Brown’s Syndrome

Brown’s Syndrome is a mechanical ocular motility disorder characterised by restriction of elevation in adduction due to an abnormality of the superior oblique (SO) tendon–trochlear complex. Although classically congenital, acquired variants exist and present with different clinical challenges. For orthoptists and students, a detailed understanding of the mechanical restriction, compensatory features, and management options is essential, especially given the unpredictability of surgical outcomes.

Aetiology

There is no known genetic basis for Brown’s Syndrome, but it is observed more commonly in females. The underlying problem lies within the SO tendon and/or the trochlear complex. Several theories have been proposed to explain the mechanism of restriction, including developmental anomalies of the tendon–trochlear interface, shortening of the SO tendon, inelasticity of the SO tendon–muscle complex, or the presence of a tendon nodule which interferes with smooth tendon movement. Regardless of the specific mechanism, the result is a mechanical restriction of elevation in adduction, which becomes the hallmark clinical sign.

Clinical Features and Investigation

The primary feature used to identify Brown’s Syndrome is the limitation of elevation in adduction. This restriction may vary in severity. In mild cases, the limitation is only noticeable during elevation in adduction and is absent in primary position and simple adduction. Moderate cases show restriction in both adduction and elevation in adduction, though elevation in primary position remains relatively preserved. Severe cases demonstrate clear restriction in primary position as well as in adduction and elevation in adduction.

Additional signs frequently accompany this pattern. Many patients exhibit a down-drift of the affected eye on contralateral gaze, sometimes accompanied by widening of the palpebral fissure. Overaction of the contralateral superior rectus may be noted, although secondary muscle sequelae are otherwise uncommon. Some patients display an A or V pattern, with the V pattern being more typical.

Symptoms can include discomfort when elevation in adduction is attempted. Repeated testing may reveal gradual improvement in the restriction, and in some cases a characteristic “click” is felt or heard. Interestingly, this click often has a good prognostic implication, as it may suggest the potential for spontaneous improvement as the tendon frees itself.

Torsional features vary depending on gaze position. Cyclotropia is typically absent in primary position and downgaze but may appear in upgaze. Abnormal head posture (AHP) is common, and patients may adopt a chin-up posture with a head tilt towards the affected side and a face turn towards the unaffected side. In bilateral symmetrical cases, a chin-up posture alone may be seen. Despite these mechanical restrictions, many patients maintain good binocular single vision (BSV) in primary position and therefore may not present with an AHP at all. Forced duction testing is generally positive, confirming the mechanical nature of the limitation.

Management

Non-surgical management is often sufficient for many cases, especially when the patient maintains comfortable BSV in the primary position. Observation is usually appropriate for congenital Brown’s Syndrome, as many children experience gradual improvement with age. When inflammation or trauma has contributed to the restriction, retrotrochlear steroid injections may be beneficial to reduce the inflammatory response or limit the development of secondary fibrosis.

Surgical management must be approached with caution, as outcomes can be unpredictable and there is a significant risk of inducing a superior oblique palsy. Attempts to explore the posterior tendon are strongly discouraged because of the high likelihood of causing fibrosis and further restricting tendon movement. Most surgical procedures are aimed at weakening or lengthening the SO tendon. Traditional partial temporal tenotomies and recession procedures have shown limited benefit in Brown’s Syndrome.

The tendon-expander technique, where a silicone spacer is inserted to lengthen the tendon, has provided more reliable improvement. Postoperatively, an initial limitation in the field of action of the SO is expected, and late improvements in motility are relatively common. Superior oblique tenectomy, involving division of the anterior tendon on the nasal side, is another option, although it frequently results in a postoperative SO palsy. For this reason, it is often combined with ipsilateral inferior oblique weakening to restore vertical balance.

Trapped Superior Oblique Tendon

The trapped SO tendon syndrome represents a separate, typically acquired condition, most often associated with trauma to the trochlear region. This leads to mechanical entrapment or scarring of the tendon, producing a more complex pattern of restriction than congenital Brown’s Syndrome.

Clinically, patients exhibit both limited elevation and depression of the affected eye. A hypotropia is usually apparent in upgaze and a hypertropia in downgaze. Vertical and torsional diplopia is common and characteristically reverses when the patient transitions between upper and lower gaze fields. Unlike congenital Brown’s Syndrome, cyclotropia may be present in primary position.

Management of trapped tendon syndrome can begin conservatively with AHP optimisation and local steroid injections to reduce fibrosis around the trochlea. Surgical removal of scar tissue is generally avoided, as it tends to worsen fibrosis. When surgery is required, an SO tendon tenectomy, with or without a tendon spacer, may be considered to relieve the restriction.

Conclusion

Brown’s Syndrome remains an important condition for orthoptists to understand due to its distinctive mechanical restriction, generally favourable prognosis, and the nuanced decision-making required around surgical intervention. While most congenital cases can be safely observed, acquired and traumatic forms require more active treatment and careful long-term follow-up to ensure stable binocular function.