[Spinal CSF-venous fistula: case report and literature review]

Syndrome of spontaneous intracranial hypotension is increasingly described in the literature as a multifactorial disease with impairment of the quality of life and risk of mortality. CSF-venous fistula as a cause of intracranial hypotension syndrome is extremely rare and requires complex diagnosis and timely surgical treatment.

OBJECTIVE

We present a 55-year-old patient with acute spontaneous intracranial hypotension and spinal CSF-venous fistula. Literature data are also analyzed.

RESULTS

Algorithm for diagnosis and efficacy of microsurgical resection of CSF-venous fistula is demonstrated.

CONCLUSION

Intracranial hypotension following spinal fistula requires careful examination. Accurate understanding of pathophysiological and anatomical features of this disease is necessary to select an effective treatment method.

[Surgical treatment of hemispheric and subcortical gliomas adjacent to corticospinal tract in children using MR tractography and intraoperative electrophysiological monitoring]

Difficult total resection of supratentorial gliomas adjacent to the corticospinal tract (CST) is due to the high risk of its injury and disability of patients. The main methods for preventing intraoperative CST damage are preoperative MR tractography and intraoperative electrophysiological monitoring. The problem of total resection of gliomas adjacent to the CST with preservation of high functional status is difficult due to immaturity and plasticity of brain structures in children. Moreover, the advantages of MR tractography combined with intraoperative monitoring have not been described. The authors present surgical treatment of supratentorial gliomas adjacent to the CST at different anatomical levels. Patients underwent preoperative and postoperative MR tractography and intraoperative electrophysiological monitoring. MR tractography provided preoperative data on CST lesion. Intraoperative monitoring made it possible to identify and preserve CST in the depth of surgical wound. MR tractography and intraoperative electrophysiological monitoring increase resection quality in patients with hemispheric and subcortical gliomas without postoperative functional deterioration.

[Anaplastic pleomorphic xanthoastrocytoma - single-center analysis of 42 patients]

Anaplastic pleomorphic xanthoastrocytoma is a rare tumor. There are still no objective data on the incidence of its diagnosis.

OBJECTIVE

To study neuroimaging, morphological features of tumors, as well as factors affecting treatment and prognosis.

MATERIAL AND METHODS

A retrospective study enrolled 42 patients operated on at the Burdenko Neurosurgery Center between 2003 and 2020. MR characteristics of anaplastic pleomorphic xanthoastrocytoma were analyzed. All patients underwent resection of tumor (total resection in 83.3% of cases). Redo surgeries were performed in 1/3 of patients. Mutational status of BRAF V600E was assessed in all patients. Adjuvant radio- and chemotherapy was performed in more than 80% of cases. Tyrosine kinase inhibitors were administered in 19% of cases. The follow-up period was 152 months (median 34 months).

RESULTS

We found no pathognomonic MR signs of this disease. Indeed, anaplastic pleomorphic xanthoastrocytoma have the same signal characteristics as other malignant gliomas. The BRAF V600E mutation status was positive in 54.8% of cases. None patient had IDH-1 mutation. Mean Ki-67 index was 12.5%. The overall survival was 79 months (range 4-152). Seven (17%) patients are alive for more than 90 months. Only Ki-67 index and BRAF mutation significantly influenced the treatment prognosis and overall survival regardless the use of tyrosine kinase inhibitors.

CONCLUSION

Such well-known factors for malignant glioma as patient age, total resection and adjuvant therapy did not significantly affect overall survival. Perhaps, searching for new molecular genetic features will reveal additional significant factors of prognosis in patients with anaplastic pleomorphic xanthoastrocytoma.

[Machine learning for resting state fMRI-based preoperative mapping: comparison with task-based fMRI and direct cortical stimulation]

OBJECTIVE

To develop a system for preoperative prediction of individual activations of motor and speech areas in patients with brain gliomas using resting state fMRI (rsfMRI), task-based fMRI (tb-fMRI), direct cortical stimulation and machine learning methods.

MATERIAL AND METHODS

Thirty-three patients with gliomas (19 females and 14 males aged 19 - 540) underwent DCS-assisted resection of tumor (19 ones with lesion of motor zones and 14 patients with lesions of speech areas). Awake craniotomy was performed in 14 cases. Preoperative mapping was performed according to special MRI protocol (T1, tb-fMRI, rs-fMRI).

