Evolution of Endoscopic Skull Base Surgery, Current Concepts, and Future Perspectives

Multicenter Survival Analysis and Application of an Olfactory Neuroblastoma Staging Modification Incorporating Hyams Grade

Importance

Current olfactory neuroblastoma (ONB) staging systems inadequately delineate locally advanced tumors, do not incorporate tumor grade, and poorly estimate survival and recurrence.

Objective

The primary aims of this study were to (1) examine the clinical covariates associated with survival and recurrence of ONB in a modern-era multicenter cohort and (2) incorporate Hyams tumor grade into existing staging systems to assess its ability to estimate survival and recurrence.

Design, Setting, and Participants

This retrospective, multicenter, case-control study included patients with ONB who underwent treatment between January 1, 2005, and December 31, 2021, at 9 North American academic medical centers.

Intervention

Standard-of-care ONB treatment.

Main Outcome and Measures

The main outcomes were overall survival (OS), disease-free survival (DFS), and disease-specific survival (DSS) as C statistics for model prediction.

Results

A total of 256 patients with ONB (mean [SD] age, 52.0 [15.6] years; 115 female [44.9%]; 141 male [55.1%]) were included. The 5-year rate for OS was 83.5% (95% CI, 78.3%-89.1%); for DFS, 70.8% (95% CI, 64.3%-78.0%); and for DSS, 94.1% (95% CI, 90.5%-97.8%). On multivariable analysis, age, American Joint Committee on Cancer (AJCC) stage, involvement of bilateral maxillary sinuses, and positive margins were associated with OS. Only AJCC stage was associated with DFS. Only N stage was associated with DSS. When assessing the ability of staging systems to estimate OS, the best-performing model was the novel modification of the Dulguerov system (C statistic, 0.66; 95% CI, 0.59-0.76), and the Kadish system performed most poorly (C statistic, 0.57; 95% CI, 0.50-0.63). Regarding estimation of DFS, the modified Kadish system performed most poorly (C statistic, 0.55; 95% CI, 0.51-0.66), while the novel modification of the AJCC system performed the best (C statistic, 0.70; 95% CI, 0.66-0.80). Regarding estimation of DSS, the modified Kadish system was the best-performing model (C statistic, 0.79; 95% CI, 0.70-0.94), and the unmodified Kadish performed the worst (C statistic, 0.56; 95% CI, 0.51-0.68). The ability for novel ONB staging systems to estimate disease progression across stages was also assessed. In the novel Kadish staging system, patients with stage VI disease were approximately 7 times as likely to experience disease progression as patients with stage I disease (hazard ratio [HR], 6.84; 95% CI, 1.60-29.20). Results were similar for the novel modified Kadish system (HR, 8.99; 95% CI, 1.62-49.85) and the novel Dulguerov system (HR, 6.86; 95% CI, 2.74-17.18).

Conclusions and Relevance

The study findings indicate that 5-year OS for ONB is favorable and that incorporation of Hyams grade into traditional ONB staging systems is associated with improved estimation of disease progression.

Anatomical Workspace Study of Endonasal Endoscopic Transsphenoidal Approach

Purpose

To determine the workspace through an anatomical dimensional study of the skull base to further facilitate the design of the robot for endonasal endoscopic transsphenoidal (EET) surgery.

Methods

There were 120 cases having a paranasal sinus CT scan in the database. The internal volumes of the nasal cavities (NC), the volumes of the sphenoid sinuses (SS), and the distance between the anterior nasal spine and base of the sellar (d-ANS-BS) were measured.

Results

The Pearson correlation coefficient (PCC) between the relevant distances and the volumes of the right NC was 0.32; between the relevant distances and the volumes of the left NC was 0.43; and between the relevant distances and volumes of NC was 0.41; with a statistically significant difference (p < 0.001). All PCCs had a statistically significant meaningful difference (p < 0.05).

Conclusion

The volume of NCs were significantly correlated with distances (p < 0.05). The safest and shortest distance to guide the robotic arm length in the EET approach could be represented by d-ANS-BS. This result was also used as primary information for further robotic design.

Systematic Review of the Effectiveness of Perioperative Prophylactic Antibiotics for Skull Base Surgeries

Background

Perioperative antibiotics are commonly used in endoscopic skull base surgeries as prophylaxis for infectious complications, e.g., meningitis. The role of perioperative prophylactic antibiotics in endoscopic sinus surgery is unclear, and the routine use of prophylactic antibiotics in endoscopic skull base surgery is also highly debated. Currently, there is no formal recommendation for perioperative antibiotic use in skull base surgery, and regimens vary greatly from one institution to the next.

