Endoscopic Skull Base Surgery Research Articles

Anterior Ethmoid Roof Configuration: A Computed Tomography Scan Analysis of Adult Nigerians with Chronic Rhinosinusitis

Abstract Context: The anterior skull base has been adjudged a high-risk area in endoscopic sinus and skull base surgery. Hence, an understanding of its complex anatomy is crucial if catastrophic intra-operative complications must be avoided. Aims: To identify the anatomical configurations of the anterior skull base by radiological analysis, and to determine the prevalence of its variations among adults with chronic rhinosinusitis. Settings and Design: A retrospective study of 99 adult patients with chronic rhinosinusitis who attended the Ear Nose and Throat clinic of Aminu Kano Teaching Hospital from July 2022 to June 2023. Methods and Materials: The patient’s records were retrieved, and the basic demographic data, clinical history, and examination findings were extracted. All patients had diagnostic nasal endoscopy, and computed tomography scans of the nose and paranasal sinuses which were analyzed using a computer software program. Statistical Analysis Used: The data was analyzed with SPSS version 22.0 using frequency, mean, Pearson Chi-square tests and the results were presented in tables and figures. Results: A total of 99 patients’ CT scans were analyzed. There were 61 males (61.6%) and 38 females 38.4%) with a mean age of 31.7 years. 37 (37.4%) and 62 (62.6%) of patients had asymmetry and symmetry in the fovea ethmoidalis respectively. The anterior ethmoid artery was found coursing through the anterior ethmoidal air cells in 73 (36.9%) and along the anterior skull base in 125 patients (63.1%). Kero’s classification showed types I in 140 (70.7%), type II in 54 (27.3%) and type III in 4 (2.0%). Conclusion: This study found that a significant proportion of the study population had ethmoid roof asymmetry and the anterior ethmoid artery was found coursing through the anterior ethmoidal air cells respectively.

Pilot Validation of a 3-Dimensional Printed Pituitary Adenoma, Vascular Injury, and Cerebrospinal Fluid Leak Surgical Simulator.

Endoscopic skull base surgery is a subspecialty field which would benefit significantly from high-fidelity surgical simulators. Giving trainees the opportunity to flatten their learning curve by practicing a variety of procedures on surgical simulators will inevitably improve patient outcomes. Four neurosurgeons, 8 otolarynologists, and 6 expert course faculty agreed to participate. All participants were asked to perform a transsphenoidal exposure and resection of a pituitary adenoma, repair a cerebrospinal fluid (CSF) leak, control a carotid injury, and repair a skull base defect. The content, face, and construct validity of the 3-dimensional printed model was examined. The heart rate of the participants significantly increased from baseline when starting the carotid injury simulation (mean 90 vs 121, P = .029) and significantly decreased once the injury was controlled (mean 121 vs 110, P = .033, respectively). The participants reported a significant improvement in anxiety in facing a major vascular injury, as well as an increase in their confidence in management of major vascular injury, resecting a pituitary adenoma and repair of a CSF leak using a 5-point Likert scale (mean 4.42 vs 3.58 P = .05, 2 vs 3.25 P < .001, 2.36 vs 4.27 P < .001 and 2.45 vs 4.0 P = .001, respectively). The mean Objective Structured Assessment of Technical Skills score for experienced stations was 4.4, significantly higher than the Objective Structured Assessment of Technical Skills score for inexperienced stations (mean 3.65, P = .016). We have demonstrated for the first time a validated 3-dimensional printed surgical simulator for endoscopic pituitary surgery that allows surgeons to practice a transsphenoidal approach, surgical resection of a pituitary adenoma, repair of a CSF leak in the diaphragma sellae, control of a carotid injury, and repair of skull base defect.

