Sixth nerve palsy

Sixth 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.

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.

The abducens nerve is the most commonly affected ocular motor nerve^[1].

• 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.

• Double vision

• Congenital fourth nerve palsy

• Animation at mrcophth.com

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