Chronic subdural hematoma is an intracranial hematoma and is the most common secondary lesion of craniocerebral trauma. Chronic subdural hematoma is a symptom that appears after 3 weeks of trauma. The hematoma is located between the dura mater and the arachnoid, and is a hematoma with an envelope. The disease occurs in middle-aged and elderly people, and can be caused by minor cranial trauma, even if the history of trauma cannot be remembered. The onset of the disease is insidious and the clinical manifestations are not obvious, which makes it easy to be misdiagnosed. The time from injury to onset is usually 1-3 months. Clinical symptoms and signs such as nausea, vomiting, diplopia, blurred vision, lateral limb weakness and mental disorder will gradually appear 2-3 months after the injury. There are mainly the following types: 1. Chronic intracranial pressure increase symptoms. There will be symptoms such as headache, nausea, vomiting and optic papillary edema; 2. Focal signs and symptoms due to hematoma compression. Such as mild hemiparesis, aphasia and limited epilepsy; 3. Symptoms of cerebral atrophy and cerebral blood supply insufficiency. For example, it can produce manifestations such as mental retardation, mental disorders and memory loss. Chronic subdural hematoma head injury is often mild and not easy to attract attention, and asymptomatic for a long time after injury especially in elderly people with large cranial volume compensation gap, when the hematoma increases causing symptoms of brain compression and symptoms of elevated intracranial pressure, patients often have forgotten the history of trauma, so it is easy to be misdiagnosed.