Operation
ProcedureAll participants are treated with burr-hole craniotomy and a drainage system as follows. Participants undergo surgical procedure under local anesthesia in the hemisphere with a lateral position, but general anesthesia is performed when participant cannot tolerate the operation. A single 1.5 cm burr hole is drilled over the maximum width of the hematoma cavity. After coagulating with bipolar diathermy, dura mater is opened with a cruciate incision. A soft catheter is placed carefully in all directions of the hematoma cavity for irrigating subdural collections with 1,000 mL warm Ringer's lactate saline until clarification. The drainage catheter is inserted ½ length of the maximum diameter of the hematoma cavity toward the frontal region. After the skin is closed, the catheter was connected to a soft collection bag that is placed under the head for passive drainage. During the drainage period, participants stay in bed until the drain is removed.