Machine learning system was built on open source data from The Human Connectome Project. MR data of 200 healthy subjects from this database were used for system pre-training. Further, this system was trained on the data of our patients with gliomas.

RESULTS

In DCS, we obtained 332 stimulations including 173 with positive response. According to comparison of functional activations between rs-fMRI and tb-fMRI, there were more positive DCS responses predicted by rs-fMRI (132 vs 112). Non-response stimulation sites (negative) prevailed in tb-fMRI activations (69 vs 44).

CONCLUSION

The developed method with machine learning based on resting state fMRI showed greater sensitivity compared to classical task-based fMRI after verification with DCS: 0.72 versus 0.66 (p<0.05) for identifying the speech zones and 0.79 versus 0.62 (p<0.05) for motor areas.

Multimodal method of tissue differentiation in neurooncology using Raman spectroscopy, fluorescence and diffuse reflectance spectroscopy

BACKGROUND

There is a need to expand the possibilities of urgent analysis of intracranial tumor type during resection. These measures are necessary to improve resection quality with preservation of intact tissues and avoiding recurrence and neurological impairment in postoperative period.

OBJECTIVE

To create optical-spectral method for differentiating the intracranial tumor types.

MATERIAL AND METHODS

We used a combination of certain methods such as fluorescence spectroscopy to analyze the content of endogenous and exogenous fluorophores in samples, diffuse reflectance spectroscopy to analyze structural integrity of tissues according to light scattering and blood filling according to hemoglobin spectrum absorption, as well as spontaneous Raman spectroscopy detecting individual molecular components of tissues. The study was conducted at the Laboratory of Neurosurgical Anatomy and Conservation of Biological Materials of the Burdenko Neurosurgical Center and included 93 tissue samples from 60 patients diagnosed with glioblastoma (n=28), meningioma (n=12), astrocytoma (n=9), oligodendroglioma (n=5), and metastasis (n=6).

RESULTS

Different types of intracranial tumors that cannot be differentiated using one of the considered spectroscopy modes can be distinguished in another one. Thus, we can conclude possible advantages of combined optical-spectral approach.

[Periventricular changes following hydrocephalus: quantitative MR-based assessment of tissue characteristics]

OBJECTIVE

To study tissue characteristics of periventricular white matter in patients with open hydrocephalus using DWI MRI and their correlations with CSF flow parameters.

MATERIAL AND METHODS

MRI was performed in 55 patients (35 women and 20 men) with open normal pressure hydrocephalus, as well as 16 patients with malignant occlusive hydrocephalus and interstitial edema (control group). We determined the correlations between severity of hydrocephalus, periventricular lesions and CSF flow parameters considering MR data. Dimensions of ventricular system were assessed using the Evans' index, periventricular changes - using visual four-level scale with calculation of apparent diffusion coefficient (ADC) and fractional anisotropy coefficient (FA).

RESULTS

Among patients with open hydrocephalus, ACD range for periventricular white matter was 1.57±0.15·10^-3 mm²/s in subgroup of patients without periventricular changes (n=29) and 1.62±0.11×10^-3 mm²/s in patients with periventricular changes (n=26). In the control group, mean ADC was 1.76±0.18·10^-3 mm²/s (p<0.05). In patients with open hydrocephalus, FA coefficient in the areas of periventricular changes was 0.70-0.80, in case of occlusive hydrocephalus - 0.68-0.82. There was a significant relationship between the Evans' index and CSF pulsation velocity amplitude, Evans' index and stroke volume, Evans' index and cerebral aqueduct cross-sectional area in patients with open hydrocephalus. Periventricular changes were pronounced in patients with open hydrocephalus and Evans' index > 0.4 (p<0.05).

CONCLUSION

According to MR data, periventricular changes in patients with open hydrocephalus differ from true periventricular interstitial edema following occlusive hydrocephalus. Severity of periventricular changes in patients with open hydrocephalus depends on patient age and width of the ventricles, but does not correlate with CSF flow parameters. In our opinion, periventricular changes are associated with dysfunction of glymphatic system. Further research is required to study the functioning of glymphatic system and related processes.

