Development of neuroendoscopy
In the early days, there was no real neuroendoscopy, and it was mostly borrowed from other clinical disciplines and used only to try to treat hydrocephalus, but due to the coarse diameter of the endoscopes used at that time, the poor optical quality and illumination, and the lack of appropriate surgical instruments, the surgery was traumatic, ineffective, and had a high mortality rate. In the 1970s, with the advent of the kins columnar lens system, neuroendoscopy entered a new era, with reports of significantly improved surgical results compared to the previous ones in the application of this endoscopic technique for ventricular choroid plexus cautery for hydrocephalus, and began to expand to other neurosurgical procedures.
In the 1980s, neurosurgery itself entered a phase of rapid development due to the advent of CT and MR, transitioning from traditional neurosurgery to micro-neurosurgery and later to minimally invasive neurosurgery.
Driven by relevant scientific progress, the speed of updating endoscopy and its supporting instruments has accelerated significantly, and gradually developed in the direction of small size, high resolution and stereoscopic magnification, through which complex operations such as illumination, flushing, suction, hemostasis, cutting, balloon dilation, photography and video can be performed, and endoscopy is more convenient to operate. The disadvantages of difficult localization and poor hemostasis in the use of endoscopy have been solved, so that the scope of endoscopic treatment has become more and more extensive. In addition to the treatment of hydrocephalus, it is also commonly used for aneurysm surgery, pontocerebellar angle surgery, observation of saddle area surgery, and treatment of transsphenoidal pituitary adenoma, epidermoid cyst, and craniopharyngioma.
Austrian neurosurgeon Auer made an outstanding achievement by applying a 6-mm diameter endoscope for intracranial hematoma, drilling only a 1-cm-sized bone hole in the skull, applying the endoscope for aspiration of the hematoma, localizing the hematoma intraoperatively with the aid of ultrasound, and using a laser for endoscopic hemostasis. He also used the above techniques for brain tumor biopsy, cyst wall resection of intracerebral cystic lesions and laser irradiation of solid tumors, all with good surgical results. 13 endoscopic surgeries were completed, with only 1.6% of surgical complications and no surgical deaths. In recent years, some scholars have also used ultrasound, stereotactic and laser technologies simultaneously for endoscopic surgery, which is called ultrasound stereotactic endoscopy.
German neurosurgeons such as Bauer have further applied this technique to the treatment of hydrocephalus, interstitial or intracerebroventricular cysts, brain abscess, intracerebral hematoma, spinal cord cavitation and other diseases, as well as the interstitial radiation treatment of low-grade glioma, and the surgery has achieved good results. The surgical mortality rate is less than 1% and the surgical disability rate is less than 3%.
1, can eliminate the dead space of the surgical field
In microscopic neurosurgery, the application of endoscopy can complete the operation of the dead angle parts that are difficult to find intraoperatively, and the observation of the area outside the operating field directly under the microscope can not only increase the exposure of the operating field and avoid missing lesions, but also reduce the strain on the brain tissue, reduce postoperative complications and alleviate postoperative reactions.
2. Panoramic view can be obtained
The surgical microscope is illuminated in a straight line and has a tubular field of view, while the endoscopic tube has a lateral view, which can obtain a panoramic view of the lesion and clearly identify the important nerve and blood vessel structures on the side of the lesion and around it, and guide the removal of the surrounding lesion tissue, which is incomparable to the surgical microscope.
3.It can reach the operating area that cannot be reached by microscope
Because the neuroendoscope has: increase the intensity of local illumination of the surgical field; local magnification of the observed object; increase the visual angle. Therefore, it can see the area that cannot be seen by microscope. At present, it is mainly used for the observation of intracranial aneurysm structure, pontocerebellar horn area or other skull base tumors.
4. Less invasive surgery, less pain and faster recovery
Disadvantages of endoscopy
1.Small neuroendoscopic surgical field, small operation space, especially difficult to handle when there is more bleeding in the operation area.
2, Fog or blood contamination may affect endoscopic imaging.
3, The freedom and coordination of the operator’s hands are limited during the operation.
4, The endoscope is imaged through monocular vision. Therefore, a qualified neuroendoscopist must not only have a thorough knowledge of the relevant anatomy of the surgical area, but also must have received standardized training in endoscopic operation.
Basic components of neuroendoscopy
Current neuroendoscopes can be divided into two types: rigid specula and flexible fiberoptic specula. Ventriculoscopes are used for intracerebroventricular operations, while angular scopes are used for endoscope-assisted microneurosurgery. A rigid speculum transmits images through a set of cylindrical lenses, while a soft fiber speculum transmits images through a fine arrangement of optical fibers.
