Cranial Base Surgery Research Articles

Improving Outcomes and Preventing Complications in Cranial Base Surgery

Skull base surgery has evolved remarkably since the pioneering techniques of early 20th-century surgeons, such as Schloffer and Cushing, who laid the foundation for transcranial and transnasal approaches [...]

The Endoscopic Transorbital Approach for Vascular Surgery: An Anterior Circulation Anatomic Study, 2-Dimensional Operative Video.

Minimally invasive endoscopic approaches in cranial base surgery have been developing in the past decades. The transorbital (TO) route is one promising alternative, yet its adequacy for intracranial vascular lesions remains unclear. The present anatomic work aimed to test the feasibility and to provide a qualitative description of the endoscopic TO approach for the anterior circulation, namely the internal carotid artery and the middle cerebral artery. Seven embalmed adult cadaveric specimens (12 sides) were used in the study. Each side was approached in 3 successive steps: (1) Superior-eyelid TO approach, with great and lesser sphenoid wing removal. (2) Removal of anterior clinoid process (ACP). (3) Removal of the lateral orbital rim. All the procedures were performed under endoscopic view. The TO approach without removing the ACP allowed to dissect the sphenoidal and lateral segments of the Sylvian fissure with an adequate identification of the middle cerebral artery bifurcation in all specimens. The removal of the ACP allowed further dissection toward the opticocarotid cistern, with the identification of the ophthalmic, posterior communicating, and the anterior choroidal arteries. The internal carotid artery bifurcation and A1 segment were also readily identified. Finally, removal of the lateral orbital rim provided a wider and more comfortable access to the above-mentioned vascular structures. According to our anatomic data, the TO approach can be used to reach the main vascular components of the anterior circulation. This opens the field for exploring its application in the treatment of vascular pathology, particularly aneurysms.

Computational image analysis of distortion, sharpness, and depth of field in a next-generation hybrid exoscopic and microsurgical operative platform.

The development of surgical microscope-associated cameras has given rise to a new operating style embodied by hybrid microsurgical and exoscopic operative systems. These platforms utilize specialized camera systems to visualize cranial neuroanatomy at various depths. Our study aims to understand how different camera settings in a novel hybrid exoscope system influence image quality in the context of neurosurgical procedures. We built an image database using captured cadaveric dissection images obtained with a prototype version of a hybrid (microsurgical/exoscopic) operative platform. We performed comprehensive 4K-resolution image capture using 76 camera settings across three magnification levels and two working distances. Computer algorithms such as structural similarity (SSIM) and mean squared error (MSE) were used to measure image distortion across different camera settings. We utilized a Laplacian filter to compute the overall sharpness of the acquired images. Additionally, a monocular depth estimation deep learning model was used to examine the image's capability to visualize the depth of deeper structures accurately. A total of 1,368 high-resolution pictures were captured. The SSIM index ranged from 0.63 to 0.85. The MSE was nearly zero for all image batches. It was determined that the exoscope could accurately detect both the sharpness and depth based on the Laplacian filter and depth maps, respectively. Our findings demonstrate that users can utilize the full range of camera settings available on the exoscope, including adjustments to aperture, color saturation, contrast, sharpness, and brilliance, without introducing significant image distortions relative to the standard mode. The evolution of the camera incorporated into a surgical microscope enables exoscopic visualization during cranial base surgery. Our result should encourage surgeons to take full advantage of the exoscope's extensive range of camera settings to match their personal preferences or specific clinical requirements of the surgical scenario. This places the exoscope as an invaluable asset in contemporary surgical practice, merging high-definition imaging with ergonomic design and adaptable operability.

Correlation Analysis on Anatomical Variants of Accessory Foramina in the Sphenoid Bone for Oncological Surgery.