[Surgical treatment of drug-resistant epilepsy following hippocampal sclerosis]

Surgery is an effective approach for drug-resistant temporal lobe epilepsy following hippocampal sclerosis. There is still no clear and unanimous opinion about advantages and disadvantages of certain surgical technique.

MATERIAL AND METHODS

There were 103 surgical interventions in 101 patients. Females prevailed (1.45:1). Age of patients ranged from 16 to 56 years (median 28). Anteromedial temporal lobectomy and selective amygdaloghippocampectomy were performed in 49 (47.6%) and 54 (52.4%) patients, respectively. In the latter group, 30 patients were operated via a 14-mm burr hole-subtemporal approach. Postoperative outcomes were assessed using the Engel grading system. The follow-up period ranged from 2 to 8 years (median 4 years).

RESULTS

By the 2^nd year, Engel class I was observed in 74 (72%) patients, Engel II, III and IV - in 20 (19.4%), 6 (5.8%) and 3 (2.9%) patients, respectively. Engel class I was achieved after anteromedial temporal lobectomy in 68% of cases, selective amygdaloghippocampectomy via standard approaches in 75% of cases, amygdaloghippocampectomy via subtemporal burr hole approach - in 80% of cases. Neurocognitive impairments after anteromedial lobectomy and selective amygdaloghippocampectomy were similar. At the same time, mental disorders de novo prevailed in the group of anteromedial lobectomy (p<0.05). There were no severe visual field disorders after subtemporal burr-hole access. In other cases, these disorders occurred in 36.2% of patients (p<0.05). There were 8 (7.8%) postoperative complications: 5 (10.2%) - after anterior temporal lobectomy, 3 (5.5%) - after selective surgeries via standard approaches. There were no complications after burr-hole surgery.

CONCLUSION

Selective amygdaloghippocampectomy is not inferior to anteromedial lobectomy. Moreover, this procedure is associated with a lower risk of complications and adverse events.

[Deep brain stimulation of the subthalamic nucleus for parkinson's disease: awake vs asleep]

BACKGROUND

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is known to be an effective and safe neurosurgical procedure for Parkinson's disease (PD). Traditionally, awake implantation of stimulation system is carried out using microelectrode registration and intraoperative stimulation. Development of neuroimaging technologies enables direct STN imaging. Therefore, asleep surgery without additional intraoperative verification is possible. This approach reduces surgery time and can potentially decrease the incidence of hemorrhagic and infectious complications. The advantages of one method or another are being discussed.

OBJECTIVE

To assess the benefits and limitations of various methods for DBS system implantation for bilateral STN stimulation, to study the issues of stereotaxic accuracy, efficiency and safety of asleep and awake electrode implantation into STN.

MATERIAL AND METHODS

We reviewed the articles published in the PubMed database. Searching algorithm included the following keywords: «asleep DBS», «Parkinson's disease», «subthalamic nucleus», «3T MRI», «SWI», «SWAN».

RESULTS

There were 31 articles devoted to asleep DBS of STN including 4 meta-analyses, 3 prospective controlled studies, 13 retrospective controlled studies and 11 studies without a control group.

CONCLUSION

Asleep implantation of electrodes for DBS of STN can be performed only after a clear imaging of STN boundaries with high-quality MRI.

[Magnetic resonance relaxometry in high-grade glioma subregion assessment - neuroimaging and morphological correlates]

OBJECTIVE

To analyze the differences of high-grade glioma subregions using magnetic resonance relaxometry with compilation of images (MAGiC) and arterial spin labeling (ASL), as well as to compare quantitative measurements of these techniques with morphological data.

MATERIAL AND METHODS

The study enrolled 35 patients with newly diagnosed supratentorial gliomas (23 - grade IV, 12 - grade III). We measured relaxometric values (T1, T2, proton density), tumor blood flow (TBF) in glioma subregions and normal-appearing brain matter. Neuronavigation was intraoperatively used to obtain tissue samples from active tumor growth zone, perifocal infiltrative edema zone and adjacent brain matter along surgical approach.

