Managing Non-acute Subdural Hematoma Using Liquid Materials：a Chinese Randomized Trial of MMA Treatment

Inclusion Criteria: 1. Patients with symptomatic non-acute SDH with mass effect (i.e., chronic or subacute SDH) 1. Mass effect refers to a shift in midline structure or deformation of local cerebral cortex due to SDH. 2. Symptomatic defined as neurological symptoms, such as headache, short-term cognitive dysfunction, language disorder or aphasia, gait instability, decreased muscle strength, sensory disturbances, epileptic seizure, etc. 2. Age ≥18 years; 3. Pre-morbid mRS score 2; 4. Informed Consent Form (ICF) signed by patient or guardian. Exclusion Criteria: 1. Radiographic imaging indicating massive cerebral infarction with corresponding symptoms; 2. Required craniotomy or craniotomy with small bone flap to remove SDH; 3. Emergency SDH removal/drainage; 4. Bilateral SDH with unknown origin of symptoms; 5. Anatomical variations that may affect the safety of MMA embolization (e.g., prominent middle MMA-ophthalmic artery anastomosis); 6. Intractable coagulation dysfunction or abnormal platelet count and function (pre-operative International Normalized Ratio \[INR\] \> 1.5 and/or platelet count \< 80109/L); 7. Contraindications to cerebral angiography, such as allergy to iodinated contrast agents, renal insufficiency (GFR \< 30 ml/min), etc.; 8. Computed tomography (CT) or magnetic resonance imaging (MRI) showing intracranial space-occupying lesions; 9. Pregnancy or planning to become pregnant; 10. Serious or fatal coexisting disease that may prevent improvement of conditions or completion of follow-up; 11. Life expectancy \< 1 year; 12. Recent operation unrelated to this study or investigators believe that they will be at higher risks if antiplatelet and/or anticoagulant drugs are discontinued; 13. Inability to complete follow-up as required by the protocol; 14. Patients participating in other clinical trials; 15. Prior surgery or interventional therapy on target SDH; 16. Inability to complete MMA embolization before trepanation and drainage.