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Background: The medial opticocarotid recess (MOCR) is located in the posterior wall of the sphenoid sinus, medial to the junction of the optic canal (OC) and the carotid prominence (CP). There is controversy in the literature in relation to the presence of the MOCR and its constancy, which is relevant when approaching the skull base through an endoscopic route. Methods: The morphometric relations of the MOCR with the surrounding structures were studied in 18 cadaveric specimens after endoscopic endonasal approach (EEA). Results: The distance between both MOCR was 11.06 ± 1.14 mm; the distance between the MOCR and the lateral opticocarotid (LOCR) recess was 5.56 ± 0.85 mm; the distance between the MOCR and the suprasellar recess was 3.72 ± 0.49 mm; the angle between the MOCR plane and the OC 13.32 ± 2.30°; the angle between the MOCR plane and the CP 13.50 ± 2.68° and; the angle between the OC and the CP 26.81 ± 4.26°. All measurements showed low variability, with low standard deviation and interquartile range. No relations were found between any of the measurements. Conclusions: The MOCR may be used as a reference point for precise location of structures during EEA. Objective measurements may be especially useful in cases with distorted sphenoid bone anatomy. [ABSTRACT FROM AUTHOR]

This article discusses the use of intraoperative ultrasound (IUS) as an adjunct to the endoscopic endonasal approach (EEA) for the surgical resection of skull base lesions. The authors present a case study where a novel small-probe IUS was used to assist in the resection of a recurrent Rathke's cleft cyst (RCC) located in an atypical retrosellar region. The small-probe IUS provided real-time imaging feedback and enhanced visualization, allowing for accurate localization of the cyst and surrounding neurovascular structures. The authors conclude that IUS is a promising surgical adjunct that can potentially increase the extent of resection and decrease operation times. [Extracted from the article]

This article compares two surgical approaches, the endoscopic endonasal approach (EEA) and the midline suboccipital subtonsillar approach (STA), for accessing the jugular tubercle (JT) in the treatment of JT meningiomas. The study conducted on human cadaveric specimens measured three morphological variables: angle of attack (AoA), surgical freedom, and angle of endoscopic exposure (AoEE). The results showed that while STA offered greater surgical freedom, EEA provided superior visualization and AoEE. The choice of surgical approach should also consider the position of the lower cranial nerves in relation to the lesion. [Extracted from the article]

This article compares two different approaches for accessing the petrous apex through endoscopic endonasal surgery. The traditional approach, called the sublabial contralateral transmaxillary (CTM) corridor, has limitations such as instrument interference and increased nasal morbidity. The study introduces a new approach, the precaruncular contralateral medial transorbital (cMTO) corridor, which offers advantages such as a shorter distance to the target, a wider visualization angle, and better maneuverability for surgical instruments. The study was conducted on cadaveric specimens and further clinical studies are needed to validate these findings in patients. [Extracted from the article]

Suprasellar extension, cavernous sinus invasion, and involvement of intracranial vascular structures and cranial nerves are among the challenges faced by surgeons operating on giant pituitary macroadenomas. Intraoperative tissue shifts may render neuronavigation techniques inaccurate. Intraoperative magnetic resonance imaging can solve this problem, but it may be costly and time consuming. However, intraoperative ultrasonography (IOUS) allows for quick, real-time feedback and may be particularly useful when facing giant invasive adenomas. Here, we present the first study examining technique for IOUS-guided resection specifically focusing on giant pituitary adenomas. To describe the use of a side-firing ultrasound probe in the resection of giant pituitary macroadenomas. We describe an operative technique using a side-firing ultrasound probe (Fujifilm/Hitachi) to identify the diaphragma sellae, confirm optic chiasm decompression, identify vascular structures related to tumor invasion, and maximize extent of resection in giant pituitary macroadenomas. Side-firing IOUS allows for identification of the diaphragma sellae to help prevent intraoperative cerebrospinal fluid leak and maximize extent of resection. Side-firing IOUS also aids in confirmation of decompression of the optic chiasm via identification of a patent chiasmatic cistern. Furthermore, direct identification of the cavernous and supraclinoid internal carotid arteries and arterial branches is achieved when resecting tumors with significant parasellar and suprasellar extension. We describe an operative technique in which side-firing IOUS may assist in maximizing extent of resection and protecting vital structures during surgery for giant pituitary adenomas. Use of this technology may be particularly valuable in settings in which intraoperative magnetic resonance imaging is not available. [ABSTRACT FROM AUTHOR]

