The surgical strategy "CSF decompression" facilitates outcomes of adults with Chiari malformation type I: An observational, real-world, single center study of 528 patients.

OBJECTIVES: We designed this study to introduce the surgical strategy "CSF decompression" in treating Chiari malformation type I (CMI), and compared the "CSF decompression" strategy with other surgical strategies to provide a solid basis for patient counseling. METHODS: A total of 528 consecutive CMI patients who underwent surgical interventions from 2012 to 2022 were enrolled. The surgical strategy for these patients was bony and dural decompression (BDD), anatomical reduction of herniated tonsils (AR) or CSF decompression (CSFD). Short-term results were determined after 3 months; long-term outcomes were evaluated at last follow-up and at least 18 months. RESULTS: The CSFD strategy was independently associated with better long- or short-term primary outcomes than AR or BDD (P < 0.001). Compared with short-term, the long-term outcomes were better in CSFD patients (P = 0.035), but were worse in BDD patients (P = 0.03). Specific surgical techniques cannot affect the long- and short-term outcomes of CMI patients. CSFD provided better long-term syringomyelia improvement than short-term (181/218, 83% vs 169/218, 77.5%; P < 0.001). CONCLUSION: The "CSF decompression" surgical strategy, but not a specific surgical technique or operative method, was associated with favorable neurological outcomes in adult CMI patients. The surgical technique and operative method should be selected according to the characteristics of each patient and the intraoperative condition to normalized CSF circulation at CVJ. The intraoperative target maybe smoothly CSF flow, out from the fourth ventricle and in to the bilateral Luschka foramina, could be observed.

Pontocerebellar Hypoplasia Type 9: A Case Study Highlighting Distinctive Magnetic Resonance Imaging Features.

Pontocerebellar hypoplasia type 9 (PCH9) is a rare, autosomal, recessive, neurodevelopmental disorder caused by a mutation in the AMPD2 gene. Despite its rarity, it presents distinctive clinical and neuroradiological features. Diagnosing it is challenging yet crucial for appropriate management. We describe a 21-month-old boy with clinical and neuroradiological manifestations of the diagnosis, including characteristic signs such as an eight-configured midbrain and hypoplasia of the brainstem and cerebellar structures. Genetic evaluation confirmed homozygous missense mutations in the AMPD2 gene. This case highlights the pathognomonic neuroradiological features of pontocerebellar hypoplasia type 9 that point toward diagnosis.

Medical management for cerebellar mutism syndrome following posterior fossa surgery: A systematic review.

INTRODUCTION: Cerebellar mutism syndrome (CMS) is a serious complication of posterior fossa surgeries affecting mainly pediatric age group. The pathophysiology is still not fully understood. It adversely affects the recovery of patients. There is no definitive and standardized management for CMS. However pharmacological therapy has been used in reported cases with variable effectiveness. We aim through this review to summarize the available evidence on pharmacological agents used to treat CMS. METHOD: A thorough systematic review until December 2022, was conducted using PubMed Central, Embase, and Web of Science, databases to identify case reports and case series of CMS patients who underwent posterior fossa surgery and received pharmacological treatment. Patients with pathologies other than posterior fossa lesions were excluded from the study. RESULTS: Of 592 initial studies, 8 studies met our eligibility criteria for inclusion, with 3 more studies were added through manual search; reporting on 13 patients. The median age of 13 years (Standard deviation SD=10.60). The most frequent agent used was Bromocriptine. Other agents were fluoxetine, midazolam, zolpidem, and arpiprazole. Most patients recovered within 48 hours of initiating medical therapy. The median follow-up period was 4 months (SD=13.8). All patients showed complete recovery at the end of follow-up period. CONCLUSION: Cerebellar mutism syndrome is reported after posterior fossa surgeries, despite attempts to identify risk factors, pathophysiology, and management of CMS, it remains a challenging condition with significant morbidity. Different Pharmacological treatments have been proposed with promising results. Further studies and formalized clinical trials are needed to evaluate available options and their effectiveness.

Using diffusion MRI to understand white matter damage and the link between brain microstructure and cognitive deficits in paediatric medulloblastoma patients.

