Endoscopic endonasal skull base surgery: advantages, limitations, and our techniques to overcome cerebrospinal fluid leakage: technical note

Anatomical basis of endoscopic endonasal internal carotid artery transposition technique-freeing the limiting structures

To investigate the relevant surgical anatomy of the endonasal endoscopic ICA transposition technique (EEITT). Six cadaveric heads were prepared for dissection. The trabeculae fibers in the cavernous sinus(CS), branches of cavernous segment ICA (csICA), dura rings and the bony structures around the ICA were meticulously dissected and photographed. The limiting structures around ICA consist of: the bony, dura structures and the tethering structures inside CS. The tethering structures in the CS could be summarized into four groups. The medial group includes the carotid clinoidal ligament (100%), the inferior hypophyseal artery (100%), the inferior parasellar ligament (91.7%) and the superior parasellar ligament (50%) The lateral group comprises the inferolateral trunk (100%), the sympathetic nerve plexus (100%), and the trabeculae fibers between internal carotid artery (ICA) and cranial nerves (CN)3 (50%), CN4 (41.7%), and CN6 (100%). The anterior group is defined by trabeculae fibers between the proximal dural ring and the anterior genu or the anterior ascending segment of the ICA (66.7%). The posterior group consists of the meningohypophyseal trunk (100%) and the trabeculae fibers (50%) between the posterior genu of the ICA and the posterior wall of the cavernous sinus. The EEITT was graded according to the detaching extent of the limiting structures: Grade 1 (disconnecting the tethering structures inside CS), Grade 2 (Grade 1 with the addition of dura ring opening), and Grade 3 (Grade 2 plus anterior clinoidectomy). The tethering structures around csICA could be classified into four groups: medial, lateral, anterior, and posterior. EEITT could be categorized into three grades according to the detaching extent of the limiting structures. This technique enlarges the working zone and increases the surgical freedom for complex lesions with parasellar extensions in endoscopic endonasl approaches.

Endoscopic Endonasal Approach Is Superior to Transcranial Approach for Small to Medium Tuberculum Sellae Meningiomas in Terms of Visual Outcome and Complications: A Retrospective Study in a Single Center

OBJECTIVE

This study compared the effectiveness of the endoscopic endonasal approach (EEA) with the conventional transcranial approach (TCA) for treating tuberculum sellae meningiomas (TSMs), aiming to identify the superior surgical method and the risk factors affecting outcomes.

METHODS

Patients treated for TSM from 1998 to 2023 at our institution were retrospectively analyzed, evaluating patient characteristics, tumor features, outcomes, and complications. A novel grading system for preoperative evaluation of TSMs was proposed.

RESULTS

Among 49 patients, 26 underwent EEA and 23 underwent TCA. The maximum diameters were comparable between the groups (mean 22 mm vs. 23 mm). Gross total resection rates were 62% for EEA and 70% for TCA, showing no significant difference. However, postsurgical visual improvement was significantly higher in the EEA group compared with the TCA group (77% vs. 44%; P = 0.020), with fewer complications in the EEA group (8% vs. 35%; P = 0.032).

CONCLUSIONS

EEA is a safe and effective treatment approach for small to medium TSMs, with outcomes comparable to TCA in terms of resection but superior in visual improvement and fewer complications. Selection of surgical approach should consider patient and tumor characteristics as well as surgeon experience.

Endoscopic Endonasal Internal Carotid Artery Transposition Technique in Tumor With Parasellar Extension: A Single-Center Experience

BACKGROUND AND OBJECTIVES

Lateralization or mobilization of the internal carotid artery (ICA) during a midline approach is required to expose lesions behind or lateral to the ICA. However, there have been no published data regarding the surgical outcomes of the endoscopic endonasal internal carotid transposition technique (EEITT). This study aimed to analyze the relevant surgical anatomy around the ICA and propose a grading scheme of EEITT.

METHODS

A retrospective review of patients who underwent EEITT at a single institution was performed. Based on structures that limited the ICA and intraoperative findings, an anatomically surgical grading scheme of EEITT was proposed.