The endoscopic endonasal transoculomotor approach (EETA) has been recently described as a doorway to access the parapeduncular space and treat pituitary adenomas with oculomotor extension. Intraoperative identification of the oculomotor triangle endonasally is challenging and dissection can put the internal carotid artery (ICA) at risk. The aim of the present study is to find reliable landmarks that identify the oculomotor triangle (OCMT) during the EETA and protect the ICA from injury. Several lines were defined for calculations. Among them, one oblique line that extends from the inferior margin of the lateral orbital canal recess to the vidian canal was named the clinoid-to-vidian line (CVL), while a vertical line that extends over the most medial point of the paraclival ICA was titled the sagittal paraclival line (SPL). Anatomic relationships between the OCMT to these lines were assessed in 7 cadaveric heads. The intersecting point between the CVL and SPL is located within 2 mm of the center of the OCMT (mean 0.8 ± 0.5 mm), and 1.1 ± 0.8 mm medially and above the parasellar ICA. CVL and SPL are reliable landmarks during the EETA that can both protect the parasellar ICA and anatomically orientate to the blind spot that corresponds with the OCMT. We recommend starting dissection medial and superior to the CVL-SPL intersecting point, and carry the dissection laterally thereafter to avoid inadvertent injury of the ICA. [ABSTRACT FROM AUTHOR]

Background: After internal carotid artery (ICA) injury during endoscopic skull base surgery, the majority of patients undergo ICA embolization or stenting to treat active extravasation or pseudoaneurysm development. However, management practices when embolization or stenting is not required have not been well described. The objective of this study was to determine how patients with ICA injury but no embolization, stenting, or ligation do long‐term and ascertain the reconstruction methods utilized. Methods: Twenty‐nine cases of ICA injury were identified in an international multi‐institutional retrospective review. Of these, we identified six cases that were not treated with embolization, stenting, or ICA sacrifice. Information was available for five cases. Results: A muscle patch was used in the immediate repair of each case. A nasoseptal flap was used in one case. Prefabricated nasal tampons were used in all cases. Nasal packing was initially left in for a median of 7 days prior to removal. The initial muscle patch was reinforced with a second muscle graft in one case. One case demonstrated ICA bleeding at the time of packing removal and was repacked an additional week. Follow‐up for each of these cases was at least 2 years. No cases of subsequent carotid rupture were found and none of these cases ultimately underwent endovascular stenting. Radiation or proton therapy has not been subsequently used in any of these patients. Conclusions: This study details the reconstruction, lessons learned, and long‐term follow‐up for five cases of ICA injury not treated with embolization, stenting, or ligation. [ABSTRACT FROM AUTHOR]

Comprehensive quantitative evaluation of the intercarotid artery distance (ICD) in the pediatric population has not been sufficiently explored. This study aims to measure the minimal ICDs at multiple levels of the skull base to assess changes in the ICD during development. Measurement of the ICDs between the paired paraclival, parasellar, and paraclinoid segments of the internal carotid artery (ICA) was performed on coronal MRI from 540 patients ranging from 0 to 17 years old (n = 30 for each age). Comparison of these indices in the very young (0–5 years, Group 1) and young (6–17 years, Group 2) patients, and assessment of the degree of sphenoid sinus pneumatization was employed. The narrowest ICD was located at the paraclinoid ICAs in the vast majority of cases (89.44%). When comparing the ICDs in very young age patients with the ICDs of 17 years old subjects, a statistically significant difference was found at the paraclival (ages 0–5), parasellar (ages 0–2), and paraclinoid (ages 0–4) ICDs (p < 0.05). Comparison of the ICDs between the intergroups (Group 1 and 2) also demonstrated a statistically significant difference (p < 0.0001). Pneumatization of the sphenoid sinus was initially noted to start at 3 years of age, and there were no patients with a non-pneumatized sphenoid sinus identified after 7 years of age in our cohort. Measurement of ICDs at multiple levels provides a valuable reference for EEA procedures in the pediatric population. While the ICD may be largely stable in the pediatric population after 5 years of age, additional anatomic factors may restrict transsphenoidal access in very young patients (0–5 years). [ABSTRACT FROM AUTHOR]

