Central 4th Nerve Palsy with Contralateral Horner's Syndrome

This is a 60-yo-woman who presented with a complaint of diplopia. Examination demonstrated a left hypertropia that worsened in right and down gaze as well as in left head tilt, and a left 4th nerve palsy was diagnosed. There was also evidence of a mild motility deficit in down/medial gaze OS, consistent with paresis of the left superior oblique muscle. There was also right ptosis and miosis consistent with a right Horner's syndrome. In her case, there was a lesion of the right midbrain (turned out to be a small met from lung cancer), involving the fascicle and/or nucleus of right cranial nerve 4 (prior to its decussation) and the adjacent right (uncrossed) oculosympathetic tract. The combination of a 4th nerve palsy with contralateral Horner's (or INO) is highly suggestive of a central 4th nerve palsy given the trochlear nerve's unique decussation. Number of Figures and legend for each: 0 Number of Videos and legend for each: 1, Right Horner's syndrome with left 4th nerve palsy