Diabetes Insipidus After Endoscopic Endonasal Pituitary Macroadenoma Resection, Correlation of Patient and Surgery-Related Risk Factors

Purpose: To identify patient and surgery related factors that could predict the development of postoperative central diabetes insipidus (CDI). Methods: This is a retrospective case-control study conducted at a single-institution tertiary referral center. Patients undergoing endoscopic endonasal skull base surgery for pituitary adenoma between November 2018 and April 2023 were recruited. The main outcome measures collected include age, gender, comorbidities, tumor type, postoperative diabetes insipidus, intraoperative and postoperative cerebrospinal fluid (CSF) leak, flow of CSF leak, number of layers required for repair, the use of nasal packing, and hospital length of stay. Results: A total of 20 patients developed DI postoperatively. Patients demographic and comorbidity profile did not correlate with DI development. The encounter of an intraoperative CSF leak was correlated with post-op DI (X2(1) =18.35, p&lt;0.001) with a RR of 2.7 (CI=1.37-5.28). The use of nasal packs was also correlated with post-op DI (X2(1) =10.17, p=0.001) with a RR of 1.8 (CI=1.15-2.87). Defects requiring a two or more layers for reconstruction also correlated with post-op DI compared to single layer repairs (X2(1) =12.15, p&lt;0.001) irrelevant of the materials used. Development of DI post-op correlated with an increased hospital length of stay (t(64) = -3.35, p =0.001). Conclusion: The physician should be careful when evaluating patients with pituitary adenomas in the postoperative period, particularly those with intraoperative CSF leak, nasal packing, and those who underwent multilayer reconstruction of the surgical defect.

Indocyanine green fluorescence visualizes landmark arteries for endoscopic sinus and skull base surgery

ObjectiveLandmark arteries during endoscopic sinus surgery are currently identified on the basis of anatomy, CT imaging and navigation, and Doppler flowmetry. However, the advantage of intraoperative fluorescence imaging during endoscopic sinus surgery has not been demonstrated. This study aimed to investigate whether Indocyanine Green (ICG) is useful for visualizing landmark arteries during endoscopic sinus and skull base surgery. MethodsEight patients who underwent endoscopic sinus and pituitary surgeries and consented to study participation were included. After planned procedures were performed as usual, landmark arteries were examined by ICG endoscope. Recorded video and preoperative CT images were analyzed for identification of five landmark arteries: anterior ethmoidal artery (AEA), posterior ethmoidal artery (PEA), internal carotid artery (ICA), sphenopalatine artery (SPA), and postnasal artery (PNA). Identification of arteries was evaluated three grades: identifiable, locatable, unrecognizable. ResultsEight patients and eleven sides were evaluated. The ICG dose was 2.5 mg/body and a single shot was sufficient for evaluation. 100 % of AEA was identified (9/9 sides), 86 % of PNA (6/7 sides), 56 % of ICA (5/9 sides), and 25 % of PEA and SPA (2/8 sides). ConclusionICG could visualize landmark arteries, even thin arteries like AEA, during endoscopic sinus and skull base surgeries. Visualization was affected by thickness of bone or soft tissue above arteries, blood clots, sensitivity setting, and angle and distance of near-infrared light irradiation. ICG visualization of landmark arteries may help avoid vascular injuries during endoscopic sinus and skull base surgeries, particularly of AEA, PNA and ICA.

Clinical outcomes for olfactory neuroblastoma.

Olfactory neuroblastoma (ONB) is a rare malignant tumor arising from the olfactory neuroepithelium. The standard of care for ONB is surgical resection; however, detailed treatment protocols vary by institution. Our treatment protocol consists of endoscopic skull base surgery (ESBS) for endoscopically resectable cases and induction chemotherapy followed by craniotomy combined with ESBS for locally advanced cases, with postoperative radiotherapy performed for all cases. Chemoradiotherapy (CRT) is performed in unresectable cases. In this study, we evaluate our treatment protocol and outcomes for ONB. A retrospective review of patients with ONB was conducted. Outcomes included survival outcomes and perioperative data. Fifteen patients (53.6%) underwent ESBS, 12 (42.9%) underwent craniotomy combined with ESBS, and 1 (3.6%) received CRT. The 5- and 10-year overall survival rates for all patients were 92.9% and 82.5%, respectively, with a median follow-up period of 81 months. The 5- and 10-year disease-free survival rates were 77.3% and 70.3%, respectively, and the 5- and 10-year local control rates were 88.2% and 80.2%, respectively. Patients undergoing ESBS demonstrated a significantly shorter operating time, period from operation to ambulation, hospitalization period, and less blood loss than those undergoing craniotomy combined with ESBS. Our treatment protocol was found to afford favorable outcomes. Patients who underwent endoscopic resection showed lower complication rates and better perioperative data than those who underwent craniotomy combined with ESBS. With appropriate case selection, ESBS is considered a useful approach for ONB.

