Dosimetric Comparison of Dedicated Radiosurgery Platforms for the Treatment of Essential Tremor: Technical Report.

Essential tremor (ET) is one of the most common adult movement disorders. As the worldwide population ages, the incidence and prevalence of ET is increasing. Although most cases can be managed conservatively, there is a subset of ET that is refractory to medical management. By virtue of being "reversible", deep brain stimulation (DBS) of the ventral intermediate nucleus (VIM) of the thalamus is one commonly accepted intervention. As an alternative to invasive and expensive DBS, there has been a renaissance in treating ET with lesion-based approaches, spearheaded most recently by high-intensity focused ultrasound (HIFU), the hallmark of which is that it is non-invasive. Meanwhile, stereotactic radiosurgical (SRS) lesioning of VIM represents another time-honored lesion-based non-invasive treatment of ET, which is especially well suited for those patients that cannot tolerate open neurosurgery and is now also getting a "second look". While multiple SRS platforms have been and continue to be used to treat ET, there is little in the way of dosimetric comparison between different technologies. In this brief technical report we compare the dosimetric profiles of three major radiosurgical platforms (Gamma Knife, CyberKnife Robotic Radiosurgery, and Zap-X Gyroscopic Radiosurgery (GRS)) for the treatment of ET. In general, the GRS and Gamma Knife were shown to have the best theoretical dosimetric profiles for VIM lesioning. Nevertheless the relevance of such superiority to clinical outcomes requires future patient studies.

Stereotactic Radiosurgery for Ependymoma in Pediatric and Adult Patients: A Single-Institution Experience.

BACKGROUND AND OBJECTIVES: Ependymoma is commonly classified as World Health Organization grade 2 with the anaplastic variant categorized as grade 3. Incomplete resection or anaplastic features can result in unfavorable outcomes. Stereotactic radiosurgery (SRS) provides a minimally invasive approach for recurrent ependymomas. Our study investigates the efficacy and safety of SRS for grade 2 and 3 ependymomas in pediatric and adult populations. METHODS: We conducted a retrospective analysis on 34 patients with 75 ependymomas after CyberKnife SRS between 1998 and 2023. Fourteen were pediatric (3-18 years), and 20 were adult (19-75 years) patients. The median age was 21 years, and the median tumor volume was 0.64 cc. The median single-fraction equivalent dose was 16.6 Gy, with SRS administered at 77% of the median isodose line. RESULTS: After a median follow-up of 42.7 months (range: 3.8-438.3), 22.7% of ependymomas progressed. The 5-year local tumor control rate was 78.1%, varying between 59.6% and 90.2% for children and adults, with grade 2 at 85.9% compared with 58.5% for grade 3 tumors. The 5-year overall survival rate was 73.6%, notably higher in adults (94.7%) than in children (41%), and 100% for grade 2 but decreased to 35.9% for grade 3 patients. The 5-year progression-free survival rate was 68.5%, with 78.3% and 49.2% for adults and children, respectively, and a favorable 88.8% for grade 2, contrasting with 32.6% for grade 3 patients. Symptom improvement was observed in 85.3% of patients. Adverse radiation effects occurred in 21.4% of pediatric patients. CONCLUSION: Our study supports SRS as a viable modality for pediatric and adult patients with grade 2 and 3 ependymomas. Despite lower local tumor control in pediatric and grade 3 cases, integrating SRS holds promise for improved outcomes. Emphasizing careful patient selection, personalized treatment planning, and long-term follow-up is crucial for optimal neurosurgical outcomes.

CyberKnife stereotactic radiosurgery for extramedullary plasmacytoma in the external auditory canal: illustrative case.

BACKGROUND: Plasmacytoma, a rare plasma cell disorder, often presents as a solitary or multiple tumors within the bone marrow or soft tissues, typically associated with multiple myeloma. Extramedullary plasmacytomas (EMPs), particularly those located in the external auditory canal (EAC), are exceedingly rare and pose significant treatment challenges given their location, anatomical complexity, and high risk of recurrence. OBSERVATIONS: The authors report the case of a 72-year-old male with a history of multiple myeloma, presenting with recurrent left EAC plasmacytoma. After initial conventional radiotherapy for the lesion, a recurrence was documented in 7 years. The patient subsequently underwent stereotactic radiosurgery, which proved successful, leading to complete resolution of the lesion without any long-term adverse effects or radiation-related complications over a 45-month period. LESSONS: This case is a unique instance of utilizing stereotactic radiosurgery for recurrent EMP in the EAC, highlighting its potential as an effective approach in managing complex plasmacytomas.

