Signs, Symptoms & Clinical Features
Sixth nerve palsy (abducens palsy)
A sixth nerve palsy is weakness of the muscle that turns the eye outward, which can occur with raised intracranial pressure and cause double vision.
In short: Sixth nerve palsy (abducens palsy)
- It is weakness of the nerve controlling outward eye movement.
- It can occur with raised intracranial pressure.
- It causes double vision (especially looking to the side).
- It is a recognized sign that can accompany hydrocephalus.
What it is
A sixth nerve palsy (abducens palsy) is weakness or paralysis of the sixth cranial nerve, which controls the muscle that turns the eye outward. It can occur with raised intracranial pressure and is a recognized sign in hydrocephalus.
Understanding Sixth nerve palsy (abducens palsy)
The sixth cranial nerve has a long course inside the skull that makes it vulnerable to being stretched or compressed when intracranial pressure rises. As a result, raised pressure (from any cause, including hydrocephalus) can cause a sixth nerve palsy, which limits the affected eye's ability to turn outward and causes double vision, especially when looking toward the affected side. Because it can result from raised pressure in general (a "false localizing sign"), a sixth nerve palsy in someone with possible hydrocephalus prompts evaluation of intracranial pressure. It is one of the eye-related signs of raised pressure.
Why it matters
Understanding sixth nerve palsy helps families and patients recognize that new double vision or difficulty moving an eye outward can be a sign of raised intracranial pressure and warrants evaluation, especially in someone with or at risk for hydrocephalus.
Common questions
What does a sixth nerve palsy do?
It limits outward movement of the eye and causes double vision.
Why can raised pressure cause it?
The nerve's long course makes it vulnerable to pressure.
Is it a sign of hydrocephalus?
It can accompany raised pressure in hydrocephalus.
Bottom line
A sixth nerve palsy is weakness of outward eye movement that can result from raised intracranial pressure, causing double vision.
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