Interdisciplinary Management of Skull Base Tumors.

Endoscopic endonasal skull base surgery has gained acceptance worldwide. Comparative analysis has demonstrated that endoscopic skull base surgery may have advantages for many pathologies of the anterior skull base, e. g., sinonasal malignant tumors; pathologies of the central skull base, e. g., pituitary adenomas, craniopharyngiomas; well-selected cases of planum sphenoidale and tuberculum sellae meningiomas; or for clival lesions, e. g., chordomas, chondrosarcomas, or selected meningiomas. Over the past three decades, interdisciplinary surgical teams, consisting of otolaryngologists and neurosurgeons, have provided detailed anatomical knowledge, suggested new approaches or modifications of established surgical techniques, and offered continued surgical education. A review of pertinent literature was conducted with an emphasis on interdisciplinary endoscopic surgery of skull base lesions. Based on the authors̓ surgical experience in two different interdisciplinary endoscopic skull base centers, the authors classify approaches for endoscopic endonasal skull base surgery, describe indications, and key anatomic landmarks for common pathologies, and highlight surgical techniques to avoid complications. Interdisciplinary endonasal endoscopic surgery combines surgical expertise, improves resection rates for many pathologies, and minimizes morbidity by reducing the incidence of surgical complications.

The importance of the palatine bone for endoscopic endonasal skull base surgery.

Endoscopic endonasal skull base surgery is increasingly prevalent, with its scope expanding from pathogens in the midline region to those in the paramedian region. Maximizing anterior sphenoidectomy is important for the median approach, and lateralizing the pterygopalatine fossa is crucial for the paramedian approach. Maximizing the surgical corridor in the nasal cavity and minimizing damage to neurovascular structures are vital for establishing a surgical field with minimal bleeding, ensuring safe, precise, and gentle procedures. However, the relationship between the maxillofacial and skull base bones in endoscopic endonasal skull base surgery is difficult to understand because these bones are intricately articulated, making it challenging to visualize each bone's outline. Understanding important bones and their related neurovascular structures is essential for all skull base surgeons to maximize the surgical corridor and minimize iatrogenic injury to neurovascular structures. This study aimed to elucidate the role of the palatine bone from a microsurgical anatomical perspective. Three dry skulls were used to demonstrate the structure of the palatine bone and its relationship with surrounding bones. A formalin-perfused cadaveric head was dissected to show the related neurovascular structures. The arteries and veins of the cadaveric heads were injected with red- and blue-colored silicon. Dissection was performed using a surgical microscope and endoscope. In addition, the utilization of the palatine bone as a landmark to identify neurovascular structures, which aids in creating a wider surgical field with less bleeding, was shown in two representative cases. The palatine bone consists of unique complex structures, including the sphenoidal process, ethmoidal crest, pterygopalatine canal, and sphenopalatine notch, which are closely related to the sphenopalatine artery, maxillary nerve, and its branches. The ethmoidal crest of the palatine bone is a well-known structure that is useful for identifying the sphenopalatine foramen, controlling the sphenopalatine artery and nerve, and safely opening the pterygopalatine fossa. The sphenoidal process of the palatine bone is a valuable landmark for identifying the palatovaginal artery, which is a landmark used to safely and efficiently expose the vidian canal. The sphenoidal process is easily cracked with an osteotome and removed to expose the palatovaginal artery, which runs along the pharyngeal groove, just medial to the vidian canal. By opening the pterygopalatine canal (also known as the greater palatine canal), further lateralization of the periosteum-covered pterygopalatine fossa contents can be achieved. Overall, the sphenoidal process and ethmoidal crest can be used as important landmarks to maximize the surgical corridor and minimize unnecessary injury to neurovascular structures.