Treatment of Refractory Bipolar Depression With Stereotactic Radiosurgery Targeting the Subgenual Cingulate Cortex.

Background The subgenual cingulate cortex (SGC) has been identified as a key structure within multiple neural circuits whose dysfunction is implicated in the neurobiology of depression. Deep brain stimulation in the SGC is thought to reduce and normalize local metabolism, causing normalization of circuit behavior and an improvement in depressive symptoms. We hypothesized that nonablative stereotactic radiosurgery (SRS) to the SGC would reduce local metabolism and reduce the severity of depression in patients with treatment-resistant bipolar depression. Methods Under the FDA's Humanitarian Device Exemption program, patients were screened for inclusion and exclusion criteria. Three volunteers meeting the criteria provided informed consent. Bilateral SGC targets were irradiated to a maximum dose of 75 Gy in one fraction. Subjects were followed for one year following the procedure with mood assessments (Hamilton Depression Rating Scale (HDRS), Clinical Global Impression-Improvement, Clinical Global Impression-Severity, and Young Mania Rating Scale), neurocognitive testing (Delis-Kaplan Executive Function System, Wechsler Adult Intelligence Scale III digit span, and California Verbal Learning Test II), and imaging. Further imaging was completed approximately two years after the procedure. Clinical improvement was defined as a ≥50% reduction in HDRS. Results Two of the three subjects showed clinical improvement in depressive symptoms during the follow-up period, while one subject showed no change in symptom severity. One of three subjects was hospitalized for the emergence of an episode of psychotic mania after discontinuing antipsychotic medications against medical advice but promptly recovered with the reinstitution of an antipsychotic. Sequential assessments did not reveal impairment in any cognitive domain assessed. For one of the three subjects, MRI imaging showed evidence of edema at 12 months post-SRS, which resolved at 22 months post-procedure. In a second of three patients, there was evidence of local edema at the target site at long-term follow-up. All imaging changes were asymptomatic. Conclusion Radiosurgical targeting of the SGC may be a noninvasive strategy for the reduction of severe depression in treatment-resistant bipolar disorder. Two out of three patients showed clinical improvement. While these results are promising, further study, including improvements in target selection and dosing considerations, is needed.

Machine Learning in Neurosurgery: Toward Complex Inputs, Actionable Predictions, and Generalizable Translations.

Machine learning can predict neurosurgical diagnosis and outcomes, power imaging analysis, and perform robotic navigation and tumor labeling. State-of-the-art models can reconstruct and generate images, predict surgical events from video, and assist in intraoperative decision-making. In this review, we will detail the neurosurgical applications of machine learning, ranging from simple to advanced models, and their potential to transform patient care. As machine learning techniques, outputs, and methods become increasingly complex, their performance is often more impactful yet increasingly difficult to evaluate. We aim to introduce these advancements to the neurosurgical audience while suggesting major potential roadblocks to their safe and effective translation. Unlike the previous generation of machine learning in neurosurgery, the safe translation of recent advancements will be contingent on neurosurgeons' involvement in model development and validation.

Stereotactic Radiosurgery for Cranial and Spinal Hemangioblastomas: A Single-Institution Retrospective Series.

BACKGROUND AND OBJECTIVES: Stereotactic radiosurgery (SRS) has been an attractive treatment modality for both cranial and spinal hemangioblastomas, especially for multiple lesions commonly associated with von Hippel-Lindau (VHL) disease. This study aims to provide the largest long-term analysis of treatment efficacy and adverse effects of SRS for cranial and spinal hemangioblastomas at a single institution. METHODS: We evaluated the clinical and radiological outcomes of patients with hemangioblastomas treated with CyberKnife SRS at our institute from 1998 to 2022. The follow-up data were available for 135 hemangioblastomas in 35 patients. Twenty-eight patients had 123 hemangioblastomas associated with VHL, and 7 had 12 sporadic hemangioblastomas. The median age was 36 years, and the median tumor volume accounted for 0.4 cc. The SRS was administered with the median single-fraction equivalent dose of 18 Gy to the 77% median isodose line. RESULTS: At a median follow-up of 57 months (range: 3-260), only 20 (16.2%) of the VHL-associated and 1 (8.3%) sporadic hemangioblastomas progressed. The 5-year local tumor control rate was 91.3% for all hemangioblastomas, 91.7% among the sporadic lesions, and 92.9% in patients with VHL. SRS improved tumor-associated symptoms of 98 (74.8%) of 131 symptomatic hemangioblastomas, including headache, neck pain, dizziness, visual disturbances, dysesthesia, ataxia, motor impairment, seizures, and dysphagia. Two patients developed radiation necrosis (5.7%), and 1 of them required surgical resection. CONCLUSION: SRS is a safe and effective treatment option for patients with hemangioblastomas in critical locations, such as the brainstem, cervicomedullary junction, and spinal cord, and in patients with multiple hemangioblastomas associated with VHL disease.

