Acquisition of surgical skills for endonasal skull base surgery: a training program

Multidisciplinary Team Care in Pituitary Tumours

The optimal care for patients with pituitary tumours is best provided in a multidisciplinary and collaborative environment, which requires the contribution of multiple medical specialties working together. The benefits and advantages of the pituitary multidisciplinary team (MDT) are broad, and all relevant international consensus and guidelines in the field recommend that patients with pituitary tumours should always be managed in a MDT. Endocrinologists and neurosurgeons are normally the leading specialties within the pituitary MDT, supported by many other specialties with significant contributions to the diagnosis and management of pituitary tumours, including neuropathology, neuroradiology, neuro-ophthalmology, and otorhinolaryngology, among others. Here, we review the literature concerning the concepts of Pituitary MDT/Pituitary Tumour Centre of Excellence (PTCOE) in terms of their mission, goals, benefits, structure, proposed models of function, and barriers, and we also provide the views of different specialists involved in our Pituitary MDT.

Sinonasal Outcomes of the Combined Transseptal/Transnasal Approach with Unilateral Nasoseptal Rescue Flap in Endoscopic Endonasal Transsphenoidal Surgery: A Propensity Score Matching Analysis

Objectives  The authors applied surgical techniques acquired during the use of endoscopic combined transseptal/transnasal approach to reduce approach-related morbidity and improve sinonasal outcomes. Study Design  This is a retrospective cohort study of a prospectively collected database. Setting  The study setting involves a tertiary referral center. Participants  A total of 86 patients who underwent endoscopic endonasal transsphenoidal surgery for newly diagnosed pituitary adenomas from April 2018 to March 2021 were included. Patients treated via the combined transseptal/transnasal approach served as the study group ( n  = 18); those treated via the bilateral transnasal approach comprised the control group ( n  = 68). From the control group, propensity score matching (PSM) analysis was further performed to account for potential confounders and selection bias. Main Outcome Measures  Paired analysis was performed for pre- and 6-month-postoperative time points in study group, control group, and PSM control group. Olfactory function was evaluated by Connecticut Chemosensory Clinical Research Center (CCCRC) test, Cross-Cultural Smell Identification Test (CCSIT), and sinonasal outcomes were assessed by Sino-Nasal Outcome Test-22 (SNOT-22). Results  In the study group, CCCRC ( p  = 0.517) and CCSIT ( p  = 0.497) did not show any significant difference before and after surgery. There was some improvement in the symptom score of SNOT-22, but it was not statistically significant ( p  = 0.115). In the control group adjusted with PSM, a significant decrease in olfaction ( p  = 0.047) was observed using CCCRC. The CCSIT score was also decreased but not significant ( p  = 0.163). Also, there was no difference in the improvement of SNOT-22 ( p  = 0.781). Conclusion  Our new surgical method preserves olfactory function without compromising surgical outcomes.

Trigeminal Schwannoma: A Retrospective Analysis of Endoscopic Endonasal Management, Treatment Outcomes, and Neuropathic Sequelae

Introduction  Trigeminal schwannomas (TS) are rare skull base tumors that have been associated with significant neuropathic sequalae for patients. The authors aim to evaluate the clinical features, treatment outcomes, and neuropathic sequelae following endoscopic endonasal approach (EEA) for TS. Methods  The study involves a retrospective review of patients who underwent EEA for resection of TS at a single academic institution between 2004 and 2020. Radiographic and clinical data were recorded and analyzed. Results  A total of 16 patients were abstracted, with a mean age at the time of surgery of 44 years with a slight female (1.83:1) predominance. Primary preoperative symptomatology included facial pain/neuralgia ( n  = 5, 31.3%), facial hypoesthesia ( n  = 4, 25.0%), and headache ( n  = 4, 25.0%). Following TS resection, patients were found to have facial hypoesthesia ( n  = 11, 68.8%), neuropathic keratopathy ( n  = 4, 25.0%), and mastication musculature atrophy ( n  = 3, 18.8%). Patients with preoperative facial pain/neuralgia ( n  = 5, 31.3%) were significantly more likely to try adjunctive pain therapies ( p  = 0.018) as well as seek pain consultation ( p  = 0.018). Patients with preoperative migraines ( n  = 2, 12.5%) were significantly more likely to trial adjunctive pain therapies ( p  = 0.025) and undergo evaluation with pain specialists ( p  = 0.025). Finally, patients with preoperative pharmacologic agent utilization were significantly more likely to trial adjunctive pain therapies ( p  = 0.036) and pursue pain consultation ( p  = 0.036). Conclusion  Some degree of trigeminal dysfunction may be more common than previously reported following EEA for TS resection. Factors that appear to play a role in the development of trigeminal dysfunction include pre-existing pain syndromes such as facial pain/neuralgia or headache and preoperative medication utilization.

Current and Future Advances in Surgical Therapy for Pituitary Adenoma

The vital physiological role of the pituitary gland, alongside its proximity to critical neurovascular structures, means that pituitary adenomas can cause significant morbidity or mortality. While enormous advancements have been made in the surgical care of pituitary adenomas, numerous challenges remain, such as treatment failure and recurrence. To meet these clinical challenges, there has been an enormous expansion of novel medical technologies (eg, endoscopy, advanced imaging, artificial intelligence). These innovations have the potential to benefit each step of the patient's journey, and ultimately, drive improved outcomes. Earlier and more accurate diagnosis addresses this in part. Analysis of novel patient data sets, such as automated facial analysis or natural language processing of medical records holds potential in achieving an earlier diagnosis. After diagnosis, treatment decision-making and planning will benefit from radiomics and multimodal machine learning models. Surgical safety and effectiveness will be transformed by smart simulation methods for trainees. Next-generation imaging techniques and augmented reality will enhance surgical planning and intraoperative navigation. Similarly, surgical abilities will be augmented by the future operative armamentarium, including advanced optical devices, smart instruments, and surgical robotics. Intraoperative support to surgical team members will benefit from a data science approach, utilizing machine learning analysis of operative videos to improve patient safety and orientate team members to a common workflow. Postoperatively, neural networks leveraging multimodal datasets will allow early detection of individuals at risk of complications and assist in the prediction of treatment failure, thus supporting patient-specific discharge and monitoring protocols. While these advancements in pituitary surgery hold promise to enhance the quality of care, clinicians must be the gatekeepers of the translation of such technologies, ensuring systematic assessment of risk and benefit prior to clinical implementation. In doing so, the synergy between these innovations can be leveraged to drive improved outcomes for patients of the future.

Endoscopic Endonasal Approach in Craniopharyngiomas: Representative Cases and Technical Nuances for the Young Neurosurgeon

Craniopharyngiomas (CPs) are Rathke's cleft-derived benign tumors originating most commonly in the dorsum sellae and representing 2% of intracranial neoplasms. CPs represent one of the more complex intracranial tumors due to their invasive nature, encasing neurovascular structures of the sellar and parasellar regions, making its resection a major challenge for the neurosurgeon with important postoperative morbidity. Nowadays, an endoscopic endonasal approach (EEA) provides an "easier" way for CPs resection allowing a direct route to the tumor with direct visualization of the surrounding structures, diminishing inadvertent injuries, and providing a better outcome for the patient. In this article, we include a comprehensive description of the EEA technique and nuances in CPs resection, including three illustrated clinical cases.

Purely nasal floor mucosa-free graft for reconstruction after endoscopic endonasal transellar approach: an anatomical and clinical analysis

BACKGROUND/OBJECTIVE

In this radioanatomical study with clinical correlate, we study a variation of the 'extended nasal floor mucosa' (ENFM) free-graft, the purely nasal floor mucosa (PuNFM) free-graft. The objectives of this study are to evaluate the coverage surface area provided by the PuNFM, study the adequacy of the PuNFM in the reconstruction of endoscopic endonasal approach (EEA) transsellar postoperative defects and compare and evaluate this reconstructive technique with current sellar region reconstruction practices.

METHODS

Dissections were performed on five cadaveric specimens. PuNFM were harvested bilaterally and the area provided for reconstruction was calculated. Twenty-five consecutive cases of pituitary adenomas resected through an EEA were analyzed to estimate the sellar defect surface area (SDSA) after a transsellar EEA and calculate the area of PuNFM bilaterally.

