ABSTRACT:AIM: To analyze the efficacy and safety of Gamma Knife radiosurgery (GKRS) in the management of thyroid cancer brain metastases (TCBM). MATERIAL and METHODS: This retrospective study analyzed patients who underwent GKRS for TCBM at two centers between September 2005 and February 2025. Patients' clinical and radiological outcomes, including local tumor control and overall follow-up, were investigated. RESULTS: Among the 3,834 patients who underwent GKRS for brain metastases at two centers, only 0.26% had primary thyroid cancer. A total of 10 patients with 40 TCBM were treated by GKRS, with a median of two metastases per patient. The most common metastasis site was the frontal lobe (47.5%), and 60% of patients had multiple metastases. Papillary carcinoma was the most frequent histological subtype (57.1%). The median latency from thyroid cancer diagnosis to the development of brain metastases was 22 months. The median GKRS dose was 23 Gy, and local failure occurred in 5% of treated metastases. Radiation-induced necrosis was observed in one case and resolved without clinical impact. Intracranial distant metastases developed in two patients. The median follow-up was 8 months, and 80% of patients died during follow-up, with one death attributed to brain metastasis. CONCLUSION: The limited number of patients and the short follow-up period, partly reflecting the aggressive nature of TCBM, may have influenced the study results. Nevertheless, despite the short follow-up, GKRS provided favorable local control without significant adverse effects, suggesting that it may be an effective treatment option for TCBM.

Background: High-grade gliomas are treatment-resistant and prone to aggressive recurrence. Although radiation therapy is a fundamental treatment, it often fails to eradicate tumors and can enhance the migratory potential of surviving cells, promoting relapse. Anti-proliferative aptamers are novel agents that show promise, but their combination with radiation therapy and their effects on invasive phenotypes require further investigation. Objectives: This study evaluated the effects of ionizing radiation on the viability and migration of human glioma cells, both alone and in combination with the anti-proliferative aptamer bi-(AID-1-T). The study aimed to determine whether the aptamer could enhance the efficacy of radiotherapy and counteract ionizing radiation-induced pro-migratory effects. Methods: The study was conducted on cell cultures of primary and relapsed human glioma. The effects of combined radiation (single dose of 20 Gy) and the bi-(AID-1-T) aptamer (10 μM) were assessed using the MTS assay, Transwell analysis, immunocytochemistry and transcriptome analysis. Results: Ionizing radiation alone reduced proliferation in primary gliomas, but increased proliferation in recurrent cultures. Ionizing radiation also increased migration in both types of gliomas. Combining ionizing radiation with the bi-(AID-1-T) aptamer produced a synergistic effect: it significantly reduced cell proliferation and migration, and suppressed the ionizing radiation-induced migratory enhancement, more effectively than either treatment alone. Transcriptome analysis revealed that combination treatment decreased the expression of pro-proliferative and migratory genes (e.g., PDPN, CDH3), while increasing the expression of anti-migratory (RND3) and pro-apoptotic genes (e.g., XAF1, SEMA3A). Thus, combination treatment significantly reduces tumor cell proliferation and migration; however, further studies on surviving cells are needed.

Stereotactic radiosurgery (SRS) of vestibular schwannomas (VS) is an effective and safe treatment method, competitive with microsurgery (MS). However, given the possibility of pseudo-progression, if the tumor continues to grow after SRS, one of the methods of additional treatment is MS, which is associated with an increased risk of dysfunction of the acoustic-facial group. Given the risks associated with MS, the decision on surgical removal of VS after SRS should be justified, taking into account the timing of the possible course of pseudo-progression. Material: from 2005 to 2015, 541 patients received radiosurgical treatment on the Gamma Knife device for vestibular schwannoma. In 17 (3.1%) cases out of 541 patients after SRS, microsurgical removal of the VS was performed, of which in 7 cases (41.1%) the only indication for tumor removal was an increase in its volume on average 40.4 months after SRS. A repeated analysis of pathomorphological preparations was performed in 11 patients to assess the signs in the tumors indicating the presence or absence of true tumor growth (recurrence). Result: in the studied material after SRS, a complete absence of Antony A and Antony B patterns predominated (63.6%), in the remaining cases their individual elements were detected. Rarefaction of cellular structures was noted in all samples. Fibrosis of the tumor stroma was noted in all patients, often in combination with foci of angiomatosis. Severe or focal edema was detected in 81.8%. Thus, it was established that after SRS, despite the continued growth of the tumor, typical post-radiation changes dominate in morphological preparations, indicating the absence of the potential of VS for further true growth.

