Neuroendoscopic cysto-cisternostomy for middle cranial fossa arachnoid cysts: a systematic review of the practice principles from 169 cases.

INTRODUCTION: Arachnoid cysts are primarily dysembryogenetic splitting or duplication of the embryonic meningeal mesenchyme, hence the paediatric preponderance. Neuroendoscopic cysto-cisternostomy is now the favoured treatment option. We pooled data on middle fossa arachnoid cysts (MCFAC) demographics, clinical presentations, cyst characteristics, neuro-endoscopic cysto-cisternostomy and its outcomes. EVIDENCE ACQUISITION: Using search words (from the keywords; 'endoscopic treatment' and 'middle fossa arachnoid cysts') combined using Boolean operators, a systematic review of the PubMed and Cochrane CENTRAL was started on 1st February 2023, as per protocol (PROSPERO CRD42023394345); 65 records and then 46 reports were screened, 169 cases were pooled from the 19 recruited reports for the qualitative and quantitative syntheses, after methodological assessment (significantly excellent 57.9% quality) using the Joanna Briggs Institute critical appraisal tools. EVIDENCE SYNTHESIS: The male-to-female ratio was 2.4:1, with a weighted average-age of 11.25 years in the modal childhood (32.0%) age-group. Headaches (53/29.3%), seizures (30/16.6%) and macrocephaly (25/13.8%) were the commonest presentations. Right-sided (30/55.6%) and Galassi II (55/48.3%) and III (53/46.5%) lesions were common. Rigid (124/93.9%) endoscopes aided cysto-cisternostomy using mostly bipolar diathermy (31/43.7%) and ventriculostomy forceps (18/25.4%); creating one (22/18.3%), two (14/11.6%) or more (78/65.0%) stomas. Fenestration sites were specifically CNIII&ICA (32/25.8%), CNII&ICA (27/21.8%), CNIII&tentorium cerebelli (23/18.6%), CNIII&PCA (1/0.8%) and through the side of CNVI (1/0.8%) into the pre-pontine cistern. Good clinical and radiological outcomes were reported. CONCLUSIONS: Largely excellent-to-good quality, low-level evidence reported MCFACs presenting in childhood with headaches, seizures and macrocephaly. At least two fenestrations using bipolar-diathermy/forceps and balloon-catheter expansion were used for cysto-cisternostomy, with good outcomes.

Fully Endoscopic Nontubular Retractor Approach for Intraaxial Tumors.

BACKGROUND: Fully endoscopic or endoscope-controlled approaches are essentially keyhole approaches in which rigid endoscopes are the sole visualization tools used during the whole procedure. At the early attempts of endoscope-assisted cranial surgery, it was noted that rigid endoscopes enabled overcoming the problem of suboptimal visualization when small exposures are used. The technical specifications and design of the currently available rigid endoscopes are associated with a group of unique features that define the endoscopic view and lay the basis for its superiority over the microscopic view during brain surgery. Fully endoscopic resection of intraparenchymal brain tumors is a minimally invasive approach that is not routinely practiced by neurosurgeons, with a few major series published so far. Unfamiliarity with the technique, steep learning curve, and concerns about inadequate exposure and decreased visibility may explain this fact. The majority of the purely endoscopic resections for intraparenchymal brain lesions are performed nowadays through tubular retractor systems. In very limited instances, however, the fully endoscopic technique is performed without tubular retractors. In this chapter, we elaborate on the surgical technique and nuances of the fully endoscopic nontubular retractor approach for intraaxial tumors. METHODS: From a prospective database of endoscopic procedures maintained by the senior author, clinical data, imaging studies, and operative charts and videos of cases undergoing fully endoscopic excision for intraaxial brain tumors were retrieved and analyzed. The pertinent literature was also reviewed. RESULTS: The surgical technique of the fully endoscopic nontubular retractor approach for intraaxial tumors was formulated. CONCLUSION: The endoscopic technique has many advantages over the conventional procedures. In our hands, the technique has proven to be feasible, efficient, and minimally invasive with excellent results.

Endoscopic Supraorbital Translaminar Approach.

Surgical selection for third ventricle tumors demands meticulous planning, given the complex anatomic milieu. Traditional open microsurgical approaches may be limited in their access to certain tumors, prompting the exploration of alternative techniques. The endoscopic supraorbital translaminar approach (ESOTLA) has emerged as a promising alternative for managing these tumors. By combining a minimally invasive keyhole approach with endoscopic visualization, the ESOTLA provides enhanced illumination and a wider angle of view within the third ventricle. This unique advantage allows for improved access to retrochiasmatic tumors and reduces the need for frontal lobe and optic chiasm retraction required of microscopic techniques, decreasing the risk of neurocognitive and visual deficits. Complications related to the ESOTLA are rare and primarily pertain to cosmetic issues and potential compromise of the hypothalamus or optic apparatus, which can be minimized through careful subarachnoid dissection. This chapter offers a comprehensive description of the technical aspects of the ESOTLA, providing insights into its application, advantages, and potential limitations. Additionally, a case description highlights the successful surgical extirpation of an intraventricular papillary craniopharyngioma via the ESOTLA followed by targeted therapy. To better illustrate the stepwise dissection through this novel approach, a series of cadaveric and intraoperative photographs are included.

Endoport-Guided Endoscopic Excision of Intraaxial Brain Tumors.

OBJECTIVE: Transcortical approaches using a spatula-based retraction system have traditionally been used for the microsurgical resection of deep-seated intraventricular and parenchymal brain tumors. Recently, transparent cylindrical or tubular retractors have been developed to provide a stable corridor to access deeper brain lesions and perform bimanual microsurgical resection. The flexible endoports minimize brain retraction injury during surgery and, along with the superior vision of endoscopes, offer several advantages over standard microsurgery. In this chapter, we describe the surgical technique of the endoport-guided endoscopic excision of deep-seated intraaxial brain tumors. METHODS: The endoscopic endoport technique that we use at our institution for the surgical management of intraventricular and intraparenchymal brain tumors has been described in detail with illustrative cases. RESULTS: Results from the literature review of intraventricular and intraparenchymal port surgery were analyzed, and the feasibility and safety of this technique were discussed. Surgical complication avoidance and management were highlighted. The port technique offers numerous potential advantages, including (1) reducing focal brain injury by distributing retraction forces homogenously, (2) minimizing white matter disruption and the risk of fascicle injury during cannulation, (3) ensuring the stability of the surgical corridor during the procedure, (4) preventing inadvertent expansion of the corticectomy and white fiber tract dissection throughout surgery, and (5) protecting the surrounding tissues against iatrogenic injuries caused by instrument entry and reentry. CONCLUSION: The endoport-assisted endoscopic technique is safe and offers an effective alternative option for the resection of intraventricular and intraparenchymal lesions.

Fully Endoscopic Retrosigmoid Approach for Cerebellopontine Angle Tumors.

BACKGROUND: Fully endoscopic or endoscope-controlled approaches are essentially keyhole approaches in which rigid endoscopes are the sole visualization tools used during the whole procedure. At the early attempts of endoscope-assisted cranial surgery, it was noted that rigid endoscopes enabled overcoming the problem of suboptimal visualization when small exposures are used. The technical specifications and design of the currently available rigid endoscopes are associated with a group of unique features that define the endoscopic view and lay the basis for its superiority over the microscopic view during brain surgery. Fully endoscopic retrosigmoid approach for cerebellopontine angle tumors is a minimally invasive approach that is not routinely practiced by neurosurgeons, with few series published so far. Unfamiliarity with the technique, steep learning curve, and concerns about inadequate exposure, neurovascular injury, and decreased visibility may explain this fact. In this chapter we elaborate on the surgical technique and nuances of the fully endoscopic retrosigmoid approach and present an overview of the published series. METHODS: From a prospective database of endoscopic procedures maintained by the senior author, clinical data, imaging studies, operative charts, and videos of cases undergoing fully endoscopic retrosigmoid approach for cerebellopontine angle tumors were retrieved and analyzed. The pertinent literature was also reviewed. RESULTS: The surgical technique of the fully endoscopic retrosigmoid approach was formulated. CONCLUSION: The endoscopic technique has many advantages over the conventional procedures. In our hands, the technique has proven to be feasible, efficient, and minimally invasive with excellent results.

Purely Endoscopic Supracerebellar Infratentorial Approach to the Pineal Region in Pediatric Population.

Pineal lesions represent less than 1% of all brain tumors (Villani et al., Clin Neurol Neurosurg 109:1-6, 2007). The abysmal location and critical neurovascular structures remain a surgical challenge, despite the advent of microneurosurgery. The classical wide surgical suboccipital craniotomy with the supracerebellar infratentorial approach, described by Sir Victor Horsley (Victor, Proc R Soc Med 3:77-78, 1910), is infamous for its considerable surgical morbidity and mortality. This was later upgraded microneurosurgically by Stein to improve surgical outcomes (Stein, J Neurosurg 35:197-202, 1971).Ruge et al. reported the first purely endoscopic fenestration of quadrigeminal arachnoid cysts via this corridor (Ruge et al., Neurosurgery 38:830-7, 1996). A cadaver-based anatomical study by Cardia et al. demonstrated the viability for endoscope-assisted techniques (Cardia et al., J Neurosurg 2006;104(6 Suppl):409-14). However, the first purely endoscopic supracerebellar infratentorial (eSCIT) approach to a pineal cyst was performed in 2008 by Gore et al. (Gore PA et al., Neurosurgery 62:108-9, 2008).Unlike transventricular endoscopy, eSCIT approach poses no mechanical risk to the fornices and can be utilized irrespective of ventricular size. More vascular control and resultant reduction in uncontrolled hemorrhage improve the feasibility of attaining complete resection, especially around corners (Zaidi et al,, World Neurosurg 84, 2015). Gravity-dependent positioning and cerebrospinal fluid (CSF) diversion aid cerebellar relaxation, creating the ideal anatomical pathway. Also, angle of the straight sinus, tentorium, and tectal adherence can often influence the choice of approach; thus direct endoscopic visualization not only counteracts access to the engorged Galenic complex but also encourages sharp dissection of the arachnoid (Cardia et al., J Neurosurg 104:409-14, 2006). These tactics help provide excellent illumination with magnification, making it less fatiguing for the surgeon (Broggi et al., Neurosurgery 67:159-65, 2010).The purely endoscopic approach thwarts the dreaded risk of air embolisms, via simple copious irrigation from a small burr hole (Shahinian and Ra, J Neurol Surg B Skull Base 74:114-7, 2013). The tiny opening and closure are rapid to create, and the smaller wound decreases postoperative pain and morbidity. Recent literature supports its numerous advantages and favorable outcomes, making it a tough contender to traditional open methods.

Fully Endoscopic Resection of Frontal Osteomas.

BACKGROUND: Osteomas are the most common primary bone tumors of the calvaria, with an incidence of less than 0.5%. In skull vault osteomas, the exostotic form that grows from the outer table is more common than the enostotic ones which arise from the inner table and grow intracranially. Osteomas of the forehead are very noticeable and disfiguring; patients usually seek medical advice for cosmetic reasons. Forehead osteomas were traditionally excised via either a direct incision over the lesion using the naturally occurring creases or a conventional bicoronal flap. More recently, endoscopic approaches for excision of forehead osteomas were introduced. The results were very encouraging and the technique was adopted by many groups worldwide yet with many technical variations. In this chapter we elaborate on the surgical technique and nuances of the fully endoscopic resection of frontal osteomas. METHODS: From a prospective database of endoscopic procedures maintained by the senior author, clinical data, imaging studies, operative charts, and videos of cases of forehead osteomas were retrieved and analyzed. The pertinent literature was also reviewed. RESULTS: The surgical technique of the fully endoscopic resection of frontal osteomas was formulated. CONCLUSION: The endoscopic technique has many advantages over the conventional procedures. In our hands, the technique has proven to be less time-consuming, efficient, and minimally invasive with excellent cosmetic results.

How I do it: Endoscopic endonasal resection of the medial wall of the cavernous sinus.

BACKGROUND: Resection of the medial wall of the cavernous sinus (MWCSR) is a growing surgical maneuver for the radical removal of pituitary adenomas. METHOD: We present a simple modification of the technique following the two dural layers of the floor of the sella turcica, allowing for early identification of the medial wall and simplifying dissection. We support this technique with an anatomical analysis on cadaveric specimens and clarifying dissection images. CONCLUSION: Recognition and dissection of the dural unfolding of the floor of the sella turcica are "key points" that lower the risk and facilitate the MWCSR.

Fluorophores in Endoscopic Neurosurgery.

The complexity of intracranial anatomy and pathologies warrants the optimization of multimodal techniques to ensure safe and effective surgical treatment. Endoscopy is being more widely implemented in intracranial procedures as an important visualization tool, as it can offer panoramic views of deep structures while reducing the invasiveness of approaches. Fluorophores are frequently utilized to augment the identification of intracranial anatomic landmarks and pathologies. This chapter discusses the integration of these two surgical adjuncts, highlighting the key fluorophores used in endoscopic neurosurgery and their clinical applications.

Endoscopic Anatomy of the Skull Base.

Presently, endoscopic skull base surgery has undergone significant advancements since its inception over two decades ago. Nevertheless, it is imperative to underscore that the fundamental basis of all surgical procedures lies in the meticulous understanding of anatomy, with particular emphasis on the ventral anatomy. This facet has recently garnered increased attention.Following the advancements in endoscopic skull base surgery techniques, this chapter will concentrate on the pertinent anatomical considerations that serve as key foundations for successful procedures. These considerations are categorized into two planes: the sagittal plane and the coronal plane.The sagittal plane is further subdivided into five distinct approaches, namely,(1) the transcribriform approach, (2) the transplanum approach, (3) the transsellar approach, (4) the transclival approach, and (5) the transodontoid approach.On the other hand, the coronal plane is delineated into seven specific zones to facilitate comprehension and potential applications: (1) the petrous apex approach, (2) the intrapetrous approach, (3) the suprapetrous approach, (4) the cavernous sinus approach, (5) the infratemporal approach, (6) the medial condyle approach, and (7) the jugular foramen approach.By organizing the anatomical aspects in this systematic manner, the information provided becomes more accessible, fostering a comprehensive understanding of the subject matter for potential future application.

Brain Tumor Anatomy with Tractography Fluorescence and Confocal Endoscopy.

Tractography fluorescence and confocal endomicroscopy are complementary technologies to targeted tumor resection, and it is certain that as our technology for fluorescent probes continues to evolve, the confocal microscope will continue to be refined. Recent work suggests that intraoperative high-resolution augmented reality endomicroscopy, a real-time alternative to invasive biopsy and histopathology, has the potential to better quantify tumor burden at the final stages of surgery and ultimately to improve patient outcomes when combined with wide-field imaging approaches. Additional studies are needed to further elucidate the clinical benefits of these new technologies for brain tumor patients.

Endoscopic Cylinder Surgery for Ventricular Lesions.

