Acute visual disturbance 3 - ocular motor palsies

Question 1

muscle that moves the eye laterally

Answer 1

lateral rectus muscle

Question 2

muscle that moves the eye medially

Answer 2

medial rectus muscle

Question 3

muscle that moves the eye inferiorly

Answer 3

inferior rectus muscle

Question 4

muscle that moves the eye superiorly

Answer 4

superior rectus muscle

Question 5

what are the two oblique muscles called

Answer 5

superior oblique muscle
inferior oblique muscle

Question 6

levator palpebrae superioris muscle

Answer 6

supplied by third cranial nerve
in a third nerve palsy, you get a ptosis because of this muscle

Question 7

Hx of cranial nerve palsies

Answer 7

diplopia
anisocoria
ptosis
ophthalmoplegia
nystagmus
pain
systemic (headache, tinnitus, polyneuropathies)
variable vision (difficulty focussing)

Question 8

acute onset is more likely to be stuff like

Answer 8

vascular, GCA, trauma, infection

Question 9

subacute onset (weeks) is more likely to be stuff like

Answer 9

demyelination eg. MS

Question 10

gradual onset (months to years) is more likely to be stuff like

Answer 10

compressive eg. slowly growing tumour

Question 11

characterise the diplopia

Answer 11

horizontal, vertical, diagonal, torsional

Question 12

important things on PMHx

Answer 12

DM, HTN, lipids, thyroid, myasthenia gravis

Question 13

element of ophthalmic examination

Answer 13

visual acuity
visual fields
pupil reflexes
opthalmoscopy
colour vision

Question 14

acronym for remembering the elements of the ophthalmic exam

Answer 14

AFROC

Question 15

third nerve palsy looks like

Answer 15

Question 16

fourth nerve palsy looks like

Answer 16

Question 17

sixth nerve palsy looks like

Answer 17

Question 18

sixth nerve palsy looks like

Answer 18

Question 19

Sixth nerve palsy is when

Answer 19

the eye is turned inward because it affects the lateral rectus muscle so the eye can’t turn fully outward.

Question 20

abducens nerve palsy is

Answer 20

sixth nerve palsy

Question 21

aetiology of abducens nerve palsy

Answer 21

microvascular, trauma, raised ICP, idiopathic, GCA

Question 22

presentation of abducens nerve palsy

Answer 22

horizontal diplopia worse when looking at a distance and on ipsilateral gaze
esotropia also worse on distance and ipsilateral gaze

Question 23

Ddx of abducens nerve palsy

Answer 23

thyroid eye disease, orbital tumour, Duane syndrome

Question 24

management of abducens nerve palsy

Answer 24

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

Question 25

forth nerve palsy is more obvious on

Answer 25

ipsilateral head tilt

Question 26

a trochlear nerve palsy is

Answer 26

fourth nerve palsy

Question 27

aetiology of forth nerve palsy

Answer 27

microvascular, congenital, trauma, idiopathic

Question 28

presentation of forth nerve palsy

Answer 28

vertical diplopia and compensatory contralateral head tilt
diplopia worse on downsize and contralateral gaze
nasal upshoot (hypertropia on adduction) and ipsilateral head tilt

Question 29

Ddx of trochlear nerve palsy

Answer 29

myasthenia graves, thyroid eye disease, third nerve palsy

Question 30

management of trochlear nerve palsy

Answer 30

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

Question 31

third nerve palsy is when the eye goes

Answer 31

down and out

Question 32

a blown pupil in third nerve palsy is suspicious for

Answer 32

aneurysm

Question 33

why is blown pupil indicative of an aneurysm in third nerve palsy

Answer 33

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)

Question 34

oculomotor nerve palsy aetiology

Answer 34

microvascular, aneurysm, tumour, trauma, infiltrative, (e.g. leukaemia)
most cases without pupil involvement are ischaemic (HTN, DM etc)

Question 35

presentation of oculomotor nerve palsy

Answer 35

diplopia, ptosis, +/- pain, +/- pupil involvement (light and accomodation)
eye turned ‘down and out’
unable to adduct/infraduct/supraduct

Question 36

Ddx of oculomotor nerve palsy

Answer 36

myasthenia gravis, thyroid orbitopathy, GCA

Question 37

management of oculomotor nerve palsy

Answer 37

acute 3rd nerve palsy with fixed dilated pupil = emergency CTA or MRI/A
FBC, ESR, CRP for ?inflammatory causes (including GCA)
medical management of vascular risk factors
driving advice, short term patching, longer term prism lenses +/- surgery

Question 38

prognosis of occulomotor nerve palsy

Answer 38

ischameic cases often resolve within 3 months

Question 39

diplopia and driving

Answer 39

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

Question 40

sudden loss of unilateral vision and driving

Answer 40

person shouldn’t be driving for an appropriate period (usually there months) to adapt to their new visual circumstance and re-etablish depth perception

Question 41

summary of eye muscles and their actions

Answer 41