Sixth nerve palsy

Overview
Sixth nerve palsy, or abducens nerve palsy, is a disorder associated with dysfunction of cranial nerve VI (the abducens nerve) which is responsible for contracting the lateral rectus muscle to abduct (i.e. turn out) the eye. The inability of an eye to turn outward results in medial strabismus of which the primary symptom is double vision in which the two images appear side-by-side.

The abducens nerve is the most commonly affected ocular motor nerve.

Alternative names

 * Cranial nerve VI palsy
 * Cranial mononeuropathy VI
 * Lateral rectus palsy

Causes
Because the nerve emerges near the bottom of the brain, it is often the first nerve compressed when there is any rise in intracranial pressure.
 * Adults
 * More common: Vasculopathic (diabetes, hypertension, atherosclerosis), trauma, idiopathic.
 * Less common: Increased intracranial pressure, giant cell arteritis, cavernous sinus mass (e.g. meningioma, aneurysm, metastasis), multiple sclerosis, sarcoidosis/vasculitis, postmyelography or lumbar puncture, stroke (usually not isolated).
 * Children
 * Benign postviral condition, Gradenigo's syndrome, pontine glioma, trauma.