BACKGROUND:Intracranial cavernous malformations (CMs) are vascular lesions that can present with seizures, focal neurological deficits, and intracranial hemorrhage. Management options include observation, microsurgical resection, and stereotactic radiosurgery (SRS), with Gamma-Knife radiosurgery (GKRS) emerging as a minimally invasive alternative. OBJECTIVE:To evaluate the effectiveness and safety of GKRS in the treatment of intracranial CMs, particularly in high-risk or eloquent brain regions. METHODS:This retrospective study analyzed 173 patients with intracranial CMs treated with GKRS at the N.N. Burdenko Neurosurgery Institute, Moscow, between November 2005 and August 2023. Patients were followed up for clinical and radiological outcomes, including hemorrhage rates, seizure control, and adverse radiation effects. RESULTS:The mean follow-up was 66.3 ± 56.8 months. The annual post-SRS hemorrhage rate was 3.2 %, with a significant reduction observed after the initial 2-year period (2 % post-2 years vs. 5.6 % within the first 2 years). Partial or complete regression of symptoms was observed in 35.7 % of patients. Adverse radiation effects were noted in 11.3 % of patients, with most cases being temporary. In patients with epileptic syndrome, complete seizure freedom (Engel Class I) was achieved in 51.5 % of cases. CONCLUSIONS:GKRS is an effective and safe treatment option for intracranial CMs, particularly in high-risk or eloquent brain regions. The study highlights the need for standardized reporting criteria and prospective trials to better evaluate long-term outcomes. A multidisciplinary approach is crucial in deciding the optimal treatment strategy for patients with intracranial CMs.

В данном разделе указаны критерии оценки клинической значимости применения дорогостоящей противоопухолевой лекарственной терапии в соответствии со шкалой, разработанной экспертной группой (см. стр. 7). В тексте они обозначены, как магнитуда клинической значимости (МКЗ).

Currently, positron emission tomography (PET) is the standard imaging modality in neuro-oncology for gliomas and metastatic lesions. The experience of PET application in meningiomas, the most frequent primary CNS neoplasms, is much less, and the interpretation of the study results has a number of differences. The aim of the study was to evaluate the possibility and peculiarities of PET application in meningiomas based on our own clinical experience and literature review. The study included 70 patients with 77 meningiomas who underwent PET/CT with C-11-methionine. The mean age at the time of examination was 57.4 years (19-86 years). The main evaluation parameter, the tumor-to-brain ratio (TBR) of C-11-methionine (C-11-MET) averaged 3.13 (1.00- 10.66). Meningiomas were characterized by high C-11-MET TBR, with 89.6% of cases having TBR greater than 1.5. In histologically verified WHO grade 1, 2, and 3 meningiomas, the median TBR was 4.06 [3.04, 4.57], 2.32 [2.12, 3.69], and 4.29 [2.60, 5.10] and did not differ significantly between groups. Meanwhile, in histologically unresectable slow- growing or non-growing incidental meningiomas, TBR of C-11-MET was significantly lower than in WHO grade 1 and 3 meningiomas. There was no significant difference in the accumulation index between irradiated meningiomas with tumor growth control (3.81 [2.97, 3.98]) and recurrence (3.62 [2.60, 4.30]). When irradiated and non-irradiated meningiomas of WHO grade 1, 2 and 3, as well as the combined group of grade 1-3 tumors were compared, no significant differences in C-11-MET TBR were found. The use of PET/CT in meningiomas has a number of important features. Meningiomas are characterized by high TBR of C-11-MET. According to our data PET/CT with C-11-MET does not allow differentiating between meningiomas of different degrees of malignancy - 1, 2 or 3 according to WHO. With effective radiotherapy, meningiomas show partial reduction of TBR or remain stable. Even with prolonged growth control after radiation treatment, meningiomas may still have high TBR of C-11-MET. When comparing growing and stable meningiomas, irradiated and non-irradiated tumors, no significant differences in TBR of( 11)C-MET are found.

