OBJECTIVE: To explore the choice of microsurgical access for craniopharyngioma. METHODS: Microsurgical approaches, complications and treatment results of 116 cases of craniopharyngioma were retrospectively analyzed to summarize the experience during clinical treatment. There were 63 cases (54,3%) in men and 53 cases (46,1%) in women. Visual acuity was changed in 83 cases (71, 6%), headache in 65 cases (56, 0%), and urinary failure in 50 cases (43, 1%). The surgery was performed via modified pterygoid approach in 93 cases; transnasal pterygoid approach in 8 cases; transcallosal approach in 4 cases; transcortical approach in 3 cases; inferior frontal approach in 3 cases; infratemporal approach in 2 cases; combined frontal approach + modified pterygoid approach in 2 cases; bilateral inferior frontal approach in 1 case. Results: 71 cases of total tumor resection, 30 cases of subtotal resection and 15 cases of majority resection. The most common postoperative complications were hypopituitarism and enuresis. At follow-up from 1 month to 60 months, 68 cases were working and living normally, 5 cases were living on their own, 5 cases needed care in life, and 3 cases died. CONCLUSION: Total resection of craniopharyngioma by microsurgery is effective; modified pterygoid approach is suitable for most patients; reasonable surgical approach should be selected according to the location and size of the tumor and general condition of patients. Data and methods 1. General data: 63 cases (54,3%) in men and 53 cases (46,1%) in women; age 3~70 years old, average 32,4 years old. There were 77 adult patients (18 years old, 66, 4%) and 39 children (18 years old, 33, 6%). There were 14 patients with recurrent craniopharyngioma. The duration of the disease ranged from 1 week to 20 years, with a mean of 1, 9 years. The diagnosis was confirmed by pathological examination in all cases. 2. Clinical manifestations: 83 cases (71,6%) of hypermetropia, hemianopia and vision loss; 65 cases (56,0%) of headache; 50 cases (43,1%) of enuresis; 32 cases (27,6%) of dysplasia; 16 cases (13,8%) of menstrual disorders with or without lactation; 12 cases (10,3%) of dysplasia of secondary sexual characteristics; 12 cases (10,3%) of decreased sexual desire. 3.Imaging data: CT and MRI of head were performed before and after surgery. 96 cases of occupying effect were found in CT, among which 49 cases were accompanied by calcification; MRI showed that the tumors had different degrees of enhancement, 43 cases were cystic, 22 cases were substantial and 51 cases were mixed. 4. Surgical approaches: 93 cases with modified pterygoid approach; 8 cases with transsphenoidal approach; 4 cases with longitudinal-callosal-interfornix approach; 3 cases with transcortical lateral ventricular approach; 3 cases with inferior frontal approach; 2 cases with combined inferior frontal approach + modified pterygoid approach; 2 cases with subtemporal approach to resect slope craniopharyngioma; 1 case with bilateral inferior frontal approach. The patients underwent postoperative cranial CT or MRI-enhanced imaging to determine the extent of tumor resection in combination with the surgery. According to the extent of surgical resection, they could be divided into total resection, subtotal resection and partial resection. Total resection means no tumor remnants were found in postoperative imaging, subtotal resection means only a small part of tumor tissue adhering to hypothalamus, pituitary gland or important vascular structures was left after surgery, and most resection means only part of the tumor was removed and there was still a large tumor remnant. In this group, 71 cases (61,7%) were completely resected, 30 cases (25,9%) were subtotal resection, and 15 cases (12,9%) were mostly resected. The pituitary stalk was anatomically preserved in 62 cases, broken in 11 cases, and the pituitary stalk was not seen intraoperatively in 43 cases. Follow-up was obtained in 81 cases from 1 month to 60 months, with a mean of 42, 3 months. According to the Glasgow prognostic score GOS, 68 cases were working and living normally, 5 cases were living on their own, 5 cases were living in need of care, and 3 cases died. 1 case died of infectious shock due to pulmonary infection; 1 case died of hypothalamic dysfunction; and 1 case died of brain herniation due to acute postoperative hydrocephalus. 5-year recurrence rate of craniopharyngioma was 16,5%. Early postoperative complications included: 99 cases (85, 3%) of urinary collapse, 85 cases (73, 3%) of hypernatremia and hyponatremia, 21 cases (18, 1%) of central fever, and 3 cases (2, 6%) of seizures. Late postoperative complications included hypopituitarism in 25 cases (30, 9%), postoperative hydrocephalus in 7 cases (8, 6%), increased appetite and obesity in 8 cases (9, 9%), and mental retardation and cognitive deficits in 4 cases (4, 9%). Discussion Craniopharyngioma is a slow-growing benign tumor with obvious envelope located mainly in the saddle area. The tumor is surrounded by a band of glial hyperplasia. The two main histological types are enamel epithelium and squamous papillary epithelium. The incidence