In our daily work, we often encounter patients with such characteristics: 1. senior in age, usually over 60 years old. 2. 2, head trauma is not obvious, some are only minor collisions, such as touching the head of the bed when getting up, touching the door when going out, etc. 3.There are no symptoms after the injury, so the experience of head trauma is often forgotten. 4.Usually in about a month, the patient starts to have chronic headache, unstable walking, urinary incontinence, etc. 5. A cranial CT examination is performed, suggesting an extensive subdural hematoma, and there is usually a significant displacement of the midline.