Neurogenic vs. Restrictive OM Flashcards
Define ‘Restrictive Eye Movements’/Mechanical?
“Caused by elements in the orbit that interfere with muscle contraction and relaxation or prevent free movement of globe”
What are some examples of Neurogenic palsies?
CNIII
CNIV
CNV
(Unilateral or Bilateral)
Individual muscle palsies
Whare some examples of Restrictive Eye Movements?
- Brown’s
- Duane’s
- Adherence syndrome
- Congenital Fibrosis of the Extraocular Muscles (CFEOM)
- Blow out
- TED
- Post retinal detachment or cataract sx
- Tumours
- Myositis
- Orbital Injuries
- Secondary Brown’s
- Post-strabismus surgery
What does Iatrogenic mean?
Caused by surgery
How does Iatrogenic Brown’s occur?
Tightened superior oblique from a SO tuck. Looking away from the leash (the tuck) it causes iatrogenic Brown’s (restricted elevation in adduction; the IO cannot elevate in adduction because the SO cannot relax)
What is a direct tether/leash?
e.g. Iatrogenic Brown’s, TED
- Tight or shortened muscle
- Limits movement when looking away from the leash
- More common
What is indirect tether/leash?
e.g. post-traumatic adhesions between conjunctiva and orbit or sinus mucocele (cystic mass). For example cyst in the lacrimal sac can cause issues in the orbit that affects the eye muscle causing a restriction.
- Limits movement when looking towards leash
- Less common
What does the deviation in pp look like in neurogenic palsies?
Size of deviation in PP is dependent on extent of the palsy
What does the deviation in pp look like in restrictive eye movements?
In many cases despite a large restriction of movement the deviation in p.p. is very small
What do OMs look like Neurogenic palsies?
Maximum limitation is in the position of the main action of the affected muscle.
The amount of movement is greater on duction than version unless a complete paralysis.
D>V
What do OMs look like in restrictive eye movements?
Restriction is usually in the opposite direction to the affected muscle & is across the field of action e.g. Blow out # restriction in elevation.
Duction & version movements are equally limited.
D=V
What is IOP like in neurogenic palsies?
Unchanged in all gaze positions.
What is IOP like in restrictive eye movements?
Raised when looking away from the site of the lesion.
Who feel pain from their eye movements? Neurogenic or Restrictive eye movements?
Neurogenic - no pain on movement
Restrictive Eye Movements - Pain in acquired lesions e.g. TED and some cases of Brown’s syndrome
What does FDT look like in neurogenic palsies?
Negative FDT
Full passive movement
unless secondary muscle contracture
has occurred e.g. in longstanding 6th
What does FDT look like in restrictive eye movements?
Positive FDT
Limited passive movement
generally in the opposite direction to the lesion, sometimes in the same direction or both directions
What are the saccades like in neurogenic palsies?
Slowed in the direction of the underaction.
What are the saccades like in restrictive eye movements?
Normal saccadic velocity until the point of the mechanical restriction, then normal movement comes to an abrupt end.
What are head postures like in neurogenic palsies?
A combination head posture is common in neurogenic vertical muscle palsies.
What are head postures like in restrictive eye movements?
Just head up / down common in mechanical restrictions.
What does the muscle sequelae look like in neurogenic palsies?
Full muscle sequelae esp. if longstanding
What does the muscle sequelae look like in restrictive eye movements?
o/a of contralateral synergist only
What does the globe look like in neurogenic palsies and in restrictive eye movements?
- No change in globe position
- Retraction of the globe when the eye is turned in the direction opposite to the restriction
What is diplopia like in neurogenic palsies?
Except in CNIII & bilateral IVth the direction of diplopia remains the same e.g. R/L
Dip may increase on one side in neurogenic but stays the same direction unless in two exceptions above