The sphenoid bone presents several anatomical variations, including accessory foramina, such as the foramen meningo-orbitale, the foramen of Vesalius, the canaliculus innominatus and the palatovaginal canal, which may be involved in tumor invasion or surgery of surrounding structures. Therefore, clinicians and surgeons have to consider these variants when planning surgical interventions of the cranial base. The prevalence of each variant is reported in the published literature, but very little information is available on the possible correlation among different variants. Here, 300 CT scans of patients (equally divided among males and females) were retrospectively assessed to investigate the presence of the foramen meningo-orbitale, the foramen of Vesalius, the canaliculus innominatus and the palatovaginal canal. Possible differences in the prevalence of each accessory foramen according to sex were assessed, as well as possible correlations among different variants through the Chi-square test (p < 0.01). Overall, the prevalence of the foramen meningo-orbitale, the foramen of Vesalius, the canaliculus innominatus and the palatovaginal canal was 30.7%, 67.7%, 14.0% and 35.3%, respectively, without any difference according to sex (p > 0.01). A significant positive correlation was found between the foramen of Vesalius and canaliculus innominatus, both in males and in females (p < 0.01). In detail, subjects with canaliculus innominatus in 85.7-100.0% of cases also showed the foramen of Vesalius, independently from sex and side. The present study provided novel data about the prevalence of four accessory foramina of the sphenoid bone in an Italian population, and a correlation between the foramen of Vesalius and the canaliculus innominatus was found for the first time. As these accessory foramina host neurovascular structures, the results of this study are thus useful for appropriate planning surgical procedures that are tailored to the anatomical configuration of the patient and for improving techniques to avoid accidental injuries in cranial base surgery. Knowledge of the topography, frequencies and the presence/absence of these additional foramina are pivotal for a successful procedure. Clinicians and surgeons may benefit from these novel data for appropriate recognition of the variants, decision-making, pre-operative and treatment planning, improvement of the procedures, screening of patients and prevention of misdiagnosis.

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

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

The comparison of the watertight and non-watertight dural closure in supratentorial craniotomy: A single-institute 10-year experience with 698 patients.

Watertight dural closure (WTDC) is considered crucial by many neurosurgeons in cranial base surgery, infratentorial craniotomy, and spinal intradural procedure. Whether WTDC also reduce complications remains controversial in supratentorial craniotomy. The objective of this study is to investigate the relationship between WTDC and CSF-related complications in supratentorial craniotomy for the resection of space-occupying lesions. A retrospective analysis of patients who suffered from intracranial space-occupying lesions at Beijing Ditan Hospital between January 2011 and December 2021 was conducted. A total of 698 cases were reviewed with attention to the operative approach, subgaleal fluid collection, wound healing impairment, postoperative infection, and post-craniotomy headaches. The study included a total of 423 patients with WTDC and 275 patients without WTDC. Patients without WTDC had a significantly higher rate of infection (10.9% vs 4.5% with WTDC, P = .001). The rate of subgaleal fluid collection was 9.7% in the WTDC group and 11.3% in the non-WTDC group, but this difference was not statistically significant (P = .502). They suffered from a greater incidence of post-craniotomy headaches in the WTDC group (13.5% vs 9.5% in the non-WTDC group), but without statistical significance (P = .109). We also found no difference in wound healing impairment (P = .719). There is less postoperative infection associated with WTDC during intracranial space-occupying lesion removal than without WTDC in supratentorial craniotomy.

Quality of Life Considerations in Endoscopic Endonasal Management of Anterior Cranial Base Tumors.

Considering quality of life (QOL) is critical when discussing treatment options for patients undergoing endoscopic endonasal skull base surgery (EESBS) for cancers at the base of the skull. Several questionnaires have been developed and validated in the last 20 years to explore QOL in this patient population, including the Anterior Skull Base Questionnaire, Skull Base Inventory, EESBS Questionnaire, and the Sino-Nasal Outcome Test for Neurosurgery. The Sino-Nasal Outcomes Test-22 and Anterior Skull Base Nasal Inventory-12 are other tools that have been used to measure sinonasal QOL in anterior cranial base surgery. In addition to pathology-related perturbations in QOL endoscopic surgical options (transsellar approaches, anterior cranial base surgery, and various reconstructive techniques) all have unique morbidities and QOL implications that should be considered. Finally, we look ahead to new and emerging techniques and tools aimed to help preserve and improve QOL for patients with anterior cranial base malignancies.