Type II odontoid fractures in the elderly presenting to the emergency department: an assessment of factors affecting in-hospital mortality and discharge to skilled nursing facilities.

BACKGROUND CONTEXT: Type II odontoid fractures (OF) are among the most common cervical spine injuries in the geriatric population. However, there is a paucity of literature regarding their epidemiology. Additionally, the optimal management of these injuries remains controversial, and no study has evaluated the short-term outcomes of geriatric patients presenting to emergency departments (ED). PURPOSE: This study aims to document the epidemiology of geriatric patients presenting to EDs with type II OFs and determine whether surgical management was associated with early adverse outcomes such as in-hospital mortality and discharge to skilled nursing facilities (SNF). STUDY DESIGN: This is a retrospective cohort study. PATIENT SAMPLE: Data was used from the 2016-2020 Nationwide Emergency Department Sample. Patient encounters corresponding to type II OFs were identified. Patients younger than 65 at the time of presentation to the ED and those with concomitant spinal pathology were excluded. OUTCOME MEASURES: The association between the surgical management of geriatric type II OFs and outcomes such as in-hospital mortality and discharge to SNFs. METHODS: Patient, fracture, and surgical management characteristics were recorded. A propensity score matched cohort was constructed to reduce differences in age, comorbidities, and injury severity between patients undergoing operative and nonoperative management. Additionally, to develop a positive control for the analysis of geriatric patients with type II OFs and no other concomitant spinal pathology, a cohort of patients that had been excluded due to the presence of a concomitant spinal cord injury (SCI) was also constructed. Multivariate regressions were then performed on both the matched and unmatched cohorts to ascertain the associations between surgical treatment and in-hospital mortality, inpatient length of stay, encounter charges, and discharge to SNFs. RESULTS: A total of 11,325 encounters were included. The mean total charge per encounter was $60,221. 634 (5.6%) patients passed away during their encounters. In total, 1,005 (8.9%) patients were managed surgically. Surgical management of type II OFs was associated with a 316% increase in visit charge (95% CI: 291%-341%, p<.001), increased inpatient length of stay (IRR: 2.87, 95% CI: 2.62-3.12, p<.001), and increased likelihood of discharge to SNFs (OR=2.62, 95% CI: 2.26-3.05, p<.001), but decreased in-hospital mortality (OR=0.32, CI: 0.21-0.45, p<.001). The propensity score matched cohort consisted of 2,010 patients, matching each of the 1,005 that underwent surgery to 1,005 that did not. These cohorts were well balanced across age (78.24 vs 77.91 years), Elixhauser Comorbidity Index (3.68 vs 3.71), and Injury Severity Score (30.15 vs 28.93). This matching did not meaningfully alter the associations determined between surgical management and in-hospital mortality (OR=0.34, CI=0.21-0.55, p<.001) or SNF discharge (OR=2.59, CI=2.13-3.16, p<.001). Lastly, the positive control cohort of patients with concurrent SCI had higher rates of SNF discharge (50.0% vs 42.6%, p<.001), surgical management (32.3% vs 9.7%, p<.001), and in-hospital mortality (28.9% vs 5.6%, p<.001). CONCLUSIONS: This study lends insight into the epidemiology of geriatric type II OFs and quantifies risk factors influencing adverse outcomes. Patient informed consent should include a discussion of the protective association between definitive surgical management and in-hospital mortality against potential operative morbidity, increased lengths of hospital stay, and increased likelihood of discharge to SNFs. This information may impact patient treatment selection and decision making.