RESULTS

ASL perfusion revealed higher tumor blood flow (TBF) in active tumor growth region compared to perifocal infiltrative edema zone (p<0.01). Relaxometric values (T1, T2, proton density) in perifocal zone were higher (p<0.01) compared to adjacent intact white matter along surgical approach. However, there were no differences in TBF between these zones. Proton density in tumor-adjacent intact white matter was higher (p<0.01) compared to normal-appearing white matter in ipsilateral hemisphere. There was inverse correlation between T2 and TBF in active tumor growth zone (Spearman rank R= -0.58; p=0.0016). We found inverse correlation between T2 and Ki67 proliferative index and direct correlation between TBF and Ki67 in this zone. Nevertheless, these relationships were insignificant after multiple test adjustment.

CONCLUSION

Our study advocates for complementary power of ASL perfusion and MR relaxometry in assessment of high-grade brain glioma subregions. More malignant tumor zones tend to have higher TBF and shorter T2. Further investigation is needed to prove the capability of MAGiC to reveal foci of increased relaxometric values in tumor-adjacent normal-appearing white matter.

[Dynamic11C-methionine PET/CT in differential diagnosis of brain gliomas]

OBJECTIVE

To evaluate the possibilities of dynamic preoperative ¹¹C-methionine (MET) PET/CT in differential diagnosis of various types of brain gliomas in adults.

MATERIAL AND METHODS

The study included 74 patients aged 48±14 years with supratentorial gliomas: Grade IV - glioblastoma (GB, n=33), Grade III - anaplastic oligodendroglioma (AOD, n=10) and anaplastic astrocytoma (AA, n=12), Grade II - diffuse astrocytoma (DA, n=13) and oligodendroglioma (OD, n=6). All patients underwent standard MRI and dynamic MET PET/CT within 20 minutes after intravenous injection of radiopharmaceutical. Then, we compared MRI and PET/CT data and comprehensively analyzed the early stages of time-activity curve using 2 parameters: the first pass peak (FPP) and the first peak of maximum uptake (Pmax).

RESULTS

We have significantly distinguished high-grade tumors (GB and AA+AOD) and certain benign gliomas (DA and OD) (p<0.05). AUC was over 0.7 and 0.8 for FPP and Pmax in differential diagnosis of various gliomas, respectively. We found that difficulties in differential diagnosis of gliomas arise mainly if oligodendrogliomas are included in the control group.

CONCLUSION

Dynamic PET/CT with analysis of FPP and Pmax increases specificity of differential diagnosis of various gliomas compared to standard static imaging. These data are valuable for choice of optimal treatment strategy, as well as fundamental research of metabolic processes and vascularization of various tumors.

[Intraosseous metastasis of K27-mutant glioma]

Glioma metastasis outside the central nervous system is a quite rare phenomenon. The disease in a young woman manifested itself as back pain and loss of vision in the left eye. Magnetic resonance imaging (MRI) revealed a tumor of the optic nerve; positron emission tomography showed multiple secondary bone changes. At the same time, MRI detected no signs of neoplasm in the midline brain structures (the brain stem and subcortical nuclei) and spinal cord. Two biopsies (superior iliac spine trephine biopsy and optic nerve tumor biopsy) were performed. There were similar histological tumors; the optic nerve tumor was found to have K27M mutation in the H3F3A gene, whereas the metastatic tumor lacked this mutation (possibly due to the quality and quantity of DNA isolated from the tumor cells). The interesting features of this case are the simultaneous detection of primary and metastatic tumors before receiving any treatment and the absence of the K27M mutation in the H3F3A gene in the metastasis.

[Combined cerebral revascularization for moyamoya disease]

INTRODUCTION

Combined cerebral revascularization with direct and indirect components is recognized as the most appropriate method for treating patients with Moyamoya disease all over the world, however, large studies on its effectiveness in Russia have not yet been conducted.

THE AIM OF THE STUDY

Was to evaluate the results of combined cerebral revascularization in patients with Moyamoya disease with an analysis of the clinical state and perfusion and angiographic features of neoangiogenesis.

MATERIAL AND METHODS

For the period from 2013 to 2020 in N.N. Burdenko National Medical Research Center of Neurosurgery 79 combined revascularizations were performed in 55 patients with Moyamoya disease. The average age was 13.9±10.11 years. All patients were examined according to a single protocol, including a comprehensive assessment of the clinical symptoms, the state of the brain tissue, the cerebral vascular system, and cerebral blood flow. The results of surgical treatment were evaluated in the early postoperative and long-term periods. The average follow-up period was 14.66±13.17 months. In the postoperative period, the dynamics of neurological status and cerebral blood flow were assessed and the features of neoangiogenesis from various components of revascularization were studied.

