Objective: Tumors arising from the upper parapharyngeal space (UPPS) may have intimate relationships with the internal carotid artery (ICA) and the internal jugular vein (IJV). The significance of the ICA in UPPS has been sufficiently articulated, whereas the relevance of the IJV has not been addressed. This study aimed to assess the anatomical variations of the IJV within the UPPS, and to explore its implications for surgical procedures. Methods: An endoscopic dissection of the IJV was performed on 10 cadaveric specimens. In addition, 30 patients who underwent transoral or transcervical resection of UPPS tumors were retrospectively reviewed to characterize the IJV and its relation to the tumor. Results: On the cadaveric specimens, the IJV was located at the posteromedial and posterolateral aspects of the styloid process in 13 (65%) and 7 (35%) sides, respectively. In our clinical series, the IJV was not encountered in 18 patients with pre-styloid tumors. In 12 patients harboring retro-styloid tumors, the IJV was partially (n = 5) or completely (n = 7) compressed and was displaced into the posterolateral aspect of the tumor. The IJV was injured intraoperatively in 1 patient, requiring an immediate conversion to an open transcervical corridor that allowed its exposure and ligation without difficulty. Conclusion: This study characterizes the IJV and its relationship with adjacent neurovascular structures in the UPPS, which may provide further safeguards during transoral and transcervical procedures in the UPPS.

The parapharyngeal internal carotid artery (pICA) could be surgically exposed through the transnasal and transoral corridors. However, their potential degree of exposure has not been established sufficiently. This study aims to elucidate the maximal exposure of the pICA via the transnasal and transoral corridors.
An endonasal transpterygoid nasopharyngectomy for exposure of the pICA was performed on eight cadaveric specimens (16 sides), while a transoral approach for exposure of the pICA was performed on six additional specimens (12 sides). In addition, the CT angiography of 60 consecutive patients (120 sides) was analyzed to establish the potential maximal exposure of the pICA through each corridor.
The hard palate becomes a restricting factor for the inferior exposure of the pICA via the transnasal approach, whereas the entire pICA segment could be adequately displayed through the transoral corridor. The maximal exposed length of the pICA for a transnasal and transoral approach was 3.08 ± 0.30 cm and 6.56 ± 0.57 cm, respectively. This difference was statistically significant (p < 0.001).
An endonasal exposure of the pICA seems limited to its superior aspect, whereas the transoral corridor could provide adequate exposure of the entire length of pICA.

BACKGROUND: Teratocarcinosarcoma traversing the anterior skull base is rarely reported in literature. The heterogenous and invasive features of the tumor pose challenges for surgical planning. With technological advancements, the endoscopic endonasal approach (EEA) has been emerging as a workhorse of anterior skull base lesions. To date, no case has been reported of EEA totally removing teratocarcinosarcomas with intracranial extensions.
METHODS: The authors provided an illustrative case of a 50-year-old otherwise healthy man who presented with left-sided epistaxis for a year. Imaging studies revealed a 31 × 60-mm communicating lesion of the anterior skull base. Gross total resection via EEA was achieved, and multilayered skull base reconstruction was performed.
CONCLUSIONS: The endoscopic approach may be safe and effective for resection of extensive teratocarcinosarcoma of the anterior skull base. To minimize the risk of postoperative cerebrospinal fluid leaks, multilayered skull base reconstruction and placement of lumbar drainage are vitally important.

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.

