Neuroendoscopic access to the third ventricle in patients with narrow foramen of monro without stenosis/obstruction: role of foraminoplasty.

OBJECT: One of the critical steps for the success of intraventricular neuroendoscopic procedures is the entry into the third ventricle and passage of the endoscopy system through the foramen of Monro (FM). A diameter larger than that of the instrument used is considered a prerequisite for safely performing the technique, as damage to this structure can lead to alterations in the fornix and vascular structures. When the foramen diameter is narrow and there is no obstruction/stenosis, the role of foraminoplasty in reducing the risk of complications has not been adequately assessed in the literature. METHODS: A review of endoscopic procedures conducted at our center since 2018 was undertaken. Cases in which preoperative imaging indicated a FM diameter < 6 mm and foraminoplasty technique was applied were examined to determine the technical and functional success of the procedure. The technical success was determined by completing the neuroendoscopic procedure with the absence of macroscopic lesions in the various structures comprising the foramen and without complications in the follow-up imaging tests. Functional success was defined as the absence of cognitive/memory alterations during the 3-month postoperative follow-up. Additionally, a review of the various forms of foraminoplasty described in the literature is conducted. RESULTS: In our cohort, six patients were identified with a preoperative FM diameter < 6 mm without obstruction or stenosis. Foraminoplasty was planned for these cases to facilitate various intraventricular neuroendoscopic procedures. In all instances, the technique was successfully performed without causing macroscopic damage to the structures comprising the foramen. Follow-up visits included various cognitive tests to assess potential sequelae related to microscopic damage to the fornix. None of the patients exhibited anomalies. CONCLUSION: Foraminoplasty in patients with a narrow FM without signs of stenosis/obstruction is a useful technique to reduce the risk of complications during the passage of the endoscopy system through this structure, enabling the safe performance of neuroendoscopic procedures.

Dynamic Workflow Proposal for Continuous Frameless Electromagnetic Neuronavigation in Rigid Neuroendoscopy.

BACKGROUND: Ventriculoscopic neuronavigation has been described in several articles. However, there are different ventriculoscopes and navigation systems. Due to these different combinations, it is difficult to find detailed neuronavigation protocols. We describe, step-by-step, a simple method to navigate both the trajectory until reaching the ventricular system, as well as the intraventricular work. METHODS: We use a rigid ventriculoscope (LOTTA, KarlStorz) with an electromagnetic stylet (S8-StealthSystem, Medtronic). The protocol is based on a modified or 3-dimensionally printed trocar for navigating the extraventricular step and on a modified pediatric nasogastric tube for the intraventricular navigation. RESULTS: This protocol can be set up in less than 10 minutes. The extraventricular part is navigated by introducing the electromagnetic stylet inside the modified or 3-dimensionally printed trocar. Intraventricular navigation is done by combining a modified pediatric nasogastric tube with the electromagnetic stylet inside the endoscope's working channel. The most critical point is to obtain a blunt-bloodless ventriculostomy while achieving perfect alignment of all targeted structures via pure straight trajectories. CONCLUSIONS: This protocol is easy-to-set-up, avoids head rigid-fixation and bulky optical-based attachments to the ventriculoscope, and allows continuous navigation of both parts of the surgery. Since we have implemented this protocol, we have noticed a significant enhancement in both simple and complex ventriculoscopic procedures because the surgery is dramatically simplified.

Transcortical transcatheter ultrasound-assisted technique for deep-seated brain tumors. Technical note.

PURPOSE: Surgery of deep-seated brain tumors can be challenging. Several methods have been described to facilitate transcortical approaches, including ultrasound-assisted resection. Ultrasound-guided placement of a standard ventricular catheter is a widely reported technique and has been used to approach these lesions via the transcortical route. We describe how we usually perform this useful technique to assist and enhance the transcortical resection of some deep-seated brain tumors. METHODS: Standard electromagnetic frameless navigation (S8 Neuronavigation System, Medtronic, Minneapolis, USA) was employed to focus the craniotomy and to plan the trajectory of the ventricular catheter. After dural opening, an ultrasound device (Arietta 850, Hitachi-Aloka Medical, Tokyo, Japan) was used for intraoperative ultrasound (IOUS) assessment. A ventricular catheter was placed from the cortex to the lateral wall of the tumor under direct real-time IOUS visualization to guide the further transcortical dissection. RESULTS: Transcortical transcatheter ultrasound-assisted technique involved minimal time and infrastructure requirements. There were no major technical difficulties during its use, providing confidence and improving subcortical white matter dissection by guiding the route to the tumor. CONCLUSIONS: Recent improvement of IOUS image-quality devices offers several attractive options for real-time navigation. The combination of conventional neuronavigation systems with real-time IOUS assessment during the intradural step provides a higher degree of control by improving the execution of the surgery. We hope this description may be a useful tool for some selected cases and contribute to the further enhancement and improvement of this widely used technique.

