Background  The middle clinoid process (MCP), particularly caroticoclinoid ring (CCR) type of the MCP, is an important part of the sphenoid bone for skull base surgery. Previous studies have shown a wide range of MCP prevalence affected by various factors. However, no study has investigated the association between the MCP and the presence of sellar lesions. Objectives  The main aim of this study was to evaluate the prevalence of the MCP in the Thai population and factors associated with its presence. Materials and Methods  We conducted a cross-sectional study on 400 sides from 200 patients (100 with and 100 without sellar lesions) using cranial computerized tomography scans. Demographic data and MCP characteristics were collected. The association between individual variables and the presence of the MCP was determined by univariate and multivariate analysis. Results  The MCP was identified in 168 of 400 sides (42%). Patients with sellar lesions had a significantly lower prevalence of the MCP compared with normal controls (29.5% versus 54.5%, p  < 0.001). Of all MCP only 6% were the CCR type. Univariate and multivariate analysis showed that the absence of the sellar lesion was the only factor significantly associated with presence of the MCP (odds ratio: 2.86; 95% confidence interval: 1.90-4.32; p < 0.001). Conclusion  The prevalence of the MCP was relatively high in the Thai population, while the prevalence of the CCR was relatively low compared with previous studies. The absence of sellar lesions was the only factor associated with the presence of the MCP.

Neuronavigation systems coupled with previously reported external anatomical landmarks assist neurosurgeons during intracranial procedures. We aimed to verify whether the posterior auricularis muscle (PAM) could be used as an external landmark for identifying the sigmoid sinus (SS) and the transverse-sigmoid sinus junction (TSSJ) during posterior cranial fossa surgery.
The PAM was dissected in 10 adult cadaveric heads and after drilling the underlying bone, the relationships with the underlying SS and TSSJ were noted. The width and length of the PAM, and the distance between the muscle and reference points (asterion, mastoid tip, and midline), were measured.
The PAM was identified in 18 sides (9 left, 9 right). The first 20 mm of the muscle length (mean 28.28 mm) consistently overlay the mastoid process anteriorly and the proximal half of the SS slightly posteriorly on all sides. The superior border was a mean of 2.22 mm inferior to the TSSJ and, especially when the muscle length exceeded 20 mm, this border extended closer to the transverse sinus; it was usually found at a mean of 3.11 mm (range 0.0-13.80 mm) inferior to the distal third of the transverse sinus.
Superficial landmarks give surgeons improved surgical access, avoiding overexposure of deep neurovascular structures and reducing brain retraction. On the basis of our cadaveric study, the PAM is a reliable and accurate direct landmark for identifying the SS and TSSJ. The PAM could potentially be used for guiding the retrosigmoid approach.

UNASSIGNED: The management of lesions involving the cavernous sinus remains a formidable challenge. To optimize care for patients with tumors extending into this skull base region a detailed understanding of the surrounding osteology as well as neural and vascular relationships is requisite. This thesis examines the gross anatomy of the region and highlights important surgical implications drawn from these as well as previously published studies.
UNASSIGNED: A review of the historical scientific, anatomic, clinical, and surgical literature extending to the present (1992) relating to the cavernous sinus has been performed and discussed. Additionally, the author has performed and described cadaveric dissections revealing novel details about the macroscopic (dural and neurovascular anatomic relationships) and microscopic structure of the cavernous sinus. A series of cases of cavernous sinus pathologies that were addressed in an interdisciplinary surgical approach at the author\'s institution is also reported.
UNASSIGNED: Included in this report is a comprehensive review of the embryology of the cavernous sinus and its associated neurovascular structures. Cadaveric dissections have also revealed novel details about dural/meningeal compartments of the cavernous sinus as well as well as associated arterial, venous, and neural relationships. Microscopic observations also reveal novel fundamental insights into the components and structure of the cavernous sinus. Clinical examples from 20 patients illustrate the critical importance for clinical application of cavernous sinus anatomic knowledge to the surgical treatment of pathologies in this region.
UNASSIGNED: The cavernous sinus is a tripartite venous osteomeningeal compartment intimately neighboring vital structures including the optic tracts, pituitary gland, cranial nerves III, IV, V, V, VI, and the internal carotid artery. Surgical management of cavernous sinus lesions has and continues to evolve with increasing anatomic and clinical study as well as advancements in diagnostic and surgical methodologies.
UNASSIGNED: NA.

