Giant, Unruptured, Partially Thrombosed Right Middle Cerebral Artery Aneurysm Treated with 2 Bypasses and Excision

Aneurysms of the middle cerebral artery (MCA) account for up to 40% of all unruptured intracranial aneurysms^1-3 and 14%-20% of ruptured ones.^4,5 Giant MCA aneurysms are rare, representing 10% of cases,⁶ but carry an aggressive natural history, with the Japanese Unruptured Cerebral Aneurysm Study reporting an annual rupture rate of approximately 17%.⁷ Additionally, patients with unruptured giant MCA aneurysms can present with neurological symptoms, including headache, focal neurological deficit, seizure, or ischemia infarcts. Here, we report a 58-year-old man with a history of alcohol abuse, hypertension, diabetes, and smoking who presented after a first-time seizure (Video 1). Imaging revealed an unruptured, giant (2.9 cm), partially thrombosed right MCA aneurysm. A microsurgical approach using clipping and bypass was planned due to the complexity of the aneurysm. The patient underwent a right frontotemporal craniotomy with radial artery graft extraction 6 weeks later, followed by 2 bypasses: an M2-to-M2 intracranial bypass and a right external carotid-to-M2 bypass using the radial artery graft. The aneurysm was successfully excised. An otolaryngologist assisted with the radial artery graft extraction during the craniotomy and neck dissection. This case highlights the technical complexities involved in managing giant aneurysms via microsurgical technique, including appropriate preoperative strategy development. Informed consent from next of kin as and institutional review board approval were obtained.