Microsurgical Fenestration of Middle Fossa Arachnoid Cyst in a Pediatric Patient Through a Keyhole Approach with Endoscopic Inspection. 2-Dimensional Operative Video.

In recent decades, the management of middle fossa arachnoid cysts in pediatric patients has evolved significantly through the integration of novel techniques, such as the utilization of endoscopy systems1 and implementation of minimally invasive approaches like keyhole craniotomy.2,3 These cystic formations, occurring within the arachnoid membrane, may lead to neurologic impairments and raised intracranial pressure if left untreated.4 The utilization of endoscopy to aid microsurgical techniques or as a complement to them provides a level of visualization and manipulation of the cyst walls that is significantly more precise than the isolated use of a microscope.1 The keyhole craniotomy allows for reduced surgical trauma, smaller incisions, and quicker recovery times.5 In Video 1, we present the case of a 2-year-old patient with bilateral middle fossa arachnoid cysts exerting mass effect on the adjacent parenchyma. The patient was referred to our institution due to developmental delay and cognitive issues related to language and social interactions. On the basis of imaging findings and clinical correlation, we opted for a microsurgical fenestration with endoscopic inspection using a keyhole craniotomy to minimize complications and enhance the benefits of both techniques. Throughout the surgical video, tricks and considerations that contribute to the combined procedure's efficiency and ease of execution are highlighted and discussed. Postoperative images showed no complications, and the patient was discharged 3 days after surgery.

Dorsum Sellae as Key Landmark in ETV With Disminished Prepontine Cistern: Technical Note and Case Series.

BACKGROUND AND OBJECTIVES: One of the key aspects in the surgical technique of endoscopic third ventriculostomy (ETV) is the perforation of the floor of the third ventricle because of the high risk of injuring vital structures located in that region. According to the standard technique, this perforation should be performed in the midline halfway between mammillary bodies and the infundibular recess to avoid damage to the structures. This can be performed without excessive complications when the diameter of the prepontine cistern is wide. However, in situations where the diameter is reduced (defined in the literature as having a prepontine interval [PPI] ≤1 mm), the probability of complications increases exponentially.In this article, we propose using dorsum sellae as a key point to safely perform ETV in patients with a decreased PPI, guiding the trajectory and its marking using neuronavigation. METHODS: A review was conducted on the latest 100 ETV procedures performed by our team in the past 5 years. The measurement of the PPI was conducted using archived preoperative MRI imaging studies, specifically between the dorsum sellae and the basilar artery. In cases where the PPI was ≤1 mm and, therefore, the use of the dorsum sellae was applied as a reference point, the technical results and procedural functions were documented. RESULTS: In the cohort, 7 patients with a PPI ≤1 mm were identified. In all 7 cases, fenestration of the tuber cinereum was successfully performed without causing vascular damage or associated complications. ETV was successful in 6 patients, with only one experiencing ETV failure necessitating the placement of a ventriculoperitoneal shunt. CONCLUSION: The utilization of the dorsum sellae as a reference point to perform ETV in reduced PPI constitutes a safe alternative to the classical technique.

Endoscopic extended transforaminal approach (medial subchoroid) as an alternative to the classical transchoroidal approach: Technical note.

The extended transforaminal endoscopic approaches allows visualization and manipulation of the middle and posterior third of the III ventricle. In selected cases where the venous anatomy is favorable, the medial subchoroidal approach can be performed as an alternative to the classic transchoroidal approach (via trans-taenia fornicis) with increased protection over the fornix and without the need to sacrifice the septal vein. We present a 14-year-old male with history of Neurofibromatosis type 1 referred for two weeks of clinical evolution with headache, dizziness, gait instability and appearance of a right VI nerve palsy. Magnetic resonance imaging showed obstructive tri-ventricular hydrocephalus due to stenosis of the aqueduct of Sylvius with suspicion of an underlying tumor. An endoscopic surgical procedure was performed through a single approach with III cisternostomy and resection of the tissue that produced the stenosis. The anatomopathological diagnosis showed reactive glial tissue with no signs of malignancy. In conclusion, the medial subchoroidal approach is a plausible alternative in the endoscopic approach to the III ventricle structures in a safe and comfortable manner.

