3rd Nerve Palsy With Preserved 4th Nerve Function

80-yo-woman with a left vasculopathic 3rd nerve palsy (minimal pupil involvement of about 1 mm relative mydriasis OS - other etiologies ruled out and resolved as expected over months). Although the inferior rectus is paretic, intact superior oblique muscle function can be demonstrated by asking the patient to look down - although depression is minimal, this video demonstrates clear incyclotorsion OS which suggests that the 4th nerve is intact. Video shows left 3rd nerve palsy with intact left 4th nerve function.