peripheral neuropathy in diabetes ?
- Trochlear palsy ?
Up and in
Abducens palsy?
Inability abduct - one eye will not move in one direction
internuclear ophthalmoplegia
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
Bell’s palsy
affects supply to movement of a side of the fact
LMN PROBLEM
facial nerve is damaged or inflammed
Causes Bell’s palsy
Herpes simplex 1 virus or varicella zoster
Inflammation
Idiopathic
Why would you get an eye patch for Bell’s Palsy?
Prevent corneal abrasions
Also give steroids - prednisolone
Ramsay Hunt Syndrome
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
Forehead sparing - in Bell’s?
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.
Which tuning fork for hearing?
512 I hear you
Weber’s
512Hz placed on forehead - shoudl be same on both sides
Infection in ear e.g. otitis media–> conductive problem = louder in affected ear.
Rinne’s
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
Conductive hearing loss
External auditory canal - wax, foreign body, otitis media
Sensorineural hearing loss
Inflammation Tumour Ototoxic drugs - aminoglycoside antibiotics (gentomycin), aspirin overdose, loop diuretics Trauma Meniere's disease
NEUROFIBROMATOSIS (type 2 causes hearing problems)
Neurofibromatosis
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