Neuronavigated foraminoplasty, shunt removal, and endoscopic third ventriculostomy in a 54-year-old patient with third shunt malfunction episode: how I do it.

BACKGROUND: The application of endoscopic third ventriculostomy (ETV) for the treatment of obstructive hydrocephalus in shunt malfunction represents a paradigm shift, as it allows hydrocephalus to be transformed from a chronic condition treated with an artificial device to a curable disease. METHODS: We present a 54-year-old male with a diagnosis of idiopathic Sylvian aqueduct stenosis treated with shunt. The patient presented to our institution with symptoms of shunt malfunction and an increase in ventricular size on imaging, which was his third episode throughout his life. Through a right precoronal approach, with prior informed consent from the patient, we performed foraminoplasty, endoscopic third ventriculostomy, and finally removal of the shunt system. CONCLUSION: ETV shows promise as a viable treatment option for shunt malfunction in noncommunicating obstructive hydrocephalic patients. Its potential to avoid VPS-related complications, preserve physiological CSF circulation, and provide an alternative drainage pathway warrants further investigation.

Neuronavigated endoscopic aqueductoplasty with panventricular stent plus septostomy for isolated fourth ventricle in complex hydrocephalus and syringomyelia associated with myelomeningocele: how I do it.

BACKGROUND: Isolated fourth ventricle (IFV) is a challenging entity to manage. In recent years, endoscopic treatment for aqueductoplasty has been on the rise. However, in patients with complex hydrocephalus and distorted ventricular system, its implementation can be complex. METHODS: We present a 3-year-old patient with myelomeningocele and postnatal hydrocephalus treated by ventriculoperitoneal shunt. In follow-up, a progressive IFV and isolated lateral ventricle with symptoms of the posterior fossa developed. An endoscopic aqueductoplasty (EA) with panventricular stent plus septostomy guided with neuronavigation was decided due to the complexity of the ventricular system. CONCLUSION: In IFV associated with complex hydrocephalus with distortion of the ventricular system, navigation can be of great help for planning and as a guide for performing EA.

ETV as treatment for obstructive hydrocephalus in an aneurysmal malformation of the vein of Galen in infants: case report and review of literature.

INTRODUCTION: A vein of Galen aneurysmal malformation (VGAM) is a high-flow arteriovenous malformation that typically presents in early childhood. Complications associated with this condition include heart failure and hydrodynamic disorders resulting from high blood flow. Hydrocephalus is one of the hydrodynamic disorders. It can present in a chronic form due to a defect in the absorption of cerebrospinal fluid (CSF) resulting from venous hypertension or in an acute/subacute form due to obstruction of normal circulation routes caused by the mass effect of the VGAM. Currently, endovascular closure of the lesion is considered the treatment of choice. However, in acute/subacute presentations of obstructive hydrocephalus, progression may occur despite endovascular treatment, necessitating a cerebrospinal fluid diversion procedure. Prior to the advent of endoscopic treatment, ventricular shunts were utilized, but outcomes were poor due to the pathological hydrodynamic parameters associated with the malformation. The role of endoscopic third ventriculostomy as a treatment option in these situations remains unclear, and there is limited literature available. Therefore, we present the case of a patient with a vein of Galen aneurysmal malformation and obstructive hydrocephalus, which was treated via ETV. Furthermore, a literature review was conducted. CASE DESCRIPTION: We present a 5-month-old infant who was diagnosed at birth with VGAM. At 2 months of age, a partial closure of the malformation was performed via endovascular. Subsequently, the patient presented at the emergency department with symptoms of irritability, lethargy, vomiting, feeding refusal, and "setting sun" sign of several days' duration due to obstructive hydrocephalus. The patient was successfully treated via ETV. Following this, a new arteriography was performed and revealed occlusion of the VGAM. The child clinically improved and currently exhibits mild psychomotor impairment after 1-year follow-up. CONCLUSION: In the literature, there are a limited number of reports on the treatment of obstructive hydrocephalus associated with VGAM via ETV. These reports have demonstrated good outcomes with minimal surgical complications. Our patient also exhibited good results. As such, ETV is a viable and safe option for the treatment of obstructive hydrocephalus associated with VGAM in pediatric patients. However, more research is needed to establish the effectiveness of ETV in comparison to other treatment options and to understand the long-term outcomes.