The current status of nanotechnological approaches to therapy and drug delivery in otolaryngology: A contemporary review.

To summarize the current standing of nanomedicine-based technology, particularly nanoparticles (NPs), for drug delivery and diagnostic mechanisms in otolaryngology and the otolaryngology subspecialties. Literature searches were performed using PubMed and Ovid MEDLINE from 2010 to 2022. The search focused on original articles describing developments and applications of nanotechnology and drug delivery in otology, neurotology, cranial base surgery, head and neck oncology, laryngology, bronchoesophagology, and rhinology. Keyword searches and cross-referencing were also performed. No statistical analysis was performed. The PubMed search yielded 29 articles, and two Ovid MEDLINE searches both yielded 7 and 26 articles, respectively. Cross-referencing and keyword searches in PubMed and Google Scholar yielded numerous articles. The results indicate that currently, NPs are the most thoroughly studied nanotechnology for drug delivery and therapy in otolaryngology. Organic NPs have been utilized for drug delivery in otology and head and neck oncology due to their high biocompatibility. Inorganic NPs have similarly been utilized for drug delivery. However, inorganic NPs seem to be studied less extensively in these fields, likely due to an increased risk for heavy metal toxicity. Due to their magnetic properties, inorganic NPs have been utilized for magnetic-guided delivery in otology and thermoradiation and magnetic resonance imaging in head and neck oncology. Applications of nanotechnology to the fields of laryngology, bronchoesophagology, and rhinology have been studied less compared with otology and head and neck oncology. However, researchers have primarily employed NPs and other nanotechnologies such as nanofibers and nanoclusters for drug elution at mucosal surfaces to reduce airway and nasal inflammation. Nanomedicine offers potential benefits in the treatment of patients in the field of otolaryngology due to enhanced control over drug release, cell-specific targeting, and the potential to reduce drug toxicity. Future work is needed to ensure the safety of these therapies to integrate this field of research into human therapies.

Enabling personalization of a robotic surgery procedure via a surgery training simulator

AbstractAlthough robotic or robot-assisted surgery has been increasingly used by many surgical disciplines, its application in cranial or skull base surgery is still in its infancy. Master-slave teleoperation setting of these robotic systems enables these surgical procedures to be replicated in a virtual reality environment for surgeon training purposes. A variety of teleoperation modes were previously determined with respect to the motion capability of the surgeon’s hand that wears the ring as the surgeon handles a surgical tool inside the surgical workspace. In this surgery training simulator developed for a robot-assisted endoscopic skull base surgery, a new strategy is developed to identify the preferred motion axes of the surgeon. This simulator is designed specifically for tuning the teleoperation system for each surgeon via the identification. This tuning capability brings flexibility to adjust the system operation with respect to the motion characteristics of the surgeon.

A Tribute to Our Teacher and Collogue, Prof. Jacob Sade´.

Otology & Neurotology publishes original articles relating to both clinical and basic science aspects of otology, neurotology, and cranial base surgery. As the foremost journal in its field, it has become the favored place for publishing the best of new science relating to the human ear and its diseases. The broadly international character of its contributing authors, editorial board, and readership provides the Journal its decidedly global perspective.

Cerebrospinal fluid rhinorrhea following COVID-19 nasal swab testing: case report

The COVID-19 pandemic has led to widespread adoption of screening tests to quickly and accurately diagnose disease. Nasopharyngeal swab tests are among the most common utilized. We present a case of a 58 year old female who suffered a cerebrospinal fluid leak from a bony defect in the sphenoid sinus immediately following a pre-procedural COVID screening test with subsequent development of meningitis. Providers should be aware of this potential risk of nasopharyngeal swab collection. Alternate COVID screening tests may be considered in patients with a history of sinonasal or cranial base surgery.

Salvage Procedures for Facial Reanimation With Neurovascular Flaps When Previous Surgeries Failed: Is Homolateral Vessel or Nerve Depletion a Contraindication?

