Sixth nerve palsy is a disorder that is characterized by dysfunction of your cranial nerve VI, which is also known as the abducens nerve. Your cranial nerve VI is the nerve that functions to contract your lateral rectus muscle to turn out (abduct) your eye.
The inability of your eye to turn outward leads to a convergent strabismus or estropia. An estropia or convergent strabismus is a squinting in which one or both of your eyes turns inward.
Sixth nerve palsy is evidenced by double vision. With sixth nerve palsy, the two images appear side-by-side.
Sixth nerve palsy usually develops unilaterally, which means that it only affects one of your eyes. However, sixth nerve palsy may also occur bilaterally, meaning that it involves both of your eyes.
This nerve palsy is referred to in other ways. It is also known as bilateral 6 nerve palsy, vlth nerve palsy, cranial mononeuropathy VI and lateral rectus palsy.
Fortunately, sixth nerve palsy is rare. This disorder occurs equally in men and women and may originate at any age of your life.
The cause of VI nerve palsy may be classified as being either congenital or acquired. Congenital VI nerve palsy is something that you are born with. This is the meaning of congenital. It means something that is present at birth.
Acquired sixth nerve palsy is when the disorder develops because something causes it. There are many things that have been set forth as leading to sixth nerve palsy. In children, the two most common causes of sixth nerve palsy are a tumor of some kind or some type of trauma.
In adults, there are several things that may bring this about. Some of these are:
Central nervous system tumors
Autoimmune disorders (disorders in which your autoimmune system mistakenly attacks the cells and tissues of your own body)
The primary sign or symptom is seeing a double vision with the two images being seen as being side by side. If it is affecting only one of your eyes, the degree of separation between the two images that you see will probably be the greatest when you stare in the direction of your eye that is affected. This degree of double vision is usually less when you gaze at something that is near, rather than something that is far away.
There are other possible signs and symptoms of sixth nerve palsy. These include:
Abnormal eye movement and/or a droopy eyelid
Decreased facial sensation.
It is possible that sixth nerve palsy may improve with the passage of time. This depends mainly on what is the cause of your disorder. If it was due to a viral disorder, you may experience complete resolution. If your sixth nerve palsy results from trauma, you may only have incomplete resolution.