The origin of craniopharyngioma is closely related to the pituitary gland and pituitary stalk, but there is no unified conclusion at present. The histogenesis theory suggests that craniopharyngioma originates from squamous metaplasia of the primitive oral cavity epithelium that will differentiate into the buccal mucosa. Neither theory fully explains the origin of craniopharyngioma, but both support the origin of craniopharyngioma in the distal part of the adenohypophysis and its nodal part. Around the third week of gestation, the Rathke’s capsule and the primitive pituitary part gradually come together, and the part of the Rathke’s capsule attached to the primitive oral cavity is called the craniopharyngeal duct. The anterior wall of Rathke’s capsule thickens to form the distal part of the pituitary gland and wraps around the funicular stalk to form the nodal part of the pituitary gland, while the posterior wall gradually degenerates to form the intermediate part of the pituitary gland [1-2]. Craniopharyngioma originates from the remnant cells of the Rathke’s bursa that gradually migrate upward as described above, so it can occur along the developmental pathway of the craniopharyngeal duct from the nasopharyngeal cavity, the pterygoid sinus, the pterygoid saddle, the suprasellar, and the trichocephalic ventricles. The adenopituitary nodes and the funicular stalk of the pituitary gland together form the pituitary stalk, and the pituitary portal system longitudinally covers the surface of the pituitary stalk. Intrasellar craniopharyngiomas originate from the adenohypophysis or the intersellar segment of the pituitary stalk, while suprasellar craniopharyngiomas originate from the suprasellar segment of the pituitary stalk. Craniopharyngiomas originating from the pituitary stalk node occur outside the soft meninges, depending on the degree of rotation of the pituitary stalk node. If the developmentally delayed soft meninges do not insert properly between the primordial orifice and the cerebral vesicles, some of the nodal cells enter the soft meninges, leading to the development of pure intracerebroventricular craniopharyngiomas [3-4]. Understanding the origin of craniopharyngioma and its relationship to the pituitary stalk is important for the intraoperative identification and preservation of the pituitary stalk. II. identification of pituitary stalk Identification of pituitary stalk is the basis of pituitary stalk preservation, and it has been reported in the literature that most normal subjects and patients with long-term uveitis are able to detect and identify pituitary stalk on preoperative imaging [1,3]. In craniopharyngioma, due to the partial origin of the pituitary stalk and tumor compression and destruction, the pituitary stalk can be displaced forward, backward and laterally, and the pituitary stalk is distorted and deformed, thinned, thinned and elongated, resulting in the pituitary stalk can be displaced to various locations on the surface of the tumor, and it is difficult to identify and detect the pituitary stalk by preoperative CT or MRI [5], and the travel direction can only be roughly determined according to the location and growth pattern of the tumor, providing some clues for intraoperative detection and It can only provide some clues for intraoperative detection and protection of the pituitary stalk based on the tumor location and growth pattern. The pituitary stalk can generally be identified intraoperatively by the following characteristics [5,6]: (1) according to the specific direction and location of the pituitary stalk: the pituitary stalk starts from the funnel at the base of the three ventricles to the septal foramen and enters the saddle to reach the pituitary gland, and the structure connecting the base of the three ventricles and the septal foramen is found to be the pituitary stalk intraoperatively, especially the septal foramen is relatively fixed, so it is easy to find the pituitary stalk; (2) according to the characteristics of the pituitary stalk itself: the long portal vein on the surface of the pituitary stalk forms a striated shape. Even if the pituitary stalk is severely displaced, these veins still maintain their original parallel shape, which is unique among all structures in the saddle. There are few reports in the literature on intraoperative identification of pituitary stalk, Yasargil [5], Honegger [7] and Shi Xiang-en [8] reported that the detection rate of pituitary stalk was 56.3%, 67.4% and 80.2%, respectively. 