Surgery and stereotactic radiosurgery for spinal leiomyosarcoma: a single-institution retrospective series and systematic review.

OBJECTIVE: Leiomyosarcoma (LMS) is a rare, aggressive soft-tissue sarcoma that seldom spreads to the bone. The spine can be either the site of LMS osseous metastases or the primary tumor site. The optimal treatment option for spinal LMS is still unclear. The authors present a cohort of patients with spinal LMS treated with either upfront surgery or upfront CyberKnife stereotactic radiosurgery (SRS). METHODS: The authors retrospectively studied the clinical and radiological outcomes of 17 patients with spinal LMS treated at their institution between 2004 and 2020. Either surgery or SRS was used as the upfront treatment. The clinical and radiological outcomes were assessed. A systematic review of the literature was also conducted. RESULTS: Of the 17 patients (20 spinal lesions), 12 (70.6%) were female. The median patient age was 61 years (range 41-80 years). Ten patients had upfront surgery for their spinal lesions, and 7 had upfront CyberKnife radiosurgery. The median follow-up was 11 months (range 0.3-130 months). The median overall survival (OS) for the entire cohort was 13 months (range 0.3-97 months). In subgroup analysis, the median OS was lower for the surgical group (13 months, range 0.3-50 months), while the median OS for the SRS group was 15 months (range 5-97 months) (p = 0.5). Forty percent (n = 4) of those treated with surgery presented with local recurrence at a median of 6.7 months (range 0.3-36 months), while only 14% (n = 1) of those treated with CyberKnife radiosurgery had local recurrence after 5 months. Local tumor control (LTC) rates at the 6-, 12-, and 18-month follow-ups were 72%, 58%, and 43%, respectively, for the SRS group and 40%, 30%, and 20%, respectively, for the surgery group (p < 0.05). The literature review included 35 papers with 70 patients harboring spinal LMS; only 2 patients were treated with SRS. The literature review confirms the clinical and radiological outcomes of the surgical group, while data on SRS are anecdotal. CONCLUSIONS: The authors present the largest series in the literature of spinal LMS and the first on SRS for spinal LMS. This study shows that LTC is statistically significantly better in patients receiving upfront SRS instead of surgery. The OS does not appear different between the two groups.

The outcome of central nervous system hemangioblastomas in Von Hippel-Lindau (VHL) disease treated with belzutifan: a single-institution retrospective experience.

PURPOSE: Belzutifan is a Hypoxia Inducible Factor 2-alpha inhibitor approved in 2021 by the FDA for the treatment of renal cell carcinoma (RCC) in patients with Von-Hippel Landau (VHL) disease. These patients can also present with central nervous system (CNS) hemangioblastomas (HBs). We aim to study the effectiveness and adverse effects of belzutifan for CNS HBs, by reporting our preliminary institutional experience. METHODS: We present a series of VHL patients with CNS HBs undergoing treatment with belzutifan for RCC. All the included patients met the RECIST inclusion criteria. The clinical and radiological outcome measures included: Objective response rate (ORR), time-to-response (TTR), adverse events (AE), and patient response. Patient response was classified as partial response (PR), complete response (CR), progressive disease (PD), or stable disease (SD). RESULTS: Seven patients with 25 HBs were included in our study. A belzutifan dose of 120 mg/day PO was administered for a median of 13 months (range 10-17). Median follow up time was 15 months (range 10-24). An ORR of 71% was observed. The median TTR was 5 months (range: 1-10). None of the patients showed CR, while 5 patients (71.4%) showed PR and 2 (28.5%) showed SD. Among patients with SD the maximum tumor response was 20% [increase/decrease] of the lesion diameter. All the patients experienced decreased hemoglobin concentration, fatigue, and dizziness. None of the patients experienced severe anemia (grade 3-4 CTCAE). CONCLUSION: Belzutifan appears to be an effective and safe treatment for CNS hemangioblastoma in VHL patients. Further clinical trials to assess the long-term effectiveness of the medication are required.

Spinal metastases of pineal region glioblastoma with primitive neuroectodermal features highlighting the importance of molecular diagnoses: illustrative case.