RESULTS

The median cadaveric SDSA was 4.77 cm², with a median left and right side PuNFM area of 5.09 and 5.19 cm², respectively. Clinically, the median SDSA was 5.36 cm², and the total radiological PuNFM surface area was 5.46 cm², with modified Knosp grade >2 tumors having larger SDSA than that of Knosp grade <2 tumors. The PuNFM graft proved to be most effective for covering modified Knosp <2 tumor defects.

CONCLUSIONS

The PuNFM represents a variation of the ENFM free-graft sellar defect reconstruction technique that provides sufficient surface area to reconstruct the majority of the sellar defects related to transsellar EAA for pituitary adenomas. This technique may positively impact sinonasal function and quality of life. Future prospective clinical studies are needed to verify these findings.

The 100 Most Cited Articles in Endoscopic Endonasal Skull Base Surgery: A Bibliometric Analysis

BACKGROUND

The accelerated growth of endoscopic endonasal skull base surgery has led to an abundance of highly cited works that have helped shape the field into its current state. Highlighting these works can serve as a guide for trainees and facilitate evidence-based clinical decision making and operative techniques.

METHODS

Elsevier's Scopus database was used to generate a list of the 100 most cited articles on endoscopic endonasal skull base surgery in September 2022. Results were categorized based on pathology, approach, study design, and study objective. A citation per year analysis was conducted to highlight later publications that may not have had the time to accumulate as many citations as older publications.

RESULTS

The average number of citations for the 100 most cited articles was 210 per article (range 104-1285). Publication dates ranged from 1997 to 2019, with the highest number of articles among the 100 most cited being published in 2008 (15 articles). The journal with the greatest number of publications was Neurosurgery (30 articles). Of the 100 most cited articles, 77 were published between 2000 and 2010. Moreover, 40 of the 100 articles reported surgical outcomes and related complications, and the most common pathology was pituitary adenoma (25 articles).

CONCLUSIONS

This article provides a list of highly influential articles in the field of endoscopic endonasal skull base surgery, highlighting its rapid evolution over the last 3 decades and demonstrating its leap from small descriptive series confined to certain pathologies to larger cohorts exploring possible boundaries and other pathologies.

Surgical Complexity and Complications: The Need for a Common Language

BACKGROUND

Quality measurement and outcome assessment have recently caught an attention of the neurosurgical community, but lack of standardized definitions and methodology significantly complicates these tasks.

OBJECTIVE

To identify a uniform definition of neurosurgical complications, to classify them according to etiology, and to evaluate them comprehensively in cases of intracranial tumor removal in order to establish a new, easy, and practical grading system capable of predicting the risk of postoperative clinical worsening of the patient condition.

METHODS

A retrospective analysis was conducted on all elective surgeries directed at removal of intracranial tumor in the authors' institution during 2-year study period. All sociodemographic, clinical, and surgical factors were extracted from prospectively compiled comprehensive patient registry. Data on all complications, defined as any deviation from the ideal postoperative course occurring within 30 days of the procedure, were collected with consideration of the required treatment and etiology. A logistic regression model was created for identification of independent factors associated with worsening of the Karnofsky Performance Scale (KPS) score at discharge after surgery in comparison with preoperative period. For each identified statistically significant independent predictor of the postoperative worsening, corresponding score was defined, and grading system, subsequently named Milan Complexity Scale (MCS), was formed.

RESULTS

Overall, 746 cases of surgeries for removal of intracranial tumor were analyzed. Postoperative complications of any kind were observed in 311 patients (41.7%). In 223 cases (29.9%), worsening of the KPS score at the time of discharge in comparison with preoperative period was noted. It was independently associated with 5 predictive factors-major brain vessel manipulation, surgery in the posterior fossa, cranial nerve manipulation, surgery in the eloquent area, tumor size >4 cm-which comprised MCS with a range of the total score from 0 to 8 (higher score indicates more complex clinical situations). Patients who demonstrated KPS worsening after surgery had significantly higher total MCS scores in comparison with individuals whose clinical status at discharge was improved or unchanged (3.24 ± 1.55 versus 1.47 ± 1.58; P < 0.001).

CONCLUSION

It is reasonable to define neurosurgical complication as any deviation from the ideal postoperative course occurring within 30 days of the procedure. Suggested MCS allows for standardized assessment of surgical complexity before intervention and for estimating the risk of clinical worsening after removal of intracranial tumor. Collection of data on surgical complexity, occurrence of complications, and postoperative outcomes, using standardized prospectively maintained comprehensive patient registries seems very important for quality measurement and should be attained in all neurosurgical centers.

Automated operative workflow analysis of endoscopic pituitary surgery using machine learning: development and preclinical evaluation (IDEAL stage 0)

OBJECTIVE

Surgical workflow analysis involves systematically breaking down operations into key phases and steps. Automatic analysis of this workflow has potential uses for surgical training, preoperative planning, and outcome prediction. Recent advances in machine learning (ML) and computer vision have allowed accurate automated workflow analysis of operative videos. In this Idea, Development, Exploration, Assessment, Long-term study (IDEAL) stage 0 study, the authors sought to use Touch Surgery for the development and validation of an ML-powered analysis of phases and steps in the endoscopic transsphenoidal approach (eTSA) for pituitary adenoma resection, a first for neurosurgery.

METHODS

The surgical phases and steps of 50 anonymized eTSA operative videos were labeled by expert surgeons. Forty videos were used to train a combined convolutional and recurrent neural network model by Touch Surgery. Ten videos were used for model evaluation (accuracy, F1 score), comparing the phase and step recognition of surgeons to the automatic detection of the ML model.

RESULTS

The longest phase was the sellar phase (median 28 minutes), followed by the nasal phase (median 22 minutes) and the closure phase (median 14 minutes). The longest steps were step 5 (tumor identification and excision, median 17 minutes); step 3 (posterior septectomy and removal of sphenoid septations, median 14 minutes); and step 4 (anterior sellar wall removal, median 10 minutes). There were substantial variations within the recorded procedures in terms of video appearances, step duration, and step order, with only 50% of videos containing all 7 steps performed sequentially in numerical order. Despite this, the model was able to output accurate recognition of surgical phases (91% accuracy, 90% F1 score) and steps (76% accuracy, 75% F1 score).

CONCLUSIONS

In this IDEAL stage 0 study, ML techniques have been developed to automatically analyze operative videos of eTSA pituitary surgery. This technology has previously been shown to be acceptable to neurosurgical teams and patients. ML-based surgical workflow analysis has numerous potential uses-such as education (e.g., automatic indexing of contemporary operative videos for teaching), improved operative efficiency (e.g., orchestrating the entire surgical team to a common workflow), and improved patient outcomes (e.g., comparison of surgical techniques or early detection of adverse events). Future directions include the real-time integration of Touch Surgery into the live operative environment as an IDEAL stage 1 (first-in-human) study, and further development of underpinning ML models using larger data sets.

Endoscopic Endonasal versus Transcranial Optic Canal Decompression: A Morphometric, Cadaveric Study

Introduction Decompression of the optic nerve within the optic canal is indicated for compressive visual decline. The two most common approaches utilized for optic canal decompression are a medial approach with an endoscopic endonasal approach and a lateral approach with a craniotomy. Our study is a cadaveric anatomical study comparing the length and circumference of the orbit decompressed via an endoscopic endonasal approach versus a frontotemporal craniotomy.

Methods Five cadaveric specimens were utilized. Predissection computed tomography (CT) scans were performed on each specimen. On each specimen, a standard frontotemporal craniotomy with anterior clinoidectomy and superolateral orbital decompression was performed on one side and an endoscopic endonasal approach with medial wall decompression was performed on the contralateral side. Post-dissection CT scans were performed. An independent radiologist provided measurements of the length (mm) and circumference (degrees) of optic canal decompression bilaterally.

Results The mean length of optic canal decompression for open and endoscopic approach was 13 mm (range 12–15 mm) and 12.4 mm (range 10–16 mm), respectively. The mean circumference of decompression for open and endoscopic approaches was 252.8 degrees (range 205–280 degrees) and 124.6 degrees (range 100–163 degrees), respectively.

Conclusion The endoscopic endonasal and the transcranial approaches provide a similar length of optic canal decompression, but the transcranial approach leads to greater circumferential decompression. The endoscopic endonasal approach has the benefit of being minimally invasive, though. Ultimately, the surgical approach decision should be based on the location of the pathology and the surgeon's comfort.