PURPOSE: Survivors of medulloblastoma face a range of challenges after treatment, involving behavioural, cognitive, language and motor skills. Post-treatment outcomes are associated with structural changes within the brain resulting from both the tumour and the treatment. Diffusion magnetic resonance imaging (MRI) has been used to investigate the microstructure of the brain. In this review, we aim to summarise the literature on diffusion MRI in patients treated for medulloblastoma and discuss future directions on how diffusion imaging can be used to improve patient quality. METHOD: This review summarises the current literature on medulloblastoma in children, focusing on the impact of both the tumour and its treatment on brain microstructure. We review studies where diffusion MRI has been correlated with either treatment characteristics or cognitive outcomes. We discuss the role diffusion MRI has taken in understanding the relationship between microstructural damage and cognitive and behavioural deficits. RESULTS: We identified 35 studies that analysed diffusion MRI changes in patients treated for medulloblastoma. The majority of these studies found significant group differences in measures of brain microstructure between patients and controls, and some of these studies showed associations between microstructure and neurocognitive outcomes, which could be influenced by patient characteristics (e.g. age), treatment, radiation dose and treatment type. CONCLUSIONS: In future, studies would benefit from being able to separate microstructural white matter damage caused by the tumour, tumour-related complications and treatment. Additionally, advanced diffusion modelling methods can be explored to understand and describe microstructural changes to white matter.

Perioperative Segmentation of the Posterior Fossa and the Keel of Goodrich in Surgical Outcomes of Chiari Malformations.

BACKGROUND: Chiari I malformation (CM- I) is defined as the extension of brain tissue into the spinal cord. This study aimed to refine the methodology for the acquisition of 3-dimensional measurements of the posterior fossa and introduce occipital keel size as a new marker and its impact in patients with CM. MATERIALS AND METHODS: In this retrospective study, all patients who underwent Chiari decompression surgery at Montefiore Medical Center from April 2012 to April 2022 were included. Perioperative clinical information was obtained in addition to maximal keel thickness (KT), foramen magnum area, and pre-and postoperative posterior fossa volumes for each patient and age-matched controls. Volumetric measurements were obtained using AI-based semiautomated segmentation. RESULTS: A total of 107 patients with CM including 37 males, and 70 females were studied with a mean age of 26.56±17.31 compared with 103 controls without CM. The comparison between the CM and the general population groups demonstrated a significantly increased keel size in Chiari patients. Keel size had a significant relationship with dysphagia, paresthesia, and intraoperative blood loss, while posterior volume change had a significant relationship with sex and early symptomatic improvement. The Foramen magnum area was related to tonsillar descent and more prominent in patients with spina bifida. CONCLUSION: The Keel of Goodrich is a new anatomical factor that should be taken into consideration when evaluating preoperative symptoms, and intraoperative complications in patients with CM-1. Volumetric analyses demonstrated that posterior fossa volume change had a significant impact on early symptom improvement in patients with Chiari, as did the choice of operative approach. The routine use of semi-automated segmentation of the posterior fossa may help stratify Chiari patients in the future and should be implemented in routine clinical care.

Enabling Navigation and Augmented Reality in the Sitting Position in Posterior Fossa Surgery Using Intraoperative Ultrasound.

Despite its broad use in cranial and spinal surgery, navigation support and microscope-based augmented reality (AR) have not yet found their way into posterior fossa surgery in the sitting position. While this position offers surgical benefits, navigation accuracy and thereof the use of navigation itself seems limited. Intraoperative ultrasound (iUS) can be applied at any time during surgery, delivering real-time images that can be used for accuracy verification and navigation updates. Within this study, its applicability in the sitting position was assessed. Data from 15 patients with lesions within the posterior fossa who underwent magnetic resonance imaging (MRI)-based navigation-supported surgery in the sitting position were retrospectively analyzed using the standard reference array and new rigid image-based MRI-iUS co-registration. The navigation accuracy was evaluated based on the spatial overlap of the outlined lesions and the distance between the corresponding landmarks in both data sets, respectively. Image-based co-registration significantly improved (p < 0.001) the spatial overlap of the outlined lesion (0.42 ± 0.30 vs. 0.65 ± 0.23) and significantly reduced (p < 0.001) the distance between the corresponding landmarks (8.69 ± 6.23 mm vs. 3.19 ± 2.73 mm), allowing for the sufficient use of navigation and AR support. Navigated iUS can therefore serve as an easy-to-use tool to enable navigation support for posterior fossa surgery in the sitting position.

