This trial is investigating the use of Sirolimus, a drug that helps control immune responses and cell growth, in patients with cerebral aneurysms. The goal is to see if Sirolimus can affect the molecular changes in the blood vessels of the brain. By altering how cells grow and repair, Sirolimus may help manage these dangerous bulges in brain blood vessels. Sirolimus has been used in various clinical settings, including kidney and liver transplantation, to reduce the risk of cancer and improve survival rates.