Background: The catastrophic and rare nature of an internal carotid artery (ICA) injury during endonasal surgery limits training opportunities. Cadaveric and animal simulation models have been proposed, but expense and complicated logistics have limited their adoption. Three‐dimensional (3D) printed models are portable, modular, reusable, less costly, and proven to improve psychomotor skills required for managing different lesions. In this study we evaluate the role of a simplified laser‐sintered model combined with standardized training in improving the effectiveness of managing an ICA injury endoscopically. Methods: A 3‐mm defect was created in the parasellar carotid canal of a laser‐sintered model representing a sphenoid sinus. Artificial blood was directed to simulate the copious bleeding arising from an ICA injury. Twenty otolaryngologists and 26 neurosurgeons, with varying training and experience levels, were individually asked to stop the "bleeding" as they would in a clinical scenario, and provided no other instructions. This was followed by individualized formative training and a second simulation. Volume of blood loss, time to hemostasis, and self‐assessed confidence scores were compared. Results: At the end of the study, time to hemostasis was reduced from 105.49 seconds to 40.41 seconds (p < 0.001). The volume of blood loss was reduced from 690 to 272 mL (p < 0.001), and the confidence scores increased in 95.7% of participants, from an average of 3 up to 8. Conclusion: This ICA injury model, along with a formal training algorithm, appears to be valuable, realistic, portable, and cost‐effective. Significant improvement in all parameters suggests the acquisition of psychomotor skills required to control an ICA injury. [ABSTRACT FROM AUTHOR]

Background/Objective The inframeatal area represents a challenging region for skull base surgeons. Various surgical corridors have been described to access this area and frequently are used in combination. Recent studies describe the expanded endoscopic endonasal approach (EEA) as an established route for midline regions, particularly medial to the internal carotid arteries (ICA). We sought to evaluate the accessibility, maneuverability, and freedom of movement of the expanded endoscopic endonasal approach to the inframeatal region. Methods An EEA combining a middle and an inferior transclival corridor with an infrapetrous and a supracondylar lateral expansion was performed in 5 embalmed human cadaveric heads. The area of exposure and the surgical freedom to access the inframeatal area were calculated. The angle of attack and distances from the lacerum segment of the ICA to several anatomical targets also were measured. Our database was searched to select clinical case examples. Results The EEA provided an exposure area of 101.26 ± 16.66 mm2 and an area of surgical freedom of 1208.50 ± 507.01 mm2. The angles of attack in both the sagittal and axial planes were wider at the lacerum segment of the ICA and narrower at the dural entrance zone of cranial nerves VII/VIII. Three chondrosarcomas are presented as case illustrations. Conclusions The EEA is a feasible route to the inframeatal area. This approach provides a safe working corridor for lesions in this region, as shown by the anatomical and clinical findings presented here. Comparative studies and large case series are warranted to further establish its clinical value. Highlights • EEA is surgically feasible for approaching lesions at the inframeatal area. • EEA inframeatal approach may avoid the need for ICA and eustachian tube mobilization. • Clinical application of this approach includes chordoma and cholesterol granuloma. • Paramedial lesions such as chondrosarcomas may warrant a combined strategy. [ABSTRACT FROM AUTHOR]

Objectives Endoscopic and endoscopic-assisted approaches to the parapharyngeal space have been reported; however, their potential for vascular exposure has not been previously assessed. This study aims to compare the potential exposure and control of the parapharyngeal internal carotid artery (ppICA) via various approaches. Design and Main Outcome Measures Ten cadaveric specimens were dissected bilaterally, exposing the ppICA via endonasal, transoral, and transcervical approaches. Length of the exposed vessel and potential control were assessed (feasibility and time required to place an encircling suture). Results Endoscopic transoral and transcervical-transmandibular approaches expose a significantly longer segment of the ppICA (6.89 and 7.09 cm) than the transoral and endonasal approaches. Vascular control was achieved via endoscopic-endonasal, endoscopic- transoral, and open techniques in 121.6, 64.8, and 5.2 seconds, respectively. Conclusion Histopathology, goals of surgery, and familiarity of the surgeon with each technique may ultimately determine the choice of approach; however, this study suggests that exposure of the ppICA by endoscopic-assisted transoral approach is comparable to that of a transcervical-transmandibular approach. Vascular controlwas feasible under elective circumstances. However, the difficulty varied widely, potentially reflecting the challenges of controlling an injured ppICA. However, one must note that active bleeding obscures the surgical field in ways that may impair ppICA control. Furthermore, the results may not reflect clinical scenarios where tumor distorts the surgical field. Nonetheless, the study suggests that, in properly selected patients, the endoscopicassisted transoral approach avoids problems associated with unsightly scars, mandibular osteotomy, and facial nerve manipulation, whereas, the transcervical--transmandibular approach offers the swiftest vascular control. [ABSTRACT FROM AUTHOR]