What is 6th nerve palsy?

Sixth nerve palsy, also known as abducens nerve palsy, is a condition in which the sixth cranial nerve becomes paralyzed. This paralysis affects the lateral rectus muscle, which controls certain eye movements. It may affect one or both eyes, depending on the cause.

The condition is the most common ocular motor paralysis in adults. It’s second-most common in children, with fourth cranial nerve palsy being the most common.

Sixth nerve palsy symptoms often improve or resolve completely within a few months and may not require treatment. However, if your doctor doesn’t note any improvement over time, treatment or surgery may be needed. 

Cranial nerve 6 function

Cranial nerve 6 (the abducens nerve) is one of three nerves responsible for the extraocular movement of the eye. The other two nerves that aid in this function are cranial nerves three (oculomotor nerve) and four (trochlear nerve).

The abducens nerve specifically controls the lateral rectus muscle of the eye. This muscle allows you to move the eye outward, away from the nose. So, when you look to the left without moving your head, the lateral rectus muscle in your left eye controls that movement. Similarly, if you look to the right without moving your head, the lateral rectus muscle of your right eye is working.

When cranial nerve six palsy occurs, it eliminates or weakens the signal from the nerve to the muscle. This results in an inability to turn the affected eye(s) outward.

SEE RELATED: Crossed eyes (esotropia)