Cranial nerves + ophthalmology Flashcards
Name the cranial nerves and which ones are sensory and/or motor
I - olfactory (S)
II - optic (S)
III - oculomotor (M)
IV - trochlear (M)
V - trigeminal (S+M)
VI - abducens (M)
VII - facial (S+M)
VIII - vestibulocochlear (S)
IX - glossopharangeal (S+M)
X - vagus (S+M)
XI - accessory (M)
XII - hypoglossal (M)
Potential ddx for cranial nerve palsy overall
Diabetes mellitus
MS
Tumours
Sarcoid
Vasculitis (temporal => blindness)
SLE
Syphilis
Anosmia ddx
Ageing (men>women)
Traumatic brain injury (cribiform plate damaged)
Tumour
Alzheimer’s
Parkinson’s (almost prodromal, first sx before motor start)
Kallman’s syndrome (RARE)
Acuity ddx
Optic neuropathy (ischaemia for old pts, MS for young pts)
Retina (age related macular degeneration, diabetic neuropathy)
Ocular media (cataracts, diabetes)
Refractive error
Compare bacterial and viral conjunctivitis
Bacterial
- unilateral
- thick discharge, ‘sticky eyes’
- reduced vision
- ?urethritis/vaginal discharge
Viral
- bilateral
- watery discharge
- normal vision
- signs of viral infection (fever, lymphadenopathy)
How may allergic conjunctivitis present?
‘Seasonal’ itchy, red, watery and oedematous eyes
Sneezing
Type I hypersensitivity (IgE)
How may cataracts present?
Older patient with painless visual impairment
O/E reduced red reflex and clouding of lens (halos around eyes)
Compare anterior and posterior uveitis
Anterior (iris + ciliary body)
- painful, ocular, hyperaemia (pink eye)
- blurry vision
- increased lacrimation and photophobia
- autoimmune conditions (RA, sarcoidosis, IBD, Bechet’s, SLE, seronegative spondyloarthropathies)
Posterior (vitreous body, choroid + retina)
- painless
- blurry vision w/ floaters and scotoma
- infective cause (Lyme disease, syphilis, TB, EBC, CMV, HSC, VZV)
Compare open and closed angle glaucomas
Open angle glaucoma (90% cases)
- bilateral
- initially asymptomatic then progressive vision loss
- mild, non-specific sx
*Closed angle glaucoma (10% cases)
- unilateral
- sudden onset, severely painful
- N&V, cloudy corners, headache, dilated pupils
*MUST rule out for any acute, red eye, glaucoma 2nd cause of blindness
**Glaucoma = vision loss from CNII damage due to increased intraocular pressure
State the visual field disturbance and possible cause based on the sight of the lesion:
a) prechiasmal
b) chiasmal
c) post chiasmal
a) prechiasmal
- one eye only, ipsilateral side to lesion
- ischaemia (TIA), inflammation (MS)
b) chiasmal
- bitemporal hemianopia
- pituitary tumour, craniopharyngioma
c) post chiasmal
- homonymous, contralateral side to lesion
- ischaemia (stroke)
Which lobe is affected in a:
a) superior homonymous quadrantanopia,
b) inferior homonymous quadrantanopia?
a) Superior vision lost => temporal lobe
b) Inferior vision lost => parietal lobe
Both combine at occipital lobe so if occipital lobe affected, both lost
What type of visual loss would occur if the following had lesions?
a) optic nerve
b) optic chiasm
c) optic tract
d) optic radiation
a) ipsilateral monocular vision loss
b) bitemporal hemianopia
c) contralateral homonymous hemianopia
d) contralateral homonymous quadrantanopia
What is neglect syndrome?
Damage to right parietal love
Only do things on the right side of the body, ignores the left
Problem of attention, not blindness
What is tested in the swinging torch test?
RAPD (relative afferent pupillary defect)
- eye starts to constrict less between unaffected and affected eye, making it look like eye is dilating in affected eye
- seen in optic neuritis (this can occur in MS, will improve)
What causes pupil constriction and dilation?
Constriction due to parasympathetic
Dilation due to sympathetic
Patient presents with ptosis, miosis and anhydrosis, what do they have and what are three potential ddx?
Horner’s syndrome (constricted pupil, droopy eyelid, absence of sweating)
1) carotid artery dissection: blood in artery expanding and compressing nerve
2) pancoast tumour: sympathetic nerve pressed on at vertebrae at apex of lung
3) brainstem stroke/tumour: hypothalamus ischaemia/compression
Ix and mx of Horner’s syndrome
Ix = CXR, CT head, MRI/MR angiography
Mx = referral asap
CNIII palsy / CNIV palsy / CNVI palsy
III:
Down and out
Ptosis
IV:
Up and in
Head trauma/microvasculopathy (DM, atherosclerosis, HTN)
VI:
Affected eye fails to abduct when looking laterally
Stroke, trauma, viral illness, tumour
Long course from brainstem so check for associated neuro sx depending on where lesion located
Compare surgical and medical CNIII palsy
Surgical:
- compressing from outside
- pupil dilation
- raised ICP
Medical:
- blood supply problems within
- no pupil dilation
- diabetes mellitus
What is and does internuclear opthalmoplegia indicate?
Lesion in tract connecting CN3 and CN6
Occurs in stroke (unilateral, old) or MS (bilateral, young)
O/E pt looks to one side and fine, looks to the other side and affected eye fails to adduct so stops while the other eye looks to side but has nystagmus
How may a CNV palsy look O/E?
Absent sensation in sensory distribution
Absent corneal reflex
Weakness/wasting of muscles of mastication
What are possible causes of CNV palsy?
Higher central
- MCA stroke (most common cause for deficient in face sensation)
- contralateral side affected
Brainstem
- raised ICP, stroke
Peripheral
- trauma, raised ICP
- lesion beyond trigeminal ganglion
What are the branches of the facial nerve?
Temporal
Zygomatic
Buccal
Marginal mandibular
Cervical
Bell’s palsy summary card
One side of face paralysed
- idiopathic, compression of facial nerve, viral infection, herpes simplex virus, varicellar zoster
- serology to check for virus
- prednisolone (speed up recovery), close eye at bedtime, wear sunglasses (prevent corneal abrasions)