Diagnostic accuracy of intrathecal fluorescein versus other radiological modalities in evaluating non-congenital skull base defects: a systematic review and meta-analysis.

The intraoperative detection of cerebrospinal fluid (CSF) leaks during endoscopic skull base surgery is critical to ensure watertight sealed defects. Intrathecal fluorescein (ITF) is a valuable adjunct to intraoperative investigation. Hence, our aim is to summarize the evidence of the efficacy of ITF as an accurate diagnostic modality and reconstruction guide for non-congenital skull base defects. Using the Cochrane Central, MEDLINE, and Embase databases, we identified studies involving the use of ITF in non-congenital CSF leaks which were published until November 2023. The STATA 18 software was used for meta-analysis. Fourteen studies met the inclusion criteria, in which seven studies were included in the meta-analysis. ITF was used in 1898 (90.3%) of patients, with a detection rate of 88.1%. The overall detection rate of non-congenital CSF leaks among ITF concentrations of 5% and 10% had a statistically significant pooled effect size of 2.6 (95% CI = 2.25, 2.95), while when comparing the ITF to other alternative radiological tests, it was not statistically significant with a mean difference of 0.88 (95% CI = -0.4, 2.16). Moreover, the pooled prevalence was statistically significant in regards of the complications associated with ITF with an effect size of 0.6 (95% CI = 0.39, 0.82), indicating that 60% of patients who underwent ITF would experience at least one of the measured complications. ITF is considered as an efficient tool in localizing skull base defects. However, there was no significant results when comparing the ITF to other alternative radiological tests. Accordingly, if the ITF intervention is indicated, patients should be carefully selected based on their clinical need.

American Rhinologic Society expert practice statement part 1: Skull base reconstruction following endoscopic skull base surgery.

The goal of this American Rhinologic Society expert practice statement (EPS) is to summarize the best available evidence for technical factors that optimize outcomes in skull base reconstruction following endoscopic skull base surgery for intradural pathologies. These topics include the use of free mucosal grafts versus vascularized pedicled nasoseptal flaps; the use of autologous versus synthetic grafts; and the roles of lumbar drains, dural sealants, and nasal packing. This EPS was developed following the recommended methodology and approval process as previously outlined. As there are a myriad of techniques and limited agreement on the accepted principles of skull base reconstruction, this EPS aims to summarize the existing evidence and provide clinically meaningful guidance on these divergent practices. Following a modified Delphi approach, five statements were developed, four of which reached consensus and one of which reached near consensus. These statements and the accompanying evidence are summarized along with an assessment of future needs.

Paediatric endoscopic endonasal middle skull base reconstruction: retrospective analysis of 78 patients treated in a single tertiary care paediatric center

