Pituitary tumors are a common benign tumor in neurosurgery, accounting for 10% of intracranial tumors, and their incidence is on the rise. In recent years, the maturation of microinvasive neuroendoscopic techniques has led to more options for the surgical treatment of pituitary tumors, and the neuroendoscopic single-nostril transsphenoidal approach to remove pituitary tumors has the advantages of less injury, convenient tumor removal, no scarring, low morbidity and mortality, and quick recovery. With the development of modern medical imaging, endoscopic technology has been continuously improved and gradually used in medical clinical multidisciplinary, and the application of endoscopic technology in transsphenoidal pituitary tumor surgery has also gradually increased, and neuroendoscopic single nasal sinus approach pituitary tumor resection is a more advanced surgical method at present, which has the advantages of simpler surgical route, no facial incision, less injury, less pain, faster postoperative recovery, and faster recovery from complications compared with traditional open surgery. It has the advantages of simpler surgical route, no facial incision, less injury, less pain, faster recovery and less complications. With the development of minimally invasive neurosurgery techniques, neuroendoscopic techniques have been adopted by more and more neurosurgeons.
The extended transsphenoidal approach is a modification of the traditional transsphenoidal surgery, which has gradually gained wide application in the field of neurosurgery because of its wide range of exposure and freedom of operation and its ability to remove lesions involving the saddle, sinus, and mid-superior slope area. In recent years, with the continuous development of surgical conditions and equipment, especially with the assistance of neuronavigation, neuroendoscopy and intraoperative MRI, the expanded transsphenoidal approach has been more and more widely used in clinical practice, and now it can be applied to a variety of lesions in the saddle, cavernous sinus and slope areas such as giant pituitary adenoma, chordoma and meningioma, and has achieved satisfactory results. At present, it is not common for domestic units to use endoscopic operation throughout the expanded transsphenoidal surgery for the following reasons.
The endoscope provides a two-dimensional image, which lacks depth and hierarchy; it requires high hand-eye coordination and is unaccustomed to operation; it usually uses one-handed operation of instruments, which is more difficult to deal with larger bleeding and harder-textured lesions in the operative area; the endoscope and instruments are in a relatively small space, which easily interfere with each other and increase the operational difficulties; conventional transsphenoidal instruments are difficult to deal with the complex situations that arise intraoperatively due to the angle and functional limitations. Therefore, influenced by the above-mentioned factors, many units in China still use microscope for the entire operation or mainly for the expanded transsphenoidal or even the conventional transsphenoidal approach.
However, the use of retractors can greatly limit the scope and angle of endoscopic observation and instrumentation, thus affecting the surgical operation. In the expanded transsphenoidal approach, instead of using retractors, the narrow natural gap in the nasal cavity is used to open the anterior wall of the pterygoid sinus and place the endoscope into the pterygoid sinus cavity, which allows for greater freedom of operation due to the stretchability of the nasal mucosa. The bilateral nasal aperture approach can effectively expand the operating space of the surgical instruments. Usually, the endoscope is placed in one nasal cavity, and then the instruments are placed in both sides or one nasal cavity for operation, which can obtain different operating angles. The special endoscopic pneumatic fixation arm can be used to change the angle at will, thus realizing “two-handed” or even “three-handed” operation under the microscope, which can better deal with intraoperative bleeding and separation of lesions, and at the same time, the fixation arm is more stable compared with the assistant’s handheld endoscope, which avoids the error caused by the assistant’s movement. At the same time, the fixed arm is more stable than the assistant-held endoscope, avoiding misuse due to assistant movement. The most representative of these instruments is our own modified suction device with different diameters and curvatures with electrocoagulation function, which can act as suction device, stripper and electrocoagulation at the same time, so that a clear operative field can be maintained at all times when bleeding occurs in different areas, and thus rapid electrocoagulation can be performed to stop the bleeding, and also help to remove the residual tumor in each blind spot in the tumor cavity. In cases with good pneumatization of the pterygoid sinus and intact skull base bone, a satisfactory surgical result can usually be achieved with the help of preoperative imaging and what is seen intraoperatively by endoscopy. However, when the lesion growth is extensive and the skull base bone is significantly damaged, the intraoperative structures are often difficult to identify, which can easily lead to damage of the surrounding important structures and residual lesions. The application of neuronavigation can better solve this problem and help improve the success rate and reduce the complications of surgery. Compared with intracerebral lesions, skull base lesions are less affected by drift and intraoperative cerebrospinal fluid release because the adjacent bony structures are more fixed, and the accuracy of navigation is less affected by drift and intraoperative cerebrospinal fluid release, etc. GE electromagnetic navigation uses physiological bony structures of the craniofacial region such as the tip of the nose, the medial canthus, and the mastoid process as markers. During the process of lesion removal, the extent of lesion removal and the site reached by the operation can be known at any time, thus effectively improving surgical safety and efficiency. In addition, neuronavigation can choose CT, MRI, PET and other image data for navigation neuronavigation, MRI for the cavernous sinus, internal carotid artery, optic nerve, normal pituitary gland and other soft tissue structures display better than CT, but the display of the pterygoid sinus, skull base and other bony structures is not as good as CT. some studies have indicated that under the same conditions, CT navigation registration time difference born affects less error than MRI, and navigation is more accurate. It is better to use CT navigation before exposing the lesion and MRI navigation during resection of the lesion, so that the advantages of both navigation modalities can be fully combined to achieve higher surgical accuracy. Although neural navigation produces less drift during transsphenoidal surgery, in cases with severe bone defects, the surrounding structures such as the skull base dura and normal pituitary gland may still be displaced during tumor resection, leading to errors in judgment. Therefore, one should not mechanically follow the instructions of navigation, but should simultaneously take advantage of endoscopy to observe more from all angles to judge the true relationship between the peripheral structures and the tumor. In conclusion, for large and complex lesions in the oblique area of the butterfly, the use of neuronavigation in conjunction with neuroendoscopy is a good combination solution that can combine the advantages of both, providing the operator with both real-time surgical directional guidance and a free range of instrumentation operation, which helps to precisely locate the tumor intraoperatively, improve the surgical resection rate, and reduce serious complications, thus making the expanded transsphenoidal approach more widely used.