BACKGROUND: Glioblastoma (GBM) is the most common primary brain tumor with poor patient prognosis. Spinal leptomeningeal metastasis has been rarely reported, with long intervals between the initial discovery of the primary tumor in the brain and eventual spine metastasis. OBSERVATIONS: Here, the authors present the case of a 51-year-old male presenting with 7 days of severe headache, nausea, and vomiting. Magnetic resonance imaging of the brain and spine demonstrated a contrast-enhancing mass in the pineal region, along with spinal metastases to T8, T12, and L5. Initial frozen-section diagnosis led to the treatment strategy for medulloblastoma, but further molecular analysis revealed characteristics of isocitrate dehydrogenase-wild type, grade 4 GBM. LESSONS: Glioblastoma has the potential to show metastatic spread at the time of diagnosis. Spinal imaging should be considered in patients with clinical suspicion of leptomeningeal spread. Furthermore, molecular analysis should be confirmed following pathological diagnosis to fine-tune treatment strategies.

Practical Guideline for Prevention of Patchy Hair Loss following CyberKnife Stereotactic Radiosurgery for Calvarial or Scalp Tumors: Retrospective Analysis of a Single Institution Experience.

INTRODUCTION: Patchy alopecia is a common adverse effect of stereotactic radiosurgery (SRS) on the calvarium and/or scalp, yet no guidelines exist for its prevention. This study aims to investigate the incidence and outcomes of patchy alopecia following SRS for patients with calvarial or scalp lesions and establish preventive guidelines. METHODS: The study included 20 patients who underwent CyberKnife SRS for calvarial or scalp lesions, resulting in a total of 30 treated lesions. SRS was administered as a single fraction for 8 lesions and hypofractionated for 22 lesions. The median SRS target volume was 9.85 cc (range: 0.81-110.7 cc), and the median prescription dose was 27 Gy (range: 16-40 Gy), delivered in 1-5 fractions (median: 3). The median follow-up was 15 months. RESULTS: Among the 30 treated lesions, 11 led to patchy alopecia, while 19 did not. All cases of alopecia resolved within 12 months, and no patients experienced other adverse radiation effects. Lesions resulting in alopecia exhibited significantly higher biologically effective dose (BED) and single-fraction equivalent dose (SFED) on the overlying scalp compared to those without alopecia. Patients with BED and SFED exceeding 60 Gy and 20 Gy, respectively, were 9.3 times more likely to experience patchy alopecia than those with lower doses. The 1-year local tumor control rate for the treated lesions was 93.3%. Chemotherapy was administered for 26 lesions, with 11 lesions receiving radiosensitizing agents. However, no statistically significant difference was found. CONCLUSION: In summary, SRS is a safe and effective treatment for patients with calvarial/scalp masses regarding patchy alopecia near the treated area. Limiting the BED under 60 Gy and SFED under 20 Gy for the overlying scalp can help prevent patchy alopecia during SRS treatment of the calvarial/scalp mass. Clinicians can use this information to inform patients about the risk of alopecia and the contributing factors.

Stereotactic Radiosurgery for Contrast-Enhancing Satellite Nodules in Recurrent Glioblastoma: A Rare Case Series From a Single Institution.

Introduction Glioblastoma (GBM) is the most common malignant adult brain tumor and is invariably fatal. The standard treatment for GBM involves resection where possible, followed by chemoradiation per Stupp's protocol. We frequently use stereotactic radiosurgery (SRS) as a single-fraction treatment for small (volume ≤ 1cc) nodular recurrent GBM to the contrast-enhancing target on T1 MRI scan. In this paper, we aimed to evaluate the safety and efficacy of SRS for patients with contrast-enhancing satellite nodules in recurrent GBM. Methods This retrospective study analyzed the clinical and radiological outcomes of five patients who underwent CyberKnife (Accuray Inc., Sunnyvale, California) SRS at the institute between 2013 and 2022. Results From 96 patients receiving SRS for GBM, five (four males, one female; median age 53) had nine distinct new satellite lesions on MRI, separate from their primary tumor beds. Those nine lesions were treated with a median margin dose of 20 Gy in a single fraction. The three-, six, and 12-month local tumor control rates were 77.8%, 66.7%, and 26.7%, respectively. Median progression-free survival (PFS) was seven months, median overall survival following SRS was 10 months, and median overall survival (OS) was 35 months. Interestingly, the only lesion that did not show radiological progression was separate from the T2-fluid attenuated inversion recovery (FLAIR) signal of the main tumor. Conclusion Our SRS treatment outcomes for recurrent GBM satellite lesions are consistent with existing findings. However, in a unique case, a satellite nodule distinct from the primary tumor's T2-FLAIR signal and treated with an enlarged target volume showed promising control until the patient's demise. This observation suggests potential research avenues, given the limited strategies for 'multicentric' GBM lesions.