RESULTS

Forty-two patients (mean age 45.6 years, 57.1% female patients) were included. Of them, 29 cases (69.0%) were Knosp grade 4 pituitary adenoma, 6 cases (14.3%) were chordoma, 6 cases (14.3%) were meningioma, and a single case (2.4%) was meningeal IgG4-related disease. The EEITT was categorized into Grades 1, 2 and 3, which was used in 24 (57.1%), 12 (28.6%), and 6 (14.3%) cases, respectively. The most common symptom was visual disturbance (45.2%). The gross total resection rate in Grade 1 (79.2%) and Grade 2 (83.3%) was much higher than that in Grade 3 (66.6%). The overall rate of visual function improvement, preoperative cranial nerve (CN) palsy improvement, and postoperative hormonal remission was 89.4%, 85.7%, and 88.9%, respectively. The rate for the following morbidities was cerebrospinal fluid leakage, 2.4%; permanent diabetes insipidus, 4.8%; new transient CN palsy, 9.5%; permanent CN palsy, 4.7%; panhypopituitarism, 7.1%; and ICA injury, 2.4%.

CONCLUSION

The EEITT is technically feasible and could be graded according to the extent of disconnection of limiting structures. For complex tumor with parasellar extensions, the distinction into Grades 1, 2, and 3 will be of benefit to clinicians in predicting risks, avoiding complications, and generating tailored individualized surgical strategies.

Endoscopic Sellar Defect Reconstruction with Avascular Modified Gasket Seal Technique for Sellar Tumors

Watertight repair of the skull base defect is necessary during endonasal skull base surgery to avoid postoperative CSF leak (poCSFl) and consequent intracranial complications. Various techniques have been described for reconstructing sphenoid-sellar defects with varying success rates. We have described the immediate and long-term outcomes following the reconstruction of sphenoid-sellar defects with our technique. A retrospective analysis of the patients following transsphenoidal sellar surgery underwent barrier restoring reconstruction by multi-layered (inlay-overlay) with autologous thigh fat, fascia lata, fibrin glue, knitted collagen, and absorbable gelatin sponge (modified gasket seal technique). A total of 44 patients were included in the study (n = 44). Reconstruction with modified gasket seal technique was done for all patients. 26 (59.1%) had intraoperative CSF leak (ioCSFl), and 9 (20.4%) patients had grade 3 Esposito-Kelly ioCSFl requiring adjunct short-term pressure reducing procedure (Lumbar drain) intraoperatively. 11/44 (25%) had poCSFl, 7/11 patients with poCSFl were managed conservatively, and 4/11 patients required rescue second surgery and ventriculoperitoneal shunting. 1 (2.3%) had severe meningitis and succumbed to it. Pneumocephalus was seen in 6 (13.6%). Multivariate analysis showed that revision surgery, GH-secreting tumors, and defects extending to the suprasellar region had higher chances of poCSFl (p < 0.001). All 43 alive patients had no CSF leak on long-term follow-up. The modified gasket seal technique is a viable technique for endoscopic sellar reconstruction for ioCSFl with an immediate success rate of 79.6% and 97.72% in the long term in preventing the postoperative CSF leak with a 13.6% rate of meningitis.

Frontiers of Cranial Base Surgery: Integrating Technique, Technology, and Teamwork for the Future of Neurosurgery

