Brown Syndrome Flashcards
How often does Brown Syndrome occur and is it more likely to be bilateral or unilateral?
- Occur once in every 430-450 cases of strabismus
- May be bilateral in approx. 10% of cases – most pxs will have unilateral
- Generally congenital disorder but are cases of acquired Brown syndrome (may have a px with new onset vertical muscle problem)
- Brown Syndrome is found in 10% to 24% of pxs with vertical muscle paresis
Describe the mechanism of Brown Syndrome?
- Brown Syndrome described Harold W Brown in 1949 as SO tendon sheath syndrome
o Shortening of anterior sheath of SO tendon - Restriction of SO tendon at trochlear pulley
- Congenitally inelastic or short tendon
- Abnormal tendon – trochlear complex
Describe the causes of Brown Syndrome?
- Iatrogenic
o SO surgery (e.g. tuck – restricts its movement
through trochlea)
o Scleral buckling surgery
o Glaucoma valve surgery – close to trochlea
area if they’ve been in at trab meshwork
o Sinus surgery - Inflammatory (more common cause)
o Rheumatoid arthritis
o Systemic lupus erythematosus
o Sjogren syndrome
o Hurler-Scheie syndrome
o Hypogammaglobulinemia
o Graves ophthalmopathy
o Enteropathy arthropathy - Infectious
o Sinusitis - Traumatic
o Blunt trauma
o Direct trauma (e.g. “canine tooth” syndrome)
Restriction of SO tendon at trochlear pulley – limits elevation in adduction of LE (if affecting LE)
What are the findings in Brown Syndrome?
- Deficient elevation in adduction
- Varying degrees – v mild form (slight limitation) to px who has no elevation in adduction (marked form)
- Less elevation deficiency in midline
- Minimal or no elevation deficiency in abducted position
- Minimal or no SO overaction (on depression in adduction)
- V pattern with divergence in upgaze
- Restricted forced ductions
What are the other findings in Brown Syndrome?
- Downshoot or hypotropia in adduction (limitation on elevation in adduction & downshooting looking down)
- Widening of palpebral fissure on adduction (as px attempts to look L&R)
- Anomalous head posture – usually chin elevation to get rid of diplopia
- Hypotropia in PP (manifest deviation)
What are the differential diagnoses of Brown Syndrome?
- IO palsy
o V rare palsy to have as a stand alone – differentiate using ductions & versions - Double elevator palsy
o If Brown syndrome has limited elevation in adduction, direct elevation & abduction - Congenital fibrosis syndrome
- Blow out fracture
- Thyroid ophthalmology
- Adherence syndrome
Describe congenital Brown Syndrome?
- Most often congenital
- Resolution of congenital Brown syndrome is unusual but possible
o Since child is shorter than adults, the repetitive looking up (of a child) can give rise to clicking Brown syndrome (get swelling through the trochlea – px hears audible click when they hear it popping through – this popping is thought to resolve it – trochlea itself is shaving off some of this swelling along the tendon side)
Describe acquired Brown Syndrome?
- Trauma in region of trochlea
- Systemic inflammatory
- Iatrogenic Brown Syndrome
- Intermittent Brown Syndrome – which may resolve spontaneously
How to differentiate an IO nerve palsy from Brown Syndrome?
- Same versional appearance
o When px looks up & to L or R – the contralateral eye will not be able to elevate in adduction (same for both conditions) - Deficient elevation in adduction that improves in abduction but often not completely
- In adduction, palpebral fissure widens & a downshoot of involved eye is often seen
o This would not be seen in IO palsy
o It can be distinguished from SO muscle overaction because downshoot in latter condition occurs less abruptly as adduction is increased
Muscle can move freely in IO (-ve forced ductions) – muscle cannot move in Brown syndrome (+ve forced ductions)
A pattern in IO – eyes are more adducted on elevation
V pattern in Brown Syndrome – eyes are diverging on elevation
SO – muscle sequelae in IO – neurogenic condition
Brown syndrome is a mechanical condition – less likely to get muscle sequelae and no SO overaction
Desribe how you know it is Brown Syndrome?
Describe how which deviations will be present in mild, moderate and severe Brown Syndrome?
Chin-up head posture & sometimes by a face turn away from affected eye in severe cases
Hypotropia in PP: mild - no, moderate - no, severe - yes
Downshoot of eye in adduction: mild - no, moderate - yes, severe - yes
- An unequivocally +ve forced duction test demonstrating restricted passive elevation in adduction is essential for diagnosis of Brown Syndrome
o Not going to do forced duction on child with congenital Brown - Retropulsion of globe – during this determination stretches the SO tendon & accentuates the restriction
- When IR muscle fibrosis or IO blowout fracture (principal entities to be differentiated) produces a restrictive elevation deficiency, the limitation to passive elevation is accentuated by forceps-induced proptosis of eye rather than by retropulsion
Describe the management of Brown Syndrome?
- Observation: alone in about 2 thirds (most) of all Brown Syndrome cases
- Rheumatoid Arthritis or other systemic inflammatory diseases Systemic tx
- Corticosteroids injected near trochlea
- Sinusitis has also led to Brown Syndrome
a. CT of orbits & paranasal sinuses - Surgical tx is indicated for the most severe cases (minimum number)
a. Primary position hypotropia
b. Anomalous head posture
i. Sheathectomy has been abandoned in favour of ipsilateral superior oblique tenotomy
c. Iatrogenic SO muscle palsy may occur postoperatively – 44-82%
SO tenotomy is most common surgery performed: small portion of SO is removed – elongates the SO tendon
Describe SO muscle palsy?
- Reduced: By careful preservation of intermuscular septum during tenotomy (v important) – often an overcorrection is created but this increases with time
o This modification often produces an early under correction that gradually improves with time - Perform simultaneous ipsilateral IO muscle weakening
o As now have potential to have SO overaction – this is why Brown Syndrome is often not operated on – it has to be a sever limitation of elevation before do this - Guarded tenotomy using an inert spacer sewn to the cut ends of the SO tendon
o Elongating SO tendon by inserting a silicone spacer or piece of Fascia Lata from px’s leg to elongate tendon - Controlling gap between cut ends from the SO tendon with an adjustable suture
o These procedures eliminate need for simultaneous IO muscle weakening but sometimes result in a downgaze restriction due to adhesions to nasal border of SR muscle
o Care must be taken to avoid contact of spacer to nearby structures by preserving the intermuscular septum
Describe the surgical options in Brown Syndrome?
SO expander procedure for Brown Syndrome & SO overaction with good results – originally this procedure has been performed with silicone band expander (Wright 1991)
* Silicon band expander
* Elongation with Fascia Lata
* Elongation with Achill Tendon – difficult to operate on someone’s eye & also give potential problems with walking afterwards
