Bilateral trochlear nerve palsy with arachnoid cyst of the quadrigeminal cistern.

Abstract

To report bilateral trochlear nerve palsy and its magnetic resonance imaging characteristics in a patient with an arachnoid cyst of the quadrigeminal cistern. We performed magnetic resonance imaging of the brainstem of a 54-year-old man who had bilateral trochlear nerve palsy and mild truncal ataxia. Magnetic resonance imaging disclosed an arachnoid cyst of the quadrigeminal cistern with enlargement of the lateral, third, and fourth ventricles. The tectum of the midbrain and the ambient and interpeduncular cisterns were markedly compressed by the arachnoid cyst. These findings suggest that the bilateral trochlear nerve palsy in this patient was caused by the arachnoid cyst of the quadrigeminal cistern.