However, due to the limitations of surgical instruments and operating techniques, there are still some problems in the surgical results and postoperative complications of the expanded transsphenoidal approach in China. The application of neuronavigation system-assisted full endoscopic technique to perform the expanded transsphenoidal approach has good results. Specifically, we can apply GE neuronavigation system; German Zeppelin neuroendoscopic system, high-definition digital video system, with endoscopic pneumatic arm fixation system, various angles and diameters of straight and curved head suction (with homemade electrocoagulation function); American Medtronic high-speed pneumatic drill, with transdural special grinding drill. The patient underwent a cranial spiral CT scan (axial, layer thickness 1 mm) 1 d before surgery, without labeling. Three-dimensional reconstruction and preoperative planning were performed. On the day of surgery, the patient was intubated with general anesthesia and the head was fixed in a head frame. The lesions were accessed using bilateral nasal aperture approaches. The opening of the pterygoid sinus was found at the posterior crypt of the bilateral nasal septum and middle and superior turbinates respectively, and the nasal mucosa of the anterior inferior wall of the pterygoid sinus was incised with an electric knife along the opening of the pterygoid sinus in a downward direction and pushed outward. The opening was enlarged toward the midline with a high-speed grinding drill or biting forceps, while the bony nasal septal root was ground away to expand the instrumentation. After exposing the saddle base and the lesion, the endoscope is fixed by the pneumatic arm and the instruments are operated with “two-handed” or “three-handed”, and the bones of the saddle base are abraded or occluded according to the navigation positioning, and care is taken to avoid the important structures such as the internal carotid artery and the optic nerve. If the dura of the saddle base is still intact, “+” incision of the dura will be made; if the dura of the saddle base has been destroyed, the dural incision will be enlarged, and then the tumor will be removed in pieces by using a combination of instruments such as scrapers, tumor extraction forceps and various types of angular suction devices, etc. Navigation and positioning will be performed at any time during the resection process, and at the same time, the scope of resection and the site to be reached will be understood by combining with the endoscopic observation, especially In the process of resection, navigation and positioning should be performed at all times. After the lesion is resected, the scope is inserted into the tumor cavity and combined with neurological navigation to observe whether there is any residual tumor and further resection as appropriate. During the operation, the presence of cerebrospinal fluid leakage was observed, and the internal jugular vein could be compressed and the air could be inflated by breathing balloon. If cerebrospinal fluid leakage was found, it was repaired with autologous adipose tissue, gel sponge or artificial dura, and the saddle base was kept open. Finally, the nasal mucosa is repositioned and one or both nasal cavities are filled with an expanding sponge.
The whole central compartment of the skull base, from the crista galli to the clivus and anterior craniocervical junction, can be accessed by means of the Endonasal endoscopy
The endoscope is introduced in the nostrils and the main anatomical landmark should be identified. The 2 nostrils ¨C 4 hands techniques is highly The 2 nostrils ¨C 4 hands technique is highly recommended: the collaboration of two surgeons (ENT and neurosurgeon) insure the best therapeutic option for the patients.
In the endonasal step, the main landmarks are: the middle turbinate (MT), the nasal septum (NS), the choana (Ch).
Finding of the ostium sphenoidalis
The roof of the choana (Ch) is a good anatomical landmark to find the ostium sphenoidalis (OS), which is located superiorly to it.
Opening of the ostium sphenoidalis
Once the ostium sphenoidalis (OS) has been identified, …
… It is enlarged using a diamond tipped burr and circular cutting punch.
According to the needs, the two openings of the right and left ostium sphenoidalis can be connected in order to get more space for surgical instrumentation .
Sphenoidal step
The introduction of the endoscope in the enlarged ostium sphenoidalis allows the visualization of additional anatomical landmarks: sellar floor (SF), clivus (C), planum sphenoidalis (PS), internal carotid artery (ICA), and optic nerve (ON).
Visualization of the optic-carotid recess
The optic-carotid recess (OCR) is a very important landmark for the identification of the internal carotid artery (ICA) and the optic nerve (ON).
The anterior cranial fossa can be reached removing the planum sphenoidalis (PS) between the optic nerves (II), visualizing the dura mater (DM) of the The endoscopic visualization shown here …
… The endoscopic visualization shown here … is compared to the transcranial visualization of the same region. the area which has to be opened is outlined.
C: Clivus
III: oculomotor nerve
Duroplasty
In cases of dural injuries, the closure technique is strictly related to the individual patient’s anatomy, the size of the CSF leak, and its Underlay, overlay, combined, and obliterative techniques have been described.
The illustration shows a combined three layer technique in which are evident: