OBJECTIVE: To optimize surgical positioning for posterior fossa surgery (PFS) using the semisitting position (SSP) to avoid venous air embolism (VAE) and its possible life-threatening consequences, the authors evaluated their experiences with the SSP by analyzing a large cohort of PFS patients.
METHODS: A retrospective analysis of the charts of 202 consecutive PFS patients (median age 54 years, IQR 41-61 years; 121 females) with various tumor or vascular conditions who underwent surgery in an SSP between 2019 and 2022 was performed. Age, sex, weight, height, BMI, American Society of Anesthesiologists (ASA) class, histology, duration of surgery, and length of hospital stay were assessed. Transesophageal echocardiography was used pre- and intraoperatively to monitor for and assess the degree of VAE.
RESULTS: Altogether, VAE occurred in 30 of 202 (14.9%) patients, with clinically relevant VAE occurring in 14 of 202 (7%) patients. The grades of VAE were I, III, and IV in 16 (8%), 4 (2%), and 10 (5%) patients, respectively. Patient height (p = 0.04), ASA class (p = 0.03), and ASA class ≤ II (p = 0.02) remained the only preoperative statistically significant risk factors for intraoperative VAE, with a median height of 178 cm (IQR 172-184 cm) in patients with clinically relevant VAE compared with 170 cm (IQR 164-176 cm) in those without VAE.
CONCLUSIONS: In summary, the data demonstrate that SSP can be used safely for PFS when taking special care to optimize positioning in tall and lower-grade ASA patients intraoperatively.

BACKGROUND: Facial nerve palsies may develop during the postoperative period of microsurgical removal of vestibular schwannomas (VSs), even after normal facial function for days or weeks after surgery. The aim of this study was to identify the pathomechanism and predictive factors of delayed palsy.
METHODS: The clinical data of 193 patients who underwent vestibular schwannoma surgery between 2012 and 2021 were retrospectively analyzed. A total of 134 patients were included. The patients showed intact facial nerve function up to 24 h after surgery. All patients (n = 20) with palsy from postoperative day 4 were included and collectively referred to as delayed facial nerve palsy (DFNP). Various factors were checked using a binomial regression analysis.
RESULTS: The mean age of patients with DFNP was 57.8 years (55% female, 45% male). 70% had VS with KOOS ≥ 3, and 60% underwent surgery via a translabyrinthine approach Among the 16 patients with DFNP-related neurotropic pathogens, 25% were seropositive for herpes simplex virus. Most patients (n = 9/20) experienced onset of palsy between postoperative days 6 and 10. Of the four variables included in the significance test, three were significant: KOOS ≥ 3 (p < .04), ipsilateral vestibular organ failure (p < .05), and age group (p < .03). After therapy, 100% of patients recovered almost complete facial nerve function. The parameters mentioned above (KOOS classification and ipsilateral vestibular dysfunction) could be proven risk factors for the occurrence of DFNP.

OBJECTIVE: Tumors of the skull base can be accessed through different routes. Recent advantages in minimally invasive techniques have shown that very different routes can be applied for optimal tumor resection depending on the technical equipment, the surgeon\'s preference, and the individual anatomy of the pathology. Here, the authors present their technique for pure endoscopic transcranial tumor resection in meningiomas.
METHODS: Out of the cases of the Department of Neurosurgery, Homburg Saar Germany of the last 10 years, all endoscopic procedures for meningiomas were analyzed. Particular attention was given to evaluating the peculiarities of those meningiomas that were treated purely endoscopically.
RESULTS: While the endoscope was used in a large number of skull base meningiomas in endonasal approaches or for endoscopic inspection in transcranial skull base surgery, only a small number of meningiomas was selected for a purely endoscopically performed resection. The characteristics of these cases were rather a small lesion, straight access, and a keyhole position of the craniotomy. A complete resection of the tumor was achieved in all cases. Conversion to the microscope was not necessary in any case. There were no technical issues or complications associated with a fully endoscopic resection.
CONCLUSIONS: The endoscope is a valuable tool for visualization in meningioma surgery. In most cases, it is applied for an endonasal route or for endoscopic inspection in transcranial microsurgical cases. However, small to medium-sized meningiomas that can be accessed through the keyhole approach are good candidates for pure endoscopic resection. Because of the very high magnification and the minimally invasive nature of this approach, it should be considered more frequently in suitable lesions.