rate is about 4% of intracranial tumors, and it is the highest incidence of suprasellar tumors in children (54%); among adult suprasellar tumors, it ranks the 2nd after pituitary adenoma. The epidemiological study found that there are two peaks in the age of onset, one between 5 and 14 years old and one between 50 and 74 years old, among which the number of children cases accounts for 1/3 of the total. For the treatment of craniopharyngioma, with the understanding of local anatomy and the development of microneurosurgery, most scholars now advocate the first total resection as far as possible without causing serious complications and neurological dysfunction. The extent of resection is determined by postoperative imaging combined with intraoperative conditions. Many cases have reported that the extent of resection of craniopharyngioma is closely related to postoperative tumor recurrence. From the analysis of this group of cases, the true meaning of total resection should be intraoperative surgical microscopic total resection of the tumor envelope with no tumor residue in the long-term postoperative follow-up. Some cases with imaging suggestive of total resection did not achieve true total resection, so there was recurrence again in the subsequent follow-up. In one case, a repeat cranial MRI on the second day after surgery suggested total resection of the tumor, and a repeat cranial MRI 4 months after surgery suggested recurrence of the tumor, and surgical resection was performed again. Therefore, for patients with craniopharyngioma, complete resection of the tumor envelope under direct vision should be achieved as far as possible during surgery, and regular postoperative review and close follow-up should be conducted. Before surgery, we must fully understand the anatomy of craniopharyngioma and its adjacent structures, especially the relationship with the third ventricle. The adhesion of the tumor to the hypothalamus and the wall of the third ventricle is the main factor that causes the tumor to be unresectable, followed by tumor calcification, adhesion to the penetrating artery and restriction of the surgical field. A reasonable surgical approach should be chosen according to the characteristics of craniopharyngioma. Most of the cases in our group adopted the modified pterygoid approach. We believe that: 1. During surgery, the arachnoid space around the saddle area should be fully utilized to fully expose the tumor, including the optic nerve space, the optic nerve and internal carotid artery space, the internal carotid artery cerebellar curtain space, the bifurcation of the internal carotid artery and the endplate pool. For some recurrent craniopharyngioma, where the peri-tumor structures are displaced and the adhesions are so severe that even the Ⅰ, Ⅱ and Ⅲ gaps cannot be separated anatomically, the superior interstices of the bifurcation of the internal carotid artery and the anterior cerebral artery gaps can be fully utilized to remove the tumor. 2.For cystic solid tumor or cystic tumor, the cystic fluid can be aspirated first and intracapsular decompression of the tumor can be performed, paying attention to protect the surrounding normal brain tissue. 3.Cut off the tumor blood supply artery to reduce intraoperative bleeding, which is especially important for pediatric patients; pay attention to protect the blood supply arteries of important structures during surgery, including hypothalamic perforating artery, anterior cerebral gyrus artery, end plate artery, posterior thalamic perforating artery and superior pituitary artery, which are very important for protecting vision and protecting hypothalamus and pituitary function. 4. Try to separate along the glial proliferation zone between brain tissue and tumor, and complete resection of tumor envelope. 5. Pay attention to protect the anatomical integrity of important structures during surgery, especially the hypothalamus and pituitary stalk. Maintaining the integrity of the pituitary stalk is the key to prevent postoperative pituitary dysfunction and uveitis. This approach can also be combined with other approaches to complete the resection of complex types of craniopharyngioma. For intra-saddle craniopharyngioma, a transnasal butterfly approach has been advocated. If the main body of the tumor is located in the saddle and expands toward the pterygoid sinus, or expands toward the saddle but is mainly cystic, the transsphenoidal approach is suitable; it has the advantages of minimally invasive, short operation time, few surgical complications, and short postoperative recovery period. Zhang Yuqi et al. concluded that the transsphenoidal approach is difficult to achieve complete resection and has a high recurrence rate; moreover, it requires incision of the pituitary gland, which further expands the degree of pituitary damage, and concluded that transcranial surgical resection is appropriate for intra-saddle craniopharyngioma. The transsphenoidal approach can only provide limited parsaddle exposure and is not suitable for tumors that extend forward or laterally, with a higher incidence of cerebrospinal fluid