Intraoperative rupture of an occult anterior cerebral artery aneurysm during olfactory groove meningioma resection: a case report

Abstract Background The coexistence of intracranial tumors and cerebral aneurysms is rare but may significantly complicate diagnosis, surgical planning, and intraoperative management. Case presentation A 56-year-old female presented with anosmia, headache, and generalized seizures. Magnetic resonance imaging demonstrated an olfactory groove meningioma. Preoperative computed tomography angiography (CTA) showed no detectable vascular abnormality. During bifrontal craniotomy and tumor resection, sudden brain swelling with transcalvarial herniation occurred intraoperatively. Postoperative imaging revealed diffuse subarachnoid hemorrhage secondary to rupture of a previously undetected anterior cerebral artery aneurysm, which was successfully treated with endovascular coil embolization. Conclusions This case highlights the diagnostic and surgical challenges associated with coexisting skull base meningiomas and occult intracranial aneurysms. Even in the presence of a negative preoperative CTA, small aneurysms may remain undetected and rupture intraoperatively. Careful preoperative vascular assessment and heightened intraoperative vigilance are recommended in selected cases.