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Cranial mononeuropathy III - diabetic type
Diabetic third nerve palsy; Pupil-sparing third cranial nerve palsy
Cranial mononeuropathy III - diabetic type -- is a mononeuropathy. This means that only one nerve is damaged. The condition affects the third cranial (oculomotor) nerve. This is one of the cranial nerves that control eye movement.
This type of damage may occur along with diabetic peripheral neuropathy. Cranial mononeuropathy III is the most common cranial nerve disorder in people with diabetes. It is due to damage to the small blood vessels that feed the nerve.
Other causes may include:
- Infarction of the nerve (tissue damage from loss of blood flow)
- Pressure on the nerve
- Mononeuritis multiplex
Symptoms may include:
- Double vision
- Drooping of one eyelid (ptosis)
- Pain in the head or behind the eye
Exams and Tests
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:
- Eyes that are not aligned
- Pupil reaction that is almost always normal
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:
- Blood tests
- Tests to look at blood vessels in the brain (cerebral angiogram, CT angiogram, MR angiogram)
- MRI or CT scan of the brain
- Spinal tap (lumbar puncture)
You may need to be referred to a doctor who specializes in vision problems related to the nerves in the eye (neuro-ophthalmologist).
There is no specific treatment to correct the nerve injury.
Treatments may include:
- Close control of blood sugar levels
- Eye patch or glasses with prisms to reduce double vision
- Pain medications
- Surgery to correct eyelid drooping or eyes that are not aligned
Some people may recover without treatment.
Many patients get better over 3 to 6 months. Some persons have permanent eye muscle weakness.
- Permanent eyelid drooping
- Permanent vision changes
When to Contact a Medical Professional
Call your health care provider if you have double vision and it does not go away in a few minutes, especially if you also have eyelid drooping.
Controlling your blood sugar level may reduce the risk of developing this disorder.
Rucker JC. Cranial neuropathies. In: Daroff RB, Fenichel GM, Jankovic J, Mazziotta JC, eds. Bradley's Neurology in Clinical Practice. 6th ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 70.
Reviewed By: Joseph V. Campellone, M.D., Division of Neurology, Cooper University Hospital, Camden, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.