All patients and their families who have undergone cranial brain surgery, even those who had intended to have surgery and then gave up for various reasons, as well as those who are being hospitalized in preparation for surgery, will encounter such an experience, that is, before the surgery, the doctor will ask everyone to sign an “Informed Consent for Surgery”, in which the important content is that the patient may have accidents and complications during or after the surgery, which can seriously lead to the death of the patient during or after the operation. Many people may not fully understand the concept of “complication” and its consequences, and they just listen to the doctor who says that it is “possible”, which means that it may not necessarily happen. Due to the widespread existence of such an understanding, once it occurs, the mind is not prepared to accept, which is also one of the main factors in the occurrence of medical disputes. Therefore, it is necessary to popularize the knowledge in this area, so that patients and their families can correctly recognize and fully understand craniocerebral surgery and post-surgical complications after consultation, before surgery and after surgery, and be well prepared to correctly treat the various treatment results that occur after the patient’s surgery. The so-called surgery or post-surgery complications means that when the doctor solves the goal of the disease, it will inevitably affect and damage the normal tissue structure and physiological function of the human body, only the strength and size of this role is different, and the impact and results of the same degree of damage will also vary from person to person. Doctors are able to estimate this situation in advance, which is called predictable complications in medicine, so they can inform patients and their families of these complications in advance, and because they are predictable, doctors will assess them before surgery and take measures and techniques to minimize the occurrence of these complications during surgery. There are also unpredictable events, i.e., events that are not recognized by current medical knowledge and clinical experience, termed “accidents” in the context of informed consent. Although neurosurgeons in the clinic take precautions and surgical techniques to prevent the occurrence of predictable surgical complications, it does not mean that these complications will not occur, but rather that due to the complexity of human medicine, the same outcome can be caused by a variety of factors, some of which may be unexplained by current medical science, but there is no denying that some of these factors are not fully understood by the surgeons who are performing the specific procedures. . The most common and difficult to avoid during craniocerebral surgery is surgical bleeding. This is because most of the diseased tissues are supplied with blood, and at the same time, they are closely connected with the surrounding normal tissues, including blood vessels, and it is almost impossible not to bleed, and if they invade a slightly larger blood vessel, a large amount of hemorrhage may occur, and surgical hemorrhage, especially in children, is very likely to lead to death by shock. At present, such intraoperative deaths due to surgical bleeding are relatively rare because of advances in blood transfusion techniques and the availability of blood, thanks to people who donate blood without compensation. Post-operative complications also include re-bleeding, which is sometimes difficult to avoid. Some small blood vessels cannot be seen to bleed when they are examined after surgery, but some time after the surgery, when the patient’s blood pressure recovers and rises, the end of the originally coagulated blood vessel ruptures again, and slow bleeding accumulates to form a hematoma, which causes changes in the patient and most of them require re-operation. Other common post-surgical complications include post-operative cerebral edema, post-operative intracranial infections, post-operative infections in other parts of the body, and blood clots, etc. These surgeries due to predictable complications are medically referred to as unintended re-operations, that is, surgeries the doctor doesn’t want to be doing. Disagreements and even disputes between patients and their families and hospitals and their doctors are often due to the quality of treatment being lower than expected, and the main factor affecting the quality of treatment is due to these complications. We hope that our doctors can do their best to prevent the occurrence of these complications, and that the families of the patients can correctly recognize and fully understand the reasons for the occurrence of these complications, so that we can jointly pay attention to human life and overcome the disease.