To date, the issue of not only timely diagnosis and treatment of patients with uveal melanoma (UM), but also the prediction of this pathology remains relevant. The technology of fine needle aspiration biopsy (FNAB) makes it possible to assess the risk of developing metastatic disease using tumor specimen in patients undergoing organ-preserving treatment by cytological and molecular genetic testing in the primary intraocular lesion. Here we present a case of newly identified locally advanced (T3a) UM, outline the possibilities of organ-preserving treatment using Gamma Knife stereotactic radiosurgery, and also demonstrate the feasibility of conducting a comprehensive prognostic testing on FNAB material, including cytological and molecular genetic and morphological prognostic factors. The results of this testing have made it possible to recommend a more frequent surveillance monitoring regime for metastatic disease, which ultimately led to the early detection of UM liver metastases, followed by their successful treatment.

Positron emission tomography combined with computed tomography (PET/CT) is currently the standard imaging method in neuro-oncology for gliomas and metastatic lesions. There is much less experience with the use of PET/CT in meningioma, the most common primary tumor of the central nervous system, and there are some differences in how results are interpreted. The aim of the present work was to assess the potential for and features of the use of PET/CT to determine the degree of malignancy of meningioma, its prevalence, responses to radiotherapy, and diagnosis of relapse and/or post-radiation changes based on our own clinical experience and review of the literature. The study included 70 patients with 77 meningiomas who underwent 11C-methionine PET/CT. Mean age at investigation was 57.4 years (range 19–86 years). The main parameter evaluated, the tumor/normal ratio (T/N) of 11C-methionine (11C-MET) in tumors, averaged 3.13 (1.00–10.66). Meningiomas had high 11C-MET T/N, with values of >1.5 in 89.6

Magnetic resonance imaging (MRI) data is heterogeneous due to differences in device manufacturers, scanning protocols, and inter-subject variability. A conventional way to mitigate MR image heterogeneity is to apply preprocessing transformations such as anatomy alignment, voxel resampling, signal intensity equalization, image denoising, and localization of regions of interest. Although a preprocessing pipeline standardizes image appearance, its influence on the quality of image segmentation and on other downstream tasks in deep neural networks has never been rigorously studied. We conduct experiments on three publicly available datasets and evaluate the effect of different preprocessing steps in intra- and inter-dataset training scenarios. Our results demonstrate that most popular standardization steps add no value to the network performance; moreover, preprocessing can hamper model performance. We suggest that image intensity normalization approaches do not contribute to model accuracy because of the reduction of signal variance with image standardization. Finally, we show that the contribution of skull-stripping in data preprocessing is almost negligible if measured in terms of estimated tumor volume. We show that the only essential transformation for accurate deep learning analysis is the unification of voxel spacing across the dataset. In contrast, inter-subjects anatomy alignment in the form of non-rigid atlas registration is not necessary and intensity equalization steps (denoising, bias-field correction and histogram matching) do not improve models' performance. The study code is accessible online https://github.com/MedImAIR/brain-mri-processing-pipeline