Objective

To assess perioperative antibiotics as prophylaxis against infectious complications in patients who underwent endoscopic skull base surgery.

Data Sources

PubMed, Ovid EMBASE, and the Cochrane Library.

Methods

A systematic review that examined perioperative antibiotic use in endoscopic skull base and craniofacial surgeries was conducted. Inclusion criteria were prospective or retrospective study design and clinical trials related to the use of antibiotics within 30 days of skull base surgery. End points included infectious complications such as (1) meningitis and (2) sinusitis.

Results

A total of 2543 articles were identified by the initial search, and 5 articles met inclusion criteria. The five eligible trials were all observational and involved different types of skull base surgical procedures and antibiotic regimens.

Conclusions

Despite institutional variability in antibiotic regimens, meningitis rarely occurs after skull base procedures and seems to be encountered most frequently in open craniofacial surgeries. A systematic review revealed a limited number of published studies, all observational in study design, which precluded a formal meta-analysis. A novel large-scale randomized-controlled clinical trial is needed to evaluate antibiotic selection and need in endoscopic skull base surgery.

Molecular typing of Meningiomas by Desorption Electrospray Ionization Mass Spectrometry Imaging for Surgical Decision-Making

Meningiomas are the most frequent intracranial tumors. The majority is benign slow-growing tumors but they can be difficult to treat depending on their location and size. While meningiomas are well delineated on magnetic resonance imaging by their uptake of contrast, surgical limitations still present themselves from not knowing the extent of invasion of the dura matter by meningioma cells. The development of tools to characterize tumor tissue in real or near real time could prevent recurrence after tumor resection by allowing for more precise surgery, i.e. removal of tumor with preservation of healthy tissue. The development of ambient ionization mass spectrometry for molecular characterization of tissue and its implementation in the surgical decision-making workflow carry the potential to fulfill this need. Here, we present the characterization of meningioma and dura mater by desorption electrospray ionization mass spectrometry to validate the technique for the molecular assessment of surgical margins and diagnosis of meningioma from surgical tissue in real-time. Nine stereotactically resected surgical samples and three autopsy samples were analyzed by standard histopathology and mass spectrometry imaging. All samples indicated a strong correlation between results from both techniques. We then highlight the value of desorption electrospray ionization mass spectrometry for the molecular subtyping/subgrouping of meningiomas from a series of forty genetically characterized specimens. The minimal sample preparation required for desorption electrospray ionization mass spectrometry offers a distinct advantage for applications relying on real-time information such as surgical decision-making. The technology here was tested to distinguish meningioma from dura mater as an approach to precisely define surgical margins. In addition we classify meningiomas into fibroblastic and meningothelial subtypes and more notably recognize meningiomas with NF2 genetic aberrations.

Immediate postoperative imaging after uncomplicated endoscopic approach to the anterior skull base: is it necessary?

BACKGROUND

Postoperative imaging is frequently performed to assess for intracranial complications following anterior skull base (ASB) surgery. However, there is little data to suggest that radiologic studies change the management of complications. In this study, the utility of postoperative imaging within 72 hours after uncomplicated ASB surgery was examined.

METHODS

A retrospective review was conducted of 143 patients who underwent endoscopic ASB surgery between 2007 and 2013 at Loyola University Medical Center. The main outcomes measures included the ability of head computed tomography (CT) scan to identify postoperative complications and hallmark symptoms associated with complications.

RESULTS

Seventy-nine patients underwent postoperative imaging within 72 hours of the initial surgery. The most common finding was pneumocephalus (35/79; 44%). Expanding pneumocephalus requiring surgical intervention developed in 3 cases. Cerebrospinal fluid (CSF) leak was the most common complication, occurring in 22 of 143 (15%) of the patients. Of the 24 patients who developed a postoperative complication, all had clinical signs or symptoms indicative of the need for surgical or medical intervention. The positive predictive value for a head CT scan to detect a complication was 12%, negative predictive value was 92%, and sensitivity and specificity were 63% and 48%, respectively.

CONCLUSION

Routine postoperative imaging may be unnecessary after uncomplicated endoscopic ASB surgery because (1) it may not alter patient management; (2) it may not detect the most common complication (CSF leak); and (3) when imaging is positive, the patient has clinical symptoms suggesting a need for intervention.

Fibrin sealants: surgical hemostat, sealant and adhesive

INTRODUCTION

Fibrin sealants (FS) have been approved for use in the United States since 1998. Since approval, they have been used in a wide variety of clinical settings and new products continue to be introduced.

