Eye Disorders: Microvascular Cranial Nerve Palsies
A patient with 3rd, 4th, or 6th cranial nerve palsy will have trouble moving the eyes in certain directions, and therefore experience double vision. Many conditions can produce a cranial nerve palsy, some of which require urgent attention. "Microvascular" is only one of those conditions. Therefore it is important that this condition be diagnosed properly. This typically occurs in an older individual with vascular risk factors, like high blood pressure and diabetes.
What causes this condition?
This condition is caused presumably by a small stroke in one of the cranial nerves. The stroke interrupts the signals that the brain is sending along the nerve to an eye muscle. The muscle imbalance causes a misalignment of the eyes, which leads double vision.
How is this condition treated?
Assuming there isn't a more serious underlying cause, this condition will likely resolve on its own. About 90% of people will have a resolution of symptoms within 3 months or less. If the symptoms and palsy are not resolved within 6 months, the diagnosis should be reconsidered. The treatment of diplopia is patching or prisms over one eye while waiting for recovery.
If at any time during the recovery the symptoms worsen, or new symptoms develop, another condition is likely present, so re-evaluation is necessary.
The North American Neuro-Ophthalmology Society publishes a web site with good patient information on this condition.