Magnetic resonance imaging features of two cases of acquired Brown's syndrome

The action of the superior oblique muscle depends on both the contractile function of the muscle belly as well as the force transmission function of the tendon trochlea complex. Brown's syndrome is a restriction to elevation in adduction presumed due to an anomaly of the superior oblique tendon trochlea complex. This report presents two patients with an unusual restriction to elevation in adduction in the affected eye, and a clinical picture consistent with a Brown's syndrome. A non-invasive analysis of the functional anatomy of the superior oblique was performed using a high-resolution MRI with surface coils. Imaging in the first case revealed a cyst in the area of the right superior oblique tendon just posterior to the trochlea in primary position. The second patient had undergone reattachment of an avulsed trochlea after a dog bite (canine tooth syndrome). Imaging in the second case revealed scarring and connective tissue disruption around the tendon impeding muscle function. These findings provide distinct mechanical explanations for Brown's syndrome.