Pituitary adenomas are common intracranial tumors, and their incidence has been on the rise in recent years, accounting for about 15% of intracranial tumors [1, 2]. Although pituitary adenomas are benign tumors, tumor growth can compress structures such as optic cross, cavernous sinus, and normal pituitary gland, causing visual field impairment, headache, and hypopituitarism; meanwhile, functional adenomas can cause clinical symptoms such as amenorrhea, lactation, infertility, hypogonadism, acromegaly, and Cushing’s disease because of excessive hormone secretion, which seriously endanger patients’ quality of life. With the development of endocrinology, pathology, radiology, neuro-ophthalmology and microsurgery. The clinical and basic research on pituitary adenoma has made a great leap, and the level of diagnosis and treatment has become higher and higher.
Surgical resection of pituitary adenoma is the main means of treating pituitary adenoma. The transsphenoidal approach was first adopted by Schoffer in 1907, but was gradually replaced by the transcranial approach because of the unsatisfactory surgical results due to the backwardness of surgical instruments and deep illumination equipment at that time. Subsequently, transsphenoidal approach to pituitary adenoma surgery gained new life and continued to develop. At present, microsurgical resection of pituitary adenoma through the pterygoid sinus approach has been widely adopted by domestic and foreign neurosurgeons. It is in continuous development. With more experience and technology development, the transsphenoidal approach can not only remove tumors in the pterygoid saddle, but also safely remove large adenomas that develop suprasellarly, even huge pituitary adenomas. The transsphenoidal approach has gradually become the most common surgical method for the treatment of pituitary adenomas, and it has been reported in the literature that about 96% of patients can be removed by the transsphenoidal approach.
The application of neuroendoscopy in the field of neurosurgery started at the beginning of the last century, initially for the treatment of hydrocephalus, which was not widely accepted by neurosurgeons for a long time due to the equipment and technology. Since then, with the continuous improvement of endoscopic equipment and instruments and further improvement of surgical skills, neuroendoscopic transsphenoidal pituitary tumor resection has developed significantly. Due to the optical illumination characteristics of the endoscope and the endoscopic angle and fisheye effect, it is easy to reveal the lesion at close range, which increases the revealing range and can clearly identify the important anatomical landmarks. Many studies have shown that compared with microscopic transsphenoidal pituitary resection, neuroendoscopy has the advantages of shorter operative time, less intraoperative bleeding, fewer postoperative complications, faster patient recovery, and higher rate of clinical symptom relief. Over the past decade, microscopic transsphenoidal surgery, which was once the leading procedure for pituitary surgery, has gradually transitioned to endoscopic intranasal transsphenoidal surgery.
The advantages of endoscopic surgery compared with microscopic surgery are as follows: ①Small trauma, neuroendoscopic surgical instruments directly use the natural channel of nasal cavity to reach the operation area, no dilator is needed to expand the nasal cavity, the damage to nasal septum and its mucosa is light, and the damage to the normal structure of nasal cavity is light, which effectively reduces the possibility of complications in nasal cavity and sinuses. After the operation, the nasal cavity is not filled with gauze, but only the ventral wall defect of the pterygoid sinus is filled, which does not affect the nasal ventilation, and the postoperative pain is small and the recovery is fast. The neuroendoscope provides closer, wider and better illumination for the operator, solves the problem of blind area in microscopic surgery, and allows the whole view of the pterygoid sinus under direct endoscopic vision, clearly identifies important signs such as internal carotid artery bulge and optic nerve bulge, and reduces serious accidents such as internal carotid artery bleeding and optic nerve injury. It expands the scope of microsurgery through the nasopalatine approach and is especially suitable for expanding the saddle area surgery through the nasopalatine approach. The anatomical study proves that the nasal endoscope is superior to the operating microscope in exposing the operative field and overcomes the disadvantage of not being able to observe the lateral wall of the butterfly sinus under the microscope. The flexible “multi-view” and “fisheye effect” of the neuroendoscope allows the operator to observe the intra-saddle structures with a wide field of view at a closer distance, preserving the pituitary function to the greatest extent and avoiding damage. The neuroendoscope can enter into the saddle to observe the tumor in the deep cavity and lateral wall, and even observe the tumor in the parasternal and suprasaddle, which increases the rate of total resection. Disadvantages: ①The neuroendoscope provides two-dimensional images, lacking the depth and hierarchy of three-dimensional images under the microscope, plus the relatively narrow space confinement, which affects the fine operation of the hand. ②When opening the saddle base dura bleeding, the endoscope is more troublesome to stop the bleeding because it is a one-handed operation, and the lens is easily covered by blood, and other disadvantages. In neuroendoscopic surgery, the operator often needs to hold the mirror with one hand and operate with the other hand, because the nasal septum is preserved, the operating space is small, and the operator should have experience in endoscopic sinus surgery and strict endoscopic training, which requires high skills of the operator and the assistant, and the intraoperative management of accidents is also limited to some extent.