Cerebellar liponeurocytoma: Rare posterior fossa tumor.

Cerebellar liponeurocytoma is a rare WHO grade II glioneuronal tumor, characterized by a benign course and a more favorable prognosis. In this paper, we report a 52-year-old man, hospitalized in emergency because of clinical signs of increased intracranial pressure, and gait disturbances. The MRI revealed a lateral well shaped solid lesion within the left cerebellar hemisphere, having a low signal intensity compared to the cerebrospinal fluid, and causing a triventicular hydrocephalus and tonsillar herniation. The patient underwent a direct approach of the tumor through a left suboccipital craniectomy. Total removal of the lesion was achieved, and the histological diagnosis was cerebellar liponeurocytoma. The tumor cell proliferation index was < 6 %, therefore, radiotherapy and chemotherapy were not implemented after surgery. After 5 years of close follow-up there were no clinical or radiological signs of recurrence. Our objective in reporting another case of this unusual tumor is to discuss clinical profile, radiologic and histologic features as well as treatment and prognosis of this rare posterior fossa tumor.

Endoscopic transorbital approach to the petrous apex: is orbital rim removal worthwhile for the exposure? An anatomical study with illustrative case.

OBJECTIVE: The endoscopic transorbital approach (ETOA) has been demonstrated to be a feasible ventral route to the petrous apex. Yet, it has been pointed to as a deep and narrow corridor for anterior petrosectomy; particularly, medialization of the instruments can become an issue when targeting the petroclival area. To overcome this limitation, an ETOA with orbital rim removal (ETOA-OR) has been suggested, but not de facto compared, with a transorbital approach without removal of the rim. This addition could augment the surgical exposure and freedom of movement when accessing the petrous apex area. METHODS: Five human cadaveric heads (10 sides) were dissected. First, anterior petrosectomy was performed via a conventional ETOA (without orbital rim removal). Second, en bloc removal of the orbital rim was performed, with enlargement of the orbital craniectomy and, subsequently, further drilling of the medial petrous apex. Qualitative and quantitative comparisons are provided. An illustrative surgical case is also shown. RESULTS: The transorbital route allowed the authors to perform an anterior petrosectomy in all specimens. The landmarks of bone removal are superposed onto those in the transcranial route. The ETOA-OR increased the volume of craniectomy (from 4.0 mL to 5.5 mL), the lateromedial angulation, and superoinferior angulation of the instruments within the petrous area. Thus, this approach improved the exposure of the medial petroclival area, allowing for an augmented petrosectomy (from 1.4 mL to 2.0 mL, 39.5% increase) and for increased maneuverability, both in the petrous area (from 44.1 cm2 to 76.5 cm2, 73.3% increase) and in the posterior fossa (from 20.2 cm2 to 52.0 cm2, 158% increase). The ETOA-OR was also pragmatically applied to treat a recurrent petroclival meningioma. Complete removal was achieved, the abducens nerve palsy improved, and the trigeminal neuralgia decreased in severity, yet still required medication. CONCLUSIONS: The authors provide the first formal anatomical comparison between the transorbital approach with preservation of the orbital rim and a transorbital approach with removal of the rim to access the petrous apex. In addition, an illustrative case is used as a proof of concept and feasibility. According to the authors' data, the ETOA-OR significantly improves surgical exposure and the surgeon's comfort in this deep region. The bony defect can be reconstructed to avoid cosmetic deformities, maintaining the minimally disruptive concept of transorbital surgery.

Importance of repeated computed tomography on pediatric traumatic acute posterior fossa subdural hematoma: A case study.