The styloid process constitutes the posterolateral boundary for an endonasal exposure of the infratemporal fossa. This study aims to explore the feasibility of a far-lateral extension to the lateral poststyloid space via an endonasal corridor. An endonasal dissection was performed on six cadaveric specimens (12 sides). Following an endoscopic endonasal access to the parapharyngeal space, the styloid process and the tympanic portion of the temporal bone were removed to reveal the jugular bulb and the extratemporal facial nerve. Distances from the anterior nasal spine to the relevant landmarks were measured using a surgical navigation device. Through an endonasal corridor, only the anteroinferior aspect of the jugular bulb was exposed. Conversely, the extratemporal facial nerve could be sufficiently exposed, and the deep temporal nerve could be transposed to the stylomastoid foramen. The average horizontal distances from the nasal spine to the posterior tract of V3 , styloid process, and facial nerve were 79.33 ± 3.41, 97.10 ± 4.74, and 104.77 ± 4.42 mm, respectively. Access to the lateral poststyloid space via an endonasal corridor is feasible, potentially providing an alternative approach to address select lesions extending to this region. The deep temporal nerve has a similar diameter to that of the facial nerve; thus, providing potential reinnervation of the facial nerve.

OBJECTIVE: Craniopharyngiomas (CPs) predominantly involving the third ventricle were commonly termed \"intraventricular\" lesions. The aim of this study was to clarify the anatomical relationship between the tumor and the third ventricle by both surgical and histological investigation.
METHODS: A retrospective review of primarily resected CPs by endoscopic endonasal surgery was performed. CPs with predominantly ventricular involvement were selected for study inclusion by preoperative imaging. The surgical procedure of each case was reviewed. The wholly removed tumor specimens were histologically analyzed, in all cases, to investigate the tumor-third ventricle relationship using hematoxylin and eosin, immunochemical, and immunofluorescence staining.
RESULTS: Twenty-six primary CPs predominantly involving the third ventricle were selected from our series of 223 CPs treated by endoscopic endonasal surgery between January 2017 and March 2021. Gross-total resection was achieved in 24 (92.3%) of 26 patients, with achievement of near-total resection in the remaining patients. A circumferential layer of stretched third ventricle floor was identified surrounding the tumor capsule, which could be peeled off easily from the ventricle floor remnants at most areas of the plane of tumor attachment. Some portions of the tumor capsule tightly adhered to the third ventricle floor were removed together with the floor. A breach of various size was observed at the third ventricle floor after tumor removal in most cases, the floor remaining intact in only two cases (7.7%). Histological examination on marked portions of tumor capsule showed that the pia mater was frequently detected at most of the tumor-brain interface, except at the antero-frontal border of tumor contacting with the third ventricle floor. At this point, a layer of gliosis with various thickness was observed between the tumor and the neural tissue of the third ventricle floor.
CONCLUSIONS: CPs with predominantly ventricular involvement should be considered as lesions with an extraventricular, epi-pia topography rather than \"intraventricular\" or \"subpial\" topography. Accurate understanding of the relationship between the third ventricle and such tumors would predict the circumferential cleavage plane of dissection, and remind neurosurgeons of performing dissection along the safe surgical plane to achieve total tumoral resection with minimizing hypothalamic damage.

UNASSIGNED: Skull base chordomas (SBCs) are rare malignant bone tumors with dismal long-term local control. Endoscopic endonasal surgeries (EESs) are increasingly adopted to resect SBCs recently. Gross total resection (GTR) favors good outcomes. However, the SBCs often invade the skull base extensively and hide behind vital neurovascular structures; the tumors were challenging to remove entirely. To improve the GTR, we established a surgical strategy for EES according to the tumor growth directions.
UNASSIGNED: A total of 112 patients with SBCs from 2018 to 2019 were classified into the derivation group. We retrospectively analyzed their radiologic images and operation videos to find the accurate tumor locations. By doing so, we confirmed the tumor growth directions and established a surgical strategy. Fifty-five patients who were operated on in 2020 were regarded as the validation group, and we performed their operations following the surgical strategy to verify its value.
UNASSIGNED: In the derivation group, 78.6% of SBCs invade the dorsum sellae and posterior clinoid process region. 62.5% and 69.6% of tumors extend to the left and right posterior spaces of cavernous ICA, respectively. 59.8% and 61.6% of tumors extend to the left and right posterior spaces of paraclival and lacerum ICA (pc-la ICA), respectively. 30.4% and 28.6% of tumors extended along the left and right petroclival fissures that extend toward the jugular foramen, respectively. 30.4% of tumors involved the foramen magnum and craniocervical junction region. The GTR was achieved in 60.8% of patients with primary SBCs in the derivation group. Based on the tumors\' growth pattern, pituitary transposition and posterior clinoidectomy techniques were adopted to resect tumors that hid behind cavernous ICA. Paraclival ICA transposition was used when the tumor invaded the posterior spaces of pc-la ICA. Lacerum fibrocartilage resection and eustachian tube transposition may be warranted to resect the tumors that extended to the jugular foramen. GTR was achieved in 75.0% of patients with primary SBCs in the validation group.
UNASSIGNED: Besides the midline clival region, the SBCs frequently grow into the eight spaces mentioned above. The surgical strategy based on the growth pattern contributes to increasing the GTR rate.