Optimizing the synergy between stereotactic radiosurgery and immunotherapy for brain metastases.

Solid tumors metastasizing to the brain are a frequent occurrence with an estimated incidence of approximately 30% of all cases. The longstanding conventional standard of care comprises surgical resection and whole-brain radiotherapy (WBRT); however, this approach is associated with limited long-term survival and local control outcomes. Consequently, stereotactic radiosurgery (SRS) has emerged as a potential alternative approach. The primary aim of SRS has been to improve long-term control rates. Nevertheless, rare observations of abscopal or out-of-field effects have sparked interest in the potential to elicit antitumor immunity via the administration of high-dose radiation. The blood-brain barrier (BBB) has traditionally posed a significant challenge to the efficacy of systemic therapy in managing intracranial metastasis. However, recent insights into the immune-brain interface and the development of immunotherapeutic agents have shown promise in preclinical and early-phase clinical trials. Researchers have investigated combining immunotherapy with SRS to enhance treatment outcomes in patients with brain metastasis. The combination approach aims to optimize long-term control and overall survival (OS) outcomes by leveraging the synergistic effects of both therapies. Initial findings have been encouraging in the management of various intracranial metastases, while further studies are required to determine the optimal order of administration, radiation doses, and fractionation regimens that have the potential for the best tumor response. Currently, several clinical trials are underway to assess the safety and efficacy of administering immunotherapeutic agents concurrently or consecutively with SRS. In this review, we conduct a comprehensive analysis of the advantages and drawbacks of integrating immunotherapy into conventional SRS protocols for the treatment of intracranial metastasis.

Stereotactic radiosurgery for sarcoma metastases to the brain: a single-institution experience.

OBJECTIVE: Brain metastases (BMs) secondary to sarcoma are rare, and their incidence ranges from 1% to 8% of all bone and soft tissue sarcomas. Although stereotactic radiosurgery (SRS) is widely used for BMs, only a few papers have reported on SRS for sarcoma metastasizing to the brain. The purpose of this study was to evaluate the safety and effectiveness of SRS for sarcoma BM. METHODS: The authors retrospectively reviewed the clinical and radiological outcomes of patients with BM secondary to histopathologically confirmed sarcoma treated with SRS, either as primary treatment or as adjuvant therapy after surgery, at their institution between January 2005 and September 2022. They also compared the outcomes of patients with hemorrhagic lesions and of those without. RESULTS: Twenty-three patients (9 females) with 150 BMs secondary to sarcoma were treated with CyberKnife SRS. Median age at the time of treatment was 48.22 years (range 4-76 years). The most common primary tumor sites were the heart, lungs, uterus, upper extremities, chest wall, and head and neck. The median Karnofsky Performance Status on presentation was 73.28 (range 40-100). Eight patients underwent SRS as a primary treatment and 15 as adjuvant therapy to the resection cavity. The median tumor volume was 24.1 cm3 (range 0.1-150.3 cm3), the median marginal dose was 24 Gy (range 18-30 Gy) delivered in a median of 1 fraction (range 1-5) to a median isodose line of 76%. The median follow-up was 8 months (range 2-40 months). Median progression-free survival and overall survival were 5.3 months (range 0.4-32 months) and 8.2 months (range 0.1-40), respectively. The 3-, 6-, and 12-month local tumor control (LTC) rates for all lesions were respectively 78%, 52%, and 30%. There were no radiation-induced adverse effects. LTC at the 3-, 6-, and 12-month follow-ups was better in patients without hemorrhagic lesions (100%, 70%, and 40%, respectively) than in those with hemorrhagic lesions (68%, 38%, and 23%, respectively). CONCLUSIONS: SRS, both as a primary treatment and as adjuvant therapy to the resection cavity after surgery, is a safe and relatively effective treatment modality for sarcoma BMs. Nonhemorrhagic lesions show better LTC than hemorrhagic lesions. Larger studies aiming to validate these results are encouraged.

Stereotactic radiosurgery for distant brain metastases secondary to esthesioneuroblastoma: a single-institution series.