Introduction  The three-dimensional (3D) endoscope is considered a new surgical tool used in different approaches in intranasal and anterior skull base surgical procedures. There are many advantages of 3D over two-dimensional (2D) endoscopy that have been demonstrated in clinical applications, surgical training, and different experimental studies. Objective  To show the difference between using the 3D and 2D endoscopes during endonasal and anterior skull base surgery and its importance. Methods  Our study is divided into two phases (clinical and cadaveric phases). In the clinical study we, have performed 52 endonasal and anterior skull base surgical procedures (26 study cases and 26 control cases). We recorded accuracy, duration, and intraoperative complication for each case. The cadaveric study was performed on three cadavers. Differences in accuracy and dissection time were recorded using 3D and 2D endoscopy for each side chosen by randomization. Results  In the clinical study, the cases done by 3D endoscope were significantly faster and more accurate with less intraoperative complications compared with cases done using 2D endoscope. In cadaveric dissection, while using 3D endoscope, there was better depth of perception regarding the anatomical landmarks compared with 2D endoscope. Conclusion  Three-dimensional endoscopy is an advanced instrument that allows better training for the coming generation of ear, nose, and throat surgeons. Both clinical and cadaveric studies offer a promising outcome in both endonasal and anterior skull base surgery.

Objectives  Cerebrospinal fluid (CSF) leaks of the anterior cranial base are frequently repaired with endonasal, multilayered reconstructions. Vascularized tissue flaps are superior to free mucosal grafts and biomaterials in many cases. Limitations of previously described flaps include reach, rotation, pedicle availability, and postoperative sinonasal morbidity. The objective of this study is to describe the superiorly based middle turbinate flap, a novel vascularized mucosal reconstruction option, and to present a case series demonstrating flap utility. Design  Cadaveric feasibility study with technical description and illustrative case series. Setting  Tertiary medical center. Participants  Three silicone-injected cadaveric specimens (6 sides); 7 patients with CSF rhinorrhea from bony dehiscence of the anterior cranial fossa repaired with a superiorly based middle turbinate flap. Outcome Measures  Cadaveric feasibility, in vivo repair outcomes, sinonasal symptoms, and postoperative healing. Results  Cadaveric dissection demonstrated a consistent vascular plexus arising from the anterior and posterior ethmoid arteries, originating at the superior attachment of the middle turbinate and traveling inferiorly to supply the mucosa of the middle turbinate. Mean surface area of the flap was 776.67 ± 114.60 mm 2 . The clinical series of 7 patients involved leaks around the cribriform plate and fovea ethmoidalis. There were no instances of repair failure. All cases showed rapid and complete remucosalization without significant sinonasal morbidity. Conclusion  The superiorly based middle turbinate flap is a reliable, versatile, and effective option for a vascularized mucosal flap onlay that can be used in anterior skull base reconstruction. This flap is particularly useful in the repair of defects involving the cribriform plate and fovea ethmoidalis.

OBJECTIVE: Endoscopic endonasal transsphenoidal approach (Endonasal approach) is commonly used to treat pituitary adenomas. The extent of dissection possibly changes the anatomy and the physiology of the nasal cavities and could give rise to post-operative morbidity and the quality of life (QoL). The purpose of this study was to investigate sinonasal morbidity and general QoL in patients who underwent surgery for treatment of pituitary adenoma, comparing Endonasal and endoscopic trans-septal transsphenoidal approach (Trans-septal approach).
METHODS: A prospective observational study, recruiting 40 patients undergoing surgery for pituitary adenoma, 20 via Endonasal approach and 20 via Trans-septal approach at our institution. Surveys with Sinonasal Outcome Test-22 (SNOT-22), Chronic Sinusitis Survey (CSS), and Short Form Health Survey 36 version 2 (SF-36v2) were obtained to collect QoL data pre- and postoperatively.
RESULTS: All the 40 patients completed the questionnaires. At 6 months postoperatively, the SNOT-22 and CSS score shows significant improvements both in Endonasal approach (p = 0.01) and in Trans-septal approach (p = 0.02). No significant difference in sinonasal morbidity is observed between the two groups for SNOT-22 (p = 0.13) and CSS scores, except for sinus headache (p = 0.49), with a better score in Endonasal approach. The mean SF-36v2 scores remain the same in pre- and post-operative periods, but an improvement in time is seen in general health (p = 0.027), and general health compared to one year ago (p < 0.001).
CONCLUSIONS: Endoscopic transsphenoidal surgery has negligible morbidity and does not negatively affect the nasal function in the long term. Endonasal approach and Trans-septal approach are comparable in terms of morbidity outcomes and general QoL, leaving the choice of the approach to the surgeon preference.