A rigid speculum produces a clearer image than a soft fiberscope, while the latter can be bent to the surgical intent without any compromise in image quality. The scope has a corresponding working trocar, which can be equipped with one, three or four working channels, in which the instrument channel allows the passage of laser knife fibers and working instruments such as monopoles, bipoles, miniature scissors and miniature clamps that are compatible with the endoscope. Rigid scopes are available with various field of view angles of 00, 300, 700 and 1100 for intraoperative observation, and the appropriate angle of endoscope should be selected and prepared as needed before surgery. Although it is possible to view the operative field directly through the scope itself, it is more effective to perform the procedure through a surveillance system. The endoscopic surveillance system mainly includes: camera, monitor and cold light source.
The camera has a single-chip camera and a three-chip camera, the latter can provide a clear and realistic image with a resolution of more than 800 lines. The cold light source has halogen light source, mercury vapor light source and xenon light source, through the conduction of the fiber guide beam connected with the speculum to provide sufficient illumination of the operating field. The monitor generally uses a screen display. Endoscopic operation can be done in two ways: hand-held operation and mechanical operation. Mechanical operation refers to the use of mechanical fixation or pneumatic fixation methods to fix the endoscope on a stand, which allows the operator to operate the surgical instruments with both hands.
Indications for neuroendoscopic surgery
With the continuous development of neuroendoscopic manufacturing process technology, the scope of application of neuroendoscopy has been expanding. At present, the application of neuroendoscopy in the field of neurosurgery can be divided into two categories: cranial and spinal.
First, the cranial brain The cranial cavity can be divided into two parts: intracerebral and extracerebral. The intracerebral part includes the ventricular system and brain parenchyma, while the extracerebral part includes each brain pool, subarachnoid space and skull base cavity.
(i). Intracerebral Most intracerebral neuroendoscopic procedures involve the ventricular system because the ventricular system is filled with clear fluid and provides a good visualization condition for endoscopic procedures.
1. ventricular system The application of neuroendoscopy in the ventricular system includes intraventricular tube surgery, recanalization after obstruction of the ventricular end of the shunt, intraventricular cystotomy (e.g. arachnoid cystotomy), membrane opening (e.g. tricortical fistula), tumor resection (e.g. glial cystotomy) and biopsy.
2. Brain parenchyma Because neuroendoscopic operation requires a certain cavity gap, the application in brain parenchyma is still limited to intracerebral hematoma and cystic tumor.
(II). Extracranial brain The extracranial gap in the cranial cavity includes the subarachnoid space and the skull base cavity. Subarachnoid applications include arachnoid cystotomy, microvascular decompression, and aneurysm clamping. Skull base procedures include transsphenoidal sinus saddle area tumor resection, transnasal cerebrospinal fluid nasal leak repair and transseptal optic nerve decompression.
Second, the spine Burman first performed spinal endoscopy on cadavers in 1931, and Pool first applied the technique to clinical practice in 1938. Nowadays, soft operable scopes are mostly used. The spinal system can be divided into two parts: epidural and intradural, and intradural can be further divided into intraspinal and extraspinal.
(i). Subdural Intramedullary neuroendoscopy is most often applied to spinal fluid accumulation, through which the septum causing fluid accumulation in the central canal can be identified and opened. Endoscopy may also be indicated for biopsy of intramedullary tumors in and around the central canal, but total excision of the tumor is very difficult. The subarachnoid space present in the extramedullary subdural space is also suitable for fine diameter fiberoptic endoscopic manipulation, so it can be applied to extramedullary arachnoid cysts or subarachnoid cysts due to spinal cord surgical adhesions.
(ii). Epidural The epidural includes both intraspinal and extraspinal, the latter being the most promising part of neuroendoscopic intraspinal applications, as many neurosurgeons abroad are now using percutaneous thoracic and abdominal endoscopes for thoracic and lumbosacral (L4-5 and L5-S1) discectomies. Paraspinal tumors can also be removed using thoracic and abdominal endoscopic techniques.
Neuroendoscopic techniques
Endoscopic surgical modalities can be divided into four types.