AREAS COVERED

This review covers the literature supporting the USA FDA-approved indications for FS products produced by Baxter Corp. Literature review of PubMed, the Cochrane Library, FDA approval documents and product websites yielded information contained in this article. Mechanism of action, efficacy and safety of these products are covered.

EXPERT OPINION

FS are generally safe, popular and are used for a wide variety of off-label indications. Their use appears to be expanding rapidly. For many uses, including approved ones, large well-controlled trials are still needed. Additionally, cost-effectiveness data for these products would be a great benefit in guiding their future use.

Structural pedicled mucochondral-osteal nasoseptal flap: a novel method for orbital floor reconstruction after sinonasal and skull base tumor resection

Unrepaired orbital floor defects after sinonasal and skull-base tumor resection can lead to herniation of orbital contents into the maxillary or ethmoidal sinuses, possibly resulting in infection and significant cosmetic and functional deficits. Orbital floor defects are usually repaired using prosthetic implants or autogenous material. Nasal septal cartilage has been used previously as a free graft for reconstruction. However, its reliance on local vascular supply can result in ischemia and necrosis in the postoperative period. The vascularized pedicled nasoseptal flap, consisting of mucoperichondrium and mucoperiosteum, is routinely used as an effective reconstruction method for endoscopic repair of cerebrospinal fluid leaks arising from skull base dural defects. However, this flap does not provide rigid structural reconstruction when used alone. We report a case of an orbital floor defect repaired using a pedicled mucochondral-osteal nasoseptal flap. This technique incorporates the structural component of the nasal septal cartilage and bone with the vascularized pedicled nasoseptal flap. This repair technique may be useful in patients requiring postoperative radiotherapy.

A robot for transnasal surgery featuring needle-sized tentacle-like arms

This paper discusses a new class of robots known as concentric tube robots and their application to transnasal skull base surgery. The endonasal approach has clear benefits for patients, but the surgery presents challenges that strongly motivate the use of robotic tools. In this paper, the concentric tube robot concept is described, and preliminary experimental results for transnasal skull base surgery are reviewed. Just as the da Vinci robot has revolutionized many laparoscopic surgeries, we expect concentric tube robots will enable the advancement of skull base surgery and the development of other minimally invasive procedures that require access through constrained paths.

A Telerobotic System for Transnasal Surgery

Mechanics-based models of concentric tube continuum robots have recently achieved a level of sophistication that makes it possible to begin to apply these robots to a variety of real-world clinical scenarios. Endonasal skull base surgery is one such application, where their small diameter and tentacle like dexterity are particularly advantageous. In this paper we provide the medical motivation for an endonasal surgical robot featuring concentric tube manipulators, and describe our model-based design and teleoperation methods, as well as a complete system incorporating image-guidance. Experimental demonstrations using a laparoscopic training task, a cadaver reachability study, and a phantom tumor resection experiment illustrate that both novice and expert users can effectively teleoperate the system, and that skull base surgeons can use the robot to achieve their objectives in a realistic surgical scenario.

Robotic surgery for the sinuses and skull base: what are the possibilities and what are the obstacles?

PURPOSE OF REVIEW

Robotic surgery in otolaryngology - head and neck surgery has become a valuable tool in certain anatomic approaches; however, its application in surgery of the paranasal sinuses and anterior skull base is still in an investigatory phase and requires further evaluation.

RECENT FINDINGS

Existing robotic surgical systems face particular limitations in their application at the skull base because of instrument size and lack of variability. Unfortunately, only one system is available commercially that is applicable in the head and neck region and FDA approved for use in patients. This system, although advantageous in many otolaryngologic procedures, is difficult to use for endoscopic sinus and skull base surgery. However, other systems that target this anatomic subsite specifically are in development and show promise. Advances in the design of robotic arms, materials, and shape will potentially give surgeons a significant advantage over traditional endoscopic techniques.

SUMMARY

This article will review the current applications of robotic systems in paranasal sinus and skull base surgery, describe the requirements of a robotic system for use in this type of surgery, and describe a system under development at our institution.

