Inclusion Criteria:

• Confirmed diagnosis of aSAH: presence of SAH symptoms, confirmed by CT scan or lumbar puncture. CTA or DSA confirms ruptured intracranial aneurysm (IA) as the cause. Decision made to perform craniotomy clipping or endovascular treatment within 72 hours aiming for a single procedure to cure the bleeding artery aneurysm;
• Age ≥ 18 years;
• The onset of symptoms should occur within 72 hours;
• The Hunt-Hess grade is between 2 and 4, and the CT imaging findings correspond to a modified Fisher grade of 2 to 4.
• Obtain the consent of the patient and their family members, and have them sign an informed consent form.

Exclusion Criteria:

• Pregnancy or lactation period;
• Patients presenting with bilateral dilated pupils upon admission;
• Patients with concurrent tumors, hemorrhagic diseases, or other severe underlying conditions (such as chronic obstructive pulmonary disease, multiple organ dysfunction syndrome, severe diabetes mellitus, congestive heart failure, and chronic kidney disease);
• Patients with a history of brain disorders or previous brain surgeries;
• Hemorrhage attributable to causes other than aneurysm;
• Aneurysmal rupture bleeding concurrent with moyamoya disease;
• Other underlying conditions that impact prognosis;
• Patients volunteering for ICP monitoring;
• Participants in other ongoing clinical trails;
• Other circumstances deemed inappropriate for inclusion (to be determined by two physicians).