Brown syndrome is a rare disorder of the eye distinguished by pathological changes of the superior oblique muscle and its tendon, resulting in the inability to elevate the eye while being in adduction. Both congenital and acquired forms are described, and the diagnosis can be made only after a thorough physical examination and a detailed patient history.
Brown syndrome is a relatively rare condition of the eye apparatus, in which various factors render the superior oblique muscle unable to perform its respective function - elevation of the eye while being in adduction, principally as a result of mechanical limitation [1] [2] [3] [4]. Numerous conditions have been implicated in the pathogenesis of this ocular disorder, including juvenile and rheumatoid arthritis, systemic diseases (scleroderma, Sjogren's syndrome, systemic lupus erythematosus), orbital metastatic deposits, but also trauma, inflammation, and surgery, all leading to restriction of superior oblique tendon movement [1] [2] [3] [5]. On the other hand, many individuals develop Brown syndrome from birth, indicating that congenital forms of the disease also exist [1] [2] [4] [5]. Furthermore, familial Brown syndrome, estimated to occur in approximately 1 in 20,000 live births, was also recognized in the literature [1] [3]. The clinical presentation is characterized by the inability of patients to elevate the eye in adduction, producing predominantly unilateral (although 10% of cases exhibit bilateral) changes in eye movement [1] [2] [3]. Consequently, a slight downward deviation of the eye on adduction is noted [1] Studies did not show a predilection toward gender or either of the eyes [1]. In the setting of the congenital Brown syndrome, spontaneous resolution is seen in 11-76% of children, but complications such as hypertropia, amblyopia, and other visual deficits may develop [1] [4] [6].
The diagnosis of Brown syndrome can be made only after an extensive workup. Because the initial diagnosis of an eye-related pathology might be made by a simple evaluation of eye movement, the role of a properly performed physical examination is pivotal in recognizing this condition. Apart from the obvious inability to perform eye elevation while being in adduction, several other features that are seen during the exam are a downward deviation in adduction, widening of the palpebral fissure when the patient adducts the eye and the absence of over-activation of the superior oblique muscle [1]. Additionally, the forced duction test, during which the limbus is grasped by a forceps with the attempt to move the eye mechanically, will be positive - restricted movement will be observed due to the mechanical nature of the disease. In that case, the diagnosis of Brown syndrome is almost definite [1]. To identify the exact cause of this condition, a thorough patient history is helpful in distinguishing between congenital and acquired forms. Age of onset, as well as a history of previous conditions or events that could lead to Brown syndrome, should be assessed. Imaging studies, such as computed tomography (CT) and magnetic resonance imaging (MRI) have been regarded as potentially useful tools in solidifying the diagnosis [5]. Thickening of the superior oblique tendon on T1 and high signal intensity on T2-weighed imaging have been reported in this condition [5].