The landscape of cranial base surgery has undergone monumental transformations over the past several decades. This article serves as a comprehensive survey, detailing both the historical and current techniques and technologies that have propelled this field into an era of unprecedented capabilities and sophistication. In the prologue, we traverse the historical evolution from rudimentary interventions to the state-of-the-art neurosurgical methodologies that define today's practice. Subsequent sections delve into the anatomical complexities of the anterior, middle, and posterior cranial fossa, shedding light on the intricacies that dictate surgical approaches. In a section dedicated to advanced techniques and modalities, we explore cutting-edge evolutions in minimally invasive procedures, pituitary surgery, and cranial base reconstruction. Here, we highlight the seamless integration of endocrinology, biomaterial science, and engineering into neurosurgical craftsmanship. The article emphasizes the paradigm shift towards "Functionally" Guided Surgery facilitated by intraoperative neuromonitoring. We explore its historical origins, current technologies, and its invaluable role in tailoring surgical interventions across diverse pathologies. Additionally, the digital era's contributions to cranial base surgery are examined. This includes breakthroughs in endoscopic technology, robotics, augmented reality, and the potential of machine learning and AI-assisted diagnostic and surgical planning. The discussion extends to radiosurgery and radiotherapy, focusing on the harmonization of precision and efficacy through advanced modalities such as Gamma Knife and CyberKnife. The article also evaluates newer protocols that optimize tumor control while preserving neural structures. In acknowledging the holistic nature of cranial base surgery, we advocate for an interdisciplinary approach. The ecosystem of this surgical field is presented as an amalgamation of various medical disciplines, including neurology, radiology, oncology, and rehabilitation, and is further enriched by insights from patient narratives and quality-of-life metrics. The epilogue contemplates future challenges and opportunities, pinpointing potential breakthroughs in stem cell research, regenerative medicine, and genomic tailoring. Ultimately, the article reaffirms the ethos of continuous learning, global collaboration, and patient-first principles, projecting an optimistic trajectory for the field of cranial base surgery in the coming decade.

Reconstruction and Cerebrospinal Fluid Leaks in Endoscopic Endonasal Approach for the Management of Clival Chordomas-A Systematic Review

The success of the endoscopic endonasal approach (EEA) to surgically manage clival chordomas (CC) relies on robust repair methods to reduce complications, such as cerebrospinal fluid (CSF) leaks. Our study aims to evaluate the existing literature to assess reconstructive techniques utilised and post-operative CSF leak rates in this cohort. A systematic review and analysis was performed of all published data related to CC patients managed with an EEA. A total of 24 articles were included, representing 363 patients and 396 procedures. A variety of reconstruction methods were used with 95.9% of studies using an intracranial repair graft, 70.8% using a nasoseptal flap (NSF), 62.5% using glue/haemostat, 58.3% using nasal packs and 75.0% employing multi-layered reconstruction. Post-operative CSF leak rate was 10.1%. The leak rate was less in subgroups where a NSF was used (9.4%) although this was not statistically significant (p = 0.273). There were no differences in leak rates when glue/haemostat (p = 0.139) or nasal packs (p = 0.550) were used. Our review is the most up-to-date synthesis of the existing literature surrounding the EEA to CCs assessing reconstruction and post-operative CSF leaks. It demonstrates most authors employ a multi-layered reconstruction method. The lack of statistical significance observed for CSF leaks in subgroups is likely due to a variety of cofounding surgeon and patient factors. Higher quality prospective randomised multi-centric studies, with reporting of specific repair techniques will enable future systematic reviews to provide a more accurate consensus regarding optimal methods of reconstruction in this field.

Skull base repair following endonasal pituitary and skull base tumour resection: a systematic review

PURPOSE

Postoperative cerebrospinal fluid rhinorrhoea (CSFR) remains a frequent complication of endonasal approaches to pituitary and skull base tumours. Watertight skull base reconstruction is important in preventing CSFR. We sought to systematically review the current literature of available skull base repair techniques.

METHODS

Pubmed and Embase databases were searched for studies (2000-2020) that (a) reported on the endonasal resection of pituitary and skull base tumours, (b) focussed on skull base repair techniques and/or postoperative CSFR risk factors, and (c) included CSFR data. Roles, advantages and disadvantages of each repair method were detailed. Random-effects meta-analyses were performed where possible.

