Definition of Cranial mononeuropathy III - compression type:

Cranial mononeuropathy III -- compression type -- is a problem with the function of the third cranial nerve that causes double vision and eyelid drooping.

Causes, incidence, and risk factors:

Cranial mononeuropathy III - compression type is a mononeuropathy, which means that only one nerve is affected. It affects the third cranial (oculomotor) nerve, one of the cranial nerves that controls eye movement. Local tumors or swelling can press on and damage the nerve.

Causes may include:

• Brain aneurysms
• Infections
• Poorly formed blood vessels (vascular malformations)
• Sinus thrombosis
• Tissue damage from loss of blood flow (infarction)
• Trauma (from head injury or caused accidentally during surgery)
• Tumors or other growths (especially tumors at the base of the brain and pituitary gland)

Rarely, people with migraine headaches may have a temporary problem with the oculomotor nerve. This is probably due to a spasm of the blood vessels. In some cases, no cause can be found.