Fenestrated oculomotor nerve caused by internal carotid-posterior communicating artery aneurysm: case report.

OBJECTIVE AND IMPORTANCE: The fenestrated oculomotor nerve associated with the internal carotid-posterior communicating artery aneurysm is very rare. CLINICAL PRESENTATION: A 48-year-old woman had a history of subarachnoid hemorrhage caused by a ruptured right middle cerebral artery aneurysm, which was wrapped with good postoperative course. Twenty years later, the patient suffered frontal headache with a mild oculomotor nerve paresis in the right side. Follow-up neuroimaging studies demonstrated a de novo right internal carotid-posterior communicating artery aneurysm. INTERVENTION: The aneurysm was exposed and clipped via a right pterional route. The fenestrated oculomotor nerve associated with the aneurysm was confirmed at surgery. CONCLUSION: We speculated that the fenestration was most likely caused, by the growth of the aneurysm.