Vestibular Schwannoma Research Articles

Purines and purinergic receptors in primary tumors of the central nervous system.

Purine nucleotides and nucleosides play critical roles in various pathological conditions, including tumor cell growth. Adenosine triphosphate (ATP) activates pro-tumor receptors, while adenosine (ADO) is a potent immunosuppressant and modulator of cell growth. This study aims to analyze the purinergic actions of ATP and its metabolites, associated enzymes, and P1 or P2 class receptors in primary central nervous system tumors. Additionally, we sought to correlate the levels of nucleosides and the density of P1, P2X, and P2Y receptors in cells with tumor progression. The results indicate that purinergic signaling depends on the receptor concentration and signaling molecules specific to each cell type, tissue, and tumor histology. The purinergic system may function as either a tumor-promoting agent or an antitumor factor, depending on the microenvironmental conditions and the concentrations of receptors and their respective activators. Notably, ATP emerges as the most significant extracellular signal, capable of being converted into other cellular stimulators pertinent to neoplasms, such as adenosine diphosphate, adenosine monophosphate, adenosine, and inosine. Consequently, a cascade of responses to these stimuli promotes tumor development, cell division, and metastasis. Purine nucleotides in central nervous system tumors are pivotal in cellular responses in glioblastoma multiforme, vestibular schwannoma, medulloblastoma, adenomas, gliomas, meningiomas, and pineal tumors. These findings hold the potential for developing novel therapeutic strategies and aiding in therapeutic management.

Evaluation of Hearing Loss: Understanding Audiologic Testing to Refine Image Interpretation.

The standard of reference for diagnosing and characterizing hearing loss is audiologic testing. The results of audiologic testing inform the imaging algorithm and the differential diagnosis for the underlying cause. Pure-tone audiometry tests the ability to hear tones across different frequencies, and the results are displayed as an audiogram. Tympanometry measures tympanic membrane compliance as a function of pressure to generate a tympanogram. Acoustic reflex testing helps differentiate third window lesions from other causes of conductive hearing loss. Clinical and audiologic assessment of sensorineural hearing loss helps in differentiating cochlear from retrocochlear causes. Symmetrical sensorineural hearing loss is typical of cochlear disease. Asymmetry increases the likelihood of a retrocochlear lesion, the most common of which among adults is vestibular schwannoma. Unlike patients with sensorineural hearing loss, who commonly have normal imaging studies, patients with conductive hearing loss are expected to have abnormal temporal bone CT studies. By incorporating the results of audiologic testing into their evaluation, radiologists can perform a more informed and more intentional search for the structural cause of hearing loss. The authors describe several audiogram configurations that suggest specific underlying mechanisms of conductive hearing loss. By providing a practical and accessible summary of the basics of audiologic testing, the authors empower the radiologist to leverage relevant clinical information and audiologic test results to interpret temporal bone imaging more confidently and more accurately, particularly temporal bone CT in the setting of conductive hearing loss. ©RSNA, 2024.

Verification of mean dose in a tumor using 3D-printed tumor-model scintillators in anthropomorphic phantoms and a spherical phantom

To enhance treatment outcomes of radiotherapy, accurate verification of dosimetric parameters such as the mean, minimum, and maximum doses is essential. This study aimed to measure the mean absorbed dose in a tumor-shaped target and compare the results with the calculated value of the treatment planning system. Tumor model scintillators (TMSs) mimicking brain tumors were fabricated with a commercial 3D printer based on stereolithography files of tumors. The TMSs were irradiated following treatment plans made with the Leksell Gamma Plan® (Elekta AB, Stockholm, Sweden), and the mean dose in each TMS was measured three times and compared with the calculated value. Eleven TMSs were set at the center of a spherical solid water phantom. Two additional TMSs were fabricated according to images of vestibular schwannomas and were set at the tumor location in head model phantoms following each patient's head shape. The mean relative differences between the measured and calculated mean doses were less than one percent. This method provides an independent parameter for evaluating the accuracy of the treatment planning system.

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

To evaluate if permanent hearing loss occurred in the unoperated ear of patients undergoing otologic and skull base surgery with high-speed otologic drilling. 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. The University of Pittsburgh Medical Center. 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%). 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. 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. A significant number of patients demonstrated poorer hearing thresholds in the contralateral, unoperated ear after otologic and skull base surgery.