RESULTS

193 studies were included. Repair methods were categorised based on function and anatomical level. There was absolute heterogeneity in repair methods used, with no independent studies sharing the same repair protocol. Techniques most commonly used for low CSFR risk cases were fat grafts, fascia lata grafts and synthetic grafts. For cases with higher CSFR risk, multilayer regimes were utilized with vascularized flaps, gasket sealing and lumbar drains. Lumbar drain use for high CSFR risk cases was supported by a randomised study (Oxford CEBM: Grade B recommendation), but otherwise there was limited high-level evidence. Pooled CSFR incidence by approach was 3.7% (CI 3-4.5%) for transsphenoidal, 9% (CI 7.2-11.3%) for expanded endonasal, and 5.3% (CI 3.4-7%) for studies describing both. Further meaningful meta-analyses of repair methods were not performed due to significant repair protocol heterogeneity.

CONCLUSIONS

Modern reconstructive protocols are heterogeneous and there is limited evidence to suggest the optimal repair technique after pituitary and skull base tumour resection. Further studies are needed to guide practice.

Heterogeneity in Outcome Reporting in Endoscopic Endonasal Skull Base Reconstruction: A Systematic Review

Objective  Presently, there are no standards for reporting outcomes of endoscopic endonasal skull base reconstruction (ESBR). This is problematic as a lack of consistent reporting makes synthesizing findings in systematic reviews and meta-analysis challenging. Thus, the aim of this study was to systematically review and describe the patterns of reporting outcomes in ESBR as a foundation for developing reporting guidelines. Study Design  Present study is a systematic review. Methods  Embase, PubMed, CINAHL, Cochrane Library, and Web of Science were searched for all publications with ≥25 patients and a focus on ESBR. The reporting patterns of each study's variables and outcomes were assessed. Results  A total of 112 studies were included in the review. The most commonly reported demographic variables were the number of included patients ( n  = 112, 100%) and types of pathologies treated ( n  = 104, 92.9%). Meanwhile, the most routinely described preoperative variable was history of prior treatment ( n  = 48, 42.9%). Type of reconstruction was a commonly reported intraoperative variable ( n  = 110, 98.2%), though the rate of intraoperative cerebrospinal fluid (CSF) leak was noted in only 76 studies (67.9%). With regard to postoperative outcomes, postoperative CSF leak rate was routinely provided ( n  = 101, 90.2%), but reporting of other surgical complications was more inconsistent. Ultimately, of the 43 variables and outcomes reviewed, a median of 12 (range: 4-22) was reported in each study. Conclusion  There is significant heterogeneity in the outcomes reported in studies relating to ESBR. This highlights the need for the development of standard reporting guidelines to minimize bias and improve interstudy comparability.

Endonasal CNS Delivery System for Blood-Brain Barrier Impermeant Therapeutic Oligonucleotides Using Heterotopic Mucosal Engrafting

The most significant obstacle in the treatment of neurological disorders is the blood-brain barrier (BBB), which prevents 98% of all potential neuropharmaceuticals from reaching the central nervous system (CNS). Brain derived neurotrophic factor (BDNF) is one of the most intensely studied targets in Parkinson’s disease (PD) as it can reverse disease progression. BDNF AntagoNAT’s (ATs) are synthetic oligonucleotide-like compounds capable of upregulating endogenous BDNF expression. Despite the significant promise of BDNF AT therapies for PD, they cannot cross the blood-brain barrier (BBB). Our group has developed an innovative endonasal heterotopic mucosal grafting technique to provide a permanent method of permeabilizing the BBB. This method is based on established endoscopic surgical procedures currently used in routine clinical practice. Our overall goal for the study was to investigate the distribution and efficacy of BDNF AT’s using an extra-cranial graft model in naïve rats using the innovative heterotopic mucosal engrafting technique. BDNF AT cationic liposomes (ideal size range 200–250 nm) were developed and characterized to enhance the delivery to rat brain. Uptake, distribution and transfection efficiency of BDNF AntagoNAT’s in saline and liposomes were evaluated qualitatively (microscopy) and quantitatively (ELISA and AT hybridization assays) in RT4-D6P2T rat schwannoma cells and in naïve rats. In vivo therapeutic efficacy of BDNF AT’s encapsulated in liposomes was evaluated in a 6-OHDA toxin model of PD using western blot and tyrosine hydroxylase immunohistochemistry. Using complimentary in vitro and in vivo techniques, our results demonstrate that grafts are capable of delivering therapeutic levels of BDNF ATs in liposomes and saline formulation throughout the brain resulting in significant BDNF upregulation in key end target regions relevant to PD. BDNF AT liposomes resulted in a better distribution in rat brain as compared to saline control. The delivered BDNF AT’s encapsulated in liposomes also conferred a neuroprotective effect in a rat 6-OHDA model of PD. As a platform technique, these results further suggest that this approach may be utilized to deliver other BBB impermeant oligonucleotide-based therapeutics thereby opening the door to additional treatment options for CNS disease.

