No shinkei geka. Neurological surgery
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The authors previously reported the effect of preoperative factors affecting the reduction of chronic subdural hematoma. In this report, we evaluated some operative factors, including operative methods, duration of drainage, and residual air volume, with newly developed CT volumetry technique. As described before, the hematoma volume reduces exponentially. ⋯ These results suggest that the residual air in the hematoma cavity may delay the reduction rate of the hematoma. Based on these results, the authors pay attention to the following points; 1) Less invasive burr hole method should be selected. 2) Patient's head position should be controlled to make the burr hole at the highest level in the operative field. 3) Hematoma cavity should be filled with saline as much as possible. 4) The inner membrane should never be injured, as it may cause tension pneumocephalus. Moreover, the drainage of cerebrospinal fluid may reduce the counter pressure and it leads to the delay of the hematoma reduction.