Exhaustive drainage versus fixed-time drainage for chronic subdural hematoma after one-burr hole craniostomy (ECHO): study protocol for a multicenter randomized controlled trial oleh Liang Wu, Yunwei Ou, Bingcheng Zhu, Xufei Guo, Xiaofan Yu, Long Xu, Jinping Li, Enshan Feng, Huaqing Li, Xiaodong Wang, Huaqun Chen, Zhaosheng Sun, Zaofu Liu, Dawei Yang, Hongbing Zhang, Zhigang Liu, Jie Tang, Shangfeng Zhao, Guobin Zhang, Jiemin Yao, Dongming Ma, Zelin Sun, Hui Zhou, Baiyun Liu, Weiming Liu, ECHO Trial Collaborators