In our clinical work, we often encounter some elderly people who come to the clinic because of headache, dizziness, unresponsiveness and so on, and through cranial CT or MRI examination, we find that there is “chronic subdural fluid” in the cranium, what exactly is this? Chronic subdural fluid is the presence of a large amount of fluid on the surface of the brain tissue inside the skull for a long time, mostly due to minor injuries or even minor injuries, and most of them have been injured many times. Analyzing this clinical feature, we believe that it is related to the characteristics of the elderly themselves, because the elderly are not handy with their legs and feet, they often have random bumps and bruises in daily life, and most of them do not care about them, and only when they feel headache, dizziness, or even nausea and vomiting after a period of time, they go to the hospital for cranial CT or MRI to find chronic subdural fluid in the skull. From clinical observation, we found that the misdiagnosis rate of this disease is high. Chronic subdural fluid in the elderly is clinically characterized by increased intracranial pressure, manifested as headache, dizziness, nausea, vomiting and diplopia in severe cases, which is easily misdiagnosed as hypertension and cervical spondylosis due to the lack or neglect of localization signs and the fact that most of the elderly themselves have chronic diseases such as cardiovascular and cerebrovascular diseases. We once admitted a patient with long-term dizziness, who had been treated with medication in the orthopedic clinic for “cervical spondylosis”, and was treated with acupuncture in the physical therapy department, but to no avail. The patient’s condition was rapidly aggravated within a short period of time, and developed into gibberish, unable to recognize family members, and then became unconscious, and only after emergency surgery was the patient turned to safety, and soon became clear, and the symptoms of dizziness and diplopia completely disappeared less than two months after discharge from the hospital. Secondly, individual patients are clinically characterized by “abnormal intellectual and mental status”, manifesting as memory and comprehension loss, irritability or silence, mental retardation, strong crying, strong laughing, and even mental disorders, with symptoms resembling Alzheimer’s disease and cerebrovascular disease, and the misdiagnosis rate is extremely high. Our hospital neurology department once admitted a patient with “mental abnormality” treated as mental illness for nearly 1 month, but the symptoms did not improve, often climbing to other beds on their own to urinate and defecate, because the cranial CT found bilateral frontal chronic subdural effusion and transferred to our department, after surgery and treatment with antipsychotic drugs for more than 1 month to heal. In addition, some traumatic subdural effusions may eventually turn into chronic subdural hematomas, which may be caused by the continuous increase of subdural effusions, resulting in the straining of the bridging veins of the superficial cerebral cortex converging to the superior sagittal sinus. When it turns into a subdural hematoma, it also requires surgical treatment. Therefore, we recommend that elderly patients with headache, dizziness, abnormal intellectual and mental status should visit a hospital specialist to rule out the presence of subdural fluid and let the specialist decide whether surgery is needed.