1, Pure Endoscopic Neurosurgery (EN), where the surgery is done entirely endoscopically and requires special endoscopic operating instruments, usually only cranial drilling, such as triculostomy;
2.Endoscope-assisted Microneurosurgery (EAM), in which the surgery is performed under a microscope and an endoscope at the same time;
3. Endoscope-controlled Microneutosurgery (ECM), which refers to the use of conventional microsurgical instruments and the completion of surgery through an endoscopic monitor (such as endoscopic transsphenoidal pituitary tumor removal surgery); 4. Endoscopic Inspection (EAM), which can be used for all neurosurgical procedures. Inspection), which can be used for all neurosurgical procedures for intraoperative observation only. The following is an introduction to triventriculostomy.
Endoscopic triventriculostomy is mainly indicated for non-traffic hydrocephalus. Etiologies include: stenosis of the midbrain aqueduct, parietal and thalamic tumors, tumors of the posterior cranial fossa, tumors of the pineal region, cervicomedullary bulges, cysts, meningitis, ventriculitis, intraventricular hemorrhage, and subarachnoid hemorrhage. Obstructive hydrocephalus caused by any occupancy between the posterior half of the three ventricles and the exit of the four ventricles is the best indication for triculostomy, while the surgical results for non-traffic hydrocephalus caused by cerebral hemorrhage and infection are not yet satisfactory. Preoperative assessment of the patient’s cerebrospinal fluid absorption capacity and postoperative monitoring of cerebrospinal fluid pressure can help improve the success rate of surgery.
The future of neuroendoscopy
Endoscopy has been used for more than 100 years. With the development and combined use of other related technologies, the main development trends of neuroendoscopy can be briefly summarized in the following two aspects.
I. Endoscope-assisted Microneurosurgery (EAM) Because of the dead angle in the direct field of view provided by the operating microscope, it is often necessary to pull the brain tissue in order to obtain satisfactory exposure, which may result in brain tissue contusion or cerebral ischemic infarction, leading to neurological impairment. In contrast, neuroendoscopy has a variety of views and can reveal areas that cannot be exposed by microscopy without pulling the brain tissue, such as the dorsal side of the operative field of an aneurysm and its adjacent vascular pathways, and can increase local illumination and show details of objects at close range with particular clarity. “Keyhole” surgery is a typical representative of the current application of endoscopy-assisted microsurgery techniques.
II. Stereotactic neuroendoscopy
Since the late 80’s, endoscopic technology and stereotactic technology are gradually used in combination, and, stereotactic neuroendoscopic technology in order to continue to adapt to the needs of the rapid development of modern neurosurgery and in the process of continuous innovation, the combination of neuronavigation technology and endoscopic technology has been accepted by the majority of neurosurgeons, which makes the surgical positioning more accurate, shorten the operating time and further improve the efficacy.
The main working principle of the neuronavigation-assisted neuroendoscopic technique is to use the instrument adapter system of the neuronavigation system (such as SureTrak of StealthStation neuronavigation system), fix it on top of the endoscopic working sheath, and use the infrared reflection device of SureTrak to transmit and receive infrared rays from the neuronavigation system, and then process it by the workstation to dynamically display The 3D spatial position of the head end of the endoscopic working sheath and the projection trajectory of the working sheath rod are then processed by the workstation.
When the navigation probe is successfully registered, the location of the intracerebral lesion, the surgical access trajectory and the corresponding surgical incision location are determined based on the reconstructed 3D imaging data from the navigation display, combined with the preoperative formulation of the surgical objective and plan. Then, the adapter SureTrak is firmly connected to the endoscopic sheath rod, and four aluminum balls reflecting infrared rays are mounted on the surface of SureTrak to determine the spatial position of the head end of the sheath and its long-axis connection with the tail end through a correction process using the passive infrared positioning principle, which indicates the trajectory of the sheath.
The head end of the working sheath is then placed at the registration point of the reference frame for confirmation. At this point, the endoscopic working sheath is fully functional as a navigation probe and is displayed as a positioning tool on the navigation display in 3D synchronization. The author has successfully treated various intra-lateral ventricular lesions including 5 cases of lateral ventricular cysts using this technique with satisfactory surgical results.
Application of endoscopy
As early as the 1990s, the concept of “endoscopic neurosurgery” was proposed to emphasize the important role of endoscopy in microscopic neurosurgery, and the neuroendoscopic operation was divided into four types of applications.
1, endoscopic neurosurgery: refers to all surgical operations are completely through the endoscope to complete, need to use special instruments through the endoscopic canal to complete the surgical operation. It is commonly used for hydrocephalus, intracranial cystic lesions and lesions of the ventricular system, such as rash at the base of the three ventricles, and ventricular a ventral shunt failure can be used. For symptomatic developmental abnormalities of the ventricular system (such as lateral fissure arachnoid cyst, intracerebral parenchymal cyst and hyaline septal cyst), the originally closed cyst can be opened to the adjacent ventricles. For intracerebroventricular tumors, biopsies can be taken under endoscopy, and small narrow-tipped tumors (choroid plexus papilloma, fluid cyst) can also be completely resected.