Volumetric Resection and Complications in Nonfunctioning Pituitary Adenoma by Fully Endoscopic Transsphenoidal Approach along 15 Years of Single-Center Experience

Objective  The aim of this study was to evaluate the rate of complications and the extent of resection (EOR) of nonfunctioning pituitary adenomas by endoscopic endonasal approach (EEA) in a 15-year learning curve. Methods  A total of 100 patients operated by the same surgical team were divided chronologically into two, three, and four groups, comparing differences in EOR measured by a semiautomatic software (Smartbrush, Brainlab), rate of immediate postoperative complications, and the visual and hormonal status at 6 months. Results  There were no significant differences over the years in rates of postoperative complications and in visual status at 6 months. A significant linear correlation between the EOR and the number of surgeries (rho = 0.259, p  = 0.007) was found. The analysis was performed in three groups because of the remarkable differences among them; the EOR were: 87.2% (early group), 93.03% (intermediate group), and 95.1% (late group) ( p  = 0.019). Gross total resection was achieved in 30.3, 51.5, and 64%, respectively ( p  = 0.017); also, the rate of reoperation and the worsening of at least one new hormonal axis were worse in the early group. Consequently, the early group had a higher risk of incomplete resection compared with the late group (odds ratio: 4.2; 95% confidence interval: 1.5-11.7). The three groups were not different in demographic and volume tumor variables preoperatively. Conclusions  The first 33 interventions were associated with a lower EOR, a high volume of residual tumor, a high reoperation rate, and a higher rate of hormonal dysfunction. We did not find differences in terms of postoperative complications and the visual status at 6-month follow-up.

Soft Gasket Seal Reconstruction after Endoscopic Endonasal Transtuberculum Resection of Craniopharyngiomas

BACKGROUND

The expanded endoscopic endonasal approach (EEA) is currently well-accepted for a variety of ventral skull base tumors. Such approach often results in a trans-dural defect and intraoperative cerebrospinal fluid (CSF) leak and adequate reconstruction is necessary to prevent postoperative CSF leak and its complications. Reconstruction is usually performed utilizing a variety of materials along with the nasoseptal flap (NSF).

OBJECTIVE

This work's aim is to describe a new reconstructive technique called 'Soft Gasket Seal' (SGS) in detail and compare it with the standard reconstructive technique at our institution for craniopharyngiomas operated via transtuberculum EEA.

METHODS

A retrospective chart review was achieved to identify patients who underwent transtubercular EEA for craniopharyngioma between 2010 and 2018, by the same neurosurgical and otolaryngology team using either the SGS or the standard reconstructive technique.

RESULTS

Of 36 patients who met criteria and were considered for analysis, 15 patients underwent the Soft Gasket Seal reconstruction and 21, the standard reconstruction. There were 16 female (44%) and 20 male (56%) patients. The median age was 42.2±20.9 years. The rate of postoperative CSF leak in the group of patients treated with the standard technique was 14.2%, and 6.6% in the SGS group (OR 0.43 [CI 95% 0.007 - 6.15, p = 0.62).

CONCLUSION

The SGS technique provides a simple reconstructive technique in conjunction with the NSF, showing a tendency of lower complications when compared to our standard technique, while avoiding donor site morbidity. Such results are encouraging, but further studies are necessary to confirm these findings.

Pituitary society expert Delphi consensus: operative workflow in endoscopic transsphenoidal pituitary adenoma resection

PURPOSE

Surgical workflow analysis seeks to systematically break down operations into hierarchal components. It facilitates education, training, and understanding of surgical variations. There are known educational demands and variations in surgical practice in endoscopic transsphenoidal approaches to pituitary adenomas. Through an iterative consensus process, we generated a surgical workflow reflective of contemporary surgical practice.

METHODS

A mixed-methods consensus process composed of a literature review and iterative Delphi surveys was carried out within the Pituitary Society. Each round of the survey was repeated until data saturation and > 90% consensus was reached.

RESULTS

There was a 100% response rate and no attrition across both Delphi rounds. Eighteen international expert panel members participated. An extensive workflow of 4 phases (nasal, sphenoid, sellar and closure) and 40 steps, with associated technical errors and adverse events, were agreed upon by 100% of panel members across rounds. Both core and case-specific or surgeon-specific variations in operative steps were captured.

CONCLUSIONS

Through an international expert panel consensus, a workflow for the performance of endoscopic transsphenoidal pituitary adenoma resection has been generated. This workflow captures a wide range of contemporary operative practice. The agreed "core" steps will serve as a foundation for education, training, assessment and technological development (e.g. models and simulators). The "optional" steps highlight areas of heterogeneity of practice that will benefit from further research (e.g. methods of skull base repair). Further adjustments could be made to increase applicability around the world.

When is a multidisciplinary surgical approach required in sinonasal tumours with cranial involvement?

The term “sinonasal tumours” includes a large spectrum of diseases, which are characterized by heterogeneous biological behavior and prognosis, and located in a critical anatomic area. Diagnosis and treatment of sinonasal tumours require the contribution of different disciplines. A narrative review was performed to highlight the role of surgeons in contributing to a multidisciplinary approach to sinonasal tumours. Diagnosis and staging of sinonasal tumours is challenging and requires collaboration between surgeons, radiologists, and pathologists. The identification and management of critical extensions (orbital or intracranial encroachment, vascular abutment or encasement) is fundamental for successful treatment. Most cases of advanced sinonasal tumours can undergo surgical intervention by an adequately trained otorhinolaryngological team. The contribution of neurosurgeons and oculoplastic surgeons is required in selected scenarios. In rare circumstances, multidisciplinary reconstructive strategies can be indicated for complex tissue defects. Furthermore, a multidisciplinary approach is pivotal in the management of perioperative complications. While surgery remains the mainstay of treatment, the role of non-surgical adjuvant or even exclusive treatments is constantly expanding.

Nasoseptal Flap for Skull Base Reconstruction in a Three-Year-Old Child With Nasofrontal Meningoencephalocele

Congenital anterior skull base defects with meningoencephaloceles causing nasal obstruction and cerebrospinal fluid (CSF) rhinorrhea are rare clinical entities. Traditionally, skull base defects have been repaired via a bifrontal craniotomy. With the introduction of pediatric endoscopic instrumentation, more of these lesions are accessible via an intranasal endoscopic approach, even in the infant population. However, due to the rarity of pediatric meningoencephaloceles, there is a lack of data demonstrating the successful adaptation of endoscopic skull base techniques to the pediatric population. In this report, we present a case of a pediatric frontonasal meningoencephalocele with an anterior skull base defect in a 3-year-old child that was successfully addressed transnasally following 4 failed transcranial approaches. The case highlights the importance of a thorough preoperative evaluation of the surgical approach as well as interdisciplinary management of these patients at a young age. Congenital anterior skull base defects with meningoencephaloceles and CSF leaks are rare clinical entities. Hence, an interdisciplinary approach is vital including experienced pediatricians, otolaryngologists, and neurosurgeons to evaluate the ideal surgical method on an individual basis. The transnasal endoscopic technique has been shown to be minimally invasive, efficient, and safe to apply even to the infant population which could positively be demonstrated in this case.

Transorbital Endoscopic Approach for Repair of Frontal Sinus Cerebrospinal Fluid Leaks: Case-Series

OBJECTIVES

To highlight the feasibility and evaluate the outcomes of the transorbital endoscopic approach (TOEA) in the management of frontal sinus cerebrospinal fluid (CSF) leaks.

STUDY DESIGN

Retrospective case series.

METHODS

The database of patients with frontal sinus CSF leaks managed with TOEA from January 2017 through December 2019 at our institution was reviewed. Two videos of clinical case examples are presented.

RESULTS

Sixteen patients (10 males, 6 females, mean age 53; range 21-61 years) underwent TOEA through the superior eyelid corridor for the repair of frontal sinus CSF leak. The most common etiology of the CSF leak was trauma (nine cases; 56.3%), followed by injury from iatrogenic causes in six cases (37.5%), and spontaneous leak in one case (6.2%). Average defect size was 8.8 mm (range 2.0-20.8 mm). Ten patients were revision cases who had undergone prior nontransorbital CSF leak repair at outside institutions. All patients underwent successful repair via TOEA without postoperative complications. Complete resolution was maintained in all cases. Mean follow-up period was 11 months (range 6-22 months).

CONCLUSIONS

TOEA is a safe minimally disruptive alternative for definitive management of frontal sinus CSF leak in well-selected primary or revision cases. Further studies are necessary to define its indications and outcomes.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:1753-1757, 2021.

The Eustachian Tube as a Landmark for Early Identification of the Abducens Nerve During Endonasal Transclival Approaches

BACKGROUND

Expanded endonasal approaches have the potential to injure the abducens nerve (cranial nerve [CN] VI). The nerve's root entry zone (REZ) and cisternal segment (CS) are particularly prone to injury during the clivus resection and dural incision of transclival approaches.

OBJECTIVE

To investigate the role of the eustachian tube (ET) as a surgical landmark for the REZ and CS of CN VI.

METHODS

Transclival expanded endonasal approaches were performed bilaterally in 6 fresh-frozen cadaveric specimens (12 sides). Anatomic relationships between ET and CN VI were documented with neuronavigation.

RESULTS

The mean vertical distance from the inferior brainstem point to the horizontal projection of CN VI REZ, CS midpoint, and interdural segment (ID) were 26.38 mm (95% confidence interval [CI] 17.36-35.4), 38.61 mm (95% CI 25.61-51.61), and 42.68 mm (95% CI 30.14-55.22), respectively. The relative vertical distance from the ET to the horizontal projections of the REZ, CS midpoint, and its ID were 6.43 mm (95% CI 3.25-9.61), 18.66 mm (95% CI 11.52-25.8), and 22.72 mm (95% CI 16.02-29.42), respectively. In the axial plane the angles between the ET and (1) the REZ and its midline horizontal projection point, (2) the midpoint and its midline horizontal projection point, and (3) ID and its midline horizontal projection point were 9.81 ± SD 5.20°, 18.50 ± SD 4.87°, and 24.71 ± SD 6.21°, respectively.

CONCLUSION

The ET may serve as a constant landmark to reliably predict the position of the REZ and CS of CN VI.

Pituitary Tumors Centers of Excellence

Pituitary tumors are common and require complex and sophisticated procedures for both diagnosis and therapy. To maintain the highest standards of quality, it is proposed to manage patients in pituitary tumors centers of excellence (PTCOEs) with patient-centric organizations, with expert clinical endocrinologists and neurosurgeons forming the core. That core needs to be supported by experts from different disciplines such as neuroradiology, neuropathology, radiation oncology, neuro-ophthalmology, otorhinolaryngology, and trained nursing. To provide high-level medical care to patients with pituitary tumors, PTCOEs further pituitary science through research publication, presentation of results at meetings, and performing clinical trials.

Anatomic Nuances of the Ophthalmic Artery Origin from a Ventral Viewpoint: Considerations and Implications for Endoscopic Endonasal Surgery

BACKGROUND

The origin of the ophthalmic artery is within the surgical field of endoscopic endonasal approaches (EEAs) to the suprasellar and parasellar regions. However, its anatomy from the endoscopic point-of-view has not been adequately elucidated.

OBJECTIVE

To highlight the anatomy of the ophthalmic artery origin from an endoscopic endonasal perspective.

METHODS

The origin of the ophthalmic artery was studied bilaterally under endoscopic visualization, after performing transplanum/transtubercular EEAs in 17 cadaveric specimens (34 arteries). Anatomic relationships relevant to surgery were evaluated. To complement the cadaveric findings, the ophthalmic artery origin was reviewed in 200 "normal" angiographic studies.

RESULTS

On the right side, 70.6% of ophthalmic arteries emerged from the superior aspect, while 17.6% and 11.8% emerged from the superomedial and superolateral aspects of the intradural internal carotid artery, respectively. On the left, 76.5%, 17.6%, and 5.9% of ophthalmic arteries emerged from the superior, superomedial, and superolateral aspects of the internal carotid, respectively. Similar findings were observed on angiography. All ophthalmic arteries emerged at the level of the medial opticocarotid recess. Overall, 47%, 26.5%, and 26.5% of ophthalmic arteries (right and left) were inferolateral, inferior, and inferomedial to the intracranial optic nerve segment, respectively. On both sides, the intracranial length of the ophthalmic artery ranged from 1.5 to 4.5 mm (mean: 2.90 ± standard deviation of 0.74 mm).

CONCLUSION

Awareness of the endoscopic nuances of the ophthalmic artery origin is paramount to minimize the risk of sight-threatening neurovascular injury during EEAs to the suprasellar and parasellar regions.

Various modifications of a vascularized nasoseptal flap for repair of extensive skull base dural defects

OBJECTIVE

Endonasal surgery of the skull base requires watertight reconstruction of the skull base that can seal the dural defect to prevent postoperative CSF rhinorrhea and consequent intracranial complications. Although the incidence of CSF leakage has decreased significantly since the introduction in 2006 of the vascularized nasoseptal flap (the Hadad-Bassagasteguy flap), reconstruction of extensive skull base dural defects remains challenging. The authors describe a new, modified vascularized nasoseptal flap for reconstruction of extensive skull base dural defects.

METHODS

A retrospective review was conducted on 39 cases from 2010 to 2017 that involved reconstruction of the skull base with an endonasal vascularized flap. Extended nasoseptal flaps were generated by adding the nasal floor and inferior meatus mucosa, inferior turbinate mucosa, or entire lateral nasal wall mucosa. The authors specifically highlight the surgical techniques for flap design and harvesting of these various modifications of the vascularized nasoseptal flap.

RESULTS

Thirty-nine endonasal vascularized flaps were used to reconstruct skull base defects in 37 patients with nonsurgical or postoperative CSF rhinorrhea. Of the 39 procedures, extended nasoseptal flaps were used in 5 cases (13%). These included 2 extended nasoseptal flaps including the inferior turbinate mucosa and 3 extended nasoseptal flaps including the entire lateral nasal wall mucosa. These 5 extended nasoseptal flaps were used in patients who had nonsurgical CSF rhinorrhea due to extensive skull base destruction by invasive pituitary tumors. All flaps healed completely and sealed off the CSF leaks. Olfactory function slightly decreased in the 3 patients with extended nasoseptal flaps including the entire lateral nasal wall mucosa. One patient experienced nasolacrimal duct obstruction, which was treated by dacryocystorhinostomy. The authors encountered no wound complication in this series, while crusting at the donor site required daily nasal toilette and frequent debridement until the completion of mucosalization, which usually takes 8 to 12 weeks after surgery.

CONCLUSIONS

Extended nasoseptal flaps are a reliable and versatile option that can be used to reconstruct extensive skull base dural defects resulting from destruction by large invasive tumors or complex endoscopic endonasal surgery. An extended nasoseptal flap that includes the entire lateral nasal wall mucosa (360° flap) is the largest endonasal vascularized flap reported to date and may be an alternative for the reconstruction of extensive skull base defects while avoiding the need for additional external approaches.

Perioperative Considerations in Endoscopic Skull Base Surgery

Purpose of the Review

Present an overview of perioperative considerations specific to endoscopic skull base surgery necessary to maximize successful outcomes.

Recent Findings

The majority of perioperative considerations for endoscopic skull base surgery lack strong supporting evidence and frequently have varied use or implementation amongst institutions. A notable exception comes from a recent randomized controlled trial demonstrating the benefit of lumbar drainage in high-risk cerebrospinal fluid leaks.

Summary

Skull base surgeons must consider a multitude of perioperative factors. While many components of perioperative management are extrapolated from related fields such as endoscopic sinus surgery or open cranial base surgery, additional high-quality studies are needed to delineate best practices specific to endoscopic skull base surgery.

How long is the tail end of the learning curve? Results from 1000 consecutive endoscopic endonasal skull base cases following the initial 200 cases

OBJECTIVE

Endoscopic endonasal approaches (EEAs) to the skull base have evolved over the last 20 years to become an essential component of a comprehensive skull base practice. Many case series show a learning curve from the earliest cases, in which the authors were inexperienced or were not using advanced closure techniques. It is generally accepted that once this learning curve is achieved, a plateau is reached with little incremental improvement. Cases performed during the early steep learning curve were eliminated to examine whether the continued improvement exists over the "tail end" of the curve.

METHODS

A prospectively acquired database of all EEA cases performed by the senior authors at Weill Cornell Medicine/NewYork-Presbyterian Hospital was reviewed. The first 200 cases were eliminated and the next 1000 consecutive cases were examined to avoid the bias created by the early learning curve.

RESULTS

Of the 1000 cases, the most common pathologies included pituitary adenoma (51%), meningoencephalocele or CSF leak repair (8.6%), meningioma (8.4%), craniopharyngioma (7.3%), basilar invagination (3.1%), Rathke's cleft cyst (2.8%), and chordoma (2.4%). Use of lumbar drains decreased from the first half to the second half of our series (p <0.05) as did the authors' use of fat alone (p <0.005) or gasket alone (p <0.005) for dural closure, while the use of a nasoseptal flap increased (p <0.005). Although mean tumor diameter was constant (on average), gross-total resection (GTR) increased from 60% in the first half to 73% in the second half (p <0.005). GTR increased for all pathologies but most significantly for chordoma (56% vs 100%, p <0.05), craniopharyngioma (47% vs 0.71%, p <0.05) and pituitary adenoma (67% vs 75%, p <0.05). Hormonal cure for secreting adenomas also increased from 83% in the first half to 89% in the second half (p <0.05). The rate of any complication was unchanged at 6.4% in the first half and 6.2% in the latter half of cases, and vascular injury occurred in only 0.6% of cases. Postoperative CSF leak occurred in 2% of cases and was unchanged between the first and second half of the series.

CONCLUSIONS

This study demonstrates that contrary to popular belief, the surgical learning curve does not plateau but can continue for several years depending on the complexity of the endpoints considered. These findings may have implications for clinical trial design, surgical education, and patient safety measures.

A Review of Physical Simulators for Neuroendoscopy Skills Training

BACKGROUND

Minimally invasive neurosurgical approaches reduce patient morbidity by providing the surgeon with better visualization and access to complex lesions, with minimal disruption to normal anatomy. The use of rigid or flexible neuroendoscopes, supplemented with a conventional stereoscopic operating microscope, has been integral to the adoption of these techniques. Neurosurgeons commonly use neuroendoscopes to perform the ventricular and endonasal approaches. It is challenging to learn neuroendoscopy skills from the existing apprenticeship model of surgical education. The training methods, which use simulation-based systems, have achieved wide acceptance. Physical simulators provide anatomic orientation and hands-on experience with repeatability. Our aim is to review the existing physical simulators on the basis of the skills training of neuroendoscopic procedures.

METHODS

We searched Scopus, Google Scholar, PubMed, IEEE Xplore, and dblp. We used the following keywords "neuroendoscopy," "training," "simulators," "physical," and "skills evaluation." A total of 351 articles were screened based on development methods, evaluation criteria, and validation studies on physical simulators for skills training in neuroendoscopy.

RESULTS

The screening of the articles resulted in classifying the physical training methods developed for neuroendoscopy surgical skills into synthetic simulators and box trainers. The existing simulators were compared based on their design, fidelity, trainee evaluation methods, and validation studies.

CONCLUSIONS

The state of simulation systems demands collaborative initiatives among translational research institutes. They need improved fidelity and validation studies for inclusion in the surgical educational curriculum. Learning should be imparted in stages with standardization of performance metrics for skills evaluation.

Patient-specific 3-dimensionally printed models for neurosurgical planning and education

OBJECTIVE

Advances in 3-dimensional (3D) printing technology permit the rapid creation of detailed anatomical models. Integration of this technology into neurosurgical practice is still in its nascence, however. One potential application is to create models depicting neurosurgical pathology. The goal of this study was to assess the clinical value of patient-specific 3D printed models for neurosurgical planning and education.

METHODS

The authors created life-sized, patient-specific models for 4 preoperative cases. Three of the cases involved adults (2 patients with petroclival meningioma and 1 with trigeminal neuralgia) and the remaining case involved a pediatric patient with craniopharyngioma. Models were derived from routine clinical imaging sequences and manufactured using commercially available software and hardware.

RESULTS

Life-sized, 3D printed models depicting bony, vascular, and neural pathology relevant to each case were successfully manufactured. A variety of commercially available software and hardware were used to create and print each model from radiological sequences. The models for the adult cases were printed in separate pieces, which had to be painted by hand, and could be disassembled for detailed study, while the model for the pediatric case was printed as a single piece in separate-colored resins and could not be disassembled for study. Two of the models were used for patient education, and all were used for presurgical planning by the surgeon.

CONCLUSIONS

Patient-specific 3D printed models are useful to neurosurgical practice. They may be used as a visualization aid for surgeons and patients, or for education of trainees.

The endoscopic endonasal approach for pediatric craniopharyngiomas: the key lessons learned

PURPOSE

The aim of this study is to highlight the role of the endoscopic endonasal approach (EEA) in pediatric craniopharyngiomas by reviewing our experience and the key lessons learned from the application of this approach in children.

METHODS

Between 1998 and 2017, 12 pediatric craniopharyngiomas were treated via EEA at our institution. Demographic data, preoperative assessment, tumor features, surgical results, complications, and recurrences were analyzed.

RESULTS

Visual defects were the most frequent presenting sign. Seven craniopharyngiomas were infradiaphragmatic, and five were supradiaphragmatic. The EEA was successfully performed in all cases with no complication related to children's sinonasal anatomy. Gross total resection (GTR) rate was of 75%. Endocrinological disturbances improved in one case (20%) and worsened in three (60%). New onset of diabetes insipidus was observed in four (36%) children. Visual defect improved in 91% of cases, with no new postoperative deficit. Postoperative cerebrospinal fluid (CSF) leak occurred in one patient (8%). Three patients (27%) experienced tumor regrowth, and one craniopharyngioma recurred (mean follow-up, 78 months).

CONCLUSIONS

The EEA offers a straight route to the sellar-suprasellar, making it the ideal approach for pediatric infradiaphragmatic craniopharyngiomas. In supradiaphragmatic craniopharyngiomas, the extended EEA provides a clearer and close-up visualization of the tumor-hypothalamus interface, which can grant better results in terms of quality of life. The pediatric skull base anatomy should not represent a contraindication for the endoscopic technique. Larger series encompassing a wider spectrum of pediatric craniopharyngiomas are needed to further support the benefits of this surgical approach.

Risk factors for postoperative intracranial infections in patients with pituitary adenoma after endoscopic endonasal transsphenoidal surgery: pneumocephalus deserves further study

OBJECTIVE

The authors sought to identify the relevance between pneumocephalus and postoperative intracranial infections, as well as bacteriological characteristics and risk factors for intracranial infections, in patients with pituitary adenomas after endoscopic endonasal transsphenoidal surgery.

METHODS

In total, data from 251 consecutive patients with pituitary adenomas who underwent pure endoscopic endonasal transsphenoidal surgeries from 2014 to 2018 were reviewed for preoperative comorbidities, intraoperative techniques, and postoperative care.

RESULTS

This retrospective study found 18 cases of postoperative pneumocephalus (7.17%), 9 CNS infections (3.59%), and 12 CSF leaks (4.78%). Of the patients with pneumocephalus, 5 (27.8%) had CNS infections. In patients with CNS infections, the culture results were positive in 7 cases and negative in 2 cases. The statistical analysis suggested that pneumocephalus (maximum bubble diameter of ≥ 1 cm), diaphragmatic defects (intraoperative CSF leak, Kelly grade ≥ 1), and a postoperative CSF leak are risk factors for postoperative CNS infections.

CONCLUSIONS

In pituitary adenoma patients who underwent pure endoscopic endonasal transsphenoidal surgeries, intraoperative saddle reconstruction has a crucial role for patients with postoperative intracranial infections. Additionally, postoperative pneumocephalus plays an important role in predicting intracranial infections that must not be neglected. Therefore, neurosurgeons should pay close attention to the discovery of postoperative intracranial pneumocephalus because this factor is as important as a postoperative CSF leak. Pneumocephalus (maximum bubble diameter of ≥ 1 cm), diaphragmatic defects (an intraoperative CSF leak, Kelly grade ≥ 1), and a postoperative CSF leak were risk factors predictive of postoperative intracranial infections. In addition, it is essential that operative procedures be carefully performed to avoid diaphragmatic defects, to reduce exposure to the external environment, and to decrease patients’ suffering.