82.6% of patients in our group could identify and find pituitary stalk intraoperatively. We have learned that, according to the characteristics of the pituitary stalk, when surgical resection of the tumor is performed, intracapsular decompression of the tumor should be performed first, and for cystic tumors, partial extraction of the cystic fluid is sufficient at the beginning, because the cyst containing the cystic fluid can provide a tense interface, which is conducive to the separation of the tumor along the interface between the cystic wall and the arachnoid membrane, and the separation along this interface and the gradual expansion of the operative field should be repeatedly and carefully identified, and the pituitary stalk should be repeatedly identified. However, in a few cases of craniopharyngioma, the pituitary stalk was completely fused with the tumor due to severe destruction of the pituitary stalk, and the pituitary stalk could not be identified and detected during the tumor resection. In 12 cases (17.3%), the pituitary stalk could not be identified intraoperatively, and no pituitary stalk was found after repeated inspection of the surgical field and tumor tissue after tumor resection. Preservation of the pituitary stalk There is still a controversy whether to preserve the pituitary stalk or not in craniopharyngioma surgery, Yasargil, Honegger, Effenterre et al [5,7,9] believed that the pituitary stalk could be sacrificed for the purpose of total surgical resection, Hoffman, Sweet et al [10,11] believed that the pituitary stalk is a root cause of craniopharyngioma recurrence and advocated sacrificing the pituitary stalk. , Tae-Young Jung et al [12] advocated preserving the integrity of the pituitary stalk as much as possible to preserve the integrity of anterior pituitary function, and Shigeru Nishizawa et al [13] advocated preserving the pituitary stalk as much as possible, even if distal dissection of the pituitary stalk would help in the recovery of distal uveitis. An increasing number of experts believe that pituitary stalk preservation has more positive implications than non-preservation, and that even if it cannot be preserved intact, the pituitary stalk should be dissected as distally as possible to provide a residual base for future reconstruction of the pituitary portal system [14]. It can also be used as a sign that the hypothalamus is protected [15]. There are few clinical studies involving pituitary stalk preservation in the literature; Yasargil [5], Effenterre [9], Honegger [7], and Shi Xiang-en [8] reported pituitary stalk preservation rates of 32%, 52%, 63%, and 62.0%, respectively; in our group of 69 patients, 41 cases had complete anatomical preservation and 9 cases had partial preservation, and the pituitary stalk The retention rate was 72.5% (50/69). In 1990, Yasargil [5] classified craniopharyngioma into 6 types according to the location of craniopharyngioma: Type I: purely intra-saddle-subdiaphragmatic, Type II: intra-saddle-supra-saddle, Type III: supra-diaphragmatic, paraventricular, extra-ventricular, Type IV: intra- and extra-ventricular, Type V: paraventricular involving type VI: purely intraventricular type. Our group used Yasargil staging according to the preoperative MRI characteristics of the tumor, and then combined with intraoperative views for confirmation and correction. We found that the ease of pituitary stalk preservation was related to the Yasargil typing, i.e., the site of the tumor. In combination with the intraoperative findings, we found that the pituitary stalk could be preserved intact because the pure intracerebroventricular craniopharyngioma did not involve the pituitary stalk. For the type of tumor originating from the saddle and growing suprasellarly and the type of tumor originating from the base of the three ventricles and growing intraventricularly-suprasellarly prominently, there is a clear interface between the tumor and the suprasellar part of the pituitary stalk, and the pituitary stalk is often more intact in these two types of tumors. Craniopharyngioma originating from the saddle septum to the pituitary stalk node of the hypothalamic funnel is roughly divided into the following types, which should be treated separately during surgery: ① superficial pituitary stalk destruction type: the tumor is at the origin of pituitary stalk, only the surface of pituitary stalk is tumorized, and the pituitary stalk can be preserved basically by carefully separating the interface between the tumor and pituitary stalk during surgery; ② partial pituitary stalk destruction type: the tumor is at the origin of pituitary stalk, and part of the pituitary stalk is tumorized. The pituitary stalk is partially destroyed: the tumor is tumorized at the origin of the pituitary stalk, and the pituitary stalk is partially preserved by wedge-shaped resection when separating the tumor tip. The pituitary stalk of type ① can be preserved basically, but a few of type ② can be easily separated from the tumor during surgery because the residual pituitary stalk is very thin, and type ③ and ④ cannot preserve the pituitary stalk in order to remove the tumor. In this group, there were 7 (10.1%) cases in which the pituitary stalk was found intraoperatively, but could not be preserved intraoperatively, mainly for ② and ③ types of tumors.