Systemic Disease and the Eye - Neurological Conditions Flashcards
what are the 2 cardinal features of neuro-ophthalmic disease?
eye movement defects (double vision) visual defects (visual acuity, field loss)
name 6 underlying causes of neuro-ophthalmic disease
vascular disease (most common) tumours (primary and secondary) trauma demyelination inflammation/infection congenital abnormalities
important aspects of investigation in neuro-ophthalmic disease?
full medical and neurological examination
blood tests
imaging - MRI = gold standard
what 3 cranial nerves control movement of the eye?
CN III
CN IV
CN VI
defects in which 2 parts of the nerve pathway can cause eye mobility defects?
inter-nuclear
supra-nuclear
which muscle is controlled by CN VI and what does it do?
lateral rectus
abducts the eye (pulls it laterally/temporally)
name 4 causes of CN VI palsy
microvascular
raised intracranial pressure
tumour
congenital
how can pressure inside the skull affect CN VI?
CN VI wraps around petrous tip which can impinge the nerve if swollen
definition of papilloedema?
swollen optic nerve/disc in context of raised intracranial pressure
what muscle is controlled by CN IV and what does it do?
superior oblique keeps eye depressed in orbit in adduction stabilises eye while head moves weak abduction intorsion
how might CN IV palsy affect posture?
patients can compensate with a head tilt
how might CN IV palsy present?
problems in depression of eye (most obvious when looking down and medially)
affected eye sits higher
images which are horizontally next to each other may appear vertical as one eye is seeing higher than the other
head tilt to the right compensates for CN IV palsy in which eye?
left
4 causes of CN IV palsy?
congenital decompensated
microvascular
tumour
bilateral - closed head trauma (susceptible to head trauma as its the longest cranial nerve in terms op ophthalmology)
what muscles are supplied by CN III?
medial rectus inferior rectus]superior rectus inferior oblique sphincter pupillae levator palpebrae superioris
position of eye with CN III palsy?
looking down and out
lid is often drooping
why does a down and out eye position occur in CN III palsy?
lateral rectus and superior oblique not innervated by CN III so their actions are unopposed
lateral rectus = looking out
superior oblique = looking down
5 causes of CN III palsy?
microvascular tumour aneurysm MS congenital
most likely cause of a painful CN III palsy?
aneurysm
pupil sparing CN III palsy?
microvascular as outside nerve fibres not affected
pupil involving CN III palsy?
probably aneurysm
always do imaging
where is the issue in inter-nuclear ophthalmoplegia?
grey matter pathways in the brainstem
what is the function of inter-nuclear pathways?
allows the eyes to work together
e. g to look left
- left eye looks left
- right eye looks left
- at the same time and same speed
what happens in inter-nuclear ophthalmoplegia?
still have ability to look tot he left, but when you do so, the affected eye flickers (nystagmus) as the muscle doesn’t work to move the eye left but the fibres are still firing telling the eye to move which causes it to flicker in that direction
sign of demyelination disease (e.g MS) on MRI?
plaques
2 causes of internuclear ophthalmoplegia?
MS
vascular
name 5 sites where a problem can occur in visual field defects?
optic nerve chiasm optic tract optic radiations cortex
4 causes of problems in visual field pathway?
vascular disease (CVA)
space occupying lesion (SOL)
demyelination (MS)
trauma (including surgical)
how can you distinguish whether a visual field defect is occurring at the optic tract or occipital cortex?
macula will be spared if at occipital cortex
what can cause a defect at the optic nerve?
ischaemic optic neuropathy optic neuritis (commonly MS) tumours - meningioma - glioma - haemangioma
what are the features of optic neuritis?
progressive visual loss (unilateral) pain behind eye, especially on movement colour desaturation central scotoma gradual recovery over weeks - months
how does visual loss due to optic nerve differ to that due to eye or brain problems?
optic nerve = either complete vision loss or visual field is divided horizontally
other causes = vertical division
what can optic neuritis progress to?
optic atrophy
name 3 pathologies of optic chiasm?
pituitary tumour
craniopharyngioma
maningioma
what is the prognosis of pituitary tumour in terms of vision?
commonly reversed after tumour is decompressed or removed
name 3 pathologies of the optic tracts and optic radiations
tumours
demyelination
vascular anomalies (including strokes)
general features of optic tract/radiation defects?
homonomous defects
macula not spared
quadrantanopia
incongruous
name 2 pathologies of occipital cortex?
vascular disease (CVA) demyelination
name 3 general features of a defect in the occipital cortex?
homonomous defect
macular sparing
congruous