Optimizing retrosigmoid approach for giant vestibular schwannoma resection: strategies and advances in surgical technique

Optimizing retrosigmoid approach for giant vestibular schwannoma resection: strategies and advances in surgical technique

Current trends in vestibular schwannoma management at a referral center in Indonesia: A cross-sectional study with retrospective data collection

Background. Vestibular schwannoma (VS) is the most common benign brain tumor of the cerebellopontine angle. Due to its location, this pathology can create both focal and general deficits. The registry system for VS in Indonesia is developing, including in the author’s institution, which eventually shows a changing trend in managing VS. Methods. We retrospectively collected data from all patients diagnosed with vestibular schwannoma, based on histological or radiological results. Treatments included craniotomy and/or Gamma Knife Radiosurgery (GKRS) from 2018 to 2023. Results. Data from 88 patients were analyzed. The number of treated patients has increased annually. VS predominantly affects females (64%). The proportion between GKRS and craniotomy procedures also shifted throughout the year. Common symptoms included hearing loss (63.6%), disequilibrium (50%), and headaches (39.7%). The most common tumor size was medium (15-30 mm; n=37; 42%). Tumors that fell into the intrameatal and small (<15 mm) categories were all treated with GKRS, whereas the other groups were divided into GKRS and craniotomy. GKRS demonstrated high efficacy in tumor control and favorable hearing and facial nerve preservation, whereas craniotomy remained crucial for larger tumors. Conclusion. The number of VS diagnosed each year has increased in our center, accompanied by a noticeable shift in preference from GKRS to craniotomy, which is influenced by the integration of intraoperative monitoring. Treatment preference was further determined based on the clinical profile and tumor size. In the future, there is a need to develop a national registry to better reflect the true incidence of VS within the Indonesian population.

The Ratio of Baseline Ventricle Volume to Total Brain Volume Predicts Postoperative Ventriculo-Peritoneal Shunt Dependency after Sporadic Vestibular Schwannoma Surgery.

Background/Objectives: Obstructive hydrocephalus associated with vestibular schwannoma (VS) is the most common in giant VS. Despite tumor removal, some patients may require ongoing ventriculo-peritoneal (VP) surgery. This investigation explores the factors contributing to the requirement for VP surgery following VS surgery in instances of persistent hydrocephalus (HCP). Methods: Volumetric MRI analyses of pre- and postoperative tumor volumes, cerebellum, cerebrum, ventricle system, fourth ventricle, brainstem, and peritumoral edema were conducted using Brainlab Smartbrush and 3D Slicer. The total brain volume was defined as the sum of the cerebrum, cerebellum, and brainstem. ROC analyses were performed to identify the optimum cut-off values of the volumetric data. Results: Permanent cerebrospinal fluid (CSF) diversion after surgery was indicated in 12 patients (12/71; 16.9%). The ratio of baseline volume fraction of brain ventricles to total brain ventricle volume (VTB ratio) was found to predict postoperative VP shunt dependency. The AUC was 0.71 (95% CI: 0.51-0.91), and the optimum threshold value (</≥0.449) yielded a sensitivity and specificity of 67% and 81%, respectively. Multivariable logistic regression analyses of imaging data (pre- and postoperative VS volume, VTB ratio, and extent of resection (%) (EoR)) and patient-specific factors revealed that an increased VTB ratio (≥0.049, OR: 6.2, 95% CI: 1.0-38.0, p = 0.047) and an EoR < 96.4% (OR: 9.1, 95% CI: 1.2-69.3, p = 0.032) were independently associated with postoperative VP shunt dependency. Conclusions: Primary tumor removal remains the best treatment to reduce the risk of postoperative persistent hydrocephalus. However, patients with an increased preoperative VTB ratio are prone to needing postoperative VP shunt surgery and may benefit from perioperative EVD placement.

