Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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October 7, 2021
Trochleitis with Acquired Brown Syndrome
- Background:
- Trochleitis is a form of trochleodynia, comprised of inflammatory lymphocytic infiltration of the trochlea, SO muscle, and adjacent connective tissues.
- Brown syndrome describes both congenital and acquired causes of SO tendon sheath syndrome, where there is some cause of dysfunction to the normal contraction of the SO muscle or function of the tendon.
- Clinical Presentation:
- Trochleitis most commonly presents as an idiopathic, unilateral process, with patients reporting upper medial orbital pain, pain worse with eye movement, and headache. These symptoms may manifest as pain with reading.
- Brown syndrome classically presents as the inability to elevate the affected eye beyond the horizon while the globe is adducted. The involved eye stays adducted while the contralateral eye elevates normally.
- Key Diagnostic Features:
- CT imaging of trochleitis demonstrates thickening and enhancement of the trochlea, superior oblique tendon, and muscle.
- Contrast MRI demonstrates similar thickening and enhancement, in addition to T2 hyperintensity of the above structures.
- The imaging manifestations of Brown syndrome are numerous and representative of each underlying cause.
- Differential Diagnoses:
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Bilateral trochleitis: The key diagnostic features may be seen bilaterally, favoring systemic causes of trochleitis to include systemic lupus erythematosus, granulomatosis with polyangiitis, adult-onset Still disease, incomplete Behçet syndrome, or others.
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Orbital pseudotumor: Rapid presentation of painful proptosis, with imaging of either poorly marginated or masslike soft-tissue enhancement involving any region of the orbit; can affect both the extraocular muscles and tendons
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Thyroid ophthalmopathy: Bilateral, symmetric involvement of the orbital muscles, which demonstrate thickening, T2 hyperintensity, and enhancement; this process tends to spare the tendons and affects the orbital rectus muscles more frequently than the superior oblique muscle. Proptosis may be present.
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Orbital sarcoidosis: Multiple, asymmetric areas of swelling and enhancement affecting the periorbital superficial tissues, lacrimal gland, optic nerve, and extraocular muscles; findings of sarcoidosis will likely be present elsewhere in the body.
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Brown syndrome may result from congenital causes (laxity in extraocular muscle pulleys, adhesive fibrotic bands, SO muscle atrophy or absence) or from acquired etiologies (trauma, extension of a local infection, cysticercosis, inflammation, impingement from an orbital neoplasm, iatrogenic injury of orbital or strabismus surgery, or scarring).
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Treatment:
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Idiopathic trochleitis is treated with NSAIDs, oral steroids, and possibly a local trochlear injection of a corticosteroid or anesthetic.
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Systemic causes of trochleitis are addressed by treating the underlying condition.
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Treatment of Brown syndrome involves addressing the underlying congenital or acquired cause.
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