Supporting left-handed trainees in sinus and skull base surgery: A call for inclusive ergonomics.

KEY POINTS: The surgeon's hand dominance impacts ergonomics in endoscopic endonasal surgery. Left-handed trainees experience difficulty learning certain surgical techniques. OR adjustments optimize ergonomics for left-handed trainees without compromising others.

Traumatic encephalocele in the nasal cavity after 6 years of trauma: a case report.

BACKGROUND: Encephalocele refers to protrusion of the meninges and brain tissue through a skull bone defect. It results from congenital, traumatic, neoplastic, or spontaneous reasons. Traumatic encephalocele occurs because of the posttraumatic fracture of the skull bone or iatrogenic causes. The manifestations vary a lot, such as rhinorrhea, seizures, headaches, and focal neurological deficits. CASE PRESENTATION: A 20-year-old Syrian male presented to our department with the complaint of clear cerebrospinal fluid drainage from his right nostril, which started 6 years ago after a head trauma, moderate headache, and episodes of tonic-clonic seizures without any response to medical treatment. Then, 2 months ago, the patient had meningoencephalitis, so he was admitted to the intensive care unit and treated for a month until he was cured. The patient underwent radiological investigations, which showed that he had a base fracture with an encephalocele in the nasal cavity. The brain tissues with the meninges herniated through the skull base fracture with a significant expansion of the subarachnoid spaces in the right hemisphere. He was advised to undergo surgical repair at that time, but he refused the surgery. During this visit, surgery was indicated. The surgery was done by a specialist who returned the herniated brain tissues to their normal location, repaired the meninges, and reconstructed the skull base with bone cement and bio-glue. The patient's recovery after the surgery was uneventful. CONCLUSION: Traumatic encephalocele is a rare and unexpected complication of trauma, but we should keep it in mind when the patient comes with head trauma because of its life-threatening consequences. This complication can happen after years of trauma if the patient refuses treatment, therefore, we must educate patients about the dangerous results of neglecting cerebrospinal fluid leakage and skull fractures.

Relationships of the vidian nerve and internal carotid artery: MRI and intraoperative surgical evaluation.

Objective: Skull base anatomy around the internal carotid artery (ICA) is extremely complex. Among anatomical landmarks studied, the vidian canal has been thoroughly evaluated, unlike the vidian nerve (VN). Our aim is to evaluate the VN-ICA relationships, and understand their role in terms of surgical planning. Methods: Fifty MRI examinations of 100 healthy petro-spheno-clival regions were reviewed in order to evaluate the relationship between the vidian nerve axis (VNA) and the petrous ICA. Twenty-seven cases of expanded endonasal approaches to petrous apex region were evaluated to check the VN-ICA relationship intraoperatively. Results: MRI evaluations showed that, in 23% of cases, the VNA was below the edge of the ICA, in 45% it was at the edge of the ICA and in 32% it ended up above the edge of the ICA. Surgically speaking, in 9 of 28 petrous apex approaches, the VN ended above the inferior edge of the petrous carotid. Conclusions: MRI evaluation adds useful information in planning the surgical approach to petro-spheno-clival regions, even if the identification of VNA, in these cases, may not be radiologically possible. Surgical experience confirms the importance of VN identification in guiding the surgeon in complex cases, and also outline the possible risks of relying only on this landmark.

Morphometric analysis of the skull base and palatal regions for gender identification using CBCT: a retrospective study.

