Microvascular Cranial Nerve Palsy
Microvascular cranial nerve palsy (MCNP) is one of the most common causes of acute double vision in the older population.
It occurs more often in patients with diabetes and high blood pressure. This condition almost always resolves on its own without leaving any double vision.
What is Microvascular cranial nerve palsy (MCNP)?
Any nerve can not function properly when its blood flow is blocked. If the 6th (Abducens) cranial nerve is affected, your eye will not be able to move to the outerside and you will be aware of double vision seeing side-by-side images. The double vision will be worse when looking in the direction of the affected muscle. If the 4th (Trochlear) cranial nerve is affected you will be aware of vertical double vision. You may be able to eliminate or decrease the double vision by tilting your head towards the opposite shoulder. The 3rd (Oculomotor) cranial nerve supplies 4 of the 6 muscles. It also controls the height of the eyelid and pupil size. When this nerve is affected, your eye may be limited in its up and down movement and gaze towards the nose. The eyelid may droop.
What causes MCNP?
It is not always clear what causes the blockage to the tiny blood vessels to the cranial nerves. In some cases diabetes or high blood pressure may be risk factors. The nerves are not permanently injured, and over a period of 6-12 weeks, normal function should recover. If the double vision does not go away it is very important to tell your ophthalmologist.
What are the signs and symptoms of MCNP?
The signs of MCNP are usually problems with movement of your eyes which lead to blurred or double vision. If severely affected, your eye may not be ale to move at all in one or more directions. Sometimes there may only be a slowing of movement.
Symptoms and findings may include:
Weakness in one or more eye muscles.
Blurred vision that improves by closing the other eye.
Double vision.
Pain in or around the eye (related to lack of blood flow to the covering of the brain) which commonly occurs at the onset of double vision.
Drooping eyelid (called ptosis)
Enlarged pupil.
If you have multiple MCNPs, involvement of the pupil or have a younger age of onset, a neurological exam and imaging study may be necessary. Anyone diagnosed with MCNP should have their blood pressure and blood sugar checked to make sure they do not have diabetes or hypertension.
How is MCNP treated?
There is no known method of accelerating the natural recovery time for MCNP. Double vision may be treated by patching the other eye. If the double vision persists, it may be possible to use prism glasses or to consider eye muscle surgery if recovery has not been complete.
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| B08000603 |
