Diabetic third nerve palsy; Pupil-sparing third cranial nerve palsy
Cranial mononeuropathy III - diabetic type is a mononeuropathy, which means that only one nerve is damaged. It affects the third cranial (oculomotor) nerve, which is one of the cranial nerves that controls eye movement.
This type of damage may occur along with diabetic peripheral neuropathy. It is due to damage to the small blood vessels that feed the nerve.
Cranial mononeuropathy III is the most common cranial nerve disorder in people with diabetes.
Causes may include:
An examination of the eyes will determine whether only the third nerve is affected or if other nerves have also been damaged. Signs may include:
Your health care provider will do a complete examination to determine the possible effect on other parts of the nervous system. Depending on the suspected cause, you may need:
You may need to be referred to a doctor who specializes in vision problems related to the nervous system (neuro-ophthalmologist).
There is no specific treatment to correct the nerve injury.
Treatments may include:
Some people may recover without treatment.
Many patients get better over 3 - 6 months, although some have permanent eye muscle weakness.
Call your health care provider if you have double vision and it doesn't go away in a few minutes, especially if you also have eyelid drooping.
Control of blood sugar levels in people with diabetes may reduce the risk of developing this disorder.
Baloh RW. Neuro-ophthalmology. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 450.
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