Introduction Skull base pathologies in the paediatric population are rare and require treatment by multiple qualified specialists. The endoscopic endonasal approach has revolutionized surgical treatment because it is less invasive than existing treatments.The goal of this study was to retrospectively review our experience with the reconstruction of paediatric skull middle base defects and associated complications. Materials and methods We analysed medical records from patients aged ≤ 18 years who were treated at our centre between 2013 and 2021. Patients treated with an endoscopic skull base approach and reconstruction, and who had complete clinical and radiological documentation and a minimum follow-up of 12 months, were included in the analysis. Personal data, reconstructive techniques, and complications were analysed. Results A total of 78 patients met the inclusion criteria and were enrolled in the study. Of these patients, 32 were male and 46 were female, and the mean age was 11.5 years. The main signs and symptoms were as follows: bitemporal hemianopsia in 53 cases, visual impairment in 23 cases, and headache in 30 cases. The most frequent aetiologies were craniopharyngioma (38 cases), pituitary adenoma (23 cases), and clivus chordoma (4 cases). All patients were treated via a pure endoscopic approach. For reconstruction, a multilayer technique was used in 18 cases, naso-septal flap in 43 cases, Gasket-Seal technique in 12 cases, and heterologous reconstruction in 5 cases. Only six patients presented a major complication: two had a postoperative cerebral spinal fluid leak, one developed a brain abscess, and three had diabetes insipidus.The mean follow-up period was 23.4 months.There were no statistically significant differences in postoperative CSF leak in relation to different reconstructive techniques. Conclusion Endoscopic endonasal skull base surgery is a safe and effective treatment for paediatric middle skull base pathologies. Reconstruction techniques have a high success rate of 96.5–100%, and the rate of associated complications is < 3%.

Special Considerations in Pediatric Endoscopic Skull Base Surgery.

Originally pioneered in adults, endoscopic endonasal approaches for skull base pathology are being increasingly applied as a minimally invasive alternative for young children. Intrinsic anatomic differences between these patient populations have sparked discussions on the feasibility, safety, and efficacy of these techniques in pediatric patients. This work aims to serve as a primer for clinicians engaged in the rapidly evolving field of pediatric endoscopic skull base surgery. A succinct overview of relevant embryology, sinonasal anatomy, and diagnostic workup is presented to emphasize key differences and unique technical considerations. Additional discussions regarding select skull base lesions, reconstructive paradigms, potential surgical complications, and postoperative care are also highlighted in the setting of multidisciplinary teams.

Short‐term urinary catheter usage in endoscopic skull base surgery and impact on urinary tract infection and reconstructive outcomes

AbstractObjectivesHospital‐acquired catheter‐associated urinary tract infections (UTIs) have been regarded as preventable adverse events, yet their risk in endoscopic skull base surgery (ESBS) has not been well described despite common use. We determine the incidence of UTI following ESBS and identify contributing clinical factors.MethodsRetrospective review was conducted for a cohort of 229 consecutive adult patients who underwent endoscopic endonasal surgery for treatment of any skull base pathology between July 2018 and June 2022 at a tertiary academic skull base surgery program. Postoperative UTI comprised the primary outcome. Independent variables included patient demographics, use and length of urinary catheterization, and pre‐existing genitourinary conditions.ResultsNosocomial UTIs were identified in 1.3% (3/229) of patients, occurring on postoperative days 2, 9, and 14, respectively; all were catheter‐associated. Overall, 86.0% (197/229) of patients received urinary catheters (mean duration 2.2 ± 1.8 days). Compared to those without, patients with UTI were older (70.0 ± 15.4 vs. 52.2 ± 16.8 years, p = 0.034), had lengthier stays (94.7 ± 126.8 vs. 5.9 ± 8.4 days, p &lt; 0.001), and had prolonged catheterizations (9.3 ± 5.5 vs. 2.1 ± 1.5 days, p &lt; 0.001). Preoperative genitourinary conditions were also associated with UTI development, namely, chronic urinary retention/obstruction (66.7% vs. 4.0%, p = 0.006), urinary incontinence (66.7% vs. 6.2%, p = 0.013), prostate disease (100.0% vs. 17.8%, p = 0.035), and renal dysfunction (100.0% vs. 9.7%, p = 0.001). Among intraoperative cerebrospinal fluid leak patients, postoperative CSF leak incidence was not associated with catheter use versus nonuse (3.3% vs. 12.5%, p = 0.276).ConclusionAlthough UTIs are uncommon in ESBS patients, advanced age, length of stay, duration of indwelling urinary catheterization, and comorbid genitourinary conditions may elevate risk.

