Early Lumbar Drainage Plus Intrathecal Urokinase in Severe Aneurysmal Subarachnoid Hemorrhage (LD-ITUK)

Inclusion Criteria: * Patient's age ≥ 18 years * First occurrence of aneurysmal subarachnoid hemorrhage * Patients without any craniotomy treatment before onset * Hunt-Hess grade III-V * mRS grade 0 or 1 before onset * Aneurysm treatment within 48 hours of onset * Informed consent given by the subject or guardian Exclusion Criteria: * Subarachnoid hemorrhage caused by arteriovenous malformation or moyamoya disease or other cerebrovascular disease * Patients requiring craniotomy to remove intracranial hematoma * modified Fisher Scale grade 0 * Prothrombin time (PT) and activated partial thromboplastin time (APTT) are greater than 2 times the extended range * Absolute contraindications for lumbar puncture (e.g., brain hernia, puncture site infection) * Patients with a life expectancy of less than 1 year due to other causes * Other concomitant serious diseases that are difficult to treat; * Pregnant woman * Patients who were known to be allergic to urokinase and excipients or had a history of severe allergy and were deemed unsuitable for inclusion by the investigators * Participated in another interventional clinical trial within 30 days before randomization * Other reasons deemed unsuitable for study participation by the investigator