Oculomotor nerve palsy

A dysfunction of the third cranial nerve (oculomotor nerve) causing paresis or paralysis of the extraocular muscles it supplies, typically resulting in ptosis, impaired eye movements, diplopia, lateral deviation of the eye (“down and out” position), and possible pupillary dilation due to parasympathetic fiber involvement.

Causes

• Microvascular ischemic neuropathy due to

  • Diabetes mellitus

  • Hypertensive small vessel disease

• Intracranial aneurysms

  • Posterior communicating artery aneurysm

  • Internal carotid artery aneurysm

  • Other compressive vascular lesions

• Traumatic causes

  • Head trauma

  • Skull base fractures

  • Surgical trauma involving the cavernous sinus or orbit

• Neoplastic causes

  • Brain tumors

  • Pituitary tumors

  • Metastatic lesions

  • Cavernous sinus tumors

  • Schwannomas or other compressive masses

• Infectious and inflammatory causes

  • Meningitis

  • Cavernous sinus inflammation or thrombosis

  • Sarcoidosis

  • Autoimmune inflammatory neuropathies

• Other neurological causes

  • Increased intracranial pressure

  • Brainstem lesions affecting the oculomotor nucleus or fascicle

  • Demyelinating disease (multiple sclerosis)

  • Postoperative or iatrogenic nerve injury

• Congenital oculomotor nerve palsy