Stereotactic radiosurgery has firmly entered the arsenal of methods for treating vestibular schwannomas along with traditional surgical removal, providing high control of tumor growth and a low level of functional complications. Meanwhile, there is evidence of a possible relationship between the irradiation performed and the subsequent development of non-occlusive hydrocephalus. Purpose: to retrospectively assess the current level of development of hydrocephalus after stereotactic radiosurgery for vestibular schwannomas. Materials and methods: of 541 patients who received treatment with the Gamma Knife for unilateral vestibular schwannoma, 456 (84.3%) patients initially had no signs of non-occlusive hydrocephalus (group 1), while in 85 (15.7%) patients, MRI signs of internal non-occlusive hydrocephalus were revealed at the time of radiosurgery (group 2), of whom in 1 case VP shunting had previously been performed. In all cases, non-occlusive hydrocephalus at the time of SRS had a compensated course without clinical manifestations. Results: after radiosurgery, the development of de novo non-occlusive hydrocephalus in 7 (1.5%) patients from group 1 and its progression in 11 (12.9%) patients from group 2 were noted. The overall incidence of non-occlusive hydrocephalus after radiosurgery was 3.3%. Ventriculoperitoneal shunting was required in 3 cases in group 1 and 7 cases in group 2 due to the occurrence of neurological symptoms (1.8%). Conclusion: In some cases, radiosurgery can lead to decompensation of existing non-occlusive hydrocephalus, but it rarely occurs de novo. The asymptomatic course of non-occlusive hydrocephalus allows for SRS, as the risk of decompensation with subsequent need for VP shunting is low. Patients with non-occlusive hydrocephalus before SRS require more careful monitoring with assessment of neurological status and control MRI.

Craniopharyngioma (CP) is a benign epithelial tumor predominantly localized in chiasmatic-sellar region and third ventricle. There are two histological variants of CP: adamantinoma-like (ACP, 85%) and papillomatous (PCP). These types differ significantly in origin and histological structure. PCP predominantly occurs in adults. Treatment of CP, including effectiveness of radiotherapy, is described in multiple studies and mainly devoted to pediatric patients. OBJECTIVE:To clarify disease-free survival in adults with newly diagnosed CP depending on resection quality; to evaluate the effectiveness of stereotactic irradiation and treatment depending on histological characteristics of tumor. MATERIAL AND METHODS:We analyzed treatment outcomes in 398 adults over 10-year follow-up. Stereotactic irradiation was performed in 11.6% of patients. The follow-up data were obtained in 68.1% of patients. We compared 5-year disease-free survival rates after different resections with and without subsequent irradiation. RESULTS:Total resection is effective and provides significantly lower risk of CP recurrence. Effectiveness of stereotactic irradiation after incomplete resection was also confirmed. CONCLUSION:Total resection of ACP and PCP provides high disease-free survival rates. Stereotactic irradiation after incomplete resection is followed by similar outcomes. PCPs are characterized by less aggressive growth and do not recur after total resection.

Hemangioblastoma (HAB) is a benign, richly vascularized tumor that accounts for 2-6% of all spinal cord neoplasms and ranks third in the structure of intramedullary space-occupying lesions of the spinal cord. Hemangioblastoma may occur sporadically or, in approximately 30% of cases, as part of the clinical picture of a hereditary disease, von Hippel-Lindau disease. The aim of this study was to evaluate the efficacy and safety of stereotactic irradiation of hemangioblastomas of the spinal localization in patients with sporadic and von Hippel-Lindau-associated hemangioblastomas The results of stereotactic radiotherapy were evaluation of 210 spinal hemangioblastomas in 74 patients. Follow-up observation was available for 67 patients with 166 tumors. The observation period ranged from 6 to 193 months. Tumor growth control with an average follow-up period of 48 months (6-193) was 99%. The use of radiosurgery and hypofractionation for spinal hemangioblastoma, including associated with VHL syndrome, allows achieving high rates of relapse-free survival and tumor growth control with minimal toxicity, including with long-term follow-up. However, in the presence of a pronounced clinical picture, removal of GAB using a microsurgical approach remains the method of choice, since regression of existing symptoms rarely occurs after stereotactic radiotherapy. Increasing the total and single doses does not lead to improved results.

