brain, spinal cord, and nerve disorders
Fourth Cranial Nerve (Trochlear Nerve) Palsy
Introduction
A palsy of the 4th cranial nerve affects vertical eye movements. Often doctors cannot identify the cause, but when they can, the cause is usually a head injury, sometimes a minor one. People see double images, but tilting the head to the side opposite the affected eye can eliminate them. Doctors suspect palsy of the 4th cranial nerve based on the symptoms, but computed tomography or magnetic resonance imaging may be done. The cause, if identified, is treated. (See also Overview of the Cranial Nerves .) Palsy refers to paralysis, which can range from partial to complete. 