Oculomotor nerve palsy associated with subarachnoid hemorrhage without aneurysmal compression: a case report

Abstract

A 64-year-old man with subarachnoid hemorrhage, disturbed consciousness, and left ptosis was referred to our hospital. He exhibited signs of left oculomotor nerve palsy, including mild dilatation of the pupil. The subarachnoid hemorrhage was localized in the left deep sylvian fissure and prepontine cistern. Three-dimensional computed tomography angiography revealed an aneurysm at the bifurcation of the left internal carotid and anterior choroidal artery. Neck clipping was performed, and no rupture point or aneurysmal compression of the oculomotor nerve was observed. However, the oculomotor nerve remained in contact with the left posterior cerebral artery. In cases of subarachnoid hemorrhage with oculomotor nerve palsy, an aneurysmal compression is typically considered to be the cause of the palsy. However, this case indicates that there are some other mechanisms that can cause oculomotor nerve palsy.