Background: Trigeminal schwannomas (TSs) are uncommon tumors found along any segment of the fifth cranial nerve (CN V). Typically located at the skull base, these benign tumors carry substantial morbidity due to the extent of traditional surgical methods. Minimally invasive endoscopic surgery such as the endoscopic transorbital approach (ETOA) presents promising new avenues for treatment, with the transorbital approach emerging as a potentially successful alternative. Methods: This review systematically assesses the application of the ETOA in treating TSs. PubMed, Ovid MEDLINE, and Embase were thoroughly searched for articles detailing the use of the ETOA in clinical case studies. The outcomes of interest encompassed epidemiological profiling, surgical results, and complication rates. Results: This study included 70 patients with TSs (from six studies), with 22 males (31.4%) and 58 females (68.6%). Patients averaged 55 years and were monitored for around 16.4 months (on average). In most tumors, the middle cranial fossa was involved to some degree. The majority (87.2%) were large (3-6 cm) and underwent gross total resection (GTR) or near-total resection in 87.2% of patients. Preoperatively, sensory alterations were common, along with proptosis, neuropathic pain, and diplopia. Postoperatively, complications included ptosis, diplopia, sensory impairment, corneal keratopathy, masticatory difficulty, and neuralgia. The pure ETOA was the primary surgical technique used in 90% of cases, with no recurrence observed during the follow-up period. Conclusions: Using the ETOA to treat TSs demonstrated an oncologic control rate of 87.2%. Postoperative complications including ptosis, diplopia, and sensory disturbances have been observed, but careful monitoring and management can mitigate these problems. The ETOA emerges as a viable surgical option, especially for tumors involving the middle cranial fossa, capable of adapting to individual patient needs and demonstrating efficacy in TS management.

The goal of this American Rhinologic Society expert practice statement (EPS) is to summarize the best available evidence regarding postoperative precautions for patients following endoscopic skull base surgery for intradural pathology. These topics include the administration of postoperative nasal hygiene; patient mobilization and activity level; the resumption of continuous positive airway pressure in patients with obstructive sleep apnea; and the timing and capacity with which a patient may be subjected to barotrauma, such as air travel postoperatively. This EPS was developed following the recommended methodology and approval process as previously outlined. Given the diverse practices and limited agreement on the accepted principles regarding postoperative precautions for patients following skull base surgery, this EPS seeks to summarize the existing literature and provide clinically relevant guidance to bring clarity to these differing practice patterns. Following a modified Delphi approach, four statements were developed, all of which reached consensus. Because of the paucity of literature on these topics, these statements represent a summation of the limited literature and the experts\' opinions. These statements and the accompanying evidence are summarized below, along with an assessment of future needs.

OBJECTIVE: In patients with inner ear schwannomas (IES), reports on hearing rehabilitation with cochlear implants (CI) have increased over the past decade, most of which are case reports or small case series. The aim of this study is to systematically review the reported hearing results with CI in patients with IES considering the different audiologic outcome measures used in different countries.
METHODS: According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline, a search of published literature was conducted. We included patients with IES (primary or with secondary extension from the internal auditory canal (IAC) to the inner ear, sporadic or NF2 related) undergoing cochlear implantation with or without tumour removal. The audiological results were divided into the categories \"monosyllables\", \"disyllables\", \"multisyllabic words or numbers\", and \"sentences\".
RESULTS: Predefined audiological outcome measures were available from 110 patients and 111 ears in 27 reports. The mean recognition scores for monosyllabic words with CI were 55% (SD: 24), for bisyllabic words 61% (SD: 36), for multisyllabic words and numbers 87% (SD: 25), and 71% (SD: 30) for sentences. Results from for multisyllabic words and numbers in general showed a tendency towards a ceiling effect. Possible risk factors for performance below average were higher complexity tumours (inner ear plus IAC/CPA), NF2, CI without tumour removal (\"CI through tumour\"), and sequential cochlear implantation after tumour removal (staged surgery).
CONCLUSIONS: Hearing loss in patients with inner ear schwannomas can be successfully rehabilitated with CI with above average speech performance in most cases. Cochlear implantation thus represents a valuable option for hearing rehabilitation also in patients with IES while at the same time maintaining the possibility of MRI follow-up. Further studies should investigate possible risk factors for poor performance. Audiological tests and outcome parameters should be reported in detail and ideally be harmonized to allow better comparison between languages.