Vascular Complications of Endoscopic Transsphenoidal Approach to Sellar Base Lesions

Objective: Vascular complications are one of the most dangerous complications of endoscopic skull base surgeries. The aim of this study was to evaluate vascular complications of endoscopic transsphenoidal surgery in patients with sellar and parasellar lesions.&#x0D; &#x0D; Methods: Between August 1997 and July 2023, a total of 5300 patients underwent endoscopic transsphenoidal surgery for skull base lesions at Kocaeli University Faculty of Medicine, Department of Neurosurgery and Pituitary Research Center. Patients with vascular complications during and after surgery were included into the study.&#x0D; &#x0D; Results: We encountered 12 major vascular injuries, 116 epistaxis, and 50 operation site hematoma in our series.&#x0D; &#x0D; Conclusion: Major vascular injuries are the most life-threatening complicastions. They can cause high mortality. The ways to prevent these injuries seems to have high experience and to investigate preoperative vascular evaluation in detail.

Tissue Sealant Impact on Skull Base Reconstruction Outcomes: A Systematic Review and Meta-Analysis.

Despite significant advances in understanding of skull base reconstruction principles, the role of tissue sealants in modifying postoperative cerebrospinal fluid (CSF) leak outcomes remains controversial. We evaluate postoperative CSF leak incidence associated with tissue sealant use in skull base defect repair during endoscopic skull base surgery (ESBS). Web of Science, PubMed/MEDLINE, Scopus, and Cochrane Library. Systematic review and meta-analysis of risk differences (RD). A search strategy identified original studies reporting CSF leakage following ESBS with disaggregation by tissue sealant use and/or type. 27 non-randomized studies (n = 2,403) were included for qualitative and meta-analysis. Reconstruction with a tissue sealant did not significantly reduce postoperative CSF leak risk compared with reconstruction without sealant (RD[95% CI] = 0.02[-0.01, 0.05]). Sub-analyses of dural sealant (-0.02[-0.11, 0.07]) and fibrin glue (0.00[-0.07, 0.07]) compared with no sealant were similarly unremarkable. Postoperative CSF leakage was not significantly modulated in further sub-analyses of DuraSeal (0.02[-0.02, 0.05]), Adherus (-0.03[-0.08, 0.03]), or Bioglue (-0.06[-0.23, 0.12]) versus no dural sealant use, or Tisseel/Tissucol versus fibrin glue nonuse (0.00[-0.05, 0.05]). No significant association was seen comparing dural sealant use versus fibrin glue use on pairwise (0.01[-0.03, 0.05]) or network meta-analysis (-0.01[-0.05, 0.04]). Limitations in source literature prevented sub-analyses stratified by leak characteristics, defect size and location, and accompanying reconstruction materials. Tissue sealant use did not appear to impact postoperative CSF leak incidence when compared with nonuse. Higher quality studies are warranted to thoroughly elucidate the clinical value of adjunct sealant use in endoscopic skull base reconstruction. N/A Laryngoscope, 2024.

The Effects of Nasal Septal Deviation on Anterior Skull Base Parameters

Abstract Introduction Functional endoscopic sinus surgery and endoscopic skull base surgery are frequently performed surgeries today. Nasal septal deviation is a common finding and can affect the surgical area. Therefore, it is important to examine the effect of this deviation on other anatomical structures. Objectıve The aim of the present study was to determine whether there is a relationship between the degree of nasal septal deviation and anterior skull base structures using computed tomography (CT). Methods A total of 312 patients (aged 18 to 65 years old) whose paranasal sinus CT images were available were included in the study. Measurements were obtained on images retrieved from Picture Archiving and Communication System (PACS) and Horos image archive systems in the bone window in the coronal and axial plane. Results The mean age of 312 patients was 33.00 years old (standard deviation [SD] 11.22 years). The presence of septal deviation was not associated with changes in olfactory fossa (OF) depths, Keros degrees, and the angle between the lateral lamella and the cribriform lamella. However, OF depths and Keros degrees on the deviated side of the septum were found to change at a significant level (p &lt; 0.05). No significant association was observed between the degree of septal deviation and cribriform lamella-lateral lamella angle. Conclusion The study showed significantly increased OF depth and Keros degree on the deviated side of the nasal septum. Performing CT scans before endoscopic sinus surgery and endoscopic skull base surgery is important to increase the chances of a successful surgical outcome and to reduce complications.

