The “Eyelet Sign” as an MRI Clue for Inflammatory Brown Syndrome

Abstract

Background: Brown syndrome is characterized by a restrictive elevation deficit of the affected eye in adduction. Besides the well-known congenital form, different acquired etiologies including inflammation, trauma, and surgery may prevent the superior oblique (SO) tendon from gliding freely through the trochlea on attempted upgaze. We present MRI findings in pediatric and adult patients with inflammatory acquired Brown syndrome. Methods: Retrospective review of clinical and MRI findings of 6 patients (4 children: median age 8.4 years [range 6.1-8.7]; 2 adults: age 46.4 and 51.1 years). Median follow-up was 23 months (range 1-52).Results: In all 6 patients, orbital MRI demonstrated inflammatory changes of the SO tendon-trochlea complex. A striking feature was circumferential contrast enhancement of the trochlea with central sparing where the tendon passes, reminiscent of an eyelet. In all cases, the motility restriction improved either spontaneously or with systemic antiinflammatory treatment. Although both adult patients had a history of known seronegative spondyloarthritis, there was no associated systemic condition in the children in our series. Conclusions: Both in children and in adults, MRI can provide evidence of inflammatory changes located at the trochlea-tendon complex in acquired Brown syndrome here referred to as the "eyelet sign," which may be helpful in confirming the clinical diagnosis and guide appropriate treatment.

An uncommon cause of diplopia: do not forget Brown syndrome

“…Contrary to inferior oblique muscle palsy, the limitation of supraduction in adduction in BS is unreversed with forced duction. 1 Brown syndrome is commonly congenital, with an onset in childhood. Acquired BS is idiopathic or due to surgery, trauma, tendon cysts, sinusitis, orbital tumors or rheumatological diseases.…”