Back ground: Chronic subdural hematoma (CSDH) is a common neurological condition that mainly occurs in the elderly. The minimally invasive procedure-twist drill craniostomy (TDC) is theoretically more suitable to treat CSDH than the traditional procedure-burr hole craniostomy (BHC). Compared with burr hole craniostomy (BHC), twist drill craniostomy (TDC) is getting increasingly popular because of its minimal invasiveness in evacuating chronic subdural hematoma (CSDH) under Local Anaesthesia. However, the TDC technique varies and is continually developing; moreover, no consensus yet exists regarding the optimal protocol and the efficacy and safety of TDC is still controversial.