Ocular Palsies

Question 1

When do you get triad of symptoms?

Answer 1

lesions of ocular motor nuclei
nerves weaken
paralyse of the EOM

Question 2

What is strabismus?

Answer 2

Deviation of the eye from the primary gaze position in the opposite directions of the muscle’s normal action

Question 3

What is diplopia?

Answer 3

Double vision

Question 4

What is external Ophthalmoplegia?

Answer 4

Limitation of eye movements in the muscles normal directions of action

Question 5

How do you get classical nerve palsies?

Answer 5

Complete (all nerves function effected)
Isolated ( no other brain or nerve involvement)
Unilateral (1 nerve and one eye only )

Question 6

Who gets 3rd nerve palsies?

Answer 6

Adult more

Question 7

Who gets 4th nerve palsies

Answer 7

Children more

Question 8

Who gets 5th Nerve palsies ?

Answer 8

Adult more

Question 9

Who gets mixed nerve palsies?

Answer 9

Equal in children and adults

Question 10

What are the potential acquired causes?

Answer 10

Nuclei in the brainstem

Intra cranial nerve (classical cause)

Intra cranial nerve (mixed multiple involvement)

Question 11

How does nuclei in the brainstem cause problems?

Answer 11

Other brainstems structures are involved

vascular infarct, tumors, inflammation

Question 12

How does classical intra cranial cause problems?

Answer 12

trauma, 
tumours, 
arterial aneurysms, 
subarachnoid space 
ischemic micro - vascular neuropathy

Question 13

How does mixed intra cranial nerve cause problems?

Answer 13

In or near cavernous sinus,

inflammation

Question 14

How is acquired classical adult palsies caused?

Answer 14

Vascular - common in type 2 diabetes in older px

25% idiopathic

Question 15

Why does each muscle have an action ?

Answer 15

contributions of their anatomy to this

Origins, orbital paths and scleral insertions

Question 16

What are the medial walls of orbits ?

Answer 16

Medial walls formed by ethmoid bones and are parallel to visual axis

Question 17

What is the angle of medial walls and lateral walls?

Answer 17

45 degrees

Question 18

What is the angle between the visual axis and orbital axis of each eye?

Answer 18

22.5 degrees

Question 19

Where does the 4 rectus and the superior oblique originate?

Answer 19

common tendon (the annulus of zinn) attached to the bone at the orbital apex, and encircling the optic canal and adjoining part of the superior orbital fissure

Question 20

Where do the 4 rectus insert?

Answer 20

insert near the limbus anterior to the equator

Question 21

What do SR and IR do?

Answer 21

SR & IR run parallel to the orbital axis 23 degrees to the visual axis in primary gaze and have a convex insertion

Question 22

Where does the SO pass?

Answer 22

The SO passes backwards through the trochlear pulley at 45 degrees to the visual axis and insert posterior to the equator

Question 23

Where does the IO originate from ?

Answer 23

From a short tendon attached to the anterior medial wall of the orbit just inferior to the rim of lacrimal fossa

Question 24

Where does the IO run?

Answer 24

Runs parallel backwards at 51 degrees to the visual axis under the IR and inserts posterior to the equator

Question 25

What are the three paths of the rectus muscles?

Answer 25

Equator of the globe Mid orbital region common annular tendon

Question 26

What does the scleral to limbus distance of rectus muscles show?

Answer 26

How strong or weak the muscle is | The closer to limbus the stronger the muscle

Question 27

Which rectus is the strongest?

Answer 27

Medial rectus - 5.5mm insertion distance sclera to limbus

Question 28

What type of insertion does the superior oblique have?

Answer 28

Wide insertion by long tendon 20mm posterior and lateral to the equator under the SR muscle

Question 29

What type of insertion does the inferior oblique have?

Answer 29

Wide insertion by short tendon

Question 30

What are the key features of classical 3rd nerve palsy?

Answer 30

Ocular deviation external ophthalmoplegia Internal ophthalmoplegia Complete or partial ptosis

Question 31

What does complete deviation show in 3rd nerve palsy?

Answer 31

complete exotropia (abduction) and some depression (hypotropia)

Question 32

What does external ophthalmoplegia show in 3rd nerve palsy?

Answer 32

limited no adduction or elevation eye movement

Question 33

What does internal ophthalmoplegia show in 3rd nerve palsy?

Answer 33

dilated unreactive pupil and loss of accommodation

Question 34

What does complete or partial potosis show in 3rd nereve palsy?

Answer 34

so no or little diplopia

Question 35

Why do you get these features in 3rd nerve palsy?

Answer 35

All adductors (MR, IR, SR) and elevators (SR, IO) are paralysed with 2 abductors (LR, SO) and depressors(SO) unopposed

Question 36

Why do you get undilated and unresponsive pupil?

Answer 36

Constriction sphincter muscle paralysed, dilator muscle unopposed

Question 37

Why do you get ptosis?

Answer 37

levator palpebrae superioris muscle paralysed, orbicularis oculi unopposed

Question 38

What is common cause of 3rd nerve palsy?

Answer 38

Posterior Communicating artery aneurysm

Question 39

What does the 3rd nerve contain?

Answer 39

parasympathetic, nerve fibres cause pupil to constrict and run from superior to inferior

Question 40

What does the 3rd nerve axons occupy?>

Answer 40

Superficial edge supplied by larger blood vessels

Question 41

What problems do you get with spared pupillomotor axons in diabetic retinopathy?

Answer 41

PCoA aneurysm somewhere else non directly on the axons and spares the pupil

Question 42

What is effected in diabetic retinopathy?

Answer 42

The deep micro vascular capillaries in the nerve

Question 43

What are clinical key features of 6th nerve palsy?

Answer 43

External ophthalmoplegia - limited no abduction eye movements ocular deviation - complete adduction Horizontal diplopia - worsening with gaze towards the affected side and at far

Question 44

What does the 6th nerve palsy have compared to 3rd nerve palsy?

Answer 44

No ptosis

Question 45

What do you have to do for 6th nerve palsy and esotropia?

Answer 45

Compensatory strategy= abnormal head posture, | reduce diplopia

Question 46

What are some causes of 6th nerve palsy?

Answer 46

Lateral head trauma to temporal bone Arterial pathology Non classical brainstem tumours

Question 47

What is meant by lateral head trauma to temporal bone

Answer 47

inward movement of petrous portion crushes nerve against the clivus at the petro-sphenoidal ligament

Question 48

What is meant by arterial pathology?

Answer 48

Hardening or aneurysm of the basilar artery or AICA near nerve exit from the brainstem

Question 49

What is meant by non classical brainstem tumours?

Answer 49

Downwards pressure ruptures nerve in the same region

Question 50

What are the clinical features of 4th nerve palsy?

Answer 50

Ocular deviations - exotorsion, hypetropia and exotropia External ophthalmoplegia - limited no adduction especially on near gaze Torsional and vertical diplopia- worse when looking down or near

Question 51

When do patients complain of SO palsy?

Answer 51

Read , walk or down the stairs

Question 52

What are the causes of 4th nerve palsy?

Answer 52

>Frontal head trauma- whiplash >Brainstem tumours that pushes brain back and forwards >Rupture nerve by displacement as long thin and unprotected by dura as it curves around the midbrain and into subarachnoid space

Question 53

What do you do in 4th nerve palsy?

Answer 53

Compensation - head tilt away from affected eye to reduce vertical and torsional components of diplopia

Question 54

What happens if you get a lesion in 6th nerve ?

Answer 54

Lesion in pons on abducens nerve - would be subarachnoid space - right eye esotropia Cause: aneurysm in artery