Differential Diagnosis of Recent & Longstanding Palsies Flashcards
What can’t we differentiate between longstanding, congenital and acquired?
Cannot differentiate between congenital and longstanding acquired
What can we use to differentiate between congenital/longstanding/acquired?
- Case History
- Questioning around symptoms
- Old photographs
- Look at prescription - focimeter them
What are the red flags we think about during case history for something being acquired?
- Report exact cause
- Recent head trauma
- Aware of AHP
- Coincidental family history
- Possible previous episode that has recovered
What are the red flags we think about during case history for something being longstanding?
- No obvious cause
- Head trauma from past
- Unaware of AHP
- Familial cases of CNIV palsy
- Attended as a child
- Possible facial asymmetry
What are the symptoms that bring up a red flag for something being acquired?
- Sudden onset
- Diplopia
- Troubled by symptoms
- Torsion CNIV palsy
What are the symptoms that bring up a red flag for something being acquired?
- Vague onset
- Diplopia absent/intermittent
- Not troubled by symptoms
- Symptoms worse when tired (can be related to ability to control)
What can we observe that brings up red flags for a palsy being acquired?
- Aware of new AHP
- AHP resolves when occluding one eye or in the dark
What can we observe that brings up red flags for a palsy being acquired?
- May have AHP from childhood (photos)
- AHP maintained on occlusion of one eye or in the dark
What are we more likely to see on CT in an acquired palsy?
- Incomitant deviation
- Small deviation for degree of symptoms
What are we more likely to see on CT in a longstanding palsy?
- Fairly concomitant deviation
- May be controlling large phoria
What are we more likely to see during VA in an acquired palsy?
- 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.
What are we more likely to see during VA in a longstanding palsy?
- Amblyopia if manifest from an early age
- Reduced VA could be cause for decompensation (can be common in cataract development)
What are we more likely to see on OM in an acquired palsy?
- Incomplete muscle sequelae (CNIII is an exception)
- Incomitant on Hess Chart
What are we more likely to see on OM in a longstanding palsy?
- Muscle sequelae developed (may have difficulty identifying originally affected muscle)
- Hess chart shows fields of similar size
What are we likely to find during binocular functions in acquired palsies?
- Normal vertical fusion range (if no constant diplopia)
- No suppression (unless childhood strabismus or elderly and ignoring the diplopic image)
What are we likely to find during binocular functions in longstanding palsies?
- 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
What did Rutstein and Corliss (1995) find out about vertical prism fusion range?
That extended vertical fusion ranges may not be present in CNIV palsy until over the age of 15 years! But small sample sizes.
What vertical prism fusion range can we use to support a congenital SO palsy?
> 10PD (Sharma & Abdul-Rahim, 1992)
10PD - 25PD (Miller, 1985)
What is the field of BSV likely to look like in an acquired nerve palsy?
Small field for size of defect
What is the field if BSV likely to look like in a longstanding nerve palsy?
Larger field for size of defect
What is the angle of deviation likely to look like in an acquired nerve palsy?
Angle greater fixing with affected eye
Secondary > Primary
What is the angle of deviation likely to look like in a longstanding nerve palsy?
Concomitant
Secondary = Primary
What is objective torsion?
Fundus photography or indirect ophthalmoscopy
What does an intorted eye look like on fundus photography?
Fovea above upper line
What does an extorted eye look like on fundus photography?
Fovea below lower line
What is the normal position of the fovea in fundus photography?
Lies level with the lower 1/3rd of the optic disc
If a deviation is longstanding what do we except with subjective torsion?
If a deviation is longstanding subjective adaptation to torsion may occur and so objective > subjective
What is ‘subjective adaptation’?
When there is a difference of >18º between subjective and objective measurement indicates subjective adaptation (McNamara et al, 1995)