Comparison of two biologically effective dose calculation models applied to single fraction stereotactic radiosurgery

BackgroundRecent studies suggest strong correlations between Biologically Effective Doses (BED) and single fraction stereotactic radiosurgery treatment outcomes, as demonstrated for vestibular schwannomas (VS), arterio-venous malformations and pituitary adenomas. The BEDs calculated in these studies consider an uniform dose delivery where the spatio-temporal aspects of dose delivery were neglected. PurposeThe aim of the study is to quantify the discrepancies between the BED values calculated with a simplified model of uniform dose delivery against the more complex model that incorporates the temporo-spatial incrementation of dose delivery and the bi-exponential effect of the sub-lethal damage repair. MethodsA software tool that computes the BED distributions based on individual isocenter dose matrices extracted from the GammaPlan (Elekta) treatment planning was developed. Two cohorts 5 VS and 5 jugular foramen schwannoma cases of various tumor volumes and isocenter number were utilized to benchmark the method. Their BEDs covering 98% of tumor volumes were compared against those determined with the uniform delivery model. ResultsThe BEDs covering 98% of the tumor volumes as calculated with both models show an approximately linear dependency with the treatment time. For all studied cases, the uniform delivery model overestimates the BEDs calculated with the full spatio-temporal delivery model. This discrepancy seems to accentuate with the tumor volume and treatment complexity. ConclusionsDespite their resemblance, the BED distributions provide a plethora of BED measures more suitable to characterize clinical outcomes than the unique peripheral BED value calculated with the simplified model of uniform dose delivery.

Interactions among Merlin, Arkadia, and SKOR2 mediate NF2-associated Schwann cell proliferation in human.

NF2-Related Schwannomatosis (previously referred to as Neurofibromatosis Type 2, or NF2) is a genetic-associated disease resulting from mutations in the gene, NF2. NF2 encodes the merlin protein, which acts as a tumor suppressor. Bilateral vestibular schwannoma (VS) is a hallmark of NF2. Although the exactly molecular mechanism mediating NF2-driven schwannomatosis remain unclear, it is known that defective Merlin protein functionality leads to abnormal cell proliferation. Herein, we utilized a human induced pluripotent stem cell (hiPSC)-based Schwann cell (SC) model to investigate the role of merlin in human SCs. SCs were derived from hiPSCs carrying a NF2 mutation (c.191 T > C; p. L64P), its isogenic wild-type control cell line, and a NF2 patient-derived hiPSC line. NF2 mutant SCs showed abnormal cellular morphology and proliferation. Proteomic analyses identified novel interaction partners for Merlin - Arkadia and SKOR2. Our results established a new model in which merlin interacts with Arkadia and SKOR2 and this interaction is required for the proper activation of the SMAD-dependent pathway in TGFβ signaling.

Role of Surgery in Vestibular Schwannoma following prior Stereotactic Radiosurgery.

Stereotactic radiosurgery (SRS) is widely used for treating vestibular schwannoma (VS), offering high tumour control rates, especially in small to medium-sized tumours. However, a subset of patients experiences SRS failure, requiring subsequent salvage microsurgery (MS). The primary reason for salvage surgery is continued tumour growth, but other causes include symptom progression and cystic enlargement. Salvage surgery is more challenging due to increased tumour adhesion to critical structures, resulting in higher complication rates, particularly for facial nerve preservation. Studies suggest subtotal resection may offer better outcomes than gross total resection in terms of facial nerve function, though treatment remains complex and outcomes vary.

William F. House: The Father of Neurotology.

William F. House (1923-2012) was an ear, nose, and throat specialist with a particular focus in otology and an inventor, with perhaps his greatest invention being the single-channel cochlear implant. Although heavily criticized at the beginning of his career for developing the single-channel cochlear implant, many individuals would soon benefit from the device that House created. He also revolutionized a new technique for the removal of vestibular schwannomas with assistance from his neurosurgeon colleague, Dr. William Hitselberger. House is considered as the "Father of Neurotology" because of his many advancements in the medical field with refined surgery techniques and life-changing devices.

Vestibular schwannoma-related increased labyrinthine post-gadolinium 3D-FLAIR signal intensity and association with hearing impairment.

