Cranial mononeuropathy III; Compression type

Definition:

A disorder involving vision changes and eyelid drooping, associated with decreased function of cranial nerve III.

Causes, incidence, and risk factors:

Cranial mononeuropathy III; Compression type is a mononeuropathy (damage to a single nerve) involving the third cranial (oculomotor) nerve, one of the cranial nerves that controls eye movement. Damage is usually caused by compression of the nerve from localized lesions or swelling in the area of the nerve. Specific causes include tumors or other lesions (especially tumors located at the base of the brain), trauma, infarction (tissue damage from loss of blood flow), some cerebral aneurysms, and disorders such as mononeuritis multiplex. On rare occasions, people with migraine headaches may demonstrate a temporary type of oculomotor nerve involvement, probably because of spasm of the blood vessels. In some cases, no cause can be found.