Currently, positron emission tomography (PET) is the standard imaging modality in neuro-oncology for gliomas and metastatic lesions. The experience of PET application in meningiomas, the most frequent primary CNS neoplasms, is much less, and the interpretation of the study results has a number of differences. The aim of the study was to evaluate the possibility and peculiarities of PET application in meningiomas based on our own clinical experience and literature review. The study included 70 patients with 77 meningiomas who underwent PET/CT with 11C-methionine. The mean age at the time of examination was 57.4 years (19–86 years). The main evaluation parameter, the tumor-to-brain ratio (TBR) of 11C-methionine (11C–MET) averaged 3.13 (1.00–10.66). Meningiomas were characterized by high 11C–MET TBR, with 89.6% of cases having TBR greater than 1.5. In histologically verified WHO grade 1, 2, and 3 meningiomas, the median TBR was 4.06 [3.04, 4.57], 2.32 [2.12, 3.69], and 4.29 [2.60, 5.10] and did not differ significantly between groups. Meanwhile, in histologically unresectable slow-growing or non-growing incidental meningiomas, TBR of 11C–MET was significantly lower than in WHO grade 1 and 3 meningiomas. There was no significant difference in the accumulation index between irradiated meningiomas with tumor growth control (3.81 [2.97, 3.98]) and recurrence (3.62 [2.60, 4.30]). When irradiated and non-irradiated meningiomas of WHO grade 1, 2 and 3, as well as the combined group of grade 1–3 tumors were compared, no significant differences in 11C–MET TBR were found. The use of PET/CT in meningiomas has a number of important features. Meningiomas are characterized by high TBR of 11C–MET. According to our data PET/CT with 11C–MET does not allow differentiating between meningiomas of different degrees of malignancy – 1, 2 or 3 according to WHO. With effective radiotherapy, meningiomas show partial reduction of TBR or remain stable. Even with prolonged growth control after radiation treatment, meningiomas may still have high TBR of 11C–MET. When comparing growing and stable meningiomas, irradiated and non-irradiated tumors, no significant differences in TBR of 11C–MET are found.

OBJECTIVE:To identify the characteristics of pain syndrome in patients with schwannomas depending on genetic predisposition.MATERIAL AND METHODS:The study included 46 patients with peripheral, spinal and intracranial schwannomas, corresponding to the schwannomatosis phenotype according to the 2022 clinical criteria. All patients underwent sequencing of the LZRT1, Nf2 and SMARCB1 and a copy number study in the NF2.RESULTS:The most severe widespread pain was observed in patients with pathogenic LZRT1 variants, while patients with mosaic variants may not even have local tumor-related pain. Patients with SMARCB1variants may have no pain or have localized pain that responds well to surgical treatment.CONCLUSION:Further studies of the molecular features of schwannomatosis and driver mutations in the pathogenesis of pain are necessary to improve the effectiveness of pain therapy in this group of patients. Schwannomatosis is a disease from the group of neurofibromatosis, manifested by the development of multiple schwannomas. Neuropathic pain is one of the main symptoms characteristic of peripheral schwannomas, however, the severity and prevalence of the pain syndrome does not always correlate with the location of the tumors. According to modern concepts, the key factors influencing the characteristics of the pain syndrome are the target gene and the type of pathogenic variant. The most severe widespread pain is observed in patients with pathogenic variants in the LZRT1 gene, while patients with mosaic variants may not even have local pain associated with tumors. Patients with variants in SMARCB1 may have no pain or localized pain that responds well to surgical treatment.