Vestibular schwannomas (VSs) are benign neurogenic tumors commonly associated with progressive unilateral hearing loss, tinnitus, and vestibular symptoms. Growing evidence links signal changes in the VS-adjacent labyrinth with sensorineural hearing loss. This study seeks to quantify the association of labyrinthine signal on post-gadolinium 3D-FLAIR imaging correlates with hearing loss and to evaluate potential longitudinal changes over time. Selected patients were identified from a prospectively maintained VS registry. Mean signal intensity ratios of the bilateral labyrinth and pons were measured on 3D-FLAIR post-gadolinium MRI. Correlations with paired audiometric data including pure tone average (PTA), word recognition score (WRS), and AAO-HNS hearing class within one year were evaluated. 125 studies obtained from 2015 to 2022 among 66 patients undergoing observational management for sporadic VS were analyzed. Increased signal intensity was noted of the VS-affected labyrinth/contralateral labyrinth (mean ratio 1.56, SD 0.58). Increased signal intensity was associated with increased PTA on both labyrinthine (correlation coefficient [CC] 0.20, p=0.03) and pontine comparisons (CC 0.24, p=0.006), and with decreased WRS on pontine comparisons (CC -0.18, p=0.04). Increased signal intensity was significantly associated with non-serviceable AAO-HNS C/D hearing when intensities were compared to the pons (p=0.01) but not the contralateral labyrinth (p=0.1). Among 44 patients with available follow-up, no statistically significant associations were identified between audiometric data and signal changes over the same interval. Increased 3D-FLAIR post-gadolinium labyrinthine signal is associated with sensorineural hearing loss; however, its relationship with hearing trajectory remains unclear. Overall findings suggest that while post-gadolinium 3D-FLAIR techniques are sensitive to inner ear involvement associated with VS, the driving mechanism and their temporal relationships with labyrinthine signal intensity and hearing impairment remain unknown. AAO-HNS =American Academy of Otolaryngology -Head and Neck Surgery. BLB =blood-labyrinth barrier. CPA = cerebellopontine angle. IAC = internal auditory canal. PTA = pure tone average; SIR = signal intensity ratio. VS = vestibular schwannoma. WRS = word recognition score.

Dynamics of tumor evolution after Gammaknife radiosurgery for sporadic vestibular schwannoma: defining volumetric patterns characterizing individual trajectory.

Definition of tumor control and treatment failure after Gammaknife radiosurgery (GKRS) for vestibular schwannoma (VS) is still debated. The lack of knowledge on the dynamics of tumor evolution can lead to misinterpretation and subsequent inappropriate second treatment. The aim of this study was to evaluate the post-GKRS dynamics of evolution of tumor volume, and characterize volumetric patterns. We included patients with sporadic VS treated by GKRS with an MRI follow-up of minimum 3 years. A clustering in 2 steps was performed: definition of the patterns of evolution based on a subset of patients with the most comprehensive follow-up, then assignment of the remaining patients on a best fit basis. The minimum length of follow-up was assessed by measuring the consistency of the clusters over time (Adjusted Rand Index and Normalized Mutual Information). An analysis of the discriminant variables was finally performed. 1,607 patients were included (median follow-up: 67 months). Five patterns were defined with one pattern gathering almost all cases of treatment failure. The clustering at 5 years afforded the highest consistency with long-term follow-up. Discriminant variables for clusters were: sex, initial symptoms, delay of diagnosis, Koos grading, fundus invasion, and number of isocenters. The definition of these robust distinct patterns is likely to help tremendously the physicians to distinguish tumor control from potential failure. We advocate for no retreatment decision before 5 years post-GKRS. Further investigations are required to decide if the dynamics of evolution can be predicted at GKRS on an individual basis.

Detecting Manifestations of Neurofibromatosis: Cutaneous Diagnostic Criteria for NF1 and NF2

Neurofibromatosis is a hereditary condition that causes tumors to form in the brain, spinal cord, and nerve regions. Neurofibromatosis Type 1 (NF1) and Neurofibromatosis Type 2 (NF2) are the two of the most common subtypes. We performed a literature review on Pubmed under the following search and included the 24 most cited papers between 2012 and 2024: “Neurofibromatosis AND (Cutaneous OR Skin) AND (Diagnostic Criteria OR Diagnosis) AND (NF1 OR NF2)”. In our review, both types can manifest cutaneous symptoms, which aid in early detection. Between the two types, NF1 is more common with an estimated prevalence of 1 in 3000, compared to NF2’s 1 in 60,000. NF1 is distinguished by café-au-lait spots, freckling, and neurofibromas; NF2 presents similar to NF1 but may also have characteristic bilateral vestibular schwannomas. While both conditions may exhibit cutaneous manifestations, NF1 primarily presents with such features, whereas NF2 is distinguished by intracranial manifestations. Early detection of cutaneous symptoms is critical for prompt intervention and management of neurofibromatosis. More research is needed to elucidate the detection of neurofibromatosis in clinical practice as differentiation may be challenging.

