How do I know that I have cranial nerve palsy?

Dysfunction of one cranial nerve will produce weakness in one or more muscles. If the eyes aren’t moving together the patient will experience blurred or double vision. If only the VIth nerve (innervating the lateral rectus) is affected the double vision will be side to side. If the IIIrd or IVth nerve is affected there will most commonly be some vertical (“one on top of the other”) double vision. This will vary depending on the direction of gaze.