UNASSIGNED: Cerebrospinal fluid rhinorrhoea (CSFR) is a common complication following endonasal skull base surgery, a technique that is fundamental to the treatment of pituitary adenomas and many other skull base tumours. The CRANIAL study explored CSFR incidence and related risk factors, particularly skull base repair techniques, via a multicentre prospective observational study. We sought to use machine learning to leverage this complex multicentre dataset for CSFR prediction and risk factor analysis.
UNASSIGNED: A dataset of 865 cases - 725 transsphenoidal approach (TSA) and 140 expanded endonasal approach (EEA) - with cerebrospinal fluid rhinorrhoea as the primary outcome, was used. Relevant variables were extracted from the data, and prediction variables were divided into two categories, preoperative risk factors; and repair techniques, with 6 and 11 variables respectively. Three types of machine learning models were developed in order to predict CSFR: logistic regression (LR); decision tree (DT); and neural network (NN). Models were validated using 5-fold cross-validation, compared via their area under the curve (AUC) evaluation metric, and key prediction variables were identified using their Shapley additive explanations (SHAP) score.
UNASSIGNED: CSFR rates were 3.9% (28/725) for the transsphenoidal approach and 7.1% (10/140) for the expanded endonasal approach. NNs outperformed LR and DT for CSFR prediction, with a mean AUC of 0.80 (0.70-0.90) for TSA and 0.78 (0.60-0.96) for EEA, when all risk factor and intraoperative repair data were integrated into the model. The presence of intraoperative CSF leak was the most prominent risk factor for CSFR. Elevated BMI and revision surgery were also associated with CSFR for the transsphenoidal approach. CSF diversion and gasket sealing appear to be strong predictors of the absence of CSFR for both approaches.
UNASSIGNED: Neural networks are effective at predicting CSFR and uncovering key CSFR predictors in patients following endonasal skull base surgery, outperforming traditional statistical methods. These models will be improved further with larger and more granular datasets, improved NN architecture, and external validation. In the future, such predictive models could be used to assist surgical decision-making and support more individualised patient counselling.

UNASSIGNED: Despite progress in endonasal skull-base neurosurgery, cerebrospinal fluid (CSF) rhinorrhoea remains common and significant. The CRANIAL study sought to determine 1) the scope of skull-base repair methods used, and 2) corresponding rates of postoperative CSF rhinorrhoea in the endonasal transsphenoidal approach (TSA) and the expanded endonasal approach (EEA) for skull-base tumors.
UNASSIGNED: A prospective observational cohort study of 30 centres performing endonasal skull-base neurosurgery in the UK and Ireland (representing 91% of adult units). Patients were identified for 6 months and followed up for 6 months. Data collection and analysis was guided by our published protocol and pilot studies. Descriptive statistics, univariate and multivariable logistic regression models were used for analysis.
UNASSIGNED: A total of 866 patients were included - 726 TSA (84%) and 140 EEA (16%). There was significant heterogeneity in repair protocols across centres. In TSA cases, nasal packing (519/726, 72%), tissue glues (474/726, 65%) and hemostatic agents (439/726, 61%) were the most common skull base repair techniques. Comparatively, pedicled flaps (90/140, 64%), CSF diversion (38/140, 27%), buttresses (17/140, 12%) and gasket sealing (11/140, 9%) were more commonly used in EEA cases. CSF rhinorrhoea (biochemically confirmed or requiring re-operation) occurred in 3.9% of TSA (28/726) and 7.1% of EEA (10/140) cases. A significant number of patients with CSF rhinorrhoea (15/38, 39%) occurred when no intraoperative CSF leak was reported. On multivariate analysis, there may be marginal benefits with using tissue glues in TSA (OR: 0.2, CI: 0.1-0.7, p<0.01), but no other technique reached significance. There was evidence that certain characteristics make CSF rhinorrhoea more likely - such as previous endonasal surgery and the presence of intraoperative CSF leak.
UNASSIGNED: There is a wide range of skull base repair techniques used across centres. Overall, CSF rhinorrhoea rates across the UK and Ireland are lower than generally reported in the literature. A large proportion of postoperative leaks occurred in the context of occult intraoperative CSF leaks, and decisions for universal sellar repairs should consider the risks and cost-effectiveness of repair strategies. Future work could include longer-term, higher-volume studies, such as a registry; and high-quality interventional studies.

