The term endovascular means “inside a blood vessel.” Endovascular neurosurgery uses tools that pass through the blood vessels to diagnose and treat diseases and conditions rather than using open surgery.The surgeon often uses radiology images to help him or her to see the part of the body involved in the procedure.ndovascular neurosurgery is a subspecialty within neurosurgery that uses catheters and radiology to diagnose and treat various conditions and diseases of the central nervous system.