Objectives: The objectives of this study were to evaluate the accuracy of morphometry of skull base and palate in gender discrimination using cone beam computed tomography (CBCT) scanning and to assess the accuracy of the results among a sample of the Arab population. Materials & Methods: Using CBCT scans, a cross-sectional analysis was conducted on 142 consented patients who underwent various dental procedures at the University Dental Hospital, Sharjah (UDHS). Of these patients, 70 were females and 72 were males, with respective means of 38.5 and 36.2 years. Eleven parameters related to skull base and palatal region were measured on the CBCT scans by two expert radiologists followed by statistical analysis. Results: There was significant gender-based difference in the mean palatal width (PW) (p = 0.001), mean palatal height (PH) (p = 0.005). Among other skull base region parameters that were significant in term of gender-based difference like; the clivus length (CL) (p < 0.001), occipital condyle height (OCH) (p < 0.001), basal angle (BA) (p = 0.006) and transverse diameter of foramen magnum (p = 0.003). Only palate variables showed a significant age difference. Discriminant analysis related to gender showed that occipital condyle height was the most accurate and best discriminator among the skull base region parameters. Conclusion: The use of discriminant analysis in CBCT based on skull base and palatal region variables provides an efficient method for determining gender, which is particularly valuable in forensic science and anthropological research. Significance of study: Accurate gender identification is crucial in forensic investigations, and the skull base region, being a stable and sexually dimorphic anatomical feature, can serve as a reliable marker for this purpose.

Upright CT-based evaluation of the effects of posture on skull-base reconstruction after endoscopic endonasal surgery.

Cerebrospinal fluid (CSF) leakage is a common complication associated with endoscopic endonasal skull-base surgery (EESBS). Postoperative mobilization-associated postural changes are considered to cause CSF leakage. However, no study has demonstrated a robust relationship between postural changes and CSF leakage. We used upright computed tomography (CT) to clarify the effects of postural changes on the reconstructed skull base (RSB) after EESBS. Thirty patients who underwent EESBS at our institution were prospectively included, and their upright and supine CTs were compared to measure morphological changes in the RSB. Patient clinical data were also collected from medical charts and surgical videos, and their relationships with morphological changes were assessed. In upright CTs, the RSB shifted intracranially by 0.94 (0.0-2.9) mm on average. This shift was larger in cases with lesions extending to the sphenoid sinus, dural defects, intraoperative pulsation of the RSB, and large bone windows. The direction of the change was opposite to intuitive movement driven by gravity because of reduced intracranial pressure in the sitting position. Thus, these shifts can be directly associated with postoperative CSF leakage caused by reconstruction material displacement. Skull-base reconstruction and postoperative postural management accounting for these morphological changes may be necessary for preventing CSF leakage.

[Endoscopic Approaches in Skull Base Surgery].

Endoscopy offers access to a clear, wide surgical field in deep-brain areas. In recent years, opportunities for the use of endoscopy in endonasal or small keyhole approaches have been increasing. However, ascertaining the tumor-specific suitability of endoscopic surgery remains unclear. In this article, we introduce the general concept of endoscopic surgery for skull base tumors. The optimal goal for all types of skull base surgeries is maximum tumor removal with preservation of function. Therefore, it is important to understand the benefits and limitations of various endoscopic approaches for the skull base.

Morphometric Analysis of Stylomastoid Foramen and its Clinical Significance / Análisis Morfométrico del Foramen Estilomastoideo y su Importancia Clínica

SUMMARY: The stylomastoid foramen is located on the inferior surface of the petrous part of the temporal bone between the base of the styloid process and mastoid processes. Through the stylomastoid foramen the facial nerve completes its intracranial part. The aim of this study was to analyze the morphometric parameters, shape and position of the stylomastoid foramen on the skulls in Serbian population, and to correlate it with gender and body side. The study included 44 dry adult skulls (88 stylomastoid foramen). After we determined the gender, the skulls were photographed, and then distances of the stylomastoid foramen from various important landmarks of the skull base were measured in programme ImageJ. The shape and position of the stylomastoid foramen were also noted. The statistical significance was found in male skulls between right and left side in relation to parameter (P2) the shortest distance from the upper end of the anterior margin of the mastoid process (MP) to the center of stylomastoid foramen (CSMF), and on the left side for parameter (P6) the shortest distance between CSMF and the line passing through the tip of the MP in relation to gender. The most common shape of the stylomastoid foramen was round in 46 (52.27 %) cases, and most common position was on the line passing through the upper end of the anterior margin of both MP in 36 (40.91 %) and medially to the line connecting the tips of the MP and styloid process in 88 (100 %) cases. The results of this study will be useful for neurosurgeons during surgeries on the facial nerve trunk or anesthetics to give facial nerve block near the foramen and prevent its complications.