UNASSIGNED: Data on the outcomes of microsurgical resection (SR) and stereotactic gamma knife radiosurgery (GKRS) in patients with trigeminal neuralgia associated with small petrous apex meningiomas are scarce.
UNASSIGNED: We conducted this study to evaluate the pain relief, tumor control, and procedure costs following SR and GKRS for small petroclival meningiomas (less than 3 cm in maximal diameter) using real-world data from our center in Egypt.
UNASSIGNED: We conducted a retrospective cohort study of 47 patients with small petrous apex meningiomas presenting with intractable trigeminal nerve pain (SR: n = 22 and GKRS: n = 25). Data regarding pain relief on Barrow Neurological Institute (BNI), procedure cost, and tumor control were retrieved and analyzed using appropriate statistical tests.
UNASSIGNED: Patients who underwent SR had lower median BNI pain intensity scores compared to those patients who underwent GKRS, and a significantly higher proportion of patients in the SR group had good BNI scores compared to those in GKRS group (P < 0.05); however, the total costs of SR were significantly less than GKRS (30,519$ vs. 92,372$, respectively).
UNASSIGNED: Both SR and GKRS provide pain relief and tumor control in patients with trigeminal neuralgia associated with petrous apex meningioma. However, in the present study, SR achieved better pain control and was more affordable than GKRS.

Objective  The jugular foramen is one of the most challenging surgical regions in skull base surgery. With the development of endoscopic techniques, the endoscopic endonasal approach (EEA) has been undertaken to treat some lesions in this area independently or combined with open approaches. The purpose of the current study is to describe the anatomical steps and landmarks for the EEA to the jugular foramen and to compare it with the degree of exposure obtained with the lateral infratemporal fossa approach. Materials and Methods  A total of 15 osseous structures related to the jugular foramen were measured in 33 adult dry skulls. Three silicone-injected adult cadaveric heads (six sides) were dissected for EEA and three heads (six sides) were used for a lateral infratemporal fossa approach (Fisch type A). The jugular foramen was exposed, relevant landmarks were demonstrated, and the distances between relevant landmarks and the jugular foramen were obtained. High-quality pictures were obtained. Results  The jugular foramen was accessed in all dissections by using either approach. Important anatomical landmarks for EEA include internal carotid artery (ICA), petroclival fissure, inferior petrosal sinus, jugular tubercle, and hypoglossal canal. The EEA exposed the anterior and medial parts of the jugular foramen, while the lateral infratemporal fossa approach (Fisch type A) exposed the lateral and posterior parts of the jugular foramen. With EEA, dissection and transposition of the facial nerve was avoided, but the upper parapharyngeal and paraclival ICA may need to be mobilized to adequately expose the jugular foramen. Conclusion  The EEA to the jugular foramen is anatomically feasible but requires mobilization of the ICA to provide access to the anterior and medial aspects of the jugular foramen. The lateral infratemporal approach requires facial nerve transposition to provide access to the lateral and posterior parts of the jugular foramen. A deep understanding of the complex anatomy of this region is paramount for safe and effective surgery of the jugular foramen. Both techniques may be complementary considering the different regions of the jugular foramen accessed with each approach.