RESULTS

In the early postoperative period, in 77.2% of cases, a good treatment result was observed, with no negative dynamics of the neurological status. Ischemic stroke in the operated hemisphere developed in 4 cases (5.1%). In the follow-up period, an improvement in neurological symptoms was observed in 76.6%. Improvement of cerebral blood flow was noted in 92.4% of cases, direct anastomoses functioned in 94.3%, and signs of neovascularization in the area of indirect synangiosis were observed in 80.0%. At the same time, a complementary influence of direct and indirect components of revascularization was revealed in ensuring good general angiographic and perfusion results.

CONCLUSIONS

Combined revascularization is a highly effective method of surgical treatment of all patients with Moyamoya disease.

[Central neurocytomas: long-term treatment outcomes]

Central neurocytoma is a rare benign brain tumor. These tumors may be giant and accompanied by compression of ventricular system and surrounding structures. Modern treatment of brain neurocytoma includes extended resection and restoration of normal CSF circulation. Surgical treatment does not often lead to total resection of these tumors. Redo resection was preferred in patients with tumor progression for a long time. In the last decade, various authors report stereotactic irradiation for continued tumor growth to ensure local growth control. This study was aimed at evaluation of postoperative outcomes in patients with brain neurocytomas, as well as treatment of tumor progression in long-term period.

OBJECTIVE

To analyze recurrence-free survival in patients with brain neurocytomas, risk factors of recurrence-free survival, effectiveness of various treatments for tumor progression and delayed complications.

MATERIAL AND METHODS

Long-term postoperative follow-up data of patients with brain neurocytomas are reported in the manuscript. We analyzed recurrence-free survival and risk factors of recurrence-free survival, treatment outcomes in patients with progression of brain neurocytomas, long-term complications and their prevention.

RESULTS

Follow-up included 84 out of 115 patients with brain neurocytoma after surgical treatment in 2008-2017. Follow-up period ranged from 2 to 10 years (mean 6 years) after resection. Most patients had regression of neurological symptoms after surgery. Continued tumor growth within 12-96 months after surgery occurred in 26 (30.19%) out of 84 patients (19 cases after partial resection and 7 cases after total resection according to MRI data). Two-year recurrence-free survival was 94%, 5-year survival - 83%. Risk factors of continued tumor growth were resection quality and Ki-67 index. Redo resection was performed in 7 cases. Eleven patients underwent stereotactic irradiation for tumor progression. Indications for stereotactic irradiation of central neurocytoma are MR data on continued growth of lateral ventricle tumor without signs of ICH and CSF flow impairment. There were no cases of hemorrhage inside the residual tumor and CSF flow impairment in early postoperative period after redo resection. In all cases (n=11), stereotactic irradiation (mean follow-up 2.5 years) ensured satisfactory control of tumor growth with reduction of the neoplasm in 4 cases and no tumor growth in 7 cases.

CONCLUSION

Resection of central neurocytoma ensures long-term recurrence-free period. The main causes of tumor recurrence are partial resection and high proliferative activity (Ki-67 index over 5%). Redo resection is advisable for tumor progression followed by CSF flow impairment. In case of continued growth of neurocytoma without signs of intracranial hypertension, stereotactic irradiation with various fractionation modes ensures effective and safe control of tumor growth.

[Stereotactic irradiation in the complex treatment of patients with intracranial pilocytic astrocytoma]

Complex management of patients with intracranial pilocytic astrocytoma (PA) consists of surgical treatment, drug therapy (mainly in young children) and radiotherapy. For many years, radiotherapy (RT) has been a standard for residual tumors, recurrence or continued growth of PA. Currently, stereotactic radiosurgery and radiotherapy are preferred for PA, because these procedures are characterized by high conformity and selectivity, precise irradiation of tumor with minimal damage to surrounding intact tissues. Stereotaxic approach is very important since PAs are localized near functionally significant and radiosensitive brain structures in most cases. There is significant experience of single-center studies devoted to radiotherapy of patients with PA at the Department of Neuroradiosurgery of the Burdenko Neurosurgery Center. In this research, the authors analyzed the results of stereotactic irradiation of 430 patients with PA for the period from 2005 to 2018.