El foramen estilomastoideo se encuentra en la superficie inferior de la parte petrosa del hueso temporal entre la base del proceso estiloides y el proceso mastoides. A través del foramen estilomastoideo el nervio facial completa su parte intracraneal. El objetivo de este estudio fue analizar los parámetros morfométricos, la forma y la posición del foramen estilomastoideo en cráneos de población serbia y correlacionarlos con el sexo y el lado del cuerpo. El estudio incluyó 44 cráneos adultos secos (88 forámenes estilomastoideos). Después de determinar el sexo, se fotografiaron los cráneos y luego se midieron en el programa ImageJ las distancias del foramen estilomastoideo desde varios puntos importantes de la base del cráneo. También se observó la forma y posición del foramen estilomastoideo. La significación estadística se encontró en cráneos de hombres entre el lado derecho e izquierdo en relación al parámetro (P2) la distancia más corta desde el extremo superior del margen anterior del proceso mastoides (PM) hasta el centro del foramen estilomastoideo (CFM), y en el lado izquierdo para el parámetro (P6) la distancia más corta entre CFM y la línea que pasa por la punta del PM en relación al sexo. La forma más común del foramen estilomastoideo era redonda en 46 (52,27 %) casos, y la posición más común estaba en la línea que pasa por el extremo superior del margen anterior de ambos PM en 36 (40,91 %) y medialmente a la línea que conecta las puntas del PM y el proceso estiloides en 88 (100 %) casos. Los resultados de este estudio serán útiles para los neurocirujanos durante las cirugías en el tronco del nervio facial o los anestésicos para bloquear el nervio facial cerca del foramen y prevenir sus complicaciones.

Hearing Loss in the Unoperated Ear After High-Speed Drilling in Otologic and Skull Base Surgery.

OBJECTIVE: To evaluate if permanent hearing loss occurred in the unoperated ear of patients undergoing otologic and skull base surgery with high-speed otologic drilling. STUDY DESIGN: We retrospectively studied 250 patients (mean age 57.8 yr; 120 males, and 130 females) undergoing otologic or skull base surgery with high-speed drilling between 2013 and 2019. SETTING: The University of Pittsburgh Medical Center. PATIENTS: We evaluated preoperative and postoperative audiograms for patients undergoing surgery for cochlear implantation (95 patients, 38.0%), cholesteatoma or chronic ear disease (88 patients, 35.2%), repair of lateral skull base encephalocele (26 patients, 10.4%), resection of vestibular schwannoma or meningioma of the cerebellopontine angle (23 patients, 9.2%), lateral temporal bone resection (8 patients, 3.2%), microvascular decompression (7 patients, 2.8%), or other operations involving a high-speed otologic drill (3 patients, 1.2%). MAIN OUTCOME MEASURES: Hearing threshold shift, measured as the difference between postoperative threshold and preoperative threshold for each frequency. The association of age, gender, tested frequency, and surgery type with hearing threshold shift was investigated with analysis of covariance. RESULTS: A total of 102 patients (40.8%) had a 10-dB or greater worsening of their hearing in at least one frequency on their postoperative audiogram in the contralateral, unoperated ear. One hundred six subjects (42.4%) had no change in hearing of 10 dB or greater at any frequency. Among patients with longitudinal postoperative audiograms, accelerated age-related hearing loss was observed in low frequencies. CONCLUSIONS: A significant number of patients demonstrated poorer hearing thresholds in the contralateral, unoperated ear after otologic and skull base surgery.

Exoscope-assisted surgery in otology and neurotology.