Sellar trough technique for endoscopic endonasal transclival repair

Background:

Endoscopic endonasal transclival approaches provide direct access to the ventral skull base allowing the treating of clival and paraclival pathology without the manipulation of the brain or neurovascular structures. Postoperative spinal fluid leak, however, remains a challenge and various techniques have been described to reconstruct the operative defect. The “gasket seal” has been well-described, but has anatomic challenges when applied to clival defects. We describe a modification of this technique for use in endonasal transclival approaches.

Methods:

Two patients who underwent an endoscopic endonasal transclival approach for tumor resection with an intraoperative spinal fluid leak underwent a modified “gasket seal” closure technique for skull base reconstruction.

Results:

A 71-year-old woman with a petroclival meningioma and a 22 year old with a clival chordoma underwent endoscopic endonasal transclival resection with the modified repair. No new postoperative deficits occurred and no postoperative spinal fluid leak was seen with a follow-up of 17 and 23 months, respectively.

Conclusion:

We describe the successful use of a simple, low risk, and technique modification of the “gasket seal” technique adapted to the clivus that allows for hard reconstruction and facilitates placement of the nasoseptal flap.

Surgical management of craniopharyngiomas in adult patients: a systematic review and consensus statement on behalf of the EANS skull base section

BACKGROUND AND OBJECTIVE

Craniopharyngiomas are locally aggressive neuroepithelial tumors infiltrating nearby critical neurovascular structures. The majority of published surgical series deal with childhood-onset craniopharyngiomas, while the optimal surgical management for adult-onset tumors remains unclear. The aim of this paper is to summarize the main principles defining the surgical strategy for the management of craniopharyngiomas in adult patients through an extensive systematic literature review in order to formulate a series of recommendations.

MATERIAL AND METHODS

The MEDLINE database was systematically reviewed (January 1970-February 2019) to identify pertinent articles dealing with the surgical management of adult-onset craniopharyngiomas. A summary of literature evidence was proposed after discussion within the EANS skull base section.

RESULTS

The EANS task force formulated 13 recommendations and 4 suggestions. Treatment of these patients should be performed in tertiary referral centers. The endonasal approach is presently recommended for midline craniopharyngiomas because of the improved GTR and superior endocrinological and visual outcomes. The rate of CSF leak has strongly diminished with the use of the multilayer reconstruction technique. Transcranial approaches are recommended for tumors presenting lateral extensions or purely intraventricular. Independent of the technique, a maximal but hypothalamic-sparing resection should be performed to limit the occurrence of postoperative hypothalamic syndromes and metabolic complications. Similar principles should also be applied for tumor recurrences. Radiotherapy or intracystic agents are alternative treatments when no further surgery is possible. A multidisciplinary long-term follow-up is necessary.

Intraoperative Repair of Cerebrospinal Fluid Rhinorrhea in Skull Base Tumor Resection: A Retrospective Study of Acellular Dermal Matrix Versus Turbinate Flap

BACKGROUND

The acellular dermal matrix (ADM) and turbinate flap (TF) have been widely used in the reconstruction of skull base defects. However, owing to the lack of reported data, the therapeutic effects have been controversial. The purpose of the present study was to compare the effect of the ADM and TF on cerebrospinal fluid (CSF) rhinorrhea after nasal endoscopic resection of a skull base tumor.