OBJECTIVE: Esthesioneuroblastoma (ENB), also known as olfactory neuroblastoma, is a rare, malignant tumor of neuroectodermal origin that arises from the olfactory neuroepithelium. In this study the authors present the first series in the literature on distant brain metastases (BMs) secondary to ENB that were treated with stereotactic radiosurgery (SRS), to evaluate the safety and effectiveness of SRS for this indication. METHODS: A retrospective analysis of clinical and radiological outcomes of patients with ENB who underwent CyberKnife (CK) SRS at a single center was conducted. The clinical and radiological outcomes of patients, including progression-free survival, overall survival, and local tumor control (LTC) were reported. RESULTS: Between 2003 and 2022, 32 distant BMs in 8 patients were treated with CK SRS at Stanford University. The median patient age at BM diagnosis was 62 years (range 47-75 years). Among 32 lesions, 2 (6%) had previously been treated with surgery, whereas for all other lesions (30 [94%]), CK SRS was used as their primary treatment modality. The median target volume was 1.5 cm3 (range 0.09-21.54 cm3). CK SRS was delivered by a median marginal dose of 23 Gy (range 15-30 Gy) and a median of 3 fractions (range 1-5 fractions) to a median isodose line of 77% (range 70%-88%). The median biologically effective dose was 48 Gy (range 21-99.9 Gy) and the median follow-up was 30 months (range 3-95 months). The LTC at 1-, 2-, and 3-year follow-up was 86%, 65%, and 50%, respectively. The median progression-free survival and overall survival were 29 months (range 11-79 months) and 51 months (range 15-79 months), respectively. None of the patients presented adverse radiation effects. CONCLUSIONS: In the authors' experience, SRS provided excellent LTC without any adverse radiation effects for BMs secondary to ENB.

CyberKnife Radiosurgery for Treatment of Residual or Recurrent Grade 1 Choroid Plexus Papilloma: A Single-Institution Experience.

BACKGROUND: Choroid plexus papillomas (CPPs) are rare intraventricular brain tumors derived from the epithelium of the choroid plexus. Gross total resection has traditionally been considered curative, but residual tumor or recurrence remains possible. Stereotactic radiosurgery (SRS) has become a more important strategy for subtotally resected and recurrent tumors. The evidence-based rationale of SRS treatment for residual or recurrent CPP in adult patients is still lacking because of the rarity of the disease. METHODS: We retrospectively reviewed the cases of histopathologically confirmed patients with residual or recurrent CPP treated with SRS at our institute in the adult population between 2005 and 2022. Three patients, with 5 lesions, were identified, with a median age of 63 years. Patients presented initially with hydrocephalus-related symptoms, although ventriculomegaly was noted in only 1 patient radiographically. The tumor location was most commonly in the fourth ventricle or along the foramen of Luschka. Treatment was delivered in a single fraction in 4 lesions and in 3 fractions in 1 patient. The median follow-up was 26 months. RESULTS: The local tumor control rate for the lesions was 80%. One patient developed a new lesion outside the SRS field, and 1 lesion developed progression without the need for subsequent treatment. There was no significant shrinkage of the lesions radiographically. None of the patients showed radiation-related adverse events. No patients required surgical management after SRS treatment at our institution. Based on the literature review, our case series was the second largest retrospective series from a single institution on SRS for recurrent or residual CPP. CONCLUSIONS: SRS for patients with recurrent or residual CPP was a safe and effective treatment modality in this case series. Larger studies are encouraged to validate the role of SRS in the treatment of recurrent or residual CPP.

Clinical and genomic differences in supratentorial versus infratentorial NF2 mutant meningiomas.