PURPOSE OF REVIEW: This review addresses the pressing need for an updated understanding of high-definition 3D exoscope role in contemporary otologic and neurotologic practice. With technological advancements driving innovations in surgical visualization, it is crucial to evaluate the efficacy of exoscope-assisted surgery compared to traditional microscopic approaches. By synthesizing recent literature, this review offers insights into the current state of exoscopic ear and lateral skull base surgery and its implications for clinical practice and research. RECENT FINDINGS: Recent literature has focused on several key themes. Firstly, studies have demonstrated the feasibility and safety of exoscopic approaches for various otologic and neurotologic procedures. Secondly, comparative studies have highlighted similar outcomes with exoscopic techniques compared to conventional microscopic surgery, particularly in terms of operative time and complication rates. Thirdly, the exoscope can be a valuable tool for the education and training of surgeons. SUMMARY: The findings from recent literature underscore the growing significance of exoscope-assisted surgery in otology and lateral skull base practice. However, challenges such as high magnification image quality and learning curve must be addressed to optimize its widespread adoption. Overall, this review highlights the importance of continued research and innovation in this rapidly evolving field.

Exploring optimal microscopic keyhole access to the skull base: an anatomical evaluation of transciliary supraorbital and transpalpebral orbitofrontal craniotomy approaches.

PURPOSE: The past two decades have witnessed the rise of keyhole microscopic minimally invasive surgeries, including the transciliary supraorbital approach (TCA) and transpalpebral approach (TPA), commonly known as the transorbital approach. This study aims to elucidate the nuances, specific indications, and advantages of each approach. METHODS: A series of dissections were conducted on five formalin-fixed, alcohol-preserved cadaver heads. The TCA was performed on one side, and the TPA on the other. Virtual measurements of working angles for both approaches were recorded. Additionally, three clinical cases were presented to illustrate the practical application of the techniques. RESULTS: For TCA, the craniotomy dimensions were 1.7 cm x 2.5 cm (Cranial-Caudal (CC) x Lateral-Lateral (LL)), while for TPA, they measured 2.1 cm x 2.9 cm (CC x LL). The measurements of anterior clinoid processes (ACP) were obtained and compared between approaches. In the TCA, the mean ipsilateral ACP measurement was 62 mm (Range: 61 -63 mm), and the mean contralateral ACP measurement was 71.2 mm (Range: 70 -72 mm). In TPA, these measurements were 47.8 mm (Range: 47 -49 mm) and 62.8 mm (Range: 62 -64 mm), respectively. TCA exhibited an average cranial-caudal angle of 14.9°, while TPA demonstrated an average of 8.3°. CONCLUSION: The anterior cranial fossa was better exposed by a TCA, which also featured shorter operative times, enhanced midline visualization, and a quicker learning curve. Conversely, the middle fossa was better exposed by a TPA, making it an excellent option for middle fossa pathologies, including those in the anterior temporal lobe. After sphenoid bone wing drilling, the TPA offers superior visualization from the lateral to the medial aspect and enhances the CC angle. Additionally, the TPA reduces the risk of postoperative frontalis palsy based on anatomic landmarks. However, the TPA requires a greater cranial osteotomy, and due to unfamiliarity with eyelid anatomy, the learning curve for most neurosurgeons is lengthier for this procedure.

Skull Base Aspergillus Infection Mimicking Tumor Recurrence: A Nasopharyngeal Carcinoma Case Study.

ABSTRACT: We report a case of recurrent nasopharyngeal carcinoma postnasopharyngectomy, presenting with headaches. MRI revealed abnormal signals of the clivus with enhancement, and FDG PET/CT indicated intense uptake in the nasopharynx, clivus, and left neck lymph nodes. Bone SPECT/CT showed bony erosion and uptake in bilateral skull base areas. Biopsy confirmed aspergillosis. Despite the challenges in distinguishing tumor invasion from Aspergillus infection on MRI, bone SPECT/CT, and FDG PET/CT, the short postsurgery period and extensive uptake suggested skull base osteomyelitis.

[Meningiomas in the Central Skull Base:From the Perspective of Endoscopic Transnasal Surgery].