Traumatic acute posterior fossa subdural hematoma (PFSDH) is a rare and potentially fatal condition in which the progressed hematoma compresses the brainstem or causes secondary hydrocephalus. Hence, vigilant monitoring of clinical and radiological findings is crucial to detect the typical sudden deterioration, which can occur in the early stages. However, managing pediatric PFSDHs poses additional challenges due to risks associated with radiation exposure from repeat computed tomography (CT) examinations, potentially impeding crucial diagnostic insights. Here, we present a rare pediatric case of fatal acute traumatic PFSDH. Despite undergoing a timely initial CT scan that indicated the presence of PFSDH, the patient experienced sudden deterioration 15 h later and eventually died. No follow-up CT examinations were conducted during this critical period. This case underscores the challenges in managing pediatric PFSDHs, particularly concerning the benefits of repeated CT examinations in initially stable patients.

Permanent Visual Loss as a Complication of Decompressive Surgery for the Treatment of Posterior Fossa Tumours: A Report of Two Cases.

Posterior fossa tumours are one of the most common types of solid neoplasia in paediatric patients. Although impaired vision can occur at presentation, it usually stabilises or improves after decompressive surgery. However, cases of permanent and profound visual loss have been reported following successful tumour resection, despite receiving little attention from the medical community. In this paper, we present two cases of young patients who experienced severe and permanent visual loss following uncomplicated surgery for posterior fossa tumour removal. We discuss the possible mechanism involved in the visual loss and measures to prevent such a dreadful complication.

The incidence of infratentorial arteriovenous malformation-associated aneurysms: an institutional case series and systematic literature review.

BACKGROUND: Arteriovenous malformation (AVM)-associated aneurysms represent a high-risk feature predisposing them to rupture. Infratentorial AVMs have been shown to have a greater incidence of associated aneurysms, however the existing data is outdated and biased. The aim of our research was to compare the incidence of supratentorial vs infratentorial AVM-associated aneurysms. METHODS: Patients were identified from our institutional AVM registry, which includes all patients with an intracranial AVM diagnosis since 2000, regardless of treatment. Records were reviewed for clinical details, AVM characteristics, nidus location (supratentorial or infratentorial), and presence of associated aneurysms. Statistical comparisons were made using Fisher's exact or Wilcoxon rank sum tests as appropriate. Multivariable logistic regression analysis determined independent predictors of AVM-associated aneurysms. As a secondary analysis, a systematic literature review was performed, where studies documenting the incidence of AVM-associated aneurysms stratified by location were of interest. RESULTS: From 2000-2024, 706 patients with 720 AVMs were identified, of which 152 (21.1%) were infratentorial. Intracranial hemorrhage was the most common AVM presentation (42.1%). The incidence of associated aneurysms was greater in infratentorial AVMs compared with supratentorial cases (45.4% vs 20.1%; P<0.0001). Multivariable logistic regression demonstrated that infratentorial nidus location was the singular predictor of an associated aneurysm, odds ratio: 2.9 (P<0.0001). Systematic literature review identified eight studies satisfying inclusion criteria. Aggregate analysis indicated infratentorial AVMs were more likely to harbor an associated aneurysm (OR 1.7) and present as ruptured (OR 3.9), P<0.0001. CONCLUSIONS: In this modern consecutive patient series, infratentorial nidus location was a significant predictor of an associated aneurysm and hemorrhagic presentation.

Operative versus non-operative management of posterior fossa epidural hematoma: A systematic review and meta-analysis.

BACKGROUND: Posterior fossa epidural hematoma (PFEDH) is rare, occurring in less than 3% of head injuries. It can be managed either operatively or non-operatively. Management guidelines date from 2006, without recent updates providing class III evidence. METHOD: We searched PubMed and other databases for English language observational studies up to 2021 that compared the two treatment approaches for PFEDH and. RESULTS: Twenty-four of the 350 references, for involving 874 patients, met the study criteria. Conservative management showed higher GOS 5 scores and lower mortality. GCS 13-15 patients were more prevalent in the conservative group. Surgical cases often involved ventriculomegaly/compression, hydrocephalus or contusion. CONCLUSION: The study shed light on surgical versus conservative PFEDH management, although evidence is sparse. Generally, conservative methods showed better initial outcomes, and should be preferred. However, respect of individual patient traits and Brain Trauma Foundation guidelines is crucial: conservative management may not suit all cases. To enhance the evidence base, RCTs are important for optimal PFEDH management. Bridging this gap can substantially improve patient outcomes and clinical decision-making, emphasizing the need to consider both the available evidence and patient-specific factors for effective guidance.

