1, middle-aged and elderly injury analysis of injuries to traffic accidents, followed by falls, head on the ground resulting in craniocerebral injury. In the early stage of injury, the main manifestation is meningeal irritation sign, followed by limb movement disorder, and pupil abnormality occurs in the late stage of disease. Due to the brain atrophy of middle-aged and old people, the brain parenchyma is reduced, the subarachnoid space is enlarged, the brittleness of blood vessels is increased, and the brain tissues in the cranial cavity move a lot when they are injured, and it is easy to make the bridging veins, cortical blood vessels and blood vessels of the base of the skull suffer damage and hemorrhage and lead to the subarachnoid hemorrhage, subdural hematoma and cerebral contusion, which is mostly decelerating injuries, and the shear stress generated by the brain tissues’ movement and rotation easily leads to the distortion of the brainstem, therefore, the consciousness disorder is more serious and the coma time is long, and the pupil is abnormal in the advanced stage of the disease. In addition, the stability of the internal environment of the elderly is weakened, and they often have vital organ insufficiency or disease before injury, the stress capacity of the body is reduced, and the injury is easy to cause the aggravation of the previous disease and complications, so the prognosis is poor, and the degree of disability and mortality rate are high; among the survivors, 38.6% of them have moderate or severe disability, and 24.0% of them are dead. In the process of disease evolution, the delayed frontal-temporal lobe contusion injury and intracerebral hematoma are common, after cerebral contusion injury, cerebral edema, brain swelling caused by increased intracranial pressure on the rupture of small blood vessels have a temporary compression effect, play a role in tamponade hemostasis effect, and after admission to the hospital, strong dehydration, surgical decompression and other factors to make the intracranial pressure drop suddenly, which reduces the tamponade hemostasis effect of the hemorrhage point, and relieves the pressure of the rupture of the small blood vessels, coupled with the brain injury zone In addition, the brain injury area releases some endogenous enzymes and carbon dioxide accumulation, coagulation mechanism disorders and vascular spasm and other factors, so that the re-bleeding hematoma formation. 2.Characteristics of craniocerebral injury in children and adolescents Children and adolescents, especially children under 10 years of age, are often injured in traffic accidents and falling from height, which is related to their low age and poor ability to foresee risk factors. The physiological anatomy of the brain of infants and young children is different from that of adults, the skull is relatively large, and the cervical muscles are underdeveloped, the protection ability is poor, and the chance of injury is greater than that of other parts of the body. Due to the elasticity of the skull, it can buffer part of the external force, and the inertial movement of the brain tissue in the skull is lighter, the incidence of hedge injury is lower than that of adults; the skull is thin, the fracture incidence is higher than that of adults, and fracture fragments puncturing the dura mater can easily lead to cerebral contusion injury and subdural hematoma secondary to intracerebral hematoma. The middle dural artery groove of the skull is shallow, and the dura is closely adhered to the skull, so the incidence of epidural hematoma is less than that of adults, but we should be alert to the delayed epidural hematoma, especially when the fracture line is close to the sagittal sinus, and we should closely observe the condition change and review the CT in time, so as to guide the treatment. Venous sinus fracture of the barrier vessels, the dural surface of the small blood vessels, resulting in venous blood seepage is the main mechanism of hematoma formation. 3, the characteristics of craniocerebral injury in young adults: ① multiple injuries, often combined with limb fracture, closed chest and abdominal injuries; ② driving motorcycle injuries are common, fast speed, high power, strong collision, craniocerebral injuries, consciousness disorder, often combined with primary brain stem injury. The incidence of cerebral contusion, subdural hematoma, intracranial hematoma is high, and the prognosis is poor. ③ The rate of reopening craniotomy is high because of the occupying effect caused by cerebral ischemia due to the delayed hematoma, and the decrease of intracranial pressure caused by the first time of removing hematoma and decompression of debridement flap can result in the enlargement of the small hematoma or hemorrhage of other parts of the brain. ④ Most of the patients had open wounds with heavy contamination and foreign bodies, and combined shock was not uncommon. All patients were admitted to the intensive care unit after admission to the hospital, so as to closely observe the changes of the condition. Routine treatment is mainly dehydration, lowering intracranial pressure, anti-inflammation, hemostasis, nutrition of brain cells and prevention of stress ulcers. If there are indications for surgery, open the green channel, and improve the relevant examinations during the preoperative preparation. During the operation, complete hemostasis, thorough removal of hematoma and necrotic brain tissue, and adequate decompression. The main surgical method is to expand the frontotemporal parietal flap to open the cranium, starting from the median line of the frontal hairline bypassing the parietal node by 2 cm, ending at the midpoint of the zygomatic arch in the forward direction, and then biting the base of the anterior cranial fossa completely flat, and then opening the dura mater or reducing the tension of the suture. For middle-aged and old people, the dosage of dehydrating drugs should be cautious to prevent the sudden drop of intracranial pressure from aggravating the original contusion or hematoma enlargement, and the addition of anti-vasospasm drugs, such as nimodipine, can prevent the occurrence of cerebral infarction; strengthen the monitoring, and leave the intracranial pressure detection probe in the operation, so as to observe the situation of intracranial pressure in the postoperative period, and to guide the treatment. To prevent complications, especially lung infection, tracheotomy should be performed as soon as possible to facilitate sputum expulsion for patients who are difficult to wake up in a short period of time. The management of comorbidities is also one of the main factors determining the therapeutic effect, first of all, we emphasize that the first physician should carefully check the body to prevent omission of diagnosis, especially for comatose patients, the body check should be more detailed, and do not be careless. Combined thoracic and abdominal closed injuries, if there are indications for surgery, can be operated at the same time with craniocerebral injuries; or craniocerebral injuries are relatively mild, the first thoracic and abdominal surgery. Combined limb fracture treatment principle is: as long as the vital signs are stable should be as early as possible for fracture repair and fixation, the two can also be performed at the same time, because comatose patients are restless, can aggravate the fracture bleeding and injury, but also to facilitate the care, and in addition to the lungs, urinary tract infections and the occurrence of bedsores have a preventive role. In conclusion, medium and heavy craniocerebral injury is the most serious injury in all kinds of trauma, and is the main cause of death, a qualified neurosurgeon in addition to basic anatomical knowledge, but also must have a high degree of responsibility, be familiar with the basic principles of craniocerebral injury, familiar with the characteristics of craniocerebral injury in different age groups, timely and accurate treatment measures, strengthen the intra-operative and post-operative brain protection, improve the specialty disease monitoring and treatment, in order to maximize the effectiveness of the treatment of craniocerebral injury. Only by strengthening intraoperative and postoperative brain protection and perfecting specialized disease monitoring and treatment can the success rate of treatment be maximized and the disability and mortality rate be reduced.