Application and development of super minimally invasive surgery concept in acoustic neuroma resection

With the development of medicine, surgery has also experienced the development and evolution from traditional surgery to minimally invasive surgery, and then to super minimally invasive surgery (SMIS). Meanwhile, reducing surgical trauma and preserving and reconstructing nerve function have gradually become new goals of modern vestibular schwannoma (VS) resection surgery. The surgery of VS can be divided into hearing-preserving surgery (retrosigmoid approach and middle fossa approach) and non-hearing-preserving surgery (traditional translabyrinthine approach), according to whether the patient has practical hearing before operation. Improving the hearing preservation rate of hearing-preserving surgery and reconstructing the hearing of patients with non-hearing-preserving surgery are major challenges and hotspots. The traditional translabyrinthine approach has the highest proportion in the Department of Otolaryngology-Head and Neck Surgery, with the advantages of high facial nerve preservation rate and few intracranial complications. However, due to the resection of the cochlear nerve and labyrinth, the cochlea develops fibrosis, and patients lose the opportunity to reconstruct hearing through cochlear implantation. The new modified translabyrinthine approach can preserve the cochlear nerve and effectively reduce cochlear fibrosis, providing an opportunity for cochlear implantation to reconstruct the hearing. This is another important breakthrough in vestibular schwannoma surgery.

Hearing preservation and quality of life in small to medium sized vestibular schwannomas after a wait and scan approach or stereotactic radiosurgery: a systematic review and meta-analysis.

The management of vestibular schwannomas (VS) encompasses a choice between conservative "wait-and-scan" (WAS) approach, stereotactic radiosurgery (SRS) or open microsurgical resection. Currently, there is no consensus on the optimal management approach for small to mediumsized VS. This study aims to compared outcomes related to hearing in patients with small and mediumsized VS who underwent initial treatment with WAS versus SRS. A systematic review of the available literature was conducted using PubMed/MEDLINE, Embase, and Cochrane up December 08, 2023. Meta-analysis was performed using a random-effect model to calculate mean difference (MD) and relative risk (RR). A leave-one-out analysis was conducted. The risk of bias was assessed via the Risk of Bias in Non-randomized Studies-Interventions (ROBINS-I) and Cochrane Risk of Bias assessment tool (RoB-2). Ultimately, the certainty of evidence was evaluated using the GRADE assessment. The primary outcomes were serviceable hearing, and pure-tone average (PTA). The secondary outcome was the Penn Acoustic Neuroma Quality of Life Scale (PANQOL) total score. Nine studies were eligible for inclusion, comprising a total of 1,275 patients. Among these, 674 (52.86%) underwent WAS, while 601 patients (47.14%) received SRS. Follow-up duration ranged from two to eight years. The meta-analysis indicated that WAS had a better outcome for serviceable hearing (0.47; 95% CI: 0.32 - 0.68; p < 0.001), as well as for postoperative functional measures including PTA score (MD 13.48; 95% CI 3.83 - 23.13; p < 0.01), and PANQOL total score (MD 3.83; 95% CI 0.42 - 7.25; p = 0.03). The overall certainty of evidence ranged from "very low" to "moderate". Treating small to mediumsized VS with WAS increases the likelihood of preserving serviceable hearing and optimized PANQOL overall postoperative score compared to SRS. Nevertheless, the limited availability of literature and the methodological weakness observed in existing studies outline the need for higher-quality studies.

The Impact of Tumor Elongation on Facial Nerve Outcome after Surgery for Koos Grade 3 and 4 Vestibular Schwannomas in the Semi-Sitting Position via the Retrosigmoid Approach.

