What is primary and secondary subarachnoid hemorrhage?

Primary subarachnoid hemorrhage refers to hemorrhage caused by rupture of blood vessels on the surface and bottom of the brain, and blood components enter the subarachnoid space, including aneurysm rupture, microaneurysm caused by atherosclerosis, and blood entering the subarachnoid space caused by rupture of arteriovenous malformation. Secondary subarachnoid hemorrhage refers to the disease in which blood comes from the brain parenchyma and has a large amount of bleeding. After the blood breaks through the brain tissue, it enters the subarachnoid structure and causes corresponding symptoms. It is a brain disease characterized by headache and reflex vomiting.