Brown Syndrome

Brown syndrome is found in 10% to 24% of patients with vertical muscle paresis. .

occur once in every 430 to 450 cases of strabismus.

.

may be bilateral in approximately10% of case

Shortening of the anterior sheath of the superior oblique tendon.

Restriction of the superior oblique tendon at the trochlear pulley

Brown syndrome was described by Harold W. Brown in 1949 as the superior oblique tendonsheath syndrome.

•this theoryabandoned

congenitally inelastic or short tendon

Abnormal tendon-trochlear complex

MECHANISM

Brown SyndromeRestriction of the superior oblique tendon at the trochlear pulley

FINDING

•1 .Deficient elevation in adduction•2 .Less elevation deficiency in midline.

•3 .Minimal or no elevation deficiency in the abducted position

•4 .Minimal or no SO overaction..

•5 .V pattern with divergence in upgaze•6 .Restricted forced ductions

OTHER FINDINGS

•1 .Downshoot or hypotropia in adduction•2 .Widening of the palpebral fissure on

adduction•3 .Anomalous head posture•4 .Hypotropia in the primary position

DIFFERENTIAL DIAGNOSIS

•1-I O PALSY•2-DOUBLE ELEVATOR PALSY•3 -CONGENITAL FIBROSIS SYNDROM•4-BLOW OUT FX•5-THYROID OPHTHALMOPATY•5-ADHERENCE SYNDROM

Brown syndrome

Congenital

Acquired form

Trauma in the region of the trochlea

Systemic inflammatory

intermittent Brown syndrome, which may resolve spontaneously.

Resolution of congenital Brown syndrome is unusual but possible

Iatrogenic Brown syndrome

Comparison of Inferior Oblique Muscle Palsy With Brown Syndrome

Inferior Oblique Muscle Palsy Brown Syndrome

Forced ductions Negative Positive

Strabismus pattern A pattern V pattern

Superior oblique muscle overaction

Usually present None or minimal

Deficient elevation in adduction that improves in abduction but often not completely

In adduction, the palpebral fissure widens and a downshoot of the involved eye is often seen; it can be distinguished from superior oblique muscle overaction because downshoot in the latter condition occurs less abruptly as adduction is increased.

Brown syndrome OSDivergence in upgaze

Down shoot in attempted elevation in adduction?

Down shoot in attempted elev. in adduct. (different than IO palsy)Down shoot in attempted elev. in adduct. (different than IO palsy)

Brown syndromemild moderate severe

hypotropiain primary position

no no yes

downshoot of the eye in adduction.

no yes yes

chin-up head posture and sometimes by a face turn away from the affected eye in sever cases

An unequivocally positive forced duction test demonstrating restricted passive elevationin adduction is essential for the diagnosis of

Brown syndrome .

Retropulsion of the globe

during this determination stretches the superior oblique tendon and accentuates

the restriction.

When inferior rectus muscle fibrosis or inferior orbital blowout fracture(the principal entities to be differentiated )produces a restrictive elevation

deficiency,the limitation to passive elevation is accentuated by forceps-induced proptosis of the eye rather than by retropulsion.

Management

1.Observation :alone in about two thirds of all Brown syndrome cases

2.rheumatoid arthritis or other systemic inflammatory diseasesSystemic treatment

3.Corticosteroids injected near the trochlea4.Sinusitis has also led to Brown syndrome

CT of the orbits and paranasal sinuses

Surgical treatment is indicated for the most severe cases

Primary position hypotropiaAnomalous head posture

Iatrogenic superior oblique muscle palsy may occur postoperatively. 44%-82%

sheathectomyhas been abandoned in favor of ipsilateral superior oblique tenotomy

Brown Syndrome SO tenotomy

SR

MR LR

IR

SR

LR

RMIR

IOIO

Superior oblique muscle palsy

Reduced :

By careful preservation of the intermuscular septum during tenotomy .

This modification often produces an early under correction that gradually improves with time

Perform simultaneous ipsilateral inferior oblique muscle weakening .

guarded tenotomy using an inert spacer sewn to the cut ends of the superior oblique tendon

Controlling the gap between the cut ends with an adjustable suture

These procedures eliminate the need for simultaneous inferior oblique muscleweakening but sometimes result in a downgaze restriction due to adhesions to the nasal

border of the superior rectus muscle .Care must be taken to avoid contact of the spacer tonearby structures by preserving the intermuscular septum

Brown Syndrome Chicken suture

In 1991, Wright described a superior oblique expander procedure for browns syndrome and superior oblique overaction with good results. Originally, this procedure has been performed with silicone band expander .

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Brown Syndrome Silicone expander

Silicon Expander

Elongation with fascia lata

Elongation with Achill Tendon