Background: Facial nerve paralysis is a severe dysfunction after vestibular schwannoma (VS) surgery. Methods: This monocentric study analyzed 61 patients who underwent sporadic VS surgery in a standardized manner. The primary endpoint was the facial nerve outcome (FNO) at 3 months after VS surgery. FNO was dichotomized into "good" (House-Brackmann (HB) score ≤ 2) and "poor" (HB > 2). Results: Poor FNO was observed in 11 patients (18.0%) at 3 months after VS surgery. Radiomic tumor shape features were analyzed, and the AUC of elongation in the prediction of a poor HB at 3 months was 0.70 (95% CI: 0.56-0.85, p = 0.03) and the optimum threshold value (≤/>0.35) yielded a sensitivity and specificity of 64.0% and 75.4%, respectively. Multivariable logistic regression analyses considering the extent of resection (</≥93.4%), preoperative tumor volume (</≥2.6 cm3), age (</≥55), sex (female/male), and elongation (≤/>0.35) revealed that more elongated VSs (≤0.35; OR: 5.8; 95%CI: 1.2-28.2; p = 0.03) and those with an increased EoR (≥93.4%; OR: 6.5; 95%CI: 1.0-42.5; p = 0.05) are independently associated with poorer FNO at 3 months after surgery. Conclusions: Highly elongated VS shape seems to be a risk factor for worsened facial nerve outcome at 3 months after surgery for Koos grade 3 and 4 tumors.

Predictors of Prolonged Hospital Stay After Microsurgery for Vestibular Schwannoma: Analysis of a Decade of Data.

Microsurgical resection is one of the treatments for vestibular schwannomas (VS). While several factors have been linked to increased length of stay (LOS) for VS patients undergoing microsurgery, a better understanding of these factors is important to provide prognostic information for patients. Determine predictors of increased LOS for VS patients undergoing microsurgical resection. Retrospective analysis using the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database from 2010 to 2020. Database review. All patients who underwent microsurgery (CPT codes 61520, 61526/61596) for the management of vestibular schwannoma (ICD9 and ICD10 codes 225.1, D33.3) were included. Analyzing perioperative factors that can predict prolonged hospital stay. A total of 2096 cases were identified and 1,188 (57%) of these patients were female. The mean age was 51.0 ± 14.0 years. Factors contributing to prolonged LOS included African American race (OR = 2.11, 95% CI: 1.32-3.36, p = 0.002), insulin-dependent diabetes mellitus (OR = 2.12, 95% CI: 1.09-4.4.11, p = 0.026), hypertension (OR = 1.26, 95% CI: 1-1.58, p = 0.046), functional dependency (OR = 5.22, 95% CI: 2.31-11.79, p = 0.001), prior steroid use (OR = 1.96, 95% CI: 1.18-3.15, p = 0.009), ASA class III (OR = 2.06, 95% CI: 1.18-3.6, p < 0.011), ASA class IV (OR = 6.34, 95% CI: 2.62-15.33, p < 0.001), and prolonged operative time (OR = 2.14, 95% CI: 1.76-2.61). Microsurgery by a translabyrinthine (TL) approach compared to a retrosigmoid (RSG) approach had lower odds of prolonged LOS (OR = 0.67, 95% CI: 0.54-0.82, p < 0.001). In a separate analysis regarding patients receiving reoperation, operative time was the only predictor of prolonged LOS (OR = 2.77, 95% CI: 1.39-5.53, p = 0.004.). Our analysis offers an analysis of the factors associated with a prolonged LOS for the surgical management of VS. By identifying healthcare disparities, targeting modifiable factors, and applying risk stratification based on demographics and comorbidities, we can work toward reducing disparities in LOS and enhancing patient outcomes.