Beyond the Learning Curve: Comparison of Microscopic and Endoscopic Incidences of Internal Carotid Injury in a Series of Highly Experienced Operators

BACKGROUND

As the endoscopic endonasal approach (EEA) has gained popularity as an alternative to microsurgery (MS) for transsphenoidal resection (TSR), numerous studies have attempted to assess the differential risk of internal carotid artery (ICA) injury between the techniques, yet results have been equivocal and contradictory. The aim of this study was to evaluate ICA injury in MS versus EEA among highly experienced neurosurgeons.

METHODS

We performed a systematic literature review of publications from 2002-2017 reporting ICA injury outcomes in ≥250 cases using MS or EEA.

RESULTS

Seventeen series reporting 11,149 patients were included: 3 MS series, 13 EEA series, and 1 series with adequate samples for each. ICA injury incidences were 0.0%-1.6% in cohorts of 275-3000. MS series documented 5 ICA injuries in 2672 operations, for an overall incidence of 0.2% (range, 0.0%-0.4%), and EEA series reported 30 ICA injuries in 8477 operations, for a 0.4% injury rate (range, 0.0%-1.6%); the difference was nonsignificant (P = 0.25). Increased operative experience was associated with decreased incidence of ICA injury, a finding preserved in the overall study cohort and within discretely examined MS and EEA subgroups (overall r² = 0.08, MS r² = 0.23, EEA r² = 0.07).

CONCLUSIONS

ICA injury is the most serious complication of TSR of pituitary neoplasms. Operator inexperience may be a more important risk factor than choice of surgical technique, given the comparably low rates of injury obtained by highly experienced surgeons independent of technique. This emphasizes the need for consolidated care in pituitary centers of excellence, improvement of high-fidelity simulators, and skull base mentorship between senior and junior staff.

"Live Cadaver" Model for Internal Carotid Artery Injury Simulation in Endoscopic Endonasal Skull Base Surgery

BACKGROUND

Intraoperative injury of the internal carotid artery (ICA) is the most dreaded complication in endoscopic endonasal surgery (EES) of skull base. Training for ICA injury is practically impossible in live operative settings.

OBJECTIVE

To evaluate a pulsatile perfusion-based live cadaveric model for ICA injury simulation in a laboratory setting. The major emphasis of the study was to evaluate various means of controlling acute bleeding and evaluating the practical utility of this model for training purposes.

METHODS

Five embalmed, uninjected cadaveric heads were prepared for study by connecting to a pulsatile perfusion pump system filled with artificial blood solution. EES approaches were used to evaluate different types of ICA injuries similar to operative scenarios. Various methods of managing ICA injuries such as packing, clipping, and trapping, were evaluated. The educational advantages of the live cadaver model were assessed using questionnaires given to participants in a hands-on dissection course.

RESULTS

The trainee was faced with several scenarios similar to those encountered during an actual intraoperative ICA injury. Packing, clipping, and trapping of the ICA injury were successfully achieved in all segments of the ICA. Clip-based reconstruction techniques were successfully developed. All trainees reported gaining new knowledge, learning new techniques. The responses to the questionnaire confirmed the significant educational value of this model.

CONCLUSION

The live cadaver model presented here provides real-life experience with major vessel injury during EES in a laboratory setting. This model could significantly improve current training for the management of intraoperative vascular injuries during EES.

Endoscopic Endonasal Surgery for Cranial Base Chondrosarcomas

BACKGROUND

Microsurgical resection via open approaches is considered the main treatment modality for cranial base chondrosarcomas (CBCs). The use of endoscopic endonasal approaches (EEAs) has been rarely reported.

OBJECTIVE

To present the endoscopic endonasal experience with CBCs at our institution.

METHODS

Retrospective review of the medical records of 35 consecutive patients who underwent EEA for CBC resection between January 2004 and April 2013. Surgical outcomes and variables that might affect extent of resection, complications, and recurrence were analyzed.

RESULTS

Forty-eight operations were performed (42 EEAs and 6 open approaches). Gross-total resection was achieved in 22 patients (62.9%), near total (≥90% tumor resection) in 11 (31.4%). Larger tumors were associated with incomplete resection in univariate and multivariate analysis ( P = .004, .015, respectively). In univariate analysis, tumors involving the lower clivus and cerebellopontine angle were associated with increased number of complications, especially postoperative cerebrospinal fluid leak ( P = .015) and new cranial neuropathy ( P = .037), respectively. Other major complications included 2 cases of meningitis and deep venous thrombosis, and 1 case of hydrocephalus and carotid injury. Involvement of the lower clivus, parapharyngeal space, and cervical spine required a combination of approaches to maximize tumor resection ( P = .017, .044, .017, respectively). No predictors were significantly associated with increased risk of recurrence. The average follow-up time was 44.6 ± 31 months.

CONCLUSIONS

EEAs may be considered a good option for managing CBCs without significant posterolateral extension beyond the basal foramina and can be used in conjunction with open approaches for maximal resection with acceptable morbidity.

The medial wall of the cavernous sinus. Part 2: Selective medial wall resection in 50 pituitary adenoma patients

OBJECTIVE

Pituitary adenomas often invade the medial wall of the cavernous sinus (CS), but this structure is generally not surgically removed because of the risk of vascular and cranial nerve injury. The purpose of this study was to report the surgical outcomes in a large series of cases of invasive pituitary adenoma in which the medial wall of the CS was selectively removed following an anatomically based, stepwise surgical technique.

METHODS

The authors' institutional database was reviewed to identify cases of pituitary adenoma with isolated invasion of the medial wall, based on an intraoperative evaluation, in which patients underwent an endoscopic endonasal approach with selective resection of the medial wall of the CS. Cases with CS invasion beyond the medial wall were excluded. Patient complications, resection, and remission rates were assessed.

RESULTS

Fifty patients were eligible for this study, 15 (30%) with nonfunctional adenomas and 35 (70%) with functional adenomas, including 16 growth hormone-, 10 prolactin-, and 9 adrenocorticotropic hormone (ACTH)-secreting tumors. The average tumor size was 2.3 cm for nonfunctional and 1.3 cm for functional adenomas. Radiographically, 11 cases (22%) were Knosp grade 1, 23 (46%) Knosp grade 2, and 16 (32%) Knosp grade 3. Complete tumor resection, based on intraoperative impression and postoperative MRI, was achieved in all cases. The mean follow-up was 30 months (range 4-64 months) for patients with functional adenomas and 16 months (range 4-30 months) for those with nonfunctional adenomas. At last follow-up, complete biochemical remission (using current criteria) without adjuvant treatment was seen in 34 cases (97%) of functional adenoma. No imaging recurrences were seen in patients who had nonfunctional adenomas. A total of 57 medial walls were removed in 50 patients. Medial wall invasion was histologically confirmed in 93% of nonfunctional adenomas and 83% of functional adenomas. There were no deaths or internal carotid artery injuries, and the average blood loss was 378 ml. Four patients (8%) developed a new, transient cranial nerve palsy, and 2 of these patients required reoperation for blood clot evacuation and fat graft removal. There were no permanent cranial nerve palsies.

CONCLUSIONS

The medial wall of the CS can be removed safely and effectively, with minimal morbidity and excellent resection and remission rates. Further follow-up is needed to determine the long-term results of this anatomically based technique, which should only be performed by very experienced endonasal skull base teams.

[Orbital complications]

A disease or symptom of disease spreading from the vicinity of the orbit to the internal structures of the orbit is referred to as an orbital complication. Orbital complications can have a traumatic, inflammatory, allergic, or autoimmunologic cause. They are more frequent in children than adults. The present review aims to provide a description of orbital complications, their etiology, pathogenesis, and treatment. Recent literature in the field is acknowledged and discussed, and results from the authors' own patient groups are analyzed. Particular attention is paid to orbital complications due to acute sinusitis and those caused by acute hemorrhage. The term "orbital phlegmon" frequently used for orbital complications with inflammatory causes is confusing and should be replaced by differentiated grading. Diagnosis and treatment of orbital complications requires interdisciplinary collaboration, whereby inclusion of ophthalmologists is particularly important. Treatment of orbital complications depends on their cause. In inflammatory cases affecting only the preseptal tissues and compartment, conservative therapy is indicated. If clinical findings worsen within 24 h of conservative therapy, or if the patient presents with a high-grade orbital complication with loss of visual acuity or impairment of globe mobility, surgery is required. In cases of acute hemorrhage into the orbit, a procedure for decreasing intra-orbital pressure is mandatory (i. e., canthotomy, cantholysis, orbital decompression).

