Inclusion Criteria:  Patients with negative subarachnoid hemorrhage diagnosed by DSA  Exclusion Criteria:  In patients with aneurysms, external ventricular drainage (EVD) alone or decompression craniotomy alone or conservative treatment was performed Have a history of trauma or prior brain injury (stroke, cerebral hemorrhage, etc., with associated chronic changes on CT) Patients with loss of imaging data and severe comorditions prior to onset of SAH