Many studies have concluded that endoscopy can improve the rate of total tumor resection and hormonal remission through different angles, all-round observation of resected tumors, clearer observation of the division between tumor and residual pituitary tissue, and endoscopic observation of microscopically invisible visual field dead space through different angles [5-7].Tabaee [8] performed a meta-analysis of data from 800 patients undergoing endoscopic pituitary adenoma surgery. The results of this analysis showed that endoscopic surgery had higher rates of complete resection, higher rates of recovery of endocrine function and recovery of vision. However, Brian et al [9] retrospectively analyzed 3,586 pituitary adenoma cases and compared the clinical outcomes of transnasal butterfly microsurgery and transnasal butterfly endoscopic surgery and found no significant differences in the extent of tumor lesion resection and postoperative hormone recovery levels, but neuroendoscopic surgery was more advantageous than microsurgery in terms of postoperative complications, operative time and postoperative hospital stay. The Meta-analysis by M.Y. Bao [3] included the results of studies from several countries and regions to comprehensively assess the efficacy and safety of endoscopic versus microscopic pituitary tumor resection surgery. We believe that there are various reasons for these different analytical results. Although transnasal endoscopic surgery theoretically has many advantages over microscopic surgery, microscopic surgery has been developed for many years, is quite technically mature, has a large number of cases, and has reached a high rate of total resection, whereas endoscopic surgery is relatively new, has different levels of technical proficiency among different operators, and has fewer cases to reach a statistically significant number of cases. Whether it is endoscopic or microscopic transnasal butterfly surgery, the tumor resection rate is highly related to the skill and experience of the operator and the perfection of the instruments, and an experienced surgeon may receive better results no matter which procedure is used, so it seems not very convincing if only the information of different operators is used for comparison. Although the two techniques do not show significant differences in resection rates, endoscopy is more advantageous in more complex procedures, where the use of angled endoscopes and their large range of motion ensure resection of tumors previously inaccessible by the conventional transsphenoidal approach. in 2000, Jarrahy [10] found tumor residual after microscopic resection in more than 40% of cases by endoscopy. In clinical practice, some surgeons will use endoscopy to assess tumor resection after microscopic resection of tumors in patients with giant or complex pituitary tumors, especially when tumor resection is difficult, so that total tumor resection is ensured. Especially in patients with residual tumor or recurrence after microscopic transsphenoidal surgery, the advantage of “multi-view” of neuroendoscopy is more obvious, which can significantly improve the tumor resection rate [11]. Reports of postoperative recurrence rates vary widely. Although some studies have shown that neuroendoscopy can significantly reduce the recurrence rate of patients after surgery, the clinical application of neuroendoscopy is relatively short, and the recurrence rate after surgery is affected by factors such as the nature of tumor pathology, size and invasion, the length of time after surgery, and the operator’s technique. A large sample of case studies on recurrence rates at different time periods after neuroendoscopy has not been reported, therefore, further confirmation is needed on whether the application of neuroendoscopy can reduce postoperative recurrence rates [12].
In terms of postoperative patient length of stay and operative time, neuroendoscopy has shown significant advantages and can significantly reduce patient length of stay and operative time [13, 14]. The average length of stay of patients after neuroendoscopy is 3-4 d, which is significantly less than that of microscopy (5-8 d). The length of stay in the endoscopic group was significantly shorter than that in the microscopic group because of less injury, better postoperative nasal ventilation, better patient comfort, and faster postoperative recovery. The time of surgery varies among reports, and some literature reports that the operating time of the endoscopic group is significantly longer than that of the microscopic group do not indicate that endoscopic surgery is time-consuming, which is related to the surgeon’s surgical proficiency. Compared to microscopy, the learning curve for neuroendoscopy is very steep and rigorous training is necessary before proficiency in neuroendoscopic techniques can be achieved.
Cerebrospinal fluid leakage is a common postoperative complication, with incidence rates of 5%-7% and 6,34%-8% for neuroendoscopic and microscopic resections, respectively [1, 3-4]. The incidence of postoperative cerebrospinal fluid leakage is lower with neuroendoscopy than with microscopy because neuroendoscopy allows clear observation of the diseased tissue and its surrounding structures, and the dead space in the field of view that is not visible under the microscope is observed through different angles of endoscopy. The incidence of cerebrospinal fluid nasal leakage after surgery (3,9%). The study showed that the use of neuroendoscopy allows the operator to visualize the relationship between the tumor and the normal tissue and significantly reduces the incidence of postoperative uropygias. There was no significant difference in the incidence of infection between the two procedures. Rare complications such as hypothalamic injury and cerebral nerve palsy can also occur, and their incidence is significantly related to the operator’s operation, and the application of neuroendoscopy can reduce the occurrence of postoperative complications to a certain extent.
