Differential diagnosis- recent v longstanding palsies Flashcards
Recent assumes
aquired
Is long standing always congenital?
may or may not be congenital
Differences
It can be difficult to tell if longstanding or congenital- poor history in adults
Congenital may have abnormal tendencies
Important to note
- determine further investigations
- awareness of preventing further investigating to relieve worry and discomfort
- be able to offer management
- consider cost on NHS and patient
History in recent palsies
May report exact cause e.g. after illness
? Previous episode that has recovered
FH coincidental
Aware of AHP
Diplopia
History in long standing palsies
No obvious cause
May have attended as a child
Familial cases of 4th NP
Unaware of AHP
? Facial asymmetry
Photographs in longstanding palsies
Might show presence of AHP from childhood
Shows progression as they age shows that it is acquired and not congenital
AHP in recent palsies
AHP resolves on occlusion of one eye or in dark
AHP in longstanding palsies
AHP maintained on occlusion of one eye or in dark
measure this due to long standing
History in recent palsies
Sudden onset of symptoms
Diplopia
Very troubled by symptoms
Torsion (4th NP)
History in long standing palsies
Vague onset of symptoms
Diplopia absent/intermittent (when manifest)
Not so troubled by symptoms
Worse when tired
History in both
Can be precise symptoms if acquired as it is new and disturbing
Bilateral 4th nerve have torsional diplopia and is also disturbing
Can be decompensating due to illness or new hobby/ job
Cover test in recent palsies
Incomitant deviation (disappears quickly)
Small deviation for degree of symptoms
Marked symptoms even in small deviation when recently acquired
Cover test in long standing palsies
Fairly concomitant deviation
May be controlling large phoria
Visual acuity in recent palsies
Any reduction in visual acuity is coincidental
(rarely could be associated with cause -pressure on optic nerve from tumour; previous retrobulbar neuritis etc)
Visual acuity in long standing palsies
Amblyopia if manifest from early age
Reduced VA could be cause for decompensation
Ocular movements and HESS in recent palsies
Incomplete muscle sequelae (may only be the first 2 stages)
Incomitant on Hess chart
Ocular movements and HESS in longstanding palsies
Muscle sequelae developed(may have difficulty identifying originally affected muscle)
Hess chart shows fields of similar size
- can be difficult to find primary muscle
Angle of deviation in recent palsies- greater when fixing with which eye
Incomitant
Angle greater fixing with affected eye
2° > 1°
Angle of deviation is longstanding palsies
Concomitant
Subjective adaptation to torsion –when measured using fundus there is discrepancy between subjective and objective measurement
Objective > subjective
difference of >18º between subjective and objective measurement indicates subjective adaptation (McNamara et al, 1995)
Sizes in both
Small palsy – small deviation
Large palsy – large deviation
Don’t have to develop full muscle sequelae or primary deviation/ incomitance
Binocular function in recent palsies
Normal vertical fusion range
If no constant diplopia
No suppression (unless child)
NB Fusion may be affected in head injuries
Do have BSV as they become manifest which gave them diplopia so after palsy disappears regain their BSV
Binocular function in longstanding palsies
VFR?
Increased vertical fusion range
If vertical deviation
Patients may have suppression in positions of gaze where manifest
Vertical fusion range
SO palsy fusion range:
> 10 may be used in support of a congenital SO palsy diagnosis(Sharma & Abdul-Rahim, 1992)
10 - 25 in congenital cases (Miller, 1985)
- study in pp
Field of BSV in recent palsies
Small field for size of defect
Field of BSV in longstanding palsies
Larger field for size of defect
Past pointing in recent palsies
Is present
Past pointing in longstanding
Is absent
To know
Importance of making differential diagnosis
If in doubt…investigate further!
Remember…patients with strabismus can also develop neurogenic palsies