[Phosphorus MR spectroscopy and 18F-FDG PET/CT in the study of energy metabolism of glial tumors]

OBJECTIVE

To study energy metabolism in glial tumors using dynamic MR spectroscopy and ¹⁸F-FDG PET/CT.

MATERIAL AND METHODS

The study included 19 patients (9 women and 10 men) with newly diagnosed supratentorial glial tumors WHO Grade I-IV (diffuse astrocytoma - 4 cases, oligodendroglioma - 4 cases, anaplastic astrocytoma - 5 cases, glioblastoma - 6 cases). All patients underwent examination and surgical treatment at the Burdenko Neurosurgery Center. Dynamic MR spectroscopy and ¹⁸F-FDG PET/CT were applied in each patient.

RESULTS

We found multiple correlations between the ratio of bioorganic phosphate peaks and parameters of glucose uptake by tumor tissue. These relationships were more significant in patients with high-grade tumors: positive significant correlation between SUVtumor and PME/PCr ratio (R_S=0.75, p=0.01), T/Nmix and βATP/Pi ratio (R_s=0.76, p=0.02), SUVpeaktumor and aATP/Pi ratio (R_S=0.77, p=0.008). Moreover, there were negative correlations between SUVtumor and PCr/bATP ratio (R_S= -0.66, p=0.05), T/Nmix and PDE/bATP ratio (R_S= -0.83, p=0.006), SUVpeaktumor and PDE/aATP ratio (R_S= -0.76, p=0.009).

CONCLUSION

High-grade gliomas were characterized by higher glucose consumption, ATP release (intensification of energy metabolism) and faster cell membrane synthesis. These processes indicate enhanced proliferation of tumor cells (intensification of plastic metabolism).

Feasibility of generalised diffusion kurtosis imaging approach for brain glioma grading

Purpose

An accurate differentiation of brain glioma grade constitutes an important clinical issue. Powerful non-invasive approach based on diffusion MRI has already demonstrated its feasibility in glioma grade stratification. However, the conventional diffusion tensor (DTI) and kurtosis imaging (DKI) demonstrated moderate sensitivity and performance in glioma grading. In the present work, we apply generalised DKI (gDKI) approach in order to assess its diagnostic accuracy and potential application in glioma grading.

Methods

Diffusion scalar metrics were obtained from 50 patients with different glioma grades confirmed by histological tests following biopsy or surgery. All patients were divided into two groups with low- and high-grade gliomas as grade II versus grades III and IV, respectively. For a comparison, trained radiologists segmented the brain tissue into three regions with solid tumour, oedema, and normal appearing white matter. For each region, we estimated the conventional and gDKI metrics including DTI maps.

Results

We found high correlations between DKI and gDKI metrics in high-grade glioma. Further, gDKI metrics enabled introduction of a complementary measure for glioma differentiation based on correlations between the conventional and generalised approaches. Both conventional and generalised DKI metrics showed quantitative maps of tumour heterogeneity and oedema behaviour. gDKI approach demonstrated largely similar sensitivity and specificity in low-high glioma differentiation as in the case of conventional DKI method.

Conclusion

The generalised diffusion kurtosis imaging enables differentiation of low- and high-grade gliomas at the same level as the conventional DKI. Additionally, gDKI exhibited higher sensitivity to tumour heterogeneity and tissue contrast between tumour and healthy tissue and, thus, may contribute as a complementary source of information on tumour differentiation.

[Anterior transperiinsular approach to the head of the caudate nucleus and mediobasal frontal lobe]

BACKGROUND

The head of the caudate nucleus and adjacent mediobasal frontal lobe are deeply localized and have complex anatomical and topographic relationships with surrounding functionally significant cerebral structures. These aspects determine difficult surgical treatment of pathology in this zone.

OBJECTIVE

To propose a new anterior transperiinsular approach for optimizing surgical access to the head of the caudate nucleus and mediobasal frontal lobe.

MATERIAL AND METHODS

Two patients with cavernoma of the head of the caudate nucleus and oligodendroglioma of the head of the caudate nucleus and mediobasal frontal lobe underwent resection via transsylvian anterior transperiinsular approach in 2018. In both cases, tumors were localized in dominant hemisphere. Standard MRI was performed before and after surgery. Luria's neurological and neuropsychological examination was carried out before surgery, in 7 days after surgery and then every 3 months.