Facial paralysis reconstruction can be difficult in extensive defects after complex facial or cranial base tumor resection and radiotherapy or when primary smile reanimation attempt has failed. The surgical challenge is more complicated when defects are associated with recipient vessels or nerves depletion. This scenario has not been well described in the literature, and the present article will address the alternatives that plastic surgeons may use in these circumstances. Seventy-five patients operated in the Hospital Gregorio Marañon between 2008 and 2020, for dynamic reconstruction of facial paralysis, were retrospectively evaluated, collecting data about previous facial nerve surgeries, radiotherapy, chemotherapy, recipient nerve for motor restoration and vessels used for free flaps, type of neurovascular free flap (NVFF), and functional score before and after the facial reanimation surgery. Patients presenting recipient vessel and/or nerve depletion after several facial surgeries requiring a variation from the common NVFF surgical protocol were included in this study. Six cases (8%) with facial paralysis and absent recipient homolateral vessels or nerves after severe cranial base surgery, parotid malignancies, or schwannoma surgery were included. Two patients had an immediate functional reconstruction during the oncologic resection surgery, and 4 patients had a delayed reconstruction. Three patients had previous reconstruction with free flaps, and the vascular pedicles of previous flaps were used for the new NVFF. In the other 3 cases, interposition vein grafts to the contralateral recipient vessels were required to perform NVFF. Masseteric nerve in 4 cases, hypoglossal nerve and posterior branch of the deep temporal nerve in 1 case each, were used as recipient nerves. House-Brackmann score improved in all patients after surgery. Neurovascular free flap can be successfully performed to restore facial motion after depletion of homolateral recipient vessels or nerves after previous facial or cranial base surgeries. In these cases, interposition vascular grafts or the pedicle of previous flaps are essential to provide vascularization as well as an optimal orientation of flaps, to reach recipient nerves in a 1-step procedure.

"NIMS" nasal mucoperiosteal flap for sublabial trans-sphenoidal surgical defect repair: A new technique under microscope.

Background: CSF rhinorrhea is a known complication that may occur after cranial base surgery, especially the trans-sphenoidal approaches to sellar tumors. It may occur following both microscopic and endoscopic procedures. Over a period, the balance has tilted toward endoscopy due to development of pedicled Hadad flap. Microscopic trans-sphenoidal surgery (TSS) continues to be performed in our institute as well as many other centers across the world due to familiarity of technique and unavailability of endoscopic equipment. Despite the fairly widespread use of this surgery, literature is devoid of any description of a local mucosal flap for repair of the surgical defect in microscopic TSS.Methods: We herein described the procedure and our experience of harvesting such flap in 42 patients operated for pituitary adenomas in our department between September 2016 and February 2020, through microscopic sublabial TSS.Results: All 42 of the patients included in this study underwent excision of pituitary tumors (macroadenomas). Thirty-nine (n = 39) patients were undergoing 1st time surgery, while three (n = 3) of these patients were undergoing second surgery following an earlier trans nasal trans-sphenoidal route. None of our cases have reported CSF leak postoperatively.Conclusion: This study attempts to highlight to ardent/obligate microscopic surgeons that a local vascularized flap can be harvested for repair of skull base defect and prevent postoperative CSF leak in microscopic sublabial TSS.

Sinonasal Symptom Outcomes following Endoscopic Anterior Cranial Base Surgery in the Pediatric Population.

Objective This study aimed to evaluate the impact of endoscopic anterior cranial base (ACB) surgery on sinonasal symptoms in the pediatric population utilizing the Sino-Nasal Outcome Test (SNOT)-22 questionnaire. Design This is a retrospective review. Setting The study was conducted at a tertiary academic medical center. Participants Thirty-four consecutive patients, age 6 to 17 years, M:F 14:20, who underwent endoscopic ACB surgery from July 2008 to August 2019. Ten patients had baseline and a minimum of two subsequent postoperative SNOT-22 questionnaires available for analysis. Main Outcome Measures Baseline and postoperative SNOT-22 scores were compared. The mean change from baseline sinonasal symptom scores in the pediatric and historical adult cohorts was compared. Results The mean baseline SNOT-22 score for our 10 patient cohort was 0.46 out of 5 for each of the first 10 sinonasal-specific questions. This worsened to 1.69 at 1 month and returned to near baseline, 0.7, at 3 months postoperatively. The mean quality-of-life score improved to 0.91 at 1 month and 0.6 at 3 months postoperatively. The mean change from baseline for the following items: need to blow nose, runny nose, postnasal discharge, thick nasal discharge, wake up at night, reduced concentration, and frustrated/restless/irritable were similar to those in our historical adult cohort at 3 months postoperatively. Conclusion Endoscopic ACB surgery in the pediatric population results in increased sinonasal symptom morbidity in the early postoperative period; however, symptoms return to near baseline by ∼3 months, and quality-of-life scores progressively improve in the postoperative period. These trends were similar to those seen in our historic adult cohort.