Melanoma of the external auditory canal (EAC) is particularly rare and poorly understood, with limited available data on management and survival. This systematic review aims to analyze existing data and provide insights into the management and prognosis the beginning of EAC melanoma. It is conducted using Pubmed and Scopus databases from the beginning to July 2023 and it follows the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) 2020 guidelines. Searches are performed using the search string \"(melanoma) AND (external auditory canal)\".
The review includes a total of 30 patients diagnosed with EAC melanoma, supplemented by an additional case from the authors\' clinical experience. The role of Breslow thickness as a determining factor for the choice of surgery remains inconclusive due to limited available data. Sentinel lymph node biopsy and adjuvant therapy are sparingly employed, indicating the need for standardized guidelines. Patients in the study demonstrate a 50% overall survival rate at 5 years.
EAC Melanoma is a rare and aggressive malignancy with limited therapeutic guidelines. Surgical interventions, including wide local excision and lateral temporal bone resection, are the primary treatment options for patients without distant metastases.

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.

BACKGROUND: Advanced skull base malignancies are a heterogenous subset of head and neck cancers, and management is often complex. In recent times, there has been a paradigm shift in surgical technique and the advent of novel systemic options. Our goal was to analyse the long-term outcomes of a single quaternary head and neck and skull base service.
METHODS: A retrospective review of 127 patients with advanced anterior skull base malignancies that were treated at our institution between 1999 and 2015 was performed. Multiple variables were investigated to assess their significance on 5 and 10-year outcomes.
RESULTS: The mean age was 60.9 (± 12.6 SD). Sixty-four percent were males and 36% were females. Ninety percent of patients had T4 disease. Median survival time was 133 months. The 5-year overall survival (OS) was 66.2%, disease-specific survival (DSS) was 74.7%, and recurrence-free survival (RFS) was 65.0%. The 10-year OS was 55.1%, DSS was 72.1%, and RFS was 53.4%. Histological type and margin status significantly affected OS & DSS.
CONCLUSIONS: Surgical management of advanced skull base tumours has evolved over the last few decades at our institution with acceptable survival outcomes and complication rates. Histological diagnosis and margin status are the main predictors of survival. The addition of neoadjuvant systemic agents in current trials may improve outcomes.

UNASSIGNED: Primary intracranial neuroendocrine tumors (NETs) are exceedingly rare, often posing diagnostic challenges, particularly in non-secreting variants. These tumors may initially present with nonspecific symptoms, leading to delayed diagnosis and potential neurological complications.
METHODS: We present the case of a 33-year-old male admitted with a one-year history of progressively worsening headache accompanied by acute left ptosis and diplopia. Initial examination revealed left eye ptosis and hypotropia, indicative of third and fourth cranial nerve paralysis. Cavoscopy revealed a mild anterior wall bulge of the sphenoid with normal mucosa. MRI imaging unveiled an expansive clival process extending towards the sellar region and left cavernous sinus, completely occupying the sphenoid sinus and exerting mass effect on the pituitary stalk. Hormonal assays were within reference ranges, ruling out a hormonally-active tumor. Endoscopic endonasal surgery for biopsy revealed a low-grade neuroendocrine tumor positive for cytokeratin AE1/AE2, chromogranin A, synaptophysin, and beta-catenin, with a Ki-67-labeling index <2 %. Somatostatin receptor scintigraphy confirmed intense hyper fixation of the tracer in the sphenoidal tumor, supporting its neuroendocrine origin. The patient declined surgical intervention after informed consent, opting for C1 somatostatin analogs prior to radiotherapy. One-year follow-up demonstrated symptom stability with no tumor progression.
UNASSIGNED: To this day, no consensus among reports concerning the optimal management of these cases. Imaging assessment is crucial to validate the primary nature of the tumor and to exclude any distant localization. Various therapeutic modalities, such as surgery, radiotherapy, and somatostatin analogs, should be considered based on the specific characteristics and extent of the tumor.
CONCLUSIONS: Our case is a clear reminder that neuroendocrine tumors should be considered as a differential diagnosis for skull base neoplasms.