2.Endoscopy-assisted micro neurosurgery: In micro neurosurgery, endoscopy is used to complete the operation of dead-end areas that are difficult to find intraoperatively. The observation of the area outside the microscope’s direct view of the surgical field not only increases the exposure of the surgical field and avoids missing lesions, but also reduces the strain on the brain tissue, decreases post-surgical complications and alleviates post-surgical reactions. It is used for aneurysm clamping, trigeminal nerve decompression and cholesteatoma resection in the pontocerebellar horn region.
3.Endoscopy-controlled microneurosurgery: It refers to microneurosurgery done with conventional microneurosurgical instruments under the guidance of endoscopic images, borrowing the light source and surveillance system of the endoscope.3 The difference between 3 and 2 is that the main operation is done under the endoscope.3 The difference between 3 and 1 is that all operations are performed inside the endoscopic tube, while 2 is performed outside the endoscope. A typical endoscopically controlled microneurosurgery is neuroendoscopic resection of pituitary adenoma through a single nostril, which has now become a routine procedure.
4. Endoscopic observation: It refers to the use of endoscope for auxiliary observation without operation in neurosurgical operations. At present, it is mainly used for observation of intracranial aneurysm structures, pontocerebellar horn region or other skull base tumors.
What diseases can be treated by endoscopy
The application of endoscopic technology in the field of neurosurgery began in the early 20th century, and now neuroendoscopic technology has been used as a major technology for less trauma, less bleeding, faster recovery and micro-invasive operation; and in recent years, with the continuous development of stereotactic technology, laser technology, ultrasound technology and neuronavigation technology, there has been a trend of combining neuroendoscopic technology with the above technologies, further promoting neuro Endoscopic technology is becoming more and more perfect. With the improvement of endoscopic performance and the continuous development of endoscopic auxiliary equipment, there are more and more neurosurgical diseases suitable for neuroendoscopic treatment.
1. Hydrocephalus: the main disease that endoscopy is applied to neurosurgery is hydrocephalus;
2. Chronic subdural hematoma: Neuroendoscopy can be applied to intracranial hematoma surgery, which has the advantage of reducing damage and achieving the purpose of minimally invasive;
3. Intracerebroventricular cystic lesions: cystic lesions of the ventricular system are ideal indications for endoscopy;
4. Arachnoid cysts: the method is endoscopically assisted drilling followed by cyst-pool fistula or cyst-ventricular fistula;
Intracerebroventricular cysticercosis: cysticercosis is the most common parasitic infection of the central nervous system and can be removed endoscopically without damaging normal tissue structures;
6. Substantial intracerebroventricular lesions: Substantial lesions in the lateral ventricles and the three ventricles, as well as common ventricular meningiomas, choroid plexus papillomas and cavernous hemangiomas, can be removed by endoscopy;
7. Pituitary tumor resection by transnasal pterygoid approach: microsurgery with endoscopic-assisted surgical microscope will become the preferred method for pituitary tumors in the future.
8. Other diseases.
Typical surgery
1. Neuroendoscopic third ventricular floor fistulotomy
(1) Overview of hydrocephalus
Hydrocephalus has a high incidence and is commonly seen in children. The most commonly used surgical procedure is ventriculoperitoneal shunt, which has many problems, complications and costs, and sometimes requires reoperation to adjust and replace the drainage tube, or even has to be removed, forcing neurosurgeons to explore better surgical approaches. Since the 1990s, endoscopy has become an important tool in microinvasive neurosurgery. Hydrocephalus is the most important and best indication for neuroendoscopic treatment. Neuroendoscopic third ventriculostomy (ETV) allows drainage of cerebrospinal fluid closer to physiological access, and according to statistics about 70% of patients with hydrocephalus can be treated by ETV without a shunt.
(2) Indications for surgery
The main surgical indications for ETV are obstructive hydrocephalus caused by stenosis or occlusion of the midbrain aqueduct, or occupying lesions in the midbrain, pineal region, or posterior cranial fossa, or Chiari malformation. ETV has also been found to treat some traffic hydrocephalus, probably due to obstruction of the flow of cerebrospinal fluid along the subarachnoid space in the posterior cranial fossa.