The role of intraoperative magnetic resonance imaging in complex meningioma surgery

Intraoperative magnetic resonance imaging (iMRI) has gained importance in the treatment of gliomas and sellar tumors. In intracranial meningiomas, the extent of surgical tumor removal is one of the most important factors in the prevention of tumor recurrence and patient survival. Complex meningiomas located at the skull base or near eloquent brain regions show higher recurrence rates, morbidity and mortality. The aim of this study was to evaluate whether iMRI contributes to more extensive surgical resection in these tumors. Patients undergoing complex meningioma resection using iMRI from January 2007 to January 2011 were included in this study. The indication for iMRI-guided tumor resection included patients presenting with meningiomas located in the skull base or compressing eloquent brain areas in whom a radical resection was considered to be difficult. Intraoperative 0.15-T MRI scan (PoleStar; Medtronic Navigation, Louisville, CO, USA) was performed before and after maximal possible resection using standard microsurgical and neuronavigation techniques. All patients underwent fluorescence-guided resection. The following data were analyzed: tumor localization, histological grade, Simpson resection grade, duration of the procedure, iMRI scan time, iMRI findings, resection extent based on postresection iMRI, hospitalization time, surgical complications and outcome, and MRI follow-up 2-27months postoperation. Twenty-seven consecutive patients undergoing complex meningioma resection using iMRI were included. In this series, only one patient (3.4%) underwent resection of tumor remnant after iMRI, although without improvement of the Simpson resection grade. Temporary neurologic deficits were found in 8 patients (27.6%) postoperatively, whereas 11 patients (37.9%) had permanent postoperative neurologic deficits. In one case (3.4%), fatal postoperative bleeding occurred which was not detected by iMRI. Our results show that iMRI has no influence on intraoperative strategy in terms of resection grade or detection of early postoperative complications. The benefits of iMRI in complex meningioma surgery are therefore doubtful; however, it may still prove to be effective in certain subsets of complex meningiomas.

Celebrating the golden anniversary of anterior skull base surgery: reflections on the past 50 years and its historical evolution

With its inception nearly half a century ago through the pioneering work of Dandy, McLean, and Smith, anterior skull base (ASB) surgery is a relatively young discipline. It became a distinct entity in 1963 when Ketcham popularized the combined transcranial transfacial approach for en bloc resection of tumors of the paranasal sinuses extending into the anterior cranial fossa. However, because these procedures resulted in major morbidities and mortalities, alternative modes of treatment were sought. Since the 1970s, the introduction and promotion of the surgical endoscope by Messerklinger, Stammberger, and Kennedy, commenced the era of endoscopic sinus surgery. Thaler and colleagues described the utility of the endoscope for ASB surgery at the turn of the century. This allowed direct visualization and safer, more accurate removal of tumors. In 2001, Casiano reported the first purely endoscopic endonasal ASB resection, a novel technique that has been adopted by major skull base centers. The success of ASB surgery can be attributed to both the development of the skull base team as well as improvements in surgical techniques, instrumentation, and visualization technology. In this article, we review the historical evolution of ASB surgery as we approach the 50th anniversary since its recognition as a distinct entity.

Salvage endoscopic nasoseptal flap repair of persistent cerebrospinal fluid leak after open skull base surgery

PURPOSE

Persistent cerebrospinal fluid (CSF) rhinorrhea after open skull base surgery can be challenging to manage due to the risk of meningitis, brain abscess, surgical morbidity associated with revision craniotomy, and the lack of available healthy autologous tissue after failure of a pericranial flap. Given the recent success of the vascularized pedicled nasoseptal flap (PNSF) for reconstruction after endoscopic skull base surgery, we have adopted this technique as a salvage method to treat recalcitrant CSF rhinorrhea after previous open skull base surgery in order to avoid revision craniotomy. To our knowledge, use of the PNSF in this setting has not been previously described in the literature.

METHODS

A retrospective analysis was performed on 4 patients who underwent endoscopic endonasal PNSF repair of persistent CSF rhinorrhea after having undergone previous open transcranial skull base operation. Pathologies consisted of one sinonasal anterior skull base squamous cell carcinoma, one recurrent petrosal skull base meningioma, and 2 traumatic gunshot wounds to the head.

RESULTS

All 4 patients underwent successful repair of CSF rhinorrhea without complications using the salvage endoscopic endonasal PNSF technique after a mean follow-up of 21.5 months.

CONCLUSIONS

In patients who have undergone previous open skull base surgery as the primary approach, persistent CSF rhinorrhea can be safely repaired using the vascularized PNSF via an endoscopic endonasal approach. This minimally invasive strategy has the advantage of providing new healthy vascularized tissue for skull base reconstruction while avoiding revision craniotomy.

[Modern skull base surgery from the perspective of neurosurgeons]

At present, modern skull base surgery is a highly sophisticated interdisciplinary collaboration of various diagnostic and therapeutic disciplines. The overall goal is the treatment of complex tumorous, traumatic, vascular and inflammatory processes or developmental disorders of the skull base with preservation of function. The paper presents modern concepts, procedures and minimally invasive strategies in skull base surgery and also critically discusses the current trend to endoscopic and robot-assisted surgical techniques.