Intraoperative vascular complications, mainly hemorrhage caused by intraoperative vascular injury, are rare complications, mostly caused by surgical operation, and the impact of this complication will be fatal to the patient once it occurs. Due to the lack of three-dimensional visual depth, neuroendoscopy is prone to forceful dilatation of the parsaddle structures and cavernous sinus during the operation, leading to vascular injury.Ammirati [16] et al [1] reported an intraoperative vascular complication rate of 1.58%, much higher than that of microscopy (0.50%). Therefore, when using neuroendoscopy, attention should be paid to the protection of the cavernous sinus and paracavernous structures, and preoperative imaging data should be carefully reviewed to analyze the relationship between the tumor and the cavernous sinus and the cavernous sinus segment of the internal carotid artery.
The 3D technology of 3D neuroendoscopy can provide the operator with clear stereoscopic images during the transnasal butterfly surgery, so that the operator’s hand movements during the endoscopic surgery can be more coordinated and fine in the narrow and deep field of view of the pterygoid sinus. It is believed that 3D neuroendoscopy will soon be applied to single-nostril pterygoid sinus approach pituitary adenoma resection, providing more minimally invasive surgical treatment for patients.
Regarding the controversial question of whether neuroendoscopic surgery can replace microsurgery as the new standard of care for pituitary tumors, the authors believe that neuroendoscopy cannot completely replace microsurgery as the new standard of care for pituitary tumors at this time; because the promotion of new technologies must be guided by evidence-based medicine and must be supported by sufficient and strong evidence. The authors believe that neuroendoscopy cannot replace microsurgery as the new standard of care for pituitary tumors. During clinical treatment, neuroendoscopic techniques and microsurgery should be used in conjunction with each other to fully assess the patient’s condition and its surgical indications before surgery, and to select the appropriate surgical approach according to the operator’s experience and proficiency in the application of different techniques.
Points: 1. The operation space of neuroendoscopic nasopalatine approach pituitary adenoma surgery is narrow, which requires the surgeon to be skilled in nasal cavity, saddle area and parsaddle, skull base anatomy and endoscopic operation.
2.The correct judgment of the position of the saddle base is the key to the success or failure of the operation, and the operation should be kept in the middle line to avoid damaging the lateral wall of the pterygoid sinus to avoid damaging the optic nerve and the internal carotid artery and other important structures. The 30° lens is mainly used for the observation of tumor cavity hemorrhage, supra- and para-anterior structures and removal of residual tumors and macroadenomas. The application of multi-angle endoscope can find the residual tumor and achieve total resection of tumor.
4. The tumor closest to the saddle base should be removed first, then the tumor near the cavernous sinus wall on both sides, then the tumor above the posterior part of the saddle, and finally the tumor above the anterior part of the saddle to avoid premature descent of the saddle diaphragm.
5.After tumor resection, if breakage of saddle diaphragm occurs and cerebrospinal fluid leakage occurs, it needs to be repaired in time, once there is obvious cerebrospinal fluid leakage and large saddle base defect during operation, effective saddle base reconstruction must be carried out.
6. Pay attention to keep the operative field clear and use the flushing device for timely flushing.
Blind spots: 1. Bleeding from the surgical cavity is an important factor affecting the endoscopic transsphenoidal approach to remove pituitary adenoma. Intraoperative care should be taken to protect the mucosa and not to excessively cauterize the mucosa. In the primary group, it was found that most of the time of the surgical approach ( as much as 2/3 or so) was spent on the turbinate mucosa hemostasis and searching for the opening of the pterygoid sinus.
2.To observe whether there is any abnormal intercavernous sinus on the dura of the saddle base, if there is a dural incision, try to avoid it, if it cannot be avoided, pay attention to compression to stop the bleeding.
3.The postoperative effect of neuroendoscopic pituitary tumor resection is closely related to the operator’s skill, experience and surgical instruments. It should not be used reluctantly simply for the sake of using endoscope. Before mastering neuroendoscopic technique skillfully, it must go through strict training and be combined with microscope first if necessary, and slowly overdo it.
4.Tumor resection rate is closely related to the operator’s experience. It is not that using endoscope is cleaner than microscopic resection, because endoscopic field of view is wide and the scope of microscopic exposure is large.
5. Endoscopic pituitary tumor resection is easy to be complicated by olfactory disorder after surgery, which is caused by postoperative complications of sinusitis.