(3) Advantages of neuroendoscopic third ventricular floor fistula (compared with ventriculo-abdominal shunt)
(1) No foreign body (ventriculo-abdominal shunt) is implanted in the third ventriculostomy, and there is no discomfort caused by foreign bodies;
(2) The cerebrospinal fluid circulation reconstructed by triventricular fundoplication is closer to the physiological circulation, and there is no overshunt, undershunt, or fluctuation of the shunt rate due to siphoning as a result of position change, so it is effective and has few postoperative discomfort;
(3) The access reconstructed by triple ventriculostomy is a thin film fistula >5 mm in diameter, which rarely blocks, thus making it a one-time operation and lifelong cure. In contrast, ventriculo-abdominal shunts are long and thin, with small lumens and complicated devices, and are more likely to block and fail;
④Triple ventriculostomy is not affected by the growth of children, whereas ventriculo-abdominal shunts require repeated reoperation to replace the shunts as children grow taller;
(5) Triple ventriculostomy can eliminate the cause of the disease, such as intracerebroventricular cysts and hemorrhage, at the same time;
(6) It has also been used for patients with non-traffic hydrocephalus who have failed shunts or infected adhesions, and has achieved good results.
(7) Triple ventriculostomy is a minimally invasive procedure with very low mortality and very few serious complications.
ETV, as a new surgical procedure, has become the treatment of choice for obstructive hydrocephalus and partial traffic hydrocephalus.
(4) Surgical approach
The patient is placed in the supine position under general anesthesia with the head elevated at 15°, and the right coronal suture is drilled 2 cm in front and 2 cm in front of the midline, and the frontal horn of the right ventricle is punctured by corticostomy. “After the initial formation of the fistula, a balloon catheter was applied to dilate the fistula to about 1 cm, and the basilar artery and posterior cerebral artery were seen as the sign of successful fistula. The success of the fistula is indicated by the visualization of the basilar artery and posterior cerebral artery. Saline irrigation was used throughout the procedure.
2.Neuroendoscopic single nostril pituitary adenoma resection
In the past decade, the neuroendoscopic resection of pituitary adenomas through single nostril has the advantages of minimally invasive, less complications, shorter operation time and complete tumor removal. Compared with the transoral nasal butterfly approach, it avoids damage to nasal structures such as lip-eye incision, nasal septum free and large area stripping of nasal killing membrane, and reduces complications such as atrophic rhinitis, lip-eye sensory loss and dental eye atrophy. Operating in the narrow cavity orifice, the endoscope has obvious advantages over the microscope in imaging.
Removal of tiny intracerebroventricular lesions Using the surveillance system of endoscopy can assist microscopic neurosurgery in removing tiny intracerebroventricular lesions, such as ventricular and ventricular pool lesions, intracranial cystic lesions, ventricular hemorrhage, and brain abscess. Neuroendoscopy not only provides a clear view of intracerebroventricular morphology and structures, but also allows the operator to clarify the location of intracerebroventricular lesions, the number of multiple lesions, and avoid blind operations. In the process of resection of deep brain lesions, it can observe and remove residual tumors in the blind and shadow areas of microsurgery, which has an important guiding role for surgery.
3.Neuroendoscopy-assisted intracranial aneurysm clamping
In the 1990s, neuroendoscopy was widely used for aneurysm clamping surgery. At present, neuroendoscopy is mainly used for aneurysm surgery by EAM, that is, using neuroendoscopic techniques to assist in observing the structure of the aneurysm, the relationship between the aneurysm and the surrounding vascular nerves as well as observing whether the aneurysm clamping is appropriately positioned after clamping the aneurysm and whether there is misclamping or incomplete clamping.
Since endoscopy requires a clear field and appropriate operating space, neuroendoscopy is most suitable for surgery of unruptured aneurysms or aneurysms that have ruptured but the subarachnoid hemorrhage has been absorbed, especially for deep aneurysms. This reduces the damage to the surrounding brain tissue, important nerves and blood vessels, reduces the incidence of postoperative complications, and helps patients recover sooner. Clamping of aneurysms with ECM means that after exposing the aneurysm and its surrounding structures under microsurgery, endoscopic observation of the specific aneurysm is used, and then clamping of the aneurysm is performed under endoscopy.
The main difference between ECM and EAM is that the endoscope plays a greater role in the ECM approach, but the disadvantage is that the endoscope occupies a certain amount of surgical space and sometimes prevents further surgical operations. The main difference between ECM and EAM is that the endoscope plays a greater role in the ECM approach, but the disadvantage is that the endoscope occupies a certain amount of surgical space and sometimes prevents further surgical operations.