OBJECTIVE: Mutations in NF2 are the most common somatic driver mutation in sporadic meningiomas. NF2 mutant meningiomas preferentially arise along the cerebral convexities-however, they can also be found in the posterior fossa. The authors investigated whether NF2 mutant meningiomas differ in clinical and genomic features based on their location relative to the tentorium. METHODS: Clinical and whole exome sequencing (WES) data for patients who underwent resection of sporadic NF2 mutant meningiomas were reviewed and analyzed. RESULTS: A total of 191 NF2 mutant meningiomas were included (165 supratentorial, 26 infratentorial). Supratentorial NF2 mutant meningiomas were significantly associated with edema (64.0% vs 28.0%, p < 0.001); higher grade-i.e., WHO grade II or III (41.8% vs 3.9%, p < 0.001); elevated Ki-67 (55.0% vs 13.6%, p < 0.001); and larger volume (mean 45.5 cm3 vs 14.9 cm3, p < 0.001). Furthermore, supratentorial tumors were more likely to harbor the higher-risk feature of chromosome 1p deletion (p = 0.038) and had a larger fraction of the genome altered with loss of heterozygosity (p < 0.001). Infratentorial meningiomas were more likely to undergo subtotal resection than supratentorial tumors (37.5% vs 15.8%, p = 0.021); however, there was no significant difference in overall (p = 0.2) or progression-free (p = 0.4) survival. CONCLUSIONS: Supratentorial NF2 mutant meningiomas are associated with more aggressive clinical and genomic features as compared with their infratentorial counterparts. Although infratentorial tumors have higher rates of subtotal resection, there is no associated difference in survival or recurrence. These findings help to better inform surgical decision-making in the management of NF2 mutant meningiomas based on location, and may guide postoperative management of these tumors.

Vascular steal and associated intratumoral aneurysms in highly vascular brain tumors: illustrative case.

BACKGROUND: Intratumoral aneurysms in highly vascular brain tumors can complicate resection depending on their location and feasibility of proximal control. Seemingly unrelated neurological symptoms may be from vascular steal that can help alert the need for additional vascular imaging and augmenting surgical strategies. OBSERVATIONS: A 29-year-old female presented with headaches and unilateral blurred vision, secondary to a large right frontal dural-based lesion with hypointense signal thought to represent calcifications. Given these latter findings and clinical suspicion for a vascular steal phenomenon to explain the blurred vision, computed tomography angiography was obtained, revealing a 4 × 2-mm intratumoral aneurysm. Diagnostic cerebral angiography confirmed this along with vascular steal by the tumor from the right ophthalmic artery. The patient underwent endovascular embolization of the intratumoral aneurysm, followed by open tumor resection in the same setting without complication, minimal blood loss, and improvement in her vision. LESSONS: Understanding the blood supply of any tumor, but highly vascular ones in particular, and the relationship with normal vasculature is undeniably important in avoiding potentially dangerous situations and optimizing maximal safe resection. Recognition of highly vascular tumors should prompt thorough understanding of the vascular supply and relationship of intracranial vasculature with consideration of endovascular adjuncts when appropriate.

Defining Occult High-Risk Cysts of the Pineal Region: A Case Series.

BACKGROUND: Absence of hydrocephalus on neuroimaging may impart a false sense of security for patients with pineal cysts. In this case series, we characterize a subset of patients with pineal cysts having an occult presentation. Unifying features of worsening paroxysmal headaches suggesting intermittent obstructive hydrocephalus and radiographic evidence of third ventricular invagination characterize these patients as high risk. OBJECTIVE: To define features of occult, high-risk pineal cysts and outcomes of endoscopic cyst fenestration. METHODS: Charts were retrospectively reviewed for patients with pineal cysts evaluated at our institution between 2018 and 2021 who underwent endoscopic cyst fenestration. To capture cysts presenting as occult, patients were excluded if hydrocephalus was noted at presentation. Relevant clinical history, imaging, operative data, and clinical outcomes were reviewed. RESULTS: Of 50 pineal cyst patients, 4 satisfied inclusion criteria. All patients presented with worsening paroxysmal headaches. In addition, 75% (3/4) also experienced intermittent syncope. Patients exhibited no hydrocephalus (n = 3) or fluctuating ventricular size on longitudinal imaging (n = 1). In all cases, high-resolution sagittal 3-dimensional T2 magnetic resonance imaging demonstrated invagination of the cyst anteriorly into the posterior third ventricle. All patients underwent endoscopic cyst fenestration with complete symptom resolution (mean follow-up of 20.6 months; range 3.5-37.4 months). CONCLUSION: The clinical history for occult, high-risk pineal cysts is notable for worsening paroxysmal headaches and episodic alterations of consciousness suggesting intermittent obstructive hydrocephalus. Because ventricular size can appear normal on standard imaging protocols, clinical suspicion should trigger workup with high-resolution magnetic resonance imaging designed to detect these cysts. Endoscopic cyst fenestration is a safe and efficacious management strategy.