Cylinder retractors have been developed to reduce the risk of brain retraction injury during surgery by dispersing retraction pressure on the brain. In recent years, various types of cylinder retractors have been developed and widely used in neurosurgery. The ventricles, being deep structures within the brain, present an effective area for cylinder retractor utilization. Endoscopy provides a bright, wide field of view in the deep surgical field, even through narrow corridors.This chapter introduces surgical techniques using an endoscope through a cylinder. Given the deep and complex shapes of the ventricles, preoperative planning is paramount. Two main surgical techniques are employed in endoscopic cylinder surgery. The wet-field technique involves the continuous irrigation of artificial cerebrospinal fluid (CSF) during the procedure, maintaining ventricle shape with natural water pressure, facilitating tumor border identification, and achieving spontaneous hemostasis. Conversely, the dry-field technique involves CSF drainage, providing a clear visual field even during hemorrhage encounters. In intraventricular surgery, both techniques are used and switched as needed.Specific approaches for lateral, third, and fourth ventricular tumors are discussed, considering their locations and surrounding anatomical structures. Detailed intraoperative findings and strategies for tumor removal and hemostasis are presented.Endoscopic cylinder surgery offers a versatile and minimally invasive option for intraventricular tumors, leading to improved surgical outcomes. Overall, this technique enhances surgical precision and patient outcomes in intraventricular tumor cases.

Endoscopic Eyebrow Approach for Aneurysms.

INTRODUCTION: Considerable effort has been made to reduce surgical invasiveness, since Axel Perneczky introduced the supraorbital eyebrow approach as a core part of his keyhole concept in neurosurgery. But a limited approach does not facilitate an already serious and demanding task as aneurysm surgery. In this regard, the enhancement of the visual field before, during, and after microsurgical aneurysm occlusion is a safe and effective method to increase the quality of treatment. Indications/Contraindications: Based on the individual anatomical findings, the supraorbital keyhole approach provides access to most aneurysms of the anterior circulation. The approach is not recommended in large complex aneurysms, giant aneurysms, BA aneurysms located beneath the dorsum sellae, as well as cases of severe subarachnoid hemorrhage (SAH) and expected brain edema. COMPLICATIONS: Experience with endoscopic procedures in aneurysm surgery is limited to several clinical retrospective articles, and no major complications in conjunction with the endoscope were observed. Outcome and Prognosis: The supraorbital eyebrow approach has a low rate of complications and provides highly favorable cosmetic results. Endoscopic inspection prior to clipping might reduce overexposure and mobilization of the aneurysm. It was found that the rate of intraoperative rupture was decreased. The endoscopic post-clipping control helped significantly to reduce aneurysm remnants and unattended parent, branch, or perforator occlusion. CONCLUSION: The supraorbital eyebrow approach is a safe, effective and elegant approach in the treatment of most aneurysms of the anterior circulation. The additional enhancement of the visual field provided by the endoscope before, during, and after microsurgical aneurysm clipping might decrease the rate of intraoperative aneurysm ruptures and unexpected findings concerning aneurysm remnant occlusion and compromise of involved parent, branching, and perforating vessels.

Purely Endoscopic Treatment for Arachnoid Cysts.

Arachnoid cysts are benign, mostly congenital lesions that are asymptomatic in most patients. In some cases, due to their location or sheer size, they produce a mass effect or hydrocephalic obstruction of the cerebrospinal fluid (CSF) flow and thus might warrant surgical treatment. The goal of the surgery is usually to reduce pressure inside the cysts, to reduce the mass effect, or to restore the CSF pathway. Surgical treatment options are resection, fenestration, or shunting of the cyst. Over the past decades, treatment under sheer endoscopic control either through a tube or via craniotomy of arachnoid cysts has been studied thoroughly and replaced open microsurgical cyst surgery in the opinion of many neurosurgeons. Endoscopic treatment has proven to be a safe and feasible technique for both patients and surgeons. In the following chapter, the authors describe their indications for surgery and pre- and postoperative workup, where precautions should be taken, and discuss the different possibilities and techniques of endoscopic cyst fenestration. The aim is to give detailed instructions and present cases for ventriculocystostomy, cystocisternostomy, ventriculocystocisternostomy, and cystoventriculostomy and point out specifics deemed to be important to avoid complications and to ensure the best possible outcome for each patient.

Purely Endoscopic Evacuation of Intracranial Hematomas.

