Differential Diagnosis of Recent & Longstanding Palsies

Question 1

What can’t we differentiate between longstanding, congenital and acquired?

Answer 1

Cannot differentiate between congenital and longstanding acquired

Question 2

What can we use to differentiate between congenital/longstanding/acquired?

Answer 2

• Case History
• Questioning around symptoms
• Old photographs
• Look at prescription - focimeter them

Question 3

What are the red flags we think about during case history for something being acquired?

Answer 3

• Report exact cause
• Recent head trauma
• Aware of AHP
• Coincidental family history
• Possible previous episode that has recovered

Question 4

What are the red flags we think about during case history for something being longstanding?

Answer 4

• No obvious cause
• Head trauma from past
• Unaware of AHP
• Familial cases of CNIV palsy
• Attended as a child
• Possible facial asymmetry

Question 5

What are the symptoms that bring up a red flag for something being acquired?

Answer 5

• Sudden onset
• Diplopia
• Troubled by symptoms
• Torsion CNIV palsy

Question 6

What are the symptoms that bring up a red flag for something being acquired?

Answer 6

• Vague onset
• Diplopia absent/intermittent
• Not troubled by symptoms
• Symptoms worse when tired (can be related to ability to control)

Question 7

What can we observe that brings up red flags for a palsy being acquired?

Answer 7

• Aware of new AHP
• AHP resolves when occluding one eye or in the dark

Question 8

What can we observe that brings up red flags for a palsy being acquired?

Answer 8

• May have AHP from childhood (photos)
• AHP maintained on occlusion of one eye or in the dark

Question 9

What are we more likely to see on CT in an acquired palsy?

Answer 9

• Incomitant deviation
• Small deviation for degree of symptoms

Question 10

What are we more likely to see on CT in a longstanding palsy?

Answer 10

• Fairly concomitant deviation
• May be controlling large phoria

Question 11

What are we more likely to see during VA in an acquired palsy?

Answer 11

• Any reduction in VA is generally coincidental
• Rare has an associated cause except pressure on optic nerve from a tumour or previous retrobulbar neuritis etc.

Question 12

What are we more likely to see during VA in a longstanding palsy?

Answer 12

• Amblyopia if manifest from an early age
• Reduced VA could be cause for decompensation (can be common in cataract development)

Question 13

What are we more likely to see on OM in an acquired palsy?

Answer 13

• Incomplete muscle sequelae (CNIII is an exception)
• Incomitant on Hess Chart

Question 14

What are we more likely to see on OM in a longstanding palsy?

Answer 14

• Muscle sequelae developed (may have difficulty identifying originally affected muscle)
• Hess chart shows fields of similar size

Question 15

What are we likely to find during binocular functions in acquired palsies?

Answer 15

• Normal vertical fusion range (if no constant diplopia)
• No suppression (unless childhood strabismus or elderly and ignoring the diplopic image)

Question 16

What are we likely to find during binocular functions in longstanding palsies?

Answer 16

• Increased vertical fusion range (if vertical deviation)
• Patients may have suppression (in positions of gaze where manifest)

BUT fusion may be affected in head injuries

Question 17

What did Rutstein and Corliss (1995) find out about vertical prism fusion range?

Answer 17

That extended vertical fusion ranges may not be present in CNIV palsy until over the age of 15 years! But small sample sizes.

Question 18

What vertical prism fusion range can we use to support a congenital SO palsy?

Answer 18

> 10PD (Sharma & Abdul-Rahim, 1992)

10PD - 25PD (Miller, 1985)

Question 19

What is the field of BSV likely to look like in an acquired nerve palsy?

Answer 19

Small field for size of defect

Question 20

What is the field if BSV likely to look like in a longstanding nerve palsy?

Answer 20

Larger field for size of defect

Question 21

What is the angle of deviation likely to look like in an acquired nerve palsy?

Answer 21

Angle greater fixing with affected eye

Secondary > Primary

Question 22

What is the angle of deviation likely to look like in a longstanding nerve palsy?

Answer 22

Concomitant

Secondary = Primary

Question 23

What is objective torsion?

Answer 23

Fundus photography or indirect ophthalmoscopy

Question 24

What does an intorted eye look like on fundus photography?

Answer 24

Fovea above upper line

Question 25

What does an extorted eye look like on fundus photography?

Answer 25

Fovea below lower line

Question 26

What is the normal position of the fovea in fundus photography?

Answer 26

Lies level with the lower 1/3rd of the optic disc

Question 27

If a deviation is longstanding what do we except with subjective torsion?

Answer 27

If a deviation is longstanding subjective adaptation to torsion may occur and so objective > subjective

Question 28

What is ‘subjective adaptation’?

Answer 28

When there is a difference of >18º between subjective and objective measurement indicates subjective adaptation (McNamara et al, 1995)