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.