Bilateral superior oblique palsy

A patient with a bilateral fourth nerve palsy demonstrates a reversing hypertropia (left hypertropia in right gaze and a right hypertropia in left gaze in the middle panels right and left). The primary position deviation is not readily apparent, because of the bilateral palsy (middle row, center panel). There is underaction of both superior oblique muscles (right lower and left lower panels). There is overaction of the inferior oblique muscle bilaterally (right upper and left upper panels).