Surgical Navigation in the Anterior Skull Base Using 3-Dimensional Endoscopy and Surface Reconstruction

Image guidance is an important adjunct for endoscopic sinus and skull base surgery. However, current systems require bulky external tracking equipment, and their use can interrupt efficient surgical workflow. To evaluate a trackerless surgical navigation system using 3-dimensional (3D) endoscopy and simultaneous localization and mapping (SLAM) algorithms in the anterior skull base. This interventional deceased donor cohort study and retrospective clinical case study was conducted at a tertiary academic medical center with human deceased donor specimens and a patient with anterior skull base pathology. Participants underwent endoscopic endonasal transsphenoidal dissection and surface model reconstruction from stereoscopic video with registration to volumetric models segmented from computed tomography (CT) and magnetic resonance imaging. To assess the fidelity of surface model reconstruction and accuracy of surgical navigation and surface-CT model coregistration, 3 metrics were calculated: reconstruction error, registration error, and localization error. In deceased donor models (n = 9), high-fidelity surface models of the posterior wall of the sphenoid sinus were reconstructed from stereoscopic video and coregistered to corresponding volumetric CT models. The mean (SD; range) reconstruction, registration, and localization errors were 0.60 (0.24; 0.36-0.93), 1.11 (0.49; 0.71-1.56) and 1.01 (0.17; 0.78-1.25) mm, respectively. In a clinical case study of a patient who underwent a 3D endoscopic endonasal transsphenoidal resection of a tubercular meningioma, a high-fidelity surface model of the posterior wall of the sphenoid was reconstructed from intraoperative stereoscopic video and coregistered to a volumetric preoperative fused CT magnetic resonance imaging model with a root-mean-square error of 1.38 mm. The results of this study suggest that SLAM algorithm-based endoscopic endonasal surgery navigation is a novel, accurate, and trackerless approach to surgical navigation that uses 3D endoscopy and SLAM-based algorithms in lieu of conventional optical or electromagnetic tracking. While multiple challenges remain before clinical readiness, a SLAM algorithm-based endoscopic endonasal surgery navigation system has the potential to improve surgical efficiency, economy of motion, and safety.

A computed tomography (CT)-based morphometric study of various skull base parameters and their anatomical relationships relevant to endoscopic endonasal skull base surgery.

Endoscopic skull base surgery requires a thorough understanding of skull base anatomy. Orientation to regional anatomy to avoid complications like internal carotid artery injury can be assisted by knowledge of certain bony landmarks. These landmarks are themselves highly variable structures. This study focuses on the radiological morphometric characterization of these landmarks, which can be of great assistance to surgeons for better planning of endoscopic skull base approaches. Computed tomography scans of patients without skull base pathologies were analyzed retrospectively for the following parameters - Vidian canal (VC) length, VC and foramen rotundum (FR) distance from midline, the angle between the axis of VC and petrous internal carotid artery (pICA) and between VC and palatovaginal canal, the horizontal, vertical and direct distances between VC and FR and the patterns of sphenoid sinus (SS) pneumatization. The VC-pICA angle was more obtuse and VC and FR were placed farther off the midline on the left as compared to the right side. Similarly, the distances between VC and FR were more on the left side. The VC length and distance of VC and FR from the midline were longer in males than in females. The VC-pICA angle was more obtuse in females. The post-sellar variant was the predominant pneumatization pattern seen (57.9%), and the incidence of lateral recess pneumatization was 15%. The results of our study can be utilized for a better understanding of the anatomy of the skull base. In skull base pathologies with distorted anatomical landmarks, a basic understanding of their interrelations can be used to have a better anatomical orientation. All these measures can help in avoiding complications and make extended endoscopic approaches safe.

Validation of Korean Olfactory Questionnaire for Perioperative Olfactory Assessment in Endoscopic Endonasal Skull Base Surgery.

