Oculomotor Nerve Palsy

Oculomotor Nerve Palsy is a topic covered in the 5-Minute Emergency Consult.

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  • Typical presentation of a 3rd cranial nerve (CN) palsy:
    • Eyelid drooping
    • Blurred or double vision
    • Light sensitivity
    • May also have other neurologic signs/symptoms:
      • Hemiplegia
      • Ataxia
      • Tremor
  • CN III controls elevation, adduction and depression of the eye. This nerve also raises the lid and mediates pupillary constriction and lens accommodation:
    • Medial rectus:
      • Moves eye medially toward nose (adduction)
    • Superior rectus:
      • Moves eye upward
      • Rotates top of eye toward nose
      • Slight adduction
    • Inferior rectus:
      • Moves eye inferiorly
      • Rotates top of eye away from nose
      • Slight adduction
    • Inferior oblique:
      • Rotates top of eye away from nose
      • Slight elevation and abduction
    • Levator palpebrae superioris:
      • Raises eyelid
  • CN IV innervates the superior oblique:
    • Moves eye down when looking medially
    • Rotates eye internally
  • CN VI innervates the lateral rectus:
    • Moves eye laterally (abduction)
    • Lesions categorized as:
    • Complete vs. incomplete
    • Pupil involving vs. pupil sparing
  • Complete: Total loss of CN III function (“down and out”):
    • Compressive lesions:
      • Aneurysms
      • Tumors
      • Brainstem herniation with compression
      • Increased intracranial pressure
  • Incomplete: Partial loss of CN III function:
    • Vascular infarction of vasa vasorum
  • Pupil involving:
    • 95–97% of compressive lesions (aneurysm, tumor, etc.) involve the pupil
    • Parasympathetic fibers sit peripherally in CN III
  • Pupil sparing:
    • Ischemic injury to nerve
    • Diabetics, uncontrolled hypertension


  • Intracranial or orbital tumor
  • Aneurysm (particularly posterior communicating artery)
  • Trauma
  • Intracranial hemorrhage
  • Diabetes mellitus
  • Migraine headache
  • Infection, meningitis
  • Arteriovenous malformation or fistula
  • Cavernous sinus thrombosis
  • Neuropathy (e.g., myasthenia gravis, Guillain–Barré)
  • Collagen vascular diseases (e.g., sarcoidosis)
  • Idiopathic

Pediatric Considerations
Trauma is the most common cause of acquired oculomotor nerve palsies

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