Predictors of poor functional outcomes in adults with type I Chiari Malformation: Clinical and surgical factors assessed with the Chicago Chiari Outcome Scale over long-term follow-up.

OBJECTIVE: This study aimed to identify clinical and surgical features associated with poor long-term postoperative outcomes in patients diagnosed with Type I Chiari Malformation (CMI) treated with posterior fossa decompression with duroplasty (PFDD), with or without tonsillar coagulation. METHODS: This retrospective, single-center study included 107 adult patients with CMI surgically treated between 2010 and 2021. The surgical technique involved a midline suboccipital craniectomy, C1 laminectomy, durotomy, arachnoid dissection, duroplasty, and tonsillar coagulation until 2014, after which tonsillar coagulation was discontinued. Postoperative outcomes were assessed using the Chicago Chiari Outcome Scale (CCOS) at a median follow-up of 35 months. Clinical, surgical, and neuroimaging data were analyzed using the Wilcoxon signed-rank test, Cox regression analysis, and Kaplan-Meier survival curves to identify predictors of poor functional outcomes. RESULTS: Of the 107 patients (mean age 43.9 years, SD 13), 81 (75.5 %) showed functional improvement, 25 (23.4 %) remained unchanged, and 1 (0.9 %) experienced worsened outcomes. Cephalalgia, bilateral motor weakness, and bilateral paresthesia were the most frequent initial symptoms. Tonsillar coagulation was performed in 31 cases (28.9 %) but was clinically associated with higher rates of unfavorable outcomes. The Wilcoxon signed-rank test indicated that long-term follow-up CCOS was significantly higher than postoperative CCOS (Z = -7.678, p < 0.000). Multivariate Cox analysis identified preoperative bilateral motor weakness (HR 6.1, 95 % CI 1.9-18.9; p = 0.002), hydrocephalus (HR 3.01, 95 % CI 1.3-6.9; p = 0.008), and unilateral motor weakness (HR 2.99, 95 % CI 1.1-8.2; p = 0.033) as significant predictors of poor outcomes on a long-term follow-up. CONCLUSION: This study highlights the high rate of functional improvement in CMI patients following PFDD. Preoperative motor weakness and hydrocephalus were significant predictors of poor long-term outcomes. Tonsillar coagulation did not demonstrate a clear clinical benefit and may be associated with worse outcomes. Our findings suggest that careful preoperative assessment and selection of surgical techniques are crucial for optimizing patient outcomes.

Surgical Management of Chiari Malformation Type I in the Pediatric Population: A Single-Center Experience.

Background: Chiari malformation type 1 (CM-1) involves the cerebellar tonsils' descent below the foramen magnum. In Chiari malformation type 1.5 (CM-1.5), both the cerebellar tonsils and the brainstem are herniated. Common symptoms include headaches and cervical pain, often associated with conditions like syringomyelia and hydrocephalus. Surgical treatment is not performed in asymptomatic patients, while the presence of syringomyelia represents an indication for surgery. Methods: This study retrospectively examined pediatric patients with CM-1 and CM-1.5 at Giannina Gaslini Hospital from 2006 to 2020, analyzing demographics, radiological findings, surgical interventions, and outcomes. Results: Out of 211 patients who underwent surgery, 83.9% were diagnosed with CM-1 and 16.1% with CM-1.5. Headaches were prevalent (69%) and cerebellar signs were noted in 29% of patients. Syringomyelia and hydrocephalus were present in 28.4% and 8% of cases, respectively. Intraoperative ultrasonography guided interventions, with 59.8% requiring bony and ligamentous decompression, and 27.1% undergoing duraplasty. Conclusions: The surgical treatment of CM-1/CM-1.5 involves posterior cranial fossa decompression. Choosing between bony decompression alone and its combination with duraplasty has always been controversial in the pediatric population. If we consider as surgical endpoint the restoration of cerebrospinal fluid (CSF) flux, intraoperative ultrasound may be a real-time helpful tool in orienting the surgical strategy, yet refinement with quantitative measures is needed.