Primary brain metastases are common in oncology. Preoperative stereotactic radiosurgery followed by surgical resection is a perspective approach. OBJECTIVE:To evaluate own experience of preoperative radiosurgery followed by surgical resection (RS+S) of metastasis regarding local control, leptomeningeal progression, surgical and radiation-induced complications; to compare treatment outcomes with surgical resection and subsequent radiotherapy (S+SRT). MATERIAL AND METHODS. A:Retrospective study included 66 patients with solitary brain metastasis. Two groups of patients were distinguished: group 1 (n=34) - postoperative irradiation, group 2 (n=32) - preoperative irradiation. The median age was 49.5 years (range 36-75). RESULTS:Local 3-, 6- and 12-month control among patients with postoperative irradiation was 88.2%, 79.4% and 42.9%, in the group of preoperative irradiation - 100%, 93.3% and 66.7%, respectively (p=0.021). Leptomeningeal progression developed in 11 patients (8 and 3 ones, respectively). The one-year survival rate was 73.5% and 84.4%, respectively (p=0.33). Long-term surgical and radiation-induced complications occurred in 12 (18.2%) patients. CONCLUSION:Preoperative radiosurgery with subsequent resection provides higher local control and lower incidence of leptomeningeal progression in patients with single brain metastases.

Введение. Увеальная меланома (УМ) является первичной злокачественной опухолью взрослых, которая демонстрирует агрессивное течение и высокий метастатический потенциал. В настоящее время общепринятым методом лечения УМ является брахитерапия. Однако в тех случаях, когда невозможно использование брахитерапии в лечении опухолей большого размера и ввиду отказа пациента от проведения энуклеации глазного яблока, в качестве альтернативы возможно использование стереотаксической радиохирургии «Гамма-нож» (СРХГН). Цель данного исследования — представить 10-летний опыт лечения пациентов с УМ методом СРХГН. Материалы и методы. Методом СРХГН за период с 2012 по 2023 гг. было пролечено 80 пациентов (80 глаз) в возрасте от 13 до 77 лет (средний возраст — 47 лет) с УМ. Среди них было 47 (58 %) женщин и 33 (42 %) мужчины, из них 3 — дети 13, 14 и 17 лет. Высота опухоли до лечения варьировалась от 3,1 до 10,8 мм (средняя — 8,0 мм), протяженность — от 8,7 до 20 мм (средняя — 13,8 мм). По международной системе TNM (2017 г.), у 56 (70 %) пациентов опухоль соответствовала стадии T3; у 16 (20 %) — T2; у 6 (7 %) — T4; у 2 (3 %) — T1. Предписанная доза в 5 случаях составляла 40 Гр, в 12 — 35 Гр, в остальных 63 случаях — 30 Гр, и предписывалась в среднем по 50 % изодозе (от 32 до 67 %). Результаты. В 94 % (n = 75) случаях удалось сохранить пролеченный глаз. Во всех случаях эти глаза, согласно КР-2020 по лечению УМ, подлежали энуклеации, из них 3 — единственные. В 5 случаях (6 %) глаза сохранить не удалось ввиду прогрессии опухоли на фоне проводимого лечения (n = 3) и развития осложнений (n = 2). У 16 (20 %) пациентов была отмечена полная регрессия, у 61 (76 %) пациента — частичная регрессия. Средняя высота опухоли после СРХГН составила 5,6 мм (от 1,6 до 11,5 мм), протяженность — 14,08 мм (от 8,7 до 20 мм). Степень регрессии опухоли в среднем составила 30 %. Осложнения имели место в 88 % (n = 70) случаев — лучевая ретинопатия (n = 48, 68 %), лучевая нейропатия (n = 6, 8 %), заднекапсулярная катаракта (n = 6, 8 %), гемофтальм (n = 4, 5 %), увеит (n = 3, 4 %), неоваскулярная глаукома (n = 3, 4 %). Выводы. Наш многолетний опыт проведения стереотаксической радиохирургии «Гамма-нож» в лечении УМ большого размера демонстрирует эффективность и безопасность данного метода.

