Oculomotor nerve palsy associated with rupture of middle cerebral artery aneurysm

Oculomotor nerve palsy (ONP) with subarachnoid hemorrhage (SAH) occurs usually when oculomotor nerve is compressed by growing or budding of posterior communicating artery (PcoA) aneurysm. Midbrain injury, increased intracranial pressure (ICP), or uncal herniation may also cause it. We report herein a rare case of ONP associated with SAH which was caused by middle cerebral artery (MCA) bifurcation aneurysm rupture. A 58-year-old woman with clear consciousness suffered from headache and sudden onset of unilateral ONP. Computed tomography showed SAH caused by the rupture of MCA aneurysm. The unilateral ONP was not associated with midbrain injury, increased ICP, or uncal herniation. The patient was treated with coil embolization, and the signs of oculomotor nerve palsy completely resolved after a few days. We suggest that bloody jet flow from the rupture of distant aneurysm other than PcoA aneurysm may also be considered as a cause of sudden unilateral ONP in patients with SAH.