Anterior communicating artery division in the endoscopic endonasal translamina terminalis approach to the third ventricle: an anatomical feasibility study

BACKGROUND

Endonasal endoscopic approaches (EEA) to the third ventricle are well described but generally use an infrachiasmatic route since the suprachiasmatic translamina terminalis corridor is blocked by the anterior communicating artery (AComA). The bifrontal basal interhemispheric translamina terminalis approach has been facilitated with transection of the AComA. The aim of the study is to describe the anatomical feasibility and limitations of the EEA translamina terminalis approach to the third ventricle augmented with AComA surgical ligation.

METHODS

Endoscopic dissections were performed on five cadaveric heads injected with colored latex using rod lens endoscopes attached to a high-definition camera and a digital video recorder system. A stepwise anatomical dissection of the endoscopic endonasal transtuberculum, transplanum, translamina terminalis approach to the third ventricle was performed. Measurements were performed before and after AComA elevation and transection using a millimeter flexible caliper.

RESULTS

Multiple comparison statistical analysis revealed a statistically significant difference in vertical exposure between the control condition and after AComA elevation, between the control condition and after AComA division and between the AComA elevation and division (p < 0.05). The mean difference in exposed surgical area was statistically significant between the control and after AComA division and between elevation and AComA division (p < 0.01), whereas it was not statistically significant between the control condition and AComA elevation (NS).

CONCLUSION

The anatomical feasibility of clipping and dividing the AComA through an EEA has been demonstrated in all the cadaveric specimens. The approach facilitates exposure of the suprachiasmatic optic recess within the third ventricle that may be a blind spot during an infrachiasmatic approach.

Validation of training levels in endoscopic endonasal surgery of the skull base

OBJECTIVE

A five-level training program was first proposed 10 years ago for surgeons learning endoscopic endonasal surgery (EES) of the skull base. Levels were based on the complexity of anatomy, risk of neurovascular injury, intradural dissection, technical difficulty and vascularity of tumors.

METHOD

A three-phase validation concept is proposed: 1) face validity (the classification is related to clinically significant elements), 2) construct validity (the classification predicts the outcome), and 3) inter-team validation (the classification applies to other surgical teams). Consecutive cases over a 1-year time span were retrospectively classified. Primary outcome measures included: complication rates (cranial nerve injury, stroke and vascular injury, cerebrospinal fluid [CSF] leak and infection), estimated blood loss and duration of surgery.

RESULTS

Two hundred and nine consecutive cases were analyzed. The distribution of cases for each category was: 63 cases in level II, 70 cases in level III, 66 cases in level IV, and 10 cases in level V. Construct validity demonstrated statistical difference with increasing rate of complications from level II to level III and from level III to level IV; also, specific rates of cranial nerve injury and CSF leak increased between levels III and IV. Face validity identified 162 citations since publication of the original article. Inter-team validation demonstrated no difference between two teams of surgeons.

CONCLUSION

This study provides a three-phase validation of training levels for endoscopic skull base surgery. Adoption of a progressive systematic approach to learning EES from least complex to advanced procedures is expected to minimize the risks while surgical teams gain experience.

LEVEL OF EVIDENCE

3 Laryngoscope, 129:2253-2257, 2019.

Watertight Robust Osteoconductive Barrier for Complex Skull Base Reconstruction: An Expanded-endoscopic Endonasal Experimental Study

Endoscopic skull base reconstruction (ESBR) following expanded-endoscopic endonasal approaches (EEA) in high-risk non-ideal endoscopic reconstructive candidates remains extremely challenging, and further innovations are still necessary. Here, the aim is to study the reconstructive knowledge gap following expanded-EEA and to introduce the watertight robust osteoconductive (WRO)-barrier as an alternative durable option. Distinctively, we focused on 10 clinical circumstances. A 3D-skull base-water system model was innovated to investigate the ESBR under realistic conditions. A large-irregular defect (31 × 89 mm) extending from the crista galli to the mid-clivus was achieved. Then, WRO-barrier was fashioned and its tolerance was evaluated under stressful settings, including an exceedingly high (55 cmH₂O) pressure, with radiological assessment. Next, the whole WRO-barrier was drilled to examine its practical-safe removal (simulating redo-EEA) and the whole experiment was repeated. Finally, WRO-barrier was kept into place to value its 18-month long-term high-tolerance. Results in all experiments of WRO-barriers were satisfactorily fashioned to conform the geometry of the created defect under realistic circumstances via EEA, tolerated an exceedingly high pressure without evidence of leak even under stressful settings, resisted sudden-elevated pressure, and remained in its position to maintain long-term watertight seal (18 months), efficiently evaluated with neuroimaging and simply removed-and-reconstructed when redo-EEA is needed. In conclusion, WRO-barrier as an osteoconductive watertight robust design for cranial base reconstruction possesses several distinct qualities that might be beneficial for patients with complex skull base tumours.

Audit of Complications in an Otolaryngology Led Skull-Base Surgical Practice

Objective  This study was aimed to classify and study complications of surgery of the cranial base, primarily from an otorhinolaryngology perspective. Design  This study was designed with consecutive cohort of skull base surgical cases. Setting  Tertiary referral academic center. Participants  Patients having skull-base surgery at a otorhinolaryngology based skull-base unit, from 2002 to 2015. Main Outcome Measures  Enumeration of complications is the main outcome of this study. Surgical procedures, categorized for complexity as per a unified system, are applicable to endoscopic and open procedures. Complications were categorized as per the British Association of Otolaryngologists coding of surgical complications. Complication classified as major if life-threatening, causing permanent disability, or compromising the result of surgery. Results  A total of 342 patients ( n  = 342) were operated; 13 patients' records were excluded due to < 6 months posttreatment follow-up. The study group constituted 204 anterior skull-base (endoscopic, 120; open/external, 84) and 125 lateral skull-base procedures. Complication rates noted to increase in both groups with increasing complexity of surgical intervention. Anterior skull-base surgery (total complications, 11%; major, 3%; death, 0.5%) noted to have significantly less surgical complications than lateral skull-base surgery (total complications, 33%; major, 15%; death, 1.6%; p  < 0.001). Among the anterior procedures no significant difference noted among endoscopic and external approaches when compared across similar surgical complexity. Conclusion  Despite improvement in surgical and perioperative care, the overall major complication rate in a contemporary otolaryngology led, primarily extradural, skull-base practice is noted at 8%. Perioperative mortality, though rare, was encountered in 1%. A standard method for categorization of surgical complexity and the grade of complications as reported here is recommended.

Acquisition of surgical skills for endoscopic ear and lateral skull base surgery: a staged training programme

SUMMARY

Endoscopic ear surgery is radically changing the treatment of several middle and inner ear pathology, but its learning presents well-known manual and technical difficulties. The aim of this paper is be to present a training programme based on a modular model of increased difficulties. The experience from 2007 to 2016 at the University Hospital of Modena and University Hospital of Verona was reviewed and analysed for further considerations and to establish stages of training. The increasing experience of expert surgeons who deal with this kind of surgery represented the main guide to establish the steps and progression of training. In addition, the potential risk of damage of vascular structures or nerves represents fundamental criteria for progression toward higher levels. Some not-mandatory skills were also suggested for stage of difficulty. Five stages of training were deemed appropriate for progressive learning of endoscopic ear and lateral skull base surgery, ranging from simple middle and external ear procedures to surgery of inner ear and internal auditory canal. Mastering of each level is suggested before attempting procedures at a higher level, in particular for procedures involving lateral skull base. Standardisation and adoption of modular incremental training are expected to facilitate improvement of otolaryngologists and neurosurgeons starting with endoscopic middle ear and lateral skull base surgery. Adherence to such a programme during the growth phase may potentially decrease the rate of complications, making the training programme safer.

Comparison of Complications, Trends, and Costs in Endoscopic vs Microscopic Pituitary Surgery: Analysis From a US Health Claims Database

BACKGROUND

Microsurgical and endoscopic techniques are commonly utilized surgical approaches to pituitary pathologies. There are limited data comparing these 2 procedures.

OBJECTIVE

To evaluate postoperative complications, associated costs, and national and regional trends of microscopic and endoscopic techniques in the United States employing a nationwide database.