Objective: To analyze changes in olfactory function after endoscopic endonasal skull base surgery and compare performance of the olfactory questionnaire with those of conventional psychophysical tests. Methods: Patients were classified into 5 categories for olfactory function evaluation (normal, mild hyposmia, moderate hyposmia, severe hyposmia, and anosmia) based on a self-assessment. Patients also underwent the butanol threshold test (BTT), Cross-Cultural Smell Identification Test (CCSIT), and 11-item olfactory questionnaire. Subjects with normosmia preoperatively and who were followed up at least 6 months after surgery were analyzed. Receiver operating characteristic curves and confusion matrix analysis were performed for BTT, CCSIT, and olfactory questionnaire to compare their diagnostic abilities. The effects of age, preoperative olfaction, septal flap, tumor pathology, and tumor size on postoperative olfaction were evaluated using multivariate linear regression analysis. Results: Data from 108 patients were analyzed. Postoperative changes in the olfactory questionnaire were significantly associated with changes in the BTT and CCSIT. The area under the curve for postoperative self-olfactory function classification was highest for olfactory questionnaire (0.894), followed by BTT (0.767) and CCSIT (0.688). Patient age at the time of surgery and preoperative BTT score were significantly related to postoperative olfactory outcomes. Conclusion: The olfactory questionnaire correlated well with conventional psychosomatic olfactory function tests. In combination with clinical parameters and preoperative psychosomatic olfactory function tests, the olfactory questionnaire is suitable for assessing subjective olfactory function after endoscopic endonasal skull base surgery.

Marsupialization as an alternative to reconstruction in endoscopic skull base surgery. How I do it

BackgroundTo treat extradural solid-cystic lesions of the ventral skull base, a pedicled nasoseptal flap (NSF) maintains patency of the marsupialized cavity and prevents restenosis and cyst recurrence.MethodsThe authors provide a step-by-step description of the surgical technique valid in different lesions of the skull base, all treated via the endoscopic endonasal approach (EEA). The application is demonstrated by an operative video.ConclusionIn selected lesions, endoscopic marsupialization using an NSF ensures drainage and ventilation of the surgical cavity. Re-epithelialization provided by a pedicled flap is a viable alternative to multilayer skull base reconstruction.

Impact of collagen matrix on reconstructive material selection and postoperative complications in endoscopic endonasal skull base surgery.

The aim of this study was to investigate the impact of collagen matrix on reconstructive material selection and postoperative complications in endoscopic endonasal skull base surgery. The authors retrospectively reviewed the data of consecutive patients who underwent purely endoscopic endonasal skull base surgery from January 2015 to March 2023. Intraoperative CSF leakage was classified according to the Esposito grade, and skull base repair was tailored to the leakage grade. The patients were divided into two groups: before (group A) and after (group B) collagen matrix implementation. The rates of autologous graft harvesting (fat, fascia, and nasoseptal flap), postoperative CSF leakage, and donor-site complications were compared between the two groups. In total, 270 patients were included. Group A included 159 patients and group B included 111 patients. There were no differences in patient characteristics, including age, pathology, and Esposito grade, between the two groups. The overall fat usage rate was significantly higher in group A (63.5%) than in group B (39.6%) (p = 0.0001), and the fascia usage rate was also significantly higher in group A (25.8%) than in group B (4.5%) (p < 0.0001). The nasoseptal flap usage rate did not differ between group A (32.7%) and group B (30.6%) (p = 0.79). Postoperative CSF leakage was similar between the two groups (0.63% in group A vs 1.8% in group B, p = 0.57), and the overall rate of CSF leakage was 1.1%. Donor-site complications occurred in 3 patients in group A, including 1 abdominal hematoma, 1 delayed abdominal infection, and 1 fluid collection after fascia lata harvesting. Collagen matrix implementation significantly decreased autologous graft harvesting without increasing postoperative CSF leakage, contributing to less invasive surgery.