With the development of society and industrialization and acceleration, craniocerebral injury is becoming more and more common, and the treatment of heavy craniocerebral injury is becoming more and more important. In the early stages of craniocerebral injury, patients suffer from metabolic disorders due to the inhibition of the central nervous system, inadequate tissue perfusion, massive release of catecholamines, increased blood glucose and free fatty acids, which lasts about 1-2 days. Although the high metabolic response can temporarily compensate for the body’s demand for energy, the energy stored in the body will inevitably be depleted due to malnutrition and weight loss and negative nitrogen balance if the nutrition is not supplemented in time and EE gradually increases. The immune function of the body will be weakened and the wound healing time will be prolonged, which will easily lead to the occurrence and development of infections (mainly intracranial infections and pulmonary infections), thus increasing the mortality and disability of traumatic brain injury, so early and long-term nutritional support after traumatic brain injury is especially important. Zeng Wensheng, Department of Neurosurgery, Dongguan Donghua Hospital Ⅰ. Review and analysis A Cochrane systematic analysis in 2005 provided evidence for when to start nutritional support in traumatic brain injury and by what route to give it [3]. Both questions were determined using outcomes, such as death, disability (disablement) and complications, as clinical endpoints. The first was the analysis of early (within 7 days) or delayed (after 7 days) nutritional support for traumatic brain injury, which resulted in a relative risk of death (RR) of 0.67, 95% CI 0.41 to 1.07 for early nutritional support in 284 patients in 7 randomized controlled studies; the RR of death and disability for early nutritional support in 3 of the randomized controlled studies This suggests that early nutritional support may improve survival and reduce disability in patients with traumatic brain injury. Another analysis of parenteral or enteral nutrition support for traumatic brain injury resulted in an RR of 0.66, 95% CI 0.41 to 1.07 for death in 207 patients on parenteral nutrition support in 5 randomized controlled studies, and an RR of 0.69, 95% Cl 0.40 to 1.19 for death and disability on parenteral nutrition support in 2 randomized controlled studies. thus suggesting that early parenteral nutrition support has a tendency to improve the survival rate and reduce the disability rate of patients with traumatic brain injury. Complications in patients with severe craniocerebral injury are common: stress hyperglycemia, various types of infections, stress ulcers, gastrointestinal bleeding, reflux esophagitis, etc.. And they promote each other and form a vicious circle, which seriously affects the recovery of the organism. In particular, the barrier function of intestinal mucosa is damaged after severe traumatic brain injury, multi-organ malfunction, and because the patient is often accompanied by coma or impaired consciousness, the hypothalamus, brainstem and other nerve centers are damaged, resulting in the suppression of gastrointestinal emptying and peristaltic function. Gastric retention is often present, and the use of gastrointestinal nutrition (EN) often results in misabsorption, reflux, and diarrhea; although there have been methods to improve EN, reflux and diarrhea cannot be eliminated, so parenteral nutrition (PN) is mostly advocated in the early stage, but some studies have shown that the structural and functional integrity of the gastrointestinal tract is an important factor affecting the prognosis of patients. Many studies have shown that active and reasonable nutritional therapy in patients with heavy craniocerebral trauma can not only improve the metabolic status of the whole body, maintain a certain level of protein in the body and reduce the negative nitrogen balance, but also improve the immune function of the body, enhance the resistance of the body, reduce the occurrence of complications and promote the recovery of neurological function, thus improving the survival quality of patients and reducing the traumatic brain injury disability and mortality rate of traumatic brain injury. The conventional nutritional support cannot significantly restore the immune function of critically ill patients. Therefore, strengthening the immune function of the patient is the main research direction at present. The development of clinical nutrition from nutritional support to nutritional therapy: intravenous hypernutrition —- total parenteral nutrition —– enteral nutrition —- PN+EN —– immunonutrition —- ecological immunonutrition. With the advancement of nutritional support techniques for critically ill patients has significantly improved their prognosis, but the treatment of patients with severe stress such as infection and trauma is still unsatisfactory. It has been found that in hypermetabolic