METHODS

The Truven MarketScan database 2010 to 2014 was queried and Current Procedural Terminology codes identified patients that underwent microscopic and/or endoscopic transsphenoidal pituitary surgery. International Classification of Diseases codes identified postoperative complications. Adjusted logistic regression and matched propensity analysis evaluated independent odds for complications.

RESULTS

Among 5886 cases studied, 54.49% were microscopic and 45.51% endoscopic. The commonest surgical indications were benign pituitary tumors. Annual trends showed increasing utilization of endoscopic techniques vs microscopic procedures. Postoperative complications occurred in 40.04% of cases, including diabetes insipidus (DI; 16.90%), syndrome of inappropriate antidiuretic hormone (SIADH; 2.02%), iatrogenic hypopituitarism (1.36%), fluid/electrolyte abnormalities (hypoosmolality/hyponatraemia [5.03%] and hyperosmolality/hypernatraemia [2.48%]), and cerebrospinal fluid (CSF) leaks (CSF rhinorrhoea [4.42%] and other CSF leak [6.52%]). In our propensity-based model, patients that underwent endoscopic surgery were more likely to develop DI (odds ratio [OR] = 1.48; 95% confidence interval [CI] = 1.28-1.72), SIADH (OR = 1.53; 95% CI = 1.04-2.24), hypoosmolality/hyponatraemia (OR = 1.17; 95% CI = 1.01-1.34), CSF rhinorrhoea (OR = 2.48; 95% CI = 1.88-3.28), other CSF leak (OR = 1.59; 95% CI = 1.28-1.98), altered mental status (OR = 1.46; 95% CI = 1.01-2.60), and postoperative fever (OR = 4.31; 95% CI = 1.14-16.23). There were no differences in hemorrhagic complications, ophthalmological complications, or bacterial meningitis. Postoperative complications resulted in longer hospitalization and increased healthcare costs.

CONCLUSION

Endoscopic approaches are increasingly being utilized to manage sellar pathologies relative to microsurgery. Postoperative complications occur in both techniques with higher incidences observed following endoscopic procedures.

Endoscopic Endonasal Clipping of Anterior Circulation Aneurysm: Surgical Techniques and Results

BACKGROUND

Endoscopic endonasal clipping of intracranial aneurysms may use microsurgical techniques as an alternative to the transcranial approach. Here we report a series of patients who underwent microsurgical clipping of anterior circulation aneurysms via an endoscopic endonasal approach (EEA).

METHODS

This retrospective chart review included all the patients who underwent standard binostril EEA for aneurysm clipping. Surgical outcomes and complications are noted. The rationality and limitations of this procedure are discussed.

RESULTS

Seven patients with 12 aneurysms of the anterior circulation underwent EEA for clipping. These 12 aneurysms consisted of 5 anterior communicating artery (AComA) aneurysms, 4 paraclinoid aneurysms, 1 ophthalmic artery aneurysm, and 2 aneurysm located in the cavernous segment of internal carotid artery (ICA). Nine of the 12 aneurysms were successfully clipped. One giant paraclinoid aneurysm could not be clipped during operation and was coiled in second endovascular stage. The 2 aneurysms located in the cavernous segment of ICA were not clipped intentionally in a single-stage procedure, after weighing the surgical benefit against the difficulty of surgical exposure and feasibility. The proximal control of ICA was achieved in all cases. There was no death, no cerebrospinal fluid leak, or other complications. All patients recovered completely.

CONCLUSIONS

EEA can provide direct access for microsurgical clipping of strictly selected anterior circulation aneurysms. All the principles of cerebrovascular surgery must be followed. These procedures require a long learning curve. Only teams with adequate experience in microvascular and endoscopic skull base surgeries should attempt this approach for treating aneurysms.

Establishment of Next-Generation Neurosurgery Research and Training Laboratory with Integrated Human Performance Monitoring

Quality of neurosurgical care and patient outcomes are inextricably linked to surgical and technical proficiency and a thorough working knowledge of microsurgical anatomy. Neurosurgical laboratory-based cadaveric training is essential for the development and refinement of technical skills before their use on a living patient. Recent biotechnological advances including 3-dimensional (3D) microscopy and endoscopy, 3D printing, virtual reality, surgical simulation, surgical robotics, and advanced neuroimaging have proved to reduce the learning curve, improve conceptual understanding of complex anatomy, and enhance visuospatial skills in neurosurgical training. Until recently, few means have allowed surgeons to obtain integrated surgical and technological training in an operating room setting. We report on a new model, currently in use at our institution, for technologically integrated surgical training and innovation using a next-generation microneurosurgery skull base laboratory designed to recreate the setting of a working operating room. Each workstation is equipped with a 3D surgical microscope, 3D endoscope, surgical drills, operating table with a Mayfield head holder, and a complete set of microsurgical tools. The laboratory also houses a neuronavigation system, a surgical robotic, a surgical planning system, 3D visualization, virtual reality, and computerized simulation for training of surgical procedures and visuospatial skills. In addition, the laboratory is equipped with neurophysiological monitoring equipment in order to conduct research into human factors in surgery and the respective roles of workload and fatigue on surgeons' performance.

Nasoseptal Flap for Skull Base Reconstruction in Children

Objective  The endoscopic endonasal approach is being increasingly used for the resection and reconstruction of anterior skull base (ASB) lesions. Vascularized nasoseptal flaps (NSF) have become the workhorse for the reconstruction of ASB defects, resulting in a significant decrease in the incidence of cerebrospinal fluid (CSF) leaks. The objective of this study was to investigate the efficacy and safety of NSF in children. Methods  This is a retrospective analysis of the medical records of all patients under the age of 18 years who underwent endoscopic repair of ASB lesions with the use of NSF at our tertiary medical center between 1/2011 and 8/2016. Results  Twelve children underwent ASB defect repair for both benign and malignant neoplasms using the endoscopic endonasal NSF technique. Four children had previously undergone ASB surgery. The male-to-female ratio was 1:1, the average age was 12.3 years, the average hospitalization time was 8.3 days, and the maximum follow-up period was 24 months, during which craniofacial growth appeared to be unimpaired. A lumbar drain was used postoperatively in six cases. Crust formation and synechia were observed in two cases. There was one case of a major long-term complication (a CSF leak followed by meningitis). Conclusions  Endoscopic endonasal NSF was both an effective and a safe technique for ASB defect reconstruction in 12 children for both benign and malignant neoplasms. It had a high success rate and a low complication rate. No apparent negative influence on craniofacial growth was observed in our series.

Objective Validation of Perfusion-Based Human Cadaveric Simulation Training Model for Management of Internal Carotid Artery Injury in Endoscopic Endonasal Sinus and Skull Base Surgery

BACKGROUND

The emergence of minimally invasive endoscopic endonasal skull base surgery has necessitated reproducible and realistic simulators of rare vascular injuries.

OBJECTIVE

To assess the face and content validity of an innovative perfusion-based cadaveric model developed to simulate internal carotid artery (ICA) injury during endoscopic surgery.

METHODS

Otolaryngology and neurosurgery trainees attempted 3 consecutive trials of endoscopic control of a parasellar ICA injury, with standardized technical feedback. Time to hemostasis (TTH) and blood loss were trended. All participants completed validated questionnaires using a 5-point Likert scale to assess the domains of confidence gain, face validity, content validity, and curriculum applicability.

RESULTS

Among all participants (n = 35), TTH and mean blood loss significantly decreased between first vs second attempt (P = .005), and first vs third attempt (P = .03). Following the first attempt, trainees experienced an average 63% reduction in blood loss and 59% reduction in TTH. In the quartile of most improved participants, average blood loss reduction was 1115 mL (84% reduction) and TTH of 259 s (84% reduction). There were no significant differences between trainees of varying postgraduate year or specialty. Average pre and postprocedural confidence scores were 1.38 and 3.16, respectively (P &lt; .0001). All trainees reported model realism, which achieved mean face validity 4.82 ± 0.41 and content validity 4.88 ± 0.33.

CONCLUSION

The perfusion-based human cadaveric ICA injury model achieves high ratings of face and content validity across all levels of surgical trainees, and enables safe, realistic simulation for standardized skull base simulation and future curriculum development. Objective improvements in performance metrics may translate to improved patient outcomes.