Open brain injury is divided into two categories: firearm injuries and non-firearm injuries. Usually the latter is more common, such as knife, axe cuts, etc., caused by a variety of firearms in wartime, the two treatment principles are basically the same. Only the firearm brain injury injuries are generally more complex and more serious. First, the classification of firearm craniocerebral injury (a) non-penetrating injuries, accounting for 70% of the total number of firearm injuries, including scalp soft tissue injuries, open skull fractures, but the dura is intact, a few can also be combined with brain contusions or intracranial hematoma. (B) penetrating, accounting for about 30% of the total number of firearm injuries, scalp injuries, skull fractures, dural rupture, brain tissue damage is more serious, often combined with hematoma, the mortality rate in the early stages of World War I was 49.3 ~ 60.6%, about 30% in the late. In the Second World War, the mortality rate dropped to 15%. In recent years, the mortality rate is still more than 10%, the causes of death are: 1, important areas of the brain injury; 2, complicated intracranial hematoma; 3, combined injuries and shock; 4, intracranial infection, etc.. According to the shape of the wound channel can be divided into: (a) blind canal injury, shrapnel or gunshot and other projectiles, stay in the cranial cavity, generally in the entrance of the projectile or wound channel proximal segment often have many broken bone fragments, while the distal end of the wound channel where the metal foreign body remains. The length of the wound channel varies, short 1 to 2 cm, long equivalent to the longitudinal or transverse diameter of the cranial cavity, or even foreign body to the opposite side of the inner plate fold back, forming a rebound wound channel. (B) penetrating injuries, most of the gunshot injuries, there are entrance and exit, intracranial can be no metal foreign body, the exit fracture range is wide, brain contusion and vascular injury is often more serious than the entrance injury. The fracture at the exit is extensive, and the brain contusion and vascular injury are often more serious than those at the entrance. Brain injury is extensive and severe, and is the highest mortality rate among penetrating injuries. (C) tangential injuries, gunshot tangential grazing through the head, resulting in scalp, skull and brain tissue groove-shaped trauma. Metal foreign body has escaped, broken bone fragments scattered in the superficial part of the brain, the brain injury area is narrow, the incidence of brain expansion and epilepsy is higher. Second, the mechanism and pathology of injury High-speed shrapnel or projectiles such as gunshot penetrate the meninges into the skull and form wound channels in the brain. The pathological changes of the wounded brain are: (1) primary wound tract area: refers to the central area of the wound tract, which contains destroyed and liquefied brain tissue fragments, hemorrhage and blood clots. Skull fragments, hair, sediment and shrapnel or gunshot etc. Fragments of bone are often located in the proximal part of the injured tract. Shrapnel or gunshot is located distal to the injured tract. Injury to the meninges, cerebral blood vessels and brain tissue hemorrhage, easy to form epidural, subdural, intracerebral or ventricular hematoma in the injury tract. The site of the hematoma within the injured tract can be located proximally, medially and distally. (2) Its periphery is the cerebral contusion area: it is caused by the moment after the high-speed projectile penetrates into the cranial cavity, forming a temporary cavity in the brain, generating the phenomenon of overpressure, and the shock wave is transmitted to the surrounding brain tissue, so that the brain tissue is immediately subjected to high pressure and successive negative pressure effects and causes cerebral contusion. The pathological signs are punctate hemorrhage and cerebral edema band. Third, the treatment of cranial firearm injuries 1, first aid and evacuation. (1) to keep the airway open, to prevent asphyxiation, the patient should take the side prone position. (2) quickly bandage the head and other parts of the wound to reduce bleeding, with brain expansion, with a dressing around it to keep the brain tissue to avoid contamination and increased injury. (3) Prevention of shock: for shock casualties, the cause should be identified and dealt with in a timely manner. (4) Emergency treatment of life-threatening intracranial hematoma. (5) Application of antimicrobial agents, and routine injection of tetanus antitoxin. 2, cranial debridement. Cranial firearm injuries, whether penetrating or non-penetrating, in principle, should be early and thorough debridement. The purpose is to turn the contaminated open wound into a clean closed wound after debridement, thus reducing the chance of cerebrospinal fluid leakage, brain bulge and intracranial infection, and reducing the chance of brain scar formation and future epilepsy. (1) Staged treatment, according to the time frame of debridement treatment: early, delayed and late. Early treatment (within 3 days after the injury), when the trauma is not yet obviously infected, is generally carried out according to the principle of thorough debridement. If the trauma is not obviously infected, it is still suitable for thorough debridement. If the infection is obvious, the wound should be cleaned and drained. After the infection is limited, the second-stage surgery should be performed. In late stage treatment (more than 7 days), the trauma is mostly infected or septic, so it is appropriate to expand the bone window, remove the broken bone fragments and drain the wound channel, and then perform the second stage treatment. (2) Principle and method of debridement: ① Excise the soft tissue of scalp and contused part, expand the original wound according to “S” shape, remove the scalp and dirt from the lower layer of scalp tissue, stop bleeding by electrocoagulation, intermittently suture the capillary tendon membrane and scalp, and place drainage under the skin for 1~2 days. Scalp defects can be repaired by plastic surgery. The central part of the fracture and its surrounding area should be exposed, the free and depressed bone fragments should be removed piece by piece, and the dirt, foreign bodies and blood clots should be removed to make a neat garden or oval-shaped bone window. If an epidural hematoma is present, the bone window needs to be enlarged for hematoma removal, and the dura should be examined for rupture and intrinsic hematoma. To decide whether to cut the dura for exploration. For penetrating injuries, the edges of the dura mater are repaired, or incised and enlarged to reveal the dura mater, and the wound channel is enlarged with brain pressure plates or retractors to aspirate the inactivated brain tissue, blood clots and foreign bodies within the wound channel and the wound channel wall, and indeed to stop bleeding. For metal objects that are too deep and difficult to reach, it is not mandatory to remove them in the first stage of debridement, and those that can be reached can be aspirated directly or with magnetic guide needles. After debridement, brain tissue should be collapsed and brain pulsation should appear compared to preoperative. If after debridement, the brain tissue is still bulging and there is no brain pulsation. It is possible that the debridement is not complete and there may still be hematoma or foreign body in the distal part of the injured tract, and the cause should be identified and treated. After thorough debridement, the dura mater should be tightly sutured in principle.