Tension Subdural Hygroma Following Resection of Posterior Fossa Tumour in a Child: A new clinico-radio-pathological entity.

Persistent hydrocephalus is common in children after resection of posterior fossa tumours. However, occurrence of subdural hygroma is very rare. We report the case of a 14-month-old child who presented at a paediatric neurology clinic in Muscat, Oman in 2021 who developed a tense subdural hygroma with stable hydrocephalus, in the early postoperative period, following posterior fossa tumour resection. We describe the distinctive clinical, radiological and pathological features associated with the development of a tense subdural hygroma. We also discuss the management by cerebrospinal fluid diversion, which includes either a ventriculoperitoneal or subduroperitoneal shunt. This unique condition is distinguished from external hydrocephalus by features that are critical to the management strategy.

Use of Artificial Intelligence in the Prediction of Chiari Malformation Type 1 Recurrence After Posterior Fossa Decompressive Surgery.

Purpose The purpose of this study was to train a deep learning-based method for the prediction of postoperative recurrence of symptoms in Chiari malformation type 1 (CM1) patients undergoing surgery. Studies suggest that certain radiological and clinical features do exist in patients with treatment failure, though these are inconsistent and poorly defined. Methodology This study was a retrospective cohort study of patients who underwent primary surgical intervention for CM1 from January 2010 to May 2020. Only patients who completed pre- and postoperative 12-item short form (SF-12) surveys were included and these were used to classify the recurrence or persistence of symptoms. Forty patients had an improvement in overall symptoms while 17 had recurrence or persistence. After magnetic resonance imaging (MRI) data augmentation, a ResNet50, pre-trained on the ImageNet dataset, was used for feature extraction, and then clustering-constrained attention multiple instance learning (CLAM), a weakly supervised multi-instance learning framework, was trained for prediction of recurrence. Five-fold cross-validation was used for the development of MRI only, clinical features only, and a combined machine learning model. Results This study included 57 patients who underwent CM1 decompression. The recurrence rate was 30%. The combined model incorporating MRI, pre-operative SF-12 physical component scale (PCS), and extent of cerebellar ectopia performed best with an area under the curve (AUC) of 0.71 and an F1 score of 0.74. Conclusion This is the first study to our knowledge to explore the prediction of postoperative recurrence of symptoms in CM1 patients using machine learning methods and represents the first step toward developing a clinically useful prognostication machine learning model. Further studies utilizing a similar deep learning approach with a larger sample size are needed to improve the performance.

Bony Surface-Matching Registration of Neuronavigation with Sectioned 3-Dimensional Skull in Prone Position.

BACKGROUND: Neuronavigation has become an essential system for brain tumor resections. It is sometimes difficult to obtain accurate registration of the neuronavigation with the patient in the prone position. Bony surface-matching registration should be more precise than skin surface-matching registration; however, it is difficult to establish bony registration with limited exposed bone. We created a new bony surface-matching method to a sectioned 3-dimensional (3D) virtual skull in a neuronavigation system and registered with a sectioned 3D skull. In this study, the bony surface-matching with sectioned 3D registration is applied to provide precise registration for brain tumor resection in the prone position. METHODS: From May 2023 to April 2024, 17 patients who underwent brain tumor resection in the prone position were enrolled. The navigation system StealthStation S8 (Medtronic, Dublin, Ireland) was used. Bony surface-matching registration with a whole 3D skull in a neuronavigation system was performed. Next, a sectioned 3D skull was made according to the surgical location to compare with the whole 3D skull registration. A phantom model was also used to validate the whole and sectioned 3D skull registration. RESULTS: Whole 3D skull registration was successful for only 2 patients (11.8%). However, sectioned 3D skull registration was successful for 16 patients (94.1%). The examinations with a phantom skull model also showed superiority of sectioned 3D skull registration to whole 3D skull registration. CONCLUSIONS: Sectioned 3D skull registration was superior to whole 3D skull registration. The sectioned 3D skull method could provide accurate registration with limited exposed bone.

Clinical outcomes of posterior fossa arteriovenous malformations: a single center experience.