leakage and a more complicated postoperative saddle base reconstruction. In our group, 8 cases of intra-saddle craniopharyngioma were resected by the transnasal butterfly approach. There were 3 cases of total resection; 5 cases of subtotal resection, and a small amount of tumor envelope remained. The main reason was that the intraoperative exposure was not good enough for total resection of the envelope under direct vision. We believe that for intra-saddle craniopharyngioma, craniotomy is appropriate, and total resection of the tumor should be the primary goal. In some cases, a transcallosal-transparent septal cavity-interdome approach is used. Indications for the transcallosal approach are tumors occupying the anterior and middle parts of the third ventricle and occupying the entire ventricle. The transcallosal-transparent septal cavity-intervallosal approach has the following advantages: firstly, the shortest distance to reach the third ventricle, which can maximize the exposure of the tumor and reveal the important structures bilaterally; secondly, there is no need to incise one side of the fornix and the anterior part of the thalamus, and there is no damage to the thalamus, the thalamic vein and the internal cerebral vein, which reduces the postoperative related complications; finally, there is no need to incise the cortex, which can reduce the possibility of postoperative brain injury and epilepsy. In this group, four cases were operated through the longitudinal fissure-callosal-interforaminal approach, and all of them were completely resected, but one case showed short-term postoperative silence, which gradually recovered; two cases showed subdural fluid, which improved after subdural fluid-abdominal shunt operation. Attention should be paid to the indications and surgical details of this approach to further improve the efficacy. The transcranial inferior approach is suitable for craniopharyngioma that extends to the parasternal or posterior saddle or involves the anterior part of the third ventricle, especially for patients with tumor protruding through the anterior space of the optic cross and normal or posterior type optic cross. This approach may result in olfactory deficit and often requires opening the frontal sinus, increasing the chance of infection compared to the trans-pterygoid point approach. This approach is not suitable for patients with anterior optic crosses. If the tumor cannot be removed completely with a single surgical approach, other surgical approaches can be combined to remove the tumor as completely as possible. Postoperative management of patients with craniopharyngioma is very important. Postoperative hypopituitarism may occur, with insufficient secretion of related hormones. Glucocorticoid replacement therapy is very important, in addition to other relevant hormones that should be supplemented according to the patient’s hormone level. Urogyria is the most common postoperative complication, and hourly and 24-h total urine output should be routinely monitored postoperatively. Treatment with posterior pituitary hormone and micronutrients is required, and those who cannot be relieved can be treated with long-acting uremic arrest. Electrolyte disturbance is a common postoperative complication. Blood electrolytes should be checked twice a day after surgery to maintain water-electrolyte balance. Some patients with postoperative thermoregulatory disorders should be treated symptomatically. Pay attention to the protection of gastric mucosa and prevention of peptic ulcer and gastrointestinal bleeding after surgery. Some patients develop postoperative epilepsy, especially for patients with low sodium who are more likely to develop uncontrollable epilepsy. Epilepsy can aggravate cerebral hypoxia and cerebral edema, leading to increased intracranial pressure and deterioration of the disease, etc. Pay attention to postoperative prevention. The group was followed up from 1 month to 60 months, with an average of 42, 3 months; judged by Glasgow prognostic score GOS, 68 cases were working and living normally, 5 cases were living on their own, 5 cases were living in need of care, and 3 cases died; the 5-year recurrence rate of craniopharyngioma was 16, 5%. This result shows that choosing a reasonable surgical approach and using microscopic neurosurgery techniques significantly improved the treatment level of craniopharyngioma. Although this group of cases showed good results with microsurgical total resection of craniopharyngioma, the surgical treatment of craniopharyngioma remains one of the important challenges for neurosurgeons. The problems of selecting the appropriate surgical approach and accurately determining the anatomical relationship between the craniopharyngioma and the surrounding normal structures during surgery still need to be further addressed. In addition to skilled micro-neurosurgery techniques and rich clinical experience, the improvement of the surgical efficacy of craniopharyngioma also needs an in-depth study of the mechanism of craniopharyngioma development and the anatomy and function of the third ventricle/hypothalamus region.