Mechanical Palsies Flashcards
(26 cards)
What causes Brown’s syndrome?
SO restriction caused by:
Short/tight tendon sheath
Inflamed tendon
Trochlea injury
Swelling or nodule on tendon
What is the restriction of movement in Brown’s syndrome?
Limited elevation in adduction
What are the signs of Brown’s syndrome?
Pain or discomfort in trochlear region on attempted elevation in adduction
AHP (chin up, tilt to affected eye)
Small limitation of elevation in all positions
Hess: dog ear shape
How should Brown’s syndrome be managed?
Treat amblyopia (unlikely)
Correct refractive error
Refer to ophthalmology for surgery
When would surgery be considered for Brown’s syndrome?
Poor cosmesis
Marked AHP
Diplopia in primary position
To allow BSV development
What direction do the limitations in mechanical palsies go?
Opposite direction to affected muscle
Why does globe retraction occur?
Co-contraction of two muscles
What will be seen on the forced duction test in mechanical palsies?
Restricted passive movement due to physical limitation
What can cause Duane’s retraction syndrome?
Mechanical or innervational causes
What are the mechanical causes of Duane’s?
Thin, elastic muscles
Muscle bound to orbital wall
MR inserted posteriorly
Inelastic and fibrotic LR with abnormal attachments
What are the innervational causes of Duane’s?
No or partially formed CNVI nucleus
Partial innervation of LR by CNIII, causing co-contraction of MR and LR on adduction
What are Huber’s classifications of Duane’s?
I - limited abduction
II - limited adduction
III - limited abduction and adduction (more limitation on abduction)
What are the signs of Duane’s?
Retraction on adduction
Widening and narrowing of palpebral fissure
AHP in primary position (turn towards problematic gaze)
Only first stage of sequelae
How should Duane’s be managed?
Correct refractive error
Treat any amblyopia (unlikely)
Surgery
When would surgery be considered for Duane’s
Strabismus or decompensation with diplopia in primary position
AHP cosmetically poor
How can you differentiate between Duane’s and a 6th nerve palsy?
Duanes:
From birth
Deviation not proportional to limitation - deviation smaller in primary position
First stage of muscle sequelae only
AHP with no problems
Globe retraction
Widening/narrowing of palpebral fissures
CNVI palsy:
Acute onset
Deviation proportional to limitation
Full muscle sequelae
AHP causes problems (bc new)
No globe retraction or palpebral fissure widening/narrowing
What is strabismus fixus?
Bilateral ESOT (sometimes EXOT) with no fusion
What adaptations can occur in strabismus fixus?
AHP - uses one eye to fixate
If develops early: no amblyopia, uses cross fixation
How can strabismus fixus be treated?
Occlusion
AHP
Surgery
What is adherence syndrome?
Two muscles connected abnormally
How is adherence syndrome treated?
Connection between muscles surgically released
What is möbius syndrome?
Underdevelopment of CNVI and VII
Causes facial weakness, ESOT, inability to abduct, difficulty blinking and developmental abnormalities
What are the signs of soft tissue injury in orbital injuries?
Oedema
Bruising
Haemorrhage
What are the signs of a blow out fracture?
Restricted movement (abnormal motility)
Pseudoptosis (due to retraction or displacement)
Facial asymmetry (if rim involved)
Squashed Hess chart
