Third Nerve Palsy

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Clinical Findings

  • Severe headaches typically associated with ruptured aneurysm
    • Note: Pain may also occur in microangiopathic lesions!
  • Double vision
  • Ptosis (complete or partial)
  • Is the pupil dilated? Poor pupil reaction?
  • Deviation of the eye to inferior temporal (complete or partial)
    • Restricted motility

Most important Causes

  • Aneurysm of the posterior communicating artery
    • Most dangerous cause, must be ruled out!
  • Stroke, tumor, demyelinating diseases
  • Giant cell arteritis
    • Rare, but consider in older patients with newly developed double vision!
      • Can rarely be the only symptom


  • Isolated third nerve palsy?
    • Other cranial nerves (IV, V, VI) affected?
      • If yes, consider other locations such as the cavernous sinus, brainstem
  • Emergency CT scan or immediate CT angiography to investigate for subarachnoid haemorrhage due to ruptured aneurysm of the posterior communicating artery
    • If immediately possible, alternatively MRI angiography
  • If CT/CT angiography negative: MRI angiography to investigate for stroke, tumor, demyelinating disease
  • Pupil involvement
    • Typical in aneurysms, trauma, uncal herniation
    • Atypical in microangiopathic causes (arterial hypertension, diabetes)
    • Theoretically, in complete oculomotor nerve palsy without pupil involvement and existing cardiovascular risk factors, imaging is not mandatory, but normally a CT head is still performed
  • If no improvement in palsy within 3 months:
    • Arrange additional MRI/MRA examination
  • In third nerve palsy and herpes zoster ophthalmicus
    • Perform MRI/MRA head including black blood sequences to investigate for cerebral vasculitis (if the latter is confirmed, intravenous antiviral therapy is indicated!)

Hess-Weiss/Tangent screen examination

Excellent Video by Dr. Andrew G. Lee