The most common cause of subarachnoid hemorrhage is the rupture of a cerebral aneurysm. The subarachnoid space is located on the surface of the brain, surrounded by three layers of meninges: from inner to outer, they are the pia mater, arachnoid mater, and dura mater. The space between the pia mater and arachnoid mater is known as the subarachnoid space. Following the rupture of a cerebral aneurysm, blood enters this subarachnoid space, leading to hemorrhage. Subarachnoid hemorrhage is a critical condition in internal medicine, with a relatively high mortality rate. The most common cause is a cerebral aneurysm, and patients who have suffered a subarachnoid hemorrhage should undergo brain MRI and vascular imaging to check for the presence of cerebral aneurysms or vascular abnormalities. If a cerebral aneurysm is present, it needs to be treated promptly. Typical interventions include placing a coiling spring to close off the aneurysm, preventing it from rupturing and thus averting a secondary subarachnoid hemorrhage, which has a mortality rate as high as 50%. Another common cause of subarachnoid hemorrhage is brain trauma, which is also a frequent cause of this condition.