Peculiarities of cerebral blood flow and vascular reactivity in patients with large and giant tumors of the cerebello-pontine angle

Background. Vestibular schwannomas and posterior fossa meningiomas are one of the most difficult tumors for surgical treatment. The mortality rate after their removal reaches 13,5 %. The main causes of death are hemorrhagic and ischemic complications. There are no studies in the literature on tissue perfusion of brainstem structures and cerebellum and reactivity of vertebral and basilar arteries in patients with extraaxial tumors of the posterior cranial fossa. Therefore, the study of the blood supply of the brainstem structures and cerebellum, as well as the functional characteristics of the vertebral and basilar arteries in these patients is of considerable interest.Aim. To evaluate tissue perfusion of the pons and cerebellum, as well asthe reactivity of the vertebral and basilar arteries in patients with large and giant vestibular schwannomas and posterior fossa meningiomas.Materials and methods. Eighty-two patients with large and giant extraaxial tumors of the base of the posterior cranial fossa were examined. The median age was 54 [44; 61] years. Vestibular schwannomas were diagnosed in 52.4 % of patients, and meningiomas of the posterior cranial fossa were diagnosed in 47.6 %. All patients underwent duplex scanning of the basilar and vertebral arteries. We evaluated linear blood flow and coefficients of reactivity and index of vasomotor reactivity. We investigated the metabolic reactivity of cerebral blood flow by conducting hyper- and hypocapnic tests. Computed tomography perfusion imaging was performed in 18 patients. We detected cerebral blood volume, cerebral blood flow, mean transit time of contrast agent and time to peak of contrast agent. Measurements were carried out in six regions of interest located symmetrically on the pons and in the white matter of the cerebellar hemispheres on the side of the tumor and on the opposite side.Results. Linear blood flow rates in the intracranial segments of the vertebral and the basilar arteries in patients with tumors were higher than in the comparison group (p&lt;0.05). These patients are characterized by a decrease of reactivity coefficients in the vertebral and basilar arteries, especially when performing hypercapnic tests (p &lt;0.05). Paradoxical reactivity and areactivity were diagnosed in 34.9 % of patients with vestibularschwannomas and 25.6 % with meningiomas. In the pons on the side of the tumor in patients with vestibularschwannomas, a decrease in cerebral blood flow by 19.3 %, an increase in cerebral blood volume by 33.3 % and an increase in mean transit time of contrast agent and in time to peak of contrast agent by 48.1 % and 71.1 % (p &lt;0.05) were found. In patients with meningiomas in the pons on the side of the tumor, all perfusion parameters were higher (p&lt;0.05). In the deep regions of the cerebellar hemisphere on the side of the tumor in patients with tumors, all perfusion parameters were higher compared to the opposite side.Conclusion. The results of the study made it possible to quantify cerebral blood flow in patients with large and giant vestibular schwannomas and meningiomas of the posterior cranial fossa base. The revealed changes indicate the risk of developing pathological vascular reactions and disorders of cerebral blood flow in the postoperative period.

Postoperative dysgeusia following microsurgical resection for acoustic neuroma: a systematic review and meta-analysis.

To determine the collated rate of postoperative dysgeusia after microsurgical intervention in acoustic neuroma patients. The systematic review with meta-analysis was undertaken following PRISMA guidelines. A thorough search of PubMed/Medline, the Cochrane Database of Systematic Reviews, and Epistemonikos was undertaken for studies published up until May 16, 2024 reporting postoperative taste disturbance rates after microsurgical intervention for acoustic neuroma. The methodological quality of the included studies was assessed via the Methodological Index for Non-Randomized research (MINORS) tool. Using MedCalc (v. 20.215) software, the random-effects model was developed for proportional meta-analysis. Eight studies, encompassing 2,402 patients (mean age = 49.06 years; 48.54% female population), were included in the analysis. The overall pooled rate of postoperative dysgeusia following microsurgical management of acoustic neuroma was 23.7% (95% CI: 9.266-42.359, p < 0.0001). When stratified by surgical approach, the rate of postoperative dysgeusia for the retrosigmoid approach was 18.8% (95% CI: 2.821-44.461, p < 0.0001). Postoperative dysgeusia data stratified for other major microsurgical approaches (subtemporal and translabirynthine approaches) was not reported by any of the included studies. Our systematic review and meta-analysis calculated a collated rate of almost 25% and recognized postoperative dysgeusia as a common complication following microsurgical management of acoustic neuromas. These results highlight the significance of preoperative counselling and the development of strategies that minimize the likelihood of harm to the chorda tympani nerve during microsurgical intervention for acoustic neuroma.