The Finnish Study of Intraoperative Irrigation Versus Drain Alone After Evacuation of Chronic Subdural Hematoma (FINISH)

Inclusion Criteria: * Patients with a symptomatic unilateral or bilateral CSDH requiring burr-hole evacuation o Predominantly hypodense or isodense on imaging (CT/MRI). * Clinical symptoms correlating with the CSDH * Patients with bilaterally operated CSDHs will be treated with the same protocol on both sides and analyzed as a single study participant Exclusion Criteria: * CSDH requiring surgical treatment other that burr-hole evacuation (e.g. craniotomy) * CSDH in a patient who has a cerebrospinal fluid shunt * Patients who have undergone any intracranial surgery before * Comatose patients (GCS 8 or lower) with absent motor responses to painful stimuli; decerebrate or decorticate posturing * Patient's postoperative cooperation is suspected to be insufficient for drain usage, i.e. disoriented or semiconscious patient * Patient has a hematogenic malignancy that has obtained active treatment within the previous five years * Patient has a central nervous system tumor or malignancy * Patient has acute infection with fever and requires antibiotic treatment at the moment * Patient has a high risk of life-threatening thrombosis (e.g. recent coronary stent, recent pulmonary embolism, low cardiac valve replacement) and discontinuation of antithrombotic medication is not recommended