Resection of Foramen Magnum Meningioma through Modified Far Lateral Approach: Surgical Principles and Technical Nuances.

Objectives Safe maximal resection is the basic principle of cranial base surgery and the grade of resection is an important factor influencing the prognostic outcome. This operative video highlights the surgical principles and technical nuances in the microsurgical resection of foramen magnum meningioma (FMM). Case Description The surgery was performed in a 45-year-old lady who presented with hoarseness of voice and spastic quadriparesis (grade 4/5). On imaging, FMM with mass effect on brainstem and spinal cord was identified. The tumor was gross totally resected through modified far lateral approach with minimal occipital condyle drilling. This video demonstrates the surgical techniques of tumor resection including early devascularization, operating in the arachnoid plane to dissect the neurovascular structures, piecemeal decompression, sharp dissection to separate tumor from lower cranial nerves (LCN), identifying the brainstem veins, and resecting the lesion from tumor–brainstem interface. Postoperatively, she had significant neurological improvement and the magnetic resonance imaging revealed excellent radiological outcome ( Figs. 1 and 2 ). Conclusion The surgery of FMM is challenging due to the deep surgical corridor, critical location, close proximity with various neurovascular structures, firm consistency, and high vascularity of the tumor. The modified far lateral approach by preserving the occipital condyle may prevent the postoperative incidence of craniovertebral junction instability. The key operative principles to achieve the best surgical outcome include careful dissection along the arachnoid plane, gentle handling of cranial nerves, veins, and perforator vessels, avoidance of traction on brainstem and spinal cord, intraoperative neurophysiological monitoring, proper hemostasis, and meticulous dural closure. The link to the video can be found at: https://youtu.be/1qvAeUmNIUw .

Perioperative Considerations in Endoscopic Skull Base Surgery.

Purpose of the ReviewPresent an overview of perioperative considerations specific to endoscopic skull base surgery necessary to maximize successful outcomes.Recent FindingsThe 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.SummarySkull 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.

Teamwork in Cranial Base Surgery: A Feasible Task or a Utopian Dream.

In the past decade or perhaps a little earlier than that the concept of teamwork evolved among the circles of surgeons especially among those involved in complicated and time consuming surgeries. Skull base surgeries were one of those surgeries where the role of teamwork was acutely felt owing to innumerable specialties involved in the consummation of such surgeries. Although teamwork in this specialty is the need of the hour but, achieving the spirit of teamwork is not that easy and perhaps a challenging task. This manuscript tackles the much needed demand of teamwork in this arena of surgery and unveils whether such a teamwork is achievable or is just an utopian dream.

Book Review: Endoscopic and Keyhole Cranial Base Surgery

Book Review: Endoscopic and Keyhole Cranial Base Surgery

Letter to the Editor Regarding “Modified Endoscopic Diving Technique without the Traditional Irrigation System in Endoscopic Cranial Base Surgery: Technical Note”

Letter to the Editor Regarding “Modified Endoscopic Diving Technique without the Traditional Irrigation System in Endoscopic Cranial Base Surgery: Technical Note”

In Reply to the Letter to the Editor Regarding “Modified Endoscopic Diving Technique Without the Traditional Irrigation System in Endoscopic Cranial Base Surgery: Technical Note”

In Reply to the Letter to the Editor Regarding “Modified Endoscopic Diving Technique Without the Traditional Irrigation System in Endoscopic Cranial Base Surgery: Technical Note”