RESULTS

Surgical access was performed via stage-by-stage proximal dissection of Sylvian fissure with visualization of anterior and superior periinsular grooves. After that, periinsular groove was dissected at the base of anterior short gyrus. Then, we moved apart white matter using microinstruments and approached the area of interest. In case of this trajectory, surgical approach was performed at the level of the upper parts of inferior frontooccipital fascicle under the arcuate fascicle. Both patients underwent total resection of tumors that was confirmed by MRI. No pre- and postoperative neurological or neuropsychological abnormalities were observed.

CONCLUSION

Anterior transperiinsular approach provides minimally invasive access to the head of the caudate nucleus and mediobasal frontal lobe. It can be used on dominant hemisphere without significant risk of speech or other cognitive impairments. The advantages of this approach are minimal damage to associative pathways and small distance between periinsular groove and zone of interest. Dissection of commissural fibers of the corpus callosum is not required compared to conventional transcallosal approach.

[Ct-angiography in assessment of critical occlusive carotid artery disease]

BACKGROUND

Occlusive carotid artery disease is still one of the major causes of ischemic stroke in the world. Progression of severe carotid stenosis may lead to critical stenosis and vascular occlusion. Nevertheless, there is still no pure definition of the concept of critical occlusive carotid artery disease.

OBJECTIVE

To define the role of CT-angiography in assessment of critical occlusive carotid artery disease.

MATERIAL AND METHODS

We analyzed data of 405 patients who underwent preoperative precise assessment of carotid arteries and subsequent surgical treatment for the period from 2016 to 2019. Contrast-enhanced CT-angiography (Philips Ict scanner, 256 slices) was made after previous ultrasound. Contrast agent injection rate was 4-5 ml/sec. CT angiography data were assessed according to a specialized protocol.

RESULTS

Critical occlusive carotid artery disease was observed in 128 (31.6%) cases including critical stenosis (24.94%), near-occlusion (5.92%) and local occlusion (0.74%). Critical stenosis was characterized by local narrowing ≥90% and normal diameter of distal arterial segment. In case of near-occlusion, local critical stenosis was accompanied by narrowing of distal arterial segment. In case of local occlusion, distal collateral supply of internal carotid artery occurred through atypically originating ascending pharyngeal artery. Patients with near-occlusion and local occlusion of internal carotid artery had no signs of ICA hypoplasia and intracranial stenoses. All elements of circle of Willis were observed in 70% of patients.

CONCLUSION

State of distal segment of internal carotid artery can be considered as a differential diagnostic criterion for critical occlusive carotid disease variants. CT-angiography provides all necessary data and can be recommended for precise preoperative assessment.

[Lesion of optic nerves and chiasm following bifocal germinoma recurrence]

The authors report a patient with recurrent bifocal germinoma of the optical nerves and chiasm after previous combined treatment. The tumor resulted progressive visual acuity loss despite subsequent therapy (glucocorticoid therapy, chemo- and radiotherapy). Differential diagnosis between tumor progression and consequences of radiotherapy was complicated by MRI negative pattern. Subsequent development of the process, signs of anterior visual pathway damage and tumor spread throughout the ventricular system and subarachnoid spaces according to neuroimaging data indicated recurrence of disease.

[Anaplastic astrocytoma and anaplastic oligodendroglioma of the brain: current state of the problem]

This review is devoted to the problem of anaplastic cerebral gliomas. The authors consider classification, neuroimaging of these tumors including comparison of magnetic resonance imaging and positron emission tomography data. Clinical manifestations of anaplastic gliomas, issues of their histological and molecular genetic classification are discussed. Moreover, the authors compare the data of neuroimaging and genetic examinations of tumors. Other issues are multicomponent treatment and prognosis in patients with anaplastic glioma of the brain.

[Orbital venous varices: modern diagnostic methods and differential diagnosis]

OBJECTIVE

To study the possibility of the modern CT and MRI methods in diagnostics of the orbital venous varices (OVV), discover the special characteristics of these lesions concerning their hemodynamic and differential diagnosis with other orbital lesions.

