This clinical study aims to learn about the efficacy and safety of aspirin continuation or discontinuation in conservative treatment for chronic subdural hematoma. All participants received standard conservative treatment for chronic subdural hematoma, with a randomized intervention to either continue or discontinue aspirin administration. By participating in this study, participants can receive additional scientific guidance on aspirin medication management beyond routine conservative treatment, thereby optimizing individualized therapy.

Chronic subdural hematoma is a common condition in neurosurgery, predominantly affecting the elderly. Its incidence increases with age, often developing gradually following minor head trauma. Clinical manifestations vary widely, with severe cases potentially leading to coma or even death, imposing a significant burden on patients and their families.

Current treatment approaches for chronic subdural hematoma include surgical intervention and conservative management. Conservative treatment is suitable for some patients with milder conditions or high surgical risk, primarily involving bed rest and medication. However, its efficacy varies among individuals, and close monitoring for multiple potential complications is essential throughout the treatment process.

Aspirin, a commonly used antiplatelet agent, is widely applied in the prevention and treatment of cardiovascular and cerebrovascular diseases. Its use in chronic subdural hematoma patients presents complexities: some patients had been taking aspirin long-term prior to onset. Whether to continue aspirin during conservative management remains controversial, necessitating further research to clarify its safety and efficacy. Continuing the medication may increase the risk of hematoma enlargement, while discontinuation may trigger thromboembolic events.

For cSDH patients on long-term aspirin therapy who opt for conservative management, there is currently no guideline or consensus on "continue vs. discontinue." Clinical decisions are often made by multidisciplinary teams (MDTs) based on individualized risk assessment of bleeding versus thrombosis (with a higher rate of discontinuation strategies). A randomized controlled trial in surgical patients (JAMA Neurology, 2025) showed that discontinuing aspirin after surgery did not reduce 6-month recurrence, and discontinuation-related complications showed no significant difference, suggesting that a "one-size-fits-all" discontinuation approach is unreasonable. However, this evidence cannot be extrapolated to the conservative treatment population, making the conduct of this RCT practically necessary.

Inclusion Criteria:

• Age ≥18 years, male or female;
• Confirmed diagnosis of chronic subdural hematoma (cSDH) by cranial CT and/or MRI;
• Intended for conservative management (i.e., no surgical evacuation indication at enrollment);
• Regular aspirin use at enrollment;
• Informed consent signed by the patient or legal representative.

Exclusion Criteria:

• Patients requiring emergency surgery to remove hematoma at enrollment;
• Concurrent use of other anticoagulants or antiplatelet agents that cannot be discontinued according to the study protocol;
• cSDH secondary to other diseases or conditions (e.g., excessive drainage from ventriculoperitoneal shunts, intracranial tumors);
• Active bleeding events or major cardiac events (e.g., acute myocardial infarction, unstable angina, or revascularization surgery) within 30 days prior to enrollment;
• Known bleeding disorders (e.g., hemophilia, severe thrombocytopenia);
• Individuals unable to provide informed consent or for whom completion of follow-up is anticipated to be difficult.