pathological processes or organ insufficiency, often accompanied by immune depression, and that infections have become a major cause of therapeutic effects. since the 1990s, a series of related studies have shown that nutritional support can modify the therapeutic effects of diseases, not only due to the correction and prevention of nutritional deficiencies in the treated subjects, but more importantly, probably through the specific nutrients in it pharmacological effects of specific nutrients. Certain nutrients not only prevent and treat nutritional deficiencies, but also stimulate immune cells in specific ways to enhance response function, maintain a normal and moderate immune response, modulate cytokine production and release, reduce harmful or excessive inflammatory responses, maintain intestinal barrier function, etc. This new concept was initially called nutritional pharmacology, and in recent years has been more commonly referred to as immunonutrition to clarify its therapeutic purpose. This kind of nutrition support is organically combined with the prevention and treatment of systemic inflammatory response syndrome and the resulting multi-organ insufficiency, i.e., some specific nutrients are added to standard enteral nutrition or parenteral nutrition, which can enhance immune function and regulate inflammatory response, and protect the barrier function of gastrointestinal mucosa. Research in this area is one of the development directions of modern surgery. It is even more important to carry out immune nutrition in patients with severe craniocerebral trauma. Nutrients with immunopharmacological effects are also increasing with the progress of research, and more researched and clinically applied nutrients include glutamine, arginine, ω-3 fatty acids, nucleotides, dietary fiber, etc. Nucleotides, dietary fiber, etc. For patients with severe craniocerebral injury, immune nutrients can be increased: for example, glutamine can promote protein synthesis, maintain the stability of serum amino acids and improve nitrogen balance; it can maintain the stability of blood glucose level; significantly reduce the permeability of intestinal mucosa, maintain the function of intestinal mucosal barrier, enhance intestinal immune function, reduce bacterial translocation and prevent the occurrence of intestinal-derived infection; maintain and support the function of glutathione, promote immune cells value-added, improve the function of immune cells and tissues, and thus improve the immune function of the body. Evidence-based medical evaluations of immunonutrition include: Heys et al. conducted a meta-analysis of 11 prospective randomized controlled studies enrolling a total of 1009 critically ill or cancer patients and found that the application of immunonutrition significantly reduced the incidence of infectious complications (RR=0.47) and shortened hospital stay by a mean of 2.5 days. beanle et al. summarized 12 prospective randomized controlled studies with a total of The results showed that IED had no effect on mortality, but significantly reduced the incidence of infectious complications (RR=0.60, p=0.005) and significantly reduced the duration of mechanical ventilation (p=0.04) and hospitalization (p=0.002). Notably, the study was evaluated separately before and after the intervention, and the results were consistent before and after the test, suggesting that immunonutrition is indeed efficacious in critically ill patients. Jiang Hua et al. conducted a meta-analysis of 17 randomized controlled trials examining the prognostic impact of immunonutrition in post-surgical and critically ill patients, enrolling a total of 2090 patients. The results showed that patients using immunonutrition had lower infection rates (OR=0.51, P=0.00001), shorter hospital stays, and a trend toward lower hospital costs compared with standard enteral nutrition. Therefore, the American Society for Parenteral Nutrition (ASPEN) introduced in 2001 one of the recommendations for the indications of immunonutrition application: patients with severe cranial trauma. Therefore, the addition of glutamine to conventional PN can maintain the barrier function of intestinal mucosa, reduce the occurrence of intestinal-derived infection and safeguard the function of vital organs; the addition of arginine has a close correlation with the immune function, protein metabolism and wound healing of the organism. In conclusion, patients with severe traumatic brain injury need to strengthen immune nutritional support while emphasizing disease treatment, with the aim of not only maximizing the nutritional status of the body, promoting nitrogen balance and the stability of amino acid and protein metabolism; but also promoting the recovery of neurological function, maintaining the barrier function of intestinal mucosa, safeguarding vital organ function, maintaining the immune function of the body, reducing the occurrence of complications, and improving the prognosis of patients.