Intraoperative ultrasound-assisted surgery in orbital apex tumours: technical note.

BACKGROUND: Since the introduction of ultrasonography (US) in the operating theatre in the early 1970s, intraoperative ultrasound (IOUS) has become a very useful tool for real-time neurosurgical procedures. The main limitation of US is its innately reduced capacity to penetrate the intact skull. This is the reason why most IOUS-assisted procedures are usually performed via transfontanellar or after a craniotomy or laminotomy is done. OBJECTIVE: We present a 54-year-old woman with a right optic nerve sheath meningioma, who was operated on by a right cranio-orbital approach and IOUS-assisted tumour removal. METHODS: Data concerning the anamnesis and complementary studies were obtained from the clinical history. Surgical images were obtained in the operating room during surgery. Images obtained by US were compared with the preoperative and postoperative imaging scans. IOUS imaging was also compared with the intraoperative findings. RESULTS: The correlation between US and both preoperative and postoperative studies was very high. During surgery, both transpalpebral and transperiorbital IOUS facilitated the resection with no specific technical difficulties or significant time consumption. CONCLUSION: Recent improvements in the image quality of IOUS devices offer several attractive options for real-time neuronavigation. We describe our initial experience with the IOUS-assisted technique for orbital apex tumours. In our patient transpalpebral and transperiorbital IOUS provided an excellent source of control over location and over the extent of tumour resection. We hope that this description of how we usually perform this procedure may be useful for some selected cases and contribute to the further enhancement and improvement of the technique.

Microsurgical training: vascular control and intraoperative vessel rupture in the human placenta infusion model.

BACKGROUND: Microsurgery is a challenging discipline. Regular lab training under the operating microscope has been the environment where most surgeons have mastered the skills and techniques inherent to most microneurosurgical procedures. However, some critical scenarios remain difficult to master or simulate. We describe a step-by-step method for how to build a low-cost, feasible, and widely available model that allows residents to familiarize themselves with demanding critical situations such as intraoperative rupture of major vessels. METHODS: After delivery, nine fresh human placentas were transferred to the lab. The umbilical vein was cannulated for normal saline infusion. Several hands-on procedures were performed under direct microscope vision. Operating microscope setup, allantoic membrane splitting, vascular dissection and vessel injury, and repair exercises were simulated and video recorded. Indocyanine green was administered to simulate intraoperative angiography. RESULTS: The model can be setup in less than 15 min, with minimal cost and infrastructure requirements. All the exercises described above can be conducted with a single placenta. Umbilical vein cannulation adds realism and allows quantification of the volume of saline required to complete the exercise. The final check with indocyanine green simulates intraoperative angiography and allows the assessment of distal vessel patency. CONCLUSIONS: Minimal infrastructure requirements, simplicity, and easy setup models provide a suitable environment for regular training. The human placenta is inexpensive and widely available, making it a feasible model for residents training. Neurosurgery residents may benefit from this model to familiarize with microsurgery and critical scenarios in a risk-free environment without time or resource constraints.

Neuroendoscopic training in neurosurgery: a simple and feasible model for neurosurgical education.

BACKGROUND: The development of high levels of technical competence and excellent decision-making skills are key goals of all neurosurgical residency training programs. This acquisition of technical skills is becoming increasingly difficult due to many factors including less exposure to operative cases, demand for more time and cost-effective practices, and resident work hour restrictions. We describe a step-by-step method for how to build a low-cost and feasible model that allows residents to improve their neuroendoscopic skills. METHODS: The bell pepper-based model was developed as an endoscopic training model. Using continuous irrigation, several hands-on procedures were proposed under direct endoscopic visualization. Endoscope setup, endoscopic third ventriculostomy, septostomy, and tumor biopsy procedures were simulated and video recorded for further edition and analysis. RESULTS: The model can be setup in less than 15 min with minimal cost and infrastructure requirements. A single model allows simulation of all the exercises described above. The model allows exposure to the camera skills, instrument handling, and hand-eye coordination inherent to most neuroendoscopic procedures. CONCLUSION: Minimal infrastructure requirements, simplicity, and easily setup models provide a proper environment for regular training. The bell pepper-based model is inexpensive, widely available, and a feasible model for routine training. Neurosurgery residents may benefit from the use of this model to accelerate their learning curve and familiarize themselves with the neuroendoscopic core principles in a risk-free environment without time or resource constraints.