Left fourth cranial nerve palsy. The patient has a right head tilt due to head-tilt-dependent hypertropia. a. In the gaze positions, the left hypertropia increases in magnitude on right gaze and left head tilt, consistent with a left superior oblique palsy based on the Parks- Bielschowsky 3-step test. There is underdepression in adduction and overelevation in adduction of the left eye, also consistent with left superior oblique palsy. b. There is facial asymmetry with midfacial hypoplasia on the right side, suggesting the palsy is congenital.