BACKGROUND: Posterior fossa arterio-venous malformations (pfAVMs) are challenging lesions due to the anatomical particularities of the posterior fossa, and the high incidence of hemorrhagic presentation. The two most important goals when treating AVMs are preserving neurological function and preventing rupture, or a second hemorrhage. The aim of this study was to analyze the clinical and imaging features of pfAVMs to identify the factors that influence the prognosis of these patients. METHODS: We conducted a single-center retrospective observational study that included patients treated at our institution with pfAVMs between January 1997 and December 2021. RESULTS: A total of 48 patients were included. A good modified Rankin score (mRS) was observed in 33 cases (69%) at presentation. Thirty-four patients (71%) presented with a ruptured AVM. Out of these, 19 patients (40%) had intraventricular hemorrhage. Microsurgical resection was performed in 33 cases (69%), while in the other cases, the patients opted for conservative management (7 cases, 15%), stereotactic radiosurgery (SRS) (6 cases, 12%), or endovascular treatment (2 cases, 4%). Patients ≤ 30 years old were more prone to hemorrhagic presentation (OR: 5.23; 95% CI: 1.42-17.19; p = 0.024) and this remained an independent risk factor for rupture after multivariate analysis as well (OR: 4.81; 95% CI: 1.07-21.53; p = 0.040). Following multivariate analysis, the only factor independently associated with poor prognosis in the surgically treated subgroup was a poor clinical status (mRS 3-5) at admission (OR: 96.14; 95% CI: 5.15-1793.9; p = 0.002). CONCLUSIONS: Management of posterior fossa AVMs is challenging, and patients who present with ruptured AVMs often have a poor clinical status at admission leading to a poor prognosis. Therefore, proper and timely management of these patients is essential.

A comparative analysis of neuroendoscopic foramen magnum decompression versus traditional open surgery for Chiari Malformation Type I.

PURPOSE: Chiari Malformation Type I (CM1) is characterized by the downward displacement of the cerebellar tonsils below the foramen magnum. The standard surgical treatment for CM1 is foramen magnum decompression and atlas laminectomy (FMD-AL). However, there is a growing interest in exploring minimally invasive techniques, such as neuroendoscopically assisted FMD-AL, to optimize surgical outcomes. The aim is to present the results of the less invasive neuroendoscopic-assisted system application as an alternative to decompression surgery in patients with CM-1 with/without syringomyelia. PATIENTS AND METHODS: A retrospective analysis was conducted on 76 patients with CMI who underwent either neuroendoscopic-assisted FMD-AL (n = 23) or open surgery (n = 53). Preoperative and postoperative assessments were performed, including pain levels, functional assessment, outcome and serum creatinine kinase (CK) levels. Surgical parameters and radiological imaging were also evaluated and compared. RESULTS: Both surgical groups showed improvements in pain levels and increase in postoperative CK levels. There were no statistically significant differences between the groups in terms of postoperative JOA scores, VAS scores, CCOS, or syrinx resolution. However, the neuroendoscopic group had significantly lower CK levels, shorter hospital stays, less blood loss, and shorter operation times compared to the open surgery group, indicating reduced muscle damage and potential benefits of the neuroendoscopic assisted approach. CONCLUSION: Both neuroendoscopy and open surgery groups can effectively alleviate symptoms and improve outcomes in patients with CM1. The neuroendoscopic assisted technique offers the advantage of reduced muscle damage and shorter hospital stays. The choice of surgical technique should be based on individual patient characteristics and preferences. LEVEL OF EVIDENCE: 3 (Retrospective case-control study) according to using the Oxford Centre for Evidence-Based Medicine (CEBM) Table.

Letter to editor: Volumetric segmentation in the context of posterior fossa­related pathologies: a systematic review.

This letter provides feedback on the article titled "Volumetric Segmentation in the Context of Posterior Fossa-Related Pathologies: A Systematic Review." It highlights the positive impacts of the review, such as its comprehensive examination of existing literature and its potential to enhance diagnostic accuracy and treatment planning. However, it also addresses limitations and challenges associated with volumetric segmentation, including variability in image quality and accessibility issues.