Ventral medial pontine cavernous malformations are challenging due to the location in eloquent tissue, surrounding critical anatomy, and potential symptomatic bleeding. Conventional approaches, such as anterolateral, lateral and dorsal approach, are associated with high risk of deleterious consequences due to excessive traction and damage to the surrounding tissues. The authors present an endoscopic endonasal approach for the resection of midline ventral pontine cavernous malformations, which follows principles of optimal access to brainstem cavernous malformations as the \"two-point method.\" No CSF leak or any other complications are obtained. The successful outcomes indicate that an individualized approach should be chosen before the surgery for brainstem cavernous malformations. With the advance of techniques, endoscopic endonasal approach could provide the most direct route to ventral pontine lesions with safety and efficiency.

A pituitary adenoma patient who underwent surgery in our department was diagnosed with COVID-19 and 14 medical staff were confirmed infected later. This case has been cited several times but without accuracy or entirety, we feel obligated to report it and share our thoughts on the epidemic among medical staff and performing endonasal endoscopic surgery during COVID-19 pandemic.
The patient developed a fever 3 d post endonasal endoscopic surgery during which cerebrospinal leak occurred, and was confirmed with SARS-CoV-2 infection later. Several medical staff outside the operating room were diagnosed with COVID-19, while the ones who participated in the surgery were not.
The deceptive nature of COVID-19 results from its most frequent onset symptom, fever, a cliché in neurosurgery, which makes it hard for surgeons to differentiate. The COVID-19 epidemic among medical staff in our department was deemed as postoperative rather than intraoperative transmission, and attributed to not applying sufficient personal airway protection. Proper personal protective equipment and social distancing between medical staff contributed to limiting epidemic since the initial outbreak. Emergency endonasal endoscopic surgeries are feasible since COVID-19 is still supposed to be containable when the surgeries are performed in negative pressure operating rooms with personal protective equipment and the patients are kept under quarantine postoperatively. However, we do not encourage elective surgeries during this pandemic, which might put patients in conditions vulnerable to COVID-19.

Background: Many techniques have been proposed to close an oroantral fistula (OAF), with most of them involving transoral repairs with oral soft tissue flaps. An additional Caldwell-Luc approach or endoscopic sinus surgery (ESS) is required to address coexisting maxillary sinusitis. Objectives: This study presents the endonasal closure of an OAF through modified endoscopic medial maxillectomy (MEMM) with a free nasal mucoperichondrial-osteal graft. Materials and methods: Sixteen OAF patients who underwent closure operations in our department from May 2013 to June 2018 were retrospectively reviewed. Results: The main cause of OAF was maxillary dental cysts (56.25%). The OAF size ranged from 2 × 2 to 10 × 15 mm. The first molar (62.5%) was the most frequently involved tooth. All closures were made via MEMM, using nasal mucoperichondrial-osteal grafts harvested from the septum or nasal base. All patients were followed up for at least six months. Successful closure after a single procedure was achieved in 93.75% of cases. No obvious complications or recurrences were observed. Conclusions: Endonasal repair of OAFs via MEMM with free nasal mucosal grafts is feasible and promising. The approach preserves the normal oral and nasal physiology after surgery. It could be used alone for the closure of small to medium-sized OAFs.