Aetiology

The aetiology of oculomotor nerve palsy is very diverse:

In adults:

• central lesions:
  • tumours:
    • due to direct invasion of the third nerve nucleus
    • due to raised intracranial pressure
  • vascular:
  • caused by a brainstem lesion
  • demyelination
    
    
• peripheral causes include:
  • compressive lesions:
    • tumour
    • aneurysm, often the posterior communicating artery
    • basal meningitis
    • nasopharyngeal carcinoma
    • orbital lesions e.g. Tolosa-Hunt syndrome
  • infarction:
  • often spares the pupillary reflex, when the condition is termed a "medical third nerve palsy"
    • often caused by diabetes mellitus

In children, the causes of a III nerve palsy include:

• congenital
• trauma
• tumour
• migraine