Acute visual disturbance 3 - ocular motor palsies Flashcards
muscle that moves the eye laterally
lateral rectus muscle
muscle that moves the eye medially
medial rectus muscle
muscle that moves the eye inferiorly
inferior rectus muscle
muscle that moves the eye superiorly
superior rectus muscle
what are the two oblique muscles called
superior oblique muscle
inferior oblique muscle
levator palpebrae superioris muscle
supplied by third cranial nerve
in a third nerve palsy, you get a ptosis because of this muscle
Hx of cranial nerve palsies
diplopia
anisocoria
ptosis
ophthalmoplegia
nystagmus
pain
systemic (headache, tinnitus, polyneuropathies)
variable vision (difficulty focussing)
acute onset is more likely to be stuff like
vascular, GCA, trauma, infection
subacute onset (weeks) is more likely to be stuff like
demyelination eg. MS
gradual onset (months to years) is more likely to be stuff like
compressive eg. slowly growing tumour
characterise the diplopia
horizontal, vertical, diagonal, torsional
vertical diplopia on downward gaze
4th nerve palsy
important things on PMHx
DM, HTN, lipids, thyroid, myasthenia gravis
element of ophthalmic examination
visual acuity
visual fields
pupil reflexes
opthalmoscopy
colour vision
testing eye movements
start off with distance target
acronym for remembering the elements of the ophthalmic exam
AFROC
third nerve palsy looks like
occulumotor nerve
down and out with ptosis
most common is vasculopathic/aneurysm
fourth nerve palsy looks like
trochlear nerve
nasal upshoot on contralateral gaze
sixth nerve palsy looks like
unopposed medial nerve action
abducens nerve
sixth nerve palsy looks like
Sixth nerve palsy is when
the eye is turned inward because it affects the lateral rectus muscle so the eye can’t turn fully outward.
abducens nerve palsy is
sixth nerve palsy
aetiology of abducens nerve palsy
microvascular, trauma, raised ICP, idiopathic, GCA
presentation of abducens nerve palsy
horizontal diplopia worse when looking at a distance and on ipsilateral gaze
esotropia also worse on distance and ipsilateral gaze
most common palsy
Ddx of abducens nerve palsy
thyroid eye disease, orbital tumour, Duane syndrome
management of abducens nerve palsy
MRI brain and orbits: patients <50years, polyneuropathy or systemic symptoms, history of cancer, no microvascular risk factors
FBC, BSL, ESR, CRP, lipids on older patients; other blood as indicated
manage vascular risk factors
driving advice, short term patching, prism lenses, botox injection or strabismus surgery
prognosis of abducens nerve palsy
70% of microvascular cases recover in 6-12 weeks
forth nerve palsy is more obvious on
ipsilateral head tilt
a trochlear nerve palsy is
fourth nerve palsy
aetiology of forth nerve palsy
microvascular, congenital, trauma, idiopathic
presentation of forth nerve palsy
vertical diplopia and compensatory contralateral head tilt
diplopia worse on downsize and contralateral gaze
nasal upshoot (hypertropia on adduction) and ipsilateral head tilt
recent head trauma
Ddx of trochlear/4th nerve palsy
myasthenia graves, thyroid eye disease, third nerve palsy
management of trochlear/4th nerve palsy
CT or MRI: dorsal midbrain lesion/contusion/infarction
control of vascular risk factors in older patients
driving advice, short term patching, longer term prisms +/- surgery
third nerve palsy is when the eye goes
down and out
a blown pupil in third nerve palsy is suspicious for
aneurysm
why is blown pupil indicative of an aneurysm in third nerve palsy
parasympathetic fibres travel on the outside of the third nerve
so when the third nerve travels near the posterior communicating artery, the outermost fibres (parasympathetic supply) are the first to be affected which causes the pupils to not be able to constrict (hence they get blown)
oculomotor nerve palsy aetiology
microvascular, aneurysm, tumour, trauma, infiltrative, (e.g. leukaemia)
most cases without pupil involvement are ischaemic (HTN, DM etc)
presentation of oculomotor nerve palsy
diplopia, ptosis, +/- pain, +/- pupil involvement (light and accomodation)
eye turned ‘down and out’
unable to adduct/infraduct/supraduct
Ddx of oculomotor nerve palsy
myasthenia gravis, thyroid orbitopathy, GCA
management of oculomotor nerve palsy
acute 3rd nerve palsy with fixed dilated pupil = emergency CTA or MRI/A
FBC, ESR, CRP for ?inflammatory causes (including GCA)
you may not need to image if there is no pupil involvement but you ned to see the patient everyday to ensure there is no new pupil involvement
medical management of vascular risk factors
driving advice, short term patching, longer term prism lenses +/- surgery
prognosis of occulomotor nerve palsy
ischameic cases often resolve within 3 months
diplopia and driving
people with diplopia are generally considered not fit to drive
for diplopia with an occluder, a three month non-driving period applies in order to reestalbish depth perception
sudden loss of unilateral vision and driving
person shouldn’t be driving for an appropriate period (usually there months) to adapt to their new visual circumstance and re-etablish depth perception
summary of eye muscles and their actions