Von Hippel-Lindau syndrome (VHL) is a rare autosomal-dominant inherited cancer syndrome with different phenotypes caused by variants in the VHL gene.Hemangioblastoma (HAB) is a benign tumor of the central nervous system and may appear as a component of VHL disease.HAB is one of the most common manifestations and a leading cause of morbidity and mortality in patients with BGL, but can also occur as a sporadic form. This tumor often has a cystic component and is multiple in nature. Mainly located subtentorially. MRI is the gold standard for diagnosis; computed tomography and perfusion techniques can also be used to make the correct diagnosis. The definitive treatment for these lesions is surgical resection, followed by SRS if necessary. Stereotactic irradiation is the method of choice for hemangioblastomas, especially with early detection of relatively small lesions, including those with multiple lesions. Radiosurgery is carried out with a high degree of efficiency with low toxicity, which is especially important for patients with minimally severe symptoms and in pediatric patients and also is recommended to patients with limited surgical alternatives (i.e., severe medical comorbidities, surgically unresectable tumors). SRS offered a satisfactory 5-year tumor control of HHB to VHL patients.The article describes a family case of hemangioblastoma, traced over several generations, provides an algorithm for the management of patients with VHL syndrome with recommendations for the required scope of their diagnosis, observation and discussion of approaches to their treatment.Careful collection of family history, genetic and follow up examination carried out systematically and correctly, monitoring of patients with VHL will allow timely establishment of the correct diagnosis and more widespread use of the stereotactic irradiation method.

BACKGROUND:Stereotactic radiosurgery (SRS) for cerebral cavernous malformations has been used for more than 30 years. However, indications for this method and outcomes are still discussable. OBJECTIVE:To analyze available literature data on SRS for cerebral cavernous malformations with assessment of indications for treatment, radiation parameters, radiological and clinical complications and outcomes. RESULTS:The final analysis included 20 reports describing post-SRS outcomes in 1834 patients with cerebral cavernous malformations. The main radiation parameter was mean radiation dose to the edge of cavernous malformation (prescribed dose, 13.25±2.16 Gy). In natural course of malformation, mean incidence of hemorrhages from cavernous malformation when counted after the second hemorrhage was 25.9±14.6%, after the patient's birth - 2.59±0.44%. Mean follow-up period after SRS was 66.7±24.1 months. Incidence of hemorrhages from cavernous malformation after SRS for the first 2 years of follow-up was assessed in 14 studies (4.67±3.51%). Incidence of hemorrhages ≥2 years after SRS was analyzed in 12 studies (1.55±0.8%). CONCLUSION:Despite significant global experience in SRS for cerebral cavernous malformations and many studies devoted to this problem, clear patient selection criteria have not yet been formulated. Modern selection principles have insufficient evidence base.

Vestibular schwannomas are the most common tumors in the cerebellopontine angle. Stereotactic radiosurgery is included in the armamentarium of methods for treating these tumors along with surgical treatment. Given the annual incidence of more than 15 radiosurgical cases of vestibular schwannomas per 1 million population, the expected need for stereotactic radiosurgery of these tumors in Russia is more than 2000 cases annually.Stereotactic radiosurgery is located at the intersection of several clinical specialties: neuroradiology, neurosurgery and radiation therapy, each of which has made a significant contribution to the development of this treatment method. The most commonly used for this is the cobalt‑based Leksell Gamma Knife, specifically intended for the treatment of intracranial neoplasms. Treatment is also possible with modern linear accelerators and proton accelerators, which provide high accuracy and conformity of irradiation. The experience gained since the first application of this method in the treatment of vestibular schwannomas has made it possible not only to optimize the radiation doses to the tumor and adjacent critical structures (brain stem, inner ear), but also to study the features of post‑radiation micro‑ and macro‑ changes, their impact on the clinical course, to develop recommendations for radiosurgery with schwannomas of various sizes. All this contributes to high control of tumor growth and a low level of functional disorders, which, along with easy tolerability and minimal hospitalization time, determines lower cost of this treatment compared to the traditional surgical approach and significant social and economic effect.This lecture is intended for neurosurgeons and radiation therapists and focuses on the most significant factors that influenced the development, promotion and active use of stereotactic radiosurgery of vestibular schwannomas in cli nical practice.