Recent advancements in endoscopic transnasal surgery(ETS)have expanded the application of this technique to meningiomas in the central skull base area, offering a less invasive alternative with a potentially lower physical burden on patients than conventional microscopic skull base surgery. Notably, while ETS allows surgeons to reach tumors without traversing the brain and nerves, thus theoretically reducing the risk of cranial nerve damage, it requires a high level of proficiency to avoid inadequate resection and tumor recurrence. In this article, we discuss the various surgical considerations, including preoperative imaging, surgical setting, nasal cavity expansion, skull base opening, tumor removal, and skull base reconstruction, as general procedures for specific meningiomas. We further describe the concept and details of our multi-layer fascial closure technique for dural repair in ETS, underlining the importance of skilled dural reconstruction in preventing postoperative complications. In conclusion, while ETS for skull base meningiomas presents a promising and less invasive treatment option, its success relies heavily on the surgeon's experience and understanding of the skull base anatomy, stressing the need for careful approach selection.

The effect of SARS-CoV-2 on the incidence of post-operative venous sinus thrombosis following skull base procedures.

PURPOSE: Sinus thrombosis is a common post-operative finding after posterior fossa surgery performed in the vicinity of the dural venous sinuses. The SARS-CoV-2 virus has been shown to confer an increased risk of venous thromboembolic events owing to eliciting a hyper-inflammatory and pro-thrombotic state. In this study, we examine the incidence of post-operative venous sinus thrombosis in patients undergoing peri-sigmoid posterior fossa surgery in the pre- and post-COVID era and investigate whether COVID infection confers an increased risk of sinus thrombosis. METHODS: A retrospective review of a single institution case series of patients underwent peri-sigmoid surgery (retrosigmoid, translabyrinthine, or far lateral) approach. Relevant clinical variables were investigated that may confer an increased risk of sinus thrombosis. RESULTS: A total of 311 patients (178 in the pre-COVID era, and 133 operated on after the pandemic began in March 2020) are included in the study. The composite incidence of sinus thrombosis seen on post-operative imaging was 7.8%. The incidence of sinus thrombosis in the pre-COVID cohort was N = 12 patients (6.7%) versus N = 12 (9%) in the post-COVID cohort (p = 0.46). A history of COVID infection was not shown to confer an increased risk of post-operative sinus thrombosis (OR: 0.61; 95% CI: 0.08-4.79, p = 0.64). Only a small number of patients (N = 7, 2.3%) required either medical or surgical intervention for post-operative sinus thrombosis. CONCLUSION: The overall incidence of post-operative sinus thrombosis is similar in the pre- and post-COVID era. The findings of this study suggest that COVID infection is not associated with a higher risk of venous sinus thrombosis.

Design and Development of a Cost-Effective Transnasal Skull Base Bone Wax Applicator: A Technical Note.

Bone wax is an important hemostatic agent used in neurosurgical practice from more than a century. It acts by mechanical tamponade effect to stop the oozing from cancellous bone. Bone wax application over the skull surface over the vertex is easy and can be applied with fingers. In deeper areas, one uses dissector to apply the bone wax; however, it becomes difficult at times to apply in transnasal surgery using the same dissectors. Author designed a cost-effective 20-cm-long different angled bone wax applicator for skull base transnasal surgery. This applicator is cost-effective and not described previously in English literature.

Endoscopic Anatomy of the Skull Base.

Presently, endoscopic skull base surgery has undergone significant advancements since its inception over two decades ago. Nevertheless, it is imperative to underscore that the fundamental basis of all surgical procedures lies in the meticulous understanding of anatomy, with particular emphasis on the ventral anatomy. This facet has recently garnered increased attention.Following the advancements in endoscopic skull base surgery techniques, this chapter will concentrate on the pertinent anatomical considerations that serve as key foundations for successful procedures. These considerations are categorized into two planes: the sagittal plane and the coronal plane.The sagittal plane is further subdivided into five distinct approaches, namely,(1) the transcribriform approach, (2) the transplanum approach, (3) the transsellar approach, (4) the transclival approach, and (5) the transodontoid approach.On the other hand, the coronal plane is delineated into seven specific zones to facilitate comprehension and potential applications: (1) the petrous apex approach, (2) the intrapetrous approach, (3) the suprapetrous approach, (4) the cavernous sinus approach, (5) the infratemporal approach, (6) the medial condyle approach, and (7) the jugular foramen approach.By organizing the anatomical aspects in this systematic manner, the information provided becomes more accessible, fostering a comprehensive understanding of the subject matter for potential future application.