METHODS

The data from 46 patients who had undergone nasal endoscopic resection of a skull base tumor and repair of CSF rhinorrhea were retrospectively analyzed. The patients were divided into ADM and TF groups according to the difference in repair materials used. We compared and analyzed the intraoperative information and postoperative outcomes.

RESULTS

The operation time, blood loss, defect area, and need for blood transfusion were not significantly different between the ALT and TF groups. The postoperative length of hospital stay (14.33 ± 3.66 vs. 16.76 ± 5.51 days; P = 0.669) and the incidence of complications, including wound infection (1 vs. 0; P = 0.270), intracranial infection (1 vs. 1; P = 0.900), hemorrhage (2 vs. 3; P = 0.788), 15-day CSF leak (1 vs. 2; P = 0.658), and respiratory infection (2 vs. 1; P = 0.450) were comparable between the 2 groups. The 6-month (0 vs. 0; P = 1.000) and 12-month (0 vs. 0; P = 1.000) incidence of recurrence also showed no significant differences.

CONCLUSION

The use of the ADM for patients with CSF rhinorrhea showed comparable results in terms of postoperative outcomes compared with the use of TF. ADM could serve as a safe and feasible alternative for endoscopic repair of CSF rhinorrhea after nasal endoscopic resection of skull base tumors.

Imaging of endoscopic approaches to the anterior and central skull base

Sinonasal endoscopy for treatment of benign sinonasal diseases is a well-established procedure. Recent advances in endoscope technology have substantially expanded its application with many institutions now offering resection of skull base lesions and sinonasal malignancies via the endoscopic approach. Its minimally invasive nature leads to faster recovery time, better cosmetic results, and fewer complications. Unfortunately, not all lesions involving the sinonasal region and skull base are accessible to sinonasal endoscopy. In addition, many of these disease processes are not directly visible on clinical examination. Therefore, the surgeon relies upon imaging to (1) determine the extent and possible nature of the disease; (2) provide guidance for surgical planning purposes, in particular, if a lesion is accessible to endoscopic surgery or if an open surgical approach is indicated. The radiologist, on the other hand, needs to be familiar with the technical limitations and contraindications of sinonasal endoscopy to provide a meaningful radiology report to the surgeon. The relative and absolute contraindications to endoscopic surgery can be categorised into technical factors, extent of a lesion, tumour vascularity, and anatomical variations and are discussed in this review article.

Endoscopic Endonasal Repair of Cerebrospinal Fluid Leakage Caused by a Rare Traumatic Clival Fracture

An 89-year-old male presented with cerebrospinal fluid (CSF) rhinorrhea associated with head trauma sustained as a pedestrian in a traffic accident. Computed tomography (CT) showed pneumocephalus and multiple cranial bone fractures, including the clivus. Although the CSF rhinorrhea was treated conservatively for a week, clinical symptoms did not improve and surgical repair was performed. Preoperative thin-sliced bone CT and steady-state magnetic resonance images revealed a bone defect at the middle clivus and a collection of CSF fluid from the clival fistula in the sphenoid sinus. Endoscopic endonasal reconstruction was performed, and the 3-mm diameter dural tear and bone defect at the middle clivus were well visualized. The fistula was repaired using a pedicled nasoseptal mucosal flap. The CSF rhinorrhea completely disappeared as a result of the endoscopic endonasal surgery. The present report describes a rare case of CSF rhinorrhea caused by a traumatic clival fracture and surgical management by endoscopic endonasal surgery.

Endoscopic Endonasal Approach for Removal of Tuberculum Sellae Meningiomas

Tuberculum sellae meningiomas are challenging lesions; their critical location and often insidious growth rate enables significant distortion of the superjacent optic apparatus before the patient notices any visual impairment. This article describes the technical nuances, selection criteria and complication avoidance strategies for the endonasal resection of tuberculum sellae meningiomas. A stepwise description of the surgical technique is presented; indications, adjuvant technologies, pitfalls and the relevant anatomy are also reviewed. Tuberculum sellae meningiomas may be safely and effectively resected through the endonasal route; invasion of the optic canals does not represent a limitation.