Cerebral hemorrhage is a frequent disease and one of the main causes of disabilities. Even in the case of cerebral hemorrhage, if there were a treatment that would improve the functional prognosis, the benefits would be immeasurable. Although there are limited reports with a high level of evidence in past studies, it has been found that surgery can be effective if a large amount of hematoma can be removed in a minimally invasive manner. Also, it has become clear that the control of bleeding becomes a problem when surgery is performed within 2 days after the onset of stroke and that the therapeutic time window might be longer. In Japan, since the introduction of the transparent sheath by Nishihara et al., endoscopic hematoma removal has been widely performed and has become the standard surgical procedure. The three basic equipment needed for this surgery are a rigid scope, a suction coagulator, and a transparent sheath. The key point of the surgery is to search for hematomas and bleeding points through a transparent sheath and coagulate the bleeding vessels. In this chapter, we will introduce surgical techniques using these devices, but it is important to carefully decide on surgical options by considering your own technique, the condition of each patient, and the devices available in the area.

Full Endoscopic Transcranial Resection of Meningiomas.

OBJECTIVE: Tumors of the skull base can be accessed through different routes. Recent advantages in minimally invasive techniques have shown that very different routes can be applied for optimal tumor resection depending on the technical equipment, the surgeon's preference, and the individual anatomy of the pathology. Here, the authors present their technique for pure endoscopic transcranial tumor resection in meningiomas. METHODS: Out of the cases of the Department of Neurosurgery, Homburg Saar Germany of the last 10 years, all endoscopic procedures for meningiomas were analyzed. Particular attention was given to evaluating the peculiarities of those meningiomas that were treated purely endoscopically. RESULTS: While the endoscope was used in a large number of skull base meningiomas in endonasal approaches or for endoscopic inspection in transcranial skull base surgery, only a small number of meningiomas was selected for a purely endoscopically performed resection. The characteristics of these cases were rather a small lesion, straight access, and a keyhole position of the craniotomy. A complete resection of the tumor was achieved in all cases. Conversion to the microscope was not necessary in any case. There were no technical issues or complications associated with a fully endoscopic resection. DISCUSSION: The endoscope is a valuable tool for visualization in meningioma surgery. In most cases, it is applied for an endonasal route or for endoscopic inspection in transcranial microsurgical cases. However, small to medium-sized meningiomas that can be accessed through the keyhole approach are good candidates for pure endoscopic resection. Because of the very high magnification and the minimally invasive nature of this approach, it should be considered more frequently in suitable lesions.

Fully Endoscopic Supraorbital Approach for Anterior Cranial Base Meningiomas.

BACKGROUND: Anterior cranial base meningiomas include those meningiomas originating from the tuberculum sellae, the planum sphenoidale, or the olfactory groove, with surgical excision being the main treatment modality for these tumors. Conventional microscopic and endoscope-assisted versions of the supraorbital keyhole approach via an eyebrow incision emerged into minimally invasive options that are frequently utilized nowadays for treating these tumors. At the early attempts of endoscope-assisted cranial surgery, it was noted that rigid endoscopes enabled overcoming the problem of suboptimal visualization when small exposures are used. The technical specifications and design of the currently available rigid endoscopes are associated with a group of unique features that define the endoscopic view and lay the basis for its superiority over the microscopic view during brain surgery. Notwithstanding, the fully endoscopic or endoscope-controlled version of the supraorbital keyhole approach is not routinely practiced by neurosurgeons, with few series published so far. In this chapter we elaborate on the surgical technique and nuances of the fully endoscopic supraorbital approach for anterior cranial base meningiomas. METHODS: From a prospective database of endoscopic procedures maintained by the senior author, clinical data, imaging studies, operative charts, and videos of cases undergoing fully endoscopic excision of anterior cranial base meningiomas via supraorbital approach were retrieved and analyzed. The pertinent literature was also reviewed. RESULTS: The surgical technique of the fully endoscopic supraorbital approach for anterior cranial base meningiomas was formulated. CONCLUSION: The fully endoscopic supraorbital approach for anterior cranial base meningiomas has many advantages over the conventional procedures. In our hands, the technique has proven to be feasible, efficient, and minimally invasive with excellent results.