Transorbital Route to Intracranial Space.

The endoscopic superior eyelid transorbital approach has emerged as a notable and increasingly utilized surgical technique in recent years. This chapter presents an overview of the approach, tracing its historical development and highlighting its growing acceptance within the skull base community.Beginning with an introduction and historical perspective, the chapter outlines the evolution of the transorbital approach, shedding light on its origins and the factors driving its adoption. Subsequently, a comprehensive exploration of the anatomic bone pillars and intracranial spaces accessible via this approach is provided. Hence, five bone pillars of the transorbital approach were identified, namely the lesser sphenoid wing, the anterior clinoid, the sagittal crest, the middle cranial fossa, and the petrous apex. A detailed correlation of those bone targets with respective intracranial areas has been reported.Furthermore, the chapter delves into the practical application of the technique through a case example, offering insights into its clinical utility, indications, and limitations.

Cranial and Spinal Cerebrospinal Fluid Leaks: Foundations of Identification and Management.

Cerebrospinal fluid (CSF) leaks may occur at the skull base or along the spinal column and can cause a variety of debilitating neurological symptoms for patients. Recognizing the potential presence of a CSF leak and then identifying its source are necessary for accurate diagnosis and definitive treatment. A standardized workflow can be followed for successful leak localization, which often requires several diagnostic studies, and for definitive leak treatment, which can range from minimally invasive, needle-based approaches to a variety of surgical corrections. This review paper provides an overview of epidemiology, pathophysiology, and diagnostic workup for CSF leaks and introduces available treatment options. An illustrative case of a skull base CSF leak demonstrating diagnosis and surgical correction is provided.

Endoscopic Endonasal Reconstruction of Intraoperative Cerebrospinal Fluid Leak in Different Skull Base Regions: Outcomes, Meningitis, and Risk Factors.

OBJECTIVES: Various nonvascularized or vascularized techniques have been adopted in endoscopic endonasal surgery (EES) for repairing intraoperative cerebrospinal fluid (CSF) leaks after tumor resection. Vascularized nasoseptal flaps, free nasoseptal grafts, free turbinate grafts, and fascia lata and mashed muscle are frequently used. Outcomes of those grafts applied in the defects of different regions need to be clarified. METHODS: The data from a series of 162 patients with skull base tumor who underwent EES that had intraoperative CSF leak between Jan 2012 and Jan 2021 were retrospectively analyzed. The regions included anterior skull base, sellar region, clivus and infratemporal fossa. Repair failure rate (RFR), meningitis rate, and associated risk factors were assessed. RESULTS: In total, 172 reconstructions were performed in 162 patients for the 4 sites of the skull base. There were 7 cases (4.3%) that had postoperative CSF leaks, which required second repair. The RFR for anterior skull base, sellar region, clivus, and infratemporal fossawas 2.6%, 2.2%, 16.7%, and 0%, respectively. The clivus defect was an independent risk factor for repair failure (P < 0.01). The postoperative meningitis rate was 5.6%. Repair failure was an independent risk factor for meningitis (P < 0.01). CONCLUSIONS: Vascularized nasoseptal flap, free nasoseptal graft, free turbinate graft, and fascia lata and mashed muscle are reliable autologous materials for repairing the dural defects in different regions during EES. Clivus reconstruction remains a great challenge, which had a higher RFR and meningitis rate. Repair failure is significantly associated with postoperative meningitis.