This study is looking at how taking aspirin regularly affects bleeding during and after brain surgery. Specifically, it focuses on patients who are having elective surgery to clip a brain aneurysm.

Aspirin is commonly used to prevent heart attacks and strokes, but it can also increase the risk of bleeding. Doctors often face a tough decision: should patients stop taking aspirin before surgery to reduce bleeding risk, or continue it to prevent blood clots?

To help answer this question, researchers will observe 100 patients, some who take aspirin regularly and some who don't, at hospitals in the U.S., Russia, and Italy. They will not change any treatments but will collect information about bleeding during surgery, blood test results, and CT scans after surgery.

The goal is to better understand the risks of continuing aspirin and to help doctors make safer decisions for future patients.

Inclusion Criteria:

• Age > or = 18 years old
• Patients willing to participate and provide an informed consent
• Patients undergoing elective craniotomy for cerebral aneurysm clipping
• Patients on chronic low-dose (75-100 mg) aspirin daily (aspirin group) or not on aspirin therapy for at least 7 days (control group) preoperatively.

Exclusion Criteria:

• Emergency craniotomy
• Use of other antiplatelet or anticoagulant medications within 7 days prior to surgery
• Known bleeding disorders (e.g. hemophilia, thrombocytopenia)
• History of intracranial hemorrhage unrelated to aneurysm
• Inability to provide informed consent

Patients scheduled for elective craniotomy for cerebral aneurysm clipping

Recruited from three international sites:

Mayo Clinic Florida (USA) Burdenko National Medical Research Center of Neurosurgery (Russia) Sapienza University of Rome (Italy)