Cranial Nerve 6 Palsy

Sixth Nerve Palsy

Eye movements are controlled by 6 muscles around the eye called extraocular muscles. These muscles receive their signals from the brain from a group of nerves called the cranial nerves. Three of these cranial nerves, cranial nerve III (3), cranial nerve IV (4) and cranial nerve VI (6) are responsible for all of the eye's movements.  Problems with these nerves can cause issues with eye position and movement including eyes turning in, turning out, or being vertically misaligned or causing double vision.


Cranial Nerve 6

Eye movement in 6thth Cranial Nerve Palsy.
Eye movement in 6thth Cranial Nerve Palsy.

Cranial nerve 6, also called the abducens nerve, controls the movement of the lateral rectus muscle. This muscle moves the eye outward, away from the nose. When this nerve is damaged, it may not be able to do its job. This condition is called a palsy. It can be total or partial.


What causes a Cranial Nerve 6 Palsy?

It can be caused by a tumor, an inflammatory disorder, trauma or stroke. Sometimes the reason is unknown (idiopathic). Some infants are born with a cranial nerve 4 palsy.


Effects of a Cranial Nerve 6 Palsy

Some or all of the following can occur:

  • The eye may turn inward

  • Inability to move the eye outward, away from the nose
  • Double vision (because the two eyes are not pointed in the same direction). The double vision is horizontal
  • Turning of the head to the side in order to avoid the double vision

Treatment for a Cranial Nerve 6 Palsy

Treatment for the underlying cause of cranial nerve 6 palsy may be needed first. Often, no treatment is needed as many patients have spontaneous recovery (complete or nearly complete resolution) within 6-8 months. During that time, treatment is aimed at relieving symptoms. Often, one eye can be covered with a patch to relieve double vision. Another option is use a Fresnel prism, a special type of overlay for glasses that can relieve double vision by bringing the two images together. If there is no improvement in symptoms after 6-8 months, surgery on the eye muscles can be done to bring the eye into a more normal position.