MATERIAL AND METHODS

In the period from 2012 to 2019 ten patients with OVV were evaluated. Four of them were men, three - women and three - children (boys aged 7, 10, and 12 years). Age of the patients varied from 7 to 75 years old (mediana - 34).

CT was performed on 9 patients using low dose protocol with injecting the contrast in standard position (supine) and in the prone position. CT-angiography was performed on 3 patients and CT-perfusion - 5 patients which allowed the assessment of the blood supply and quantitative lesions hemodynamic by calculating blood flow (BF_OVV), blood volume (BV_OVV) and mean transit time (MTT_OVV).

MRI with contrast injection and Fat Sat technology was performed on 9 patients, 3 of them were both in the supine and prone positions. 4 patients were evaluated by bolus MR-angiography (TRICKS).

RESULTS

The majority of the OVV was localized in the medial compartments and apex of the orbit. Left sided lesions were found in 6 cases, right - 3. One patient had both sided OVV. In one of the cases in 10-year-old child, we revealed malformation of the Galen vein associated with bilateral varicose enlargement of the intraorbital veins (secondary OVV).

In CT studies all of the lesions enhanced after the contrast injection. When the patients were study in the prone position, all lesions were enlarging; which lead to the diagnosis of OVV. CT-angiography (venous blood flow) proved vascular nature of the lesions. While studying the quantitative lesion hemodynamic by the CT perfusion technology, it was discovered, that OVV tend to have high blood volume (BV_OVV=19.61±3.23(ml/100g) and high blood flow (BF_OVV= 60.87±8.11) and the prolongation of mean transit time (MTT_OVV=19.23±3.07). Normal parameters measured in white matter were CBV_N=1.37±0.69(ml/100g), CBF_N=38.4±4.31(ml/100g/min), MTT_N=2.89±0.44s.

In MRI studies all the lesions had iso-hypointense MR-signal on T1- and hyperintense on T2-images. The pattern of contrast enhancement was inhomogeneous, however reaching homogeneity after some time. TRICKS MR-angiography was more sensitive than CT-angiography (venous phase). Moreover, the absence of radiation exposition was an additional advantage of the MR-venography.

CONCLUSION

Diagnosis of orbital vascular pathology requires an understanding of the classification of vascular lesions, the integration of the patient's medical history with epidemiological data, as well as a through analysis of the results of instrumental diagnostic methods. CT or MRI, including scanning in the prone position, as well as minimally invasive CT- and MR-TRICKS-angiography and ophthalmological studies of the patient, determine a comprehensive approach to the diagnosis and selection of adequate treatment for orbital venous varices.

In the differential diagnosis of OVV with other neoplasms of the orbit, we recommend CT-perfusion study with determine the quantitative characteristics of its hemodynamics.

[Broca's area intraoperative mapping with cortico-cortical evoked potentials]

OBJECTIVE

Mapping of effective speech connections between the frontal and temporal lobes with cortico-cortical evoked potentials.

MATERIAL AND METHODS

There were 3 patients with brain tumors in the left frontoparietal region. The neoplasms were localized in the dominant hemisphere near cortical speech centers and pathways. Cortico-cortical evoked potentials were intraoperatively recorded in response to bipolar stimulation with a direct current delivered through the subdural electrodes (single rectangular biphasic impulses with duration of 300 μs and frequency of 1 Hz). Stimulation intensity was gradually increased from 2 mA within 3-4 mA. Registration was carried out by averaging ECoG (30-50 stimuli in each session) in the 300-ms epoch after stimulus. Direct cortical stimulation was used to validate the results of cortico-cortical speech mapping with cortico-cortical evoked potentials.

RESULTS

In our cases, we obtained cortico-cortical evoked potentials from inferior frontal gyrus after stimulation of superior temporal gyrus. In one case, this effective relationship was unidirectional, in the other two patients reciprocal. Mean latency of N1 peak was 65 ms (range 49.6-90 ms), mean amplitude 71 µV (range 50-100 µV). Cortico-cortical mapping data were confirmed by detection of Broca's area in 2 out of 3 cases out during direct cortical stimulation with maximum amplitude of N1 wave. «Awake craniotomy» protocol was applied. In one case, Broca's area was not detected during direct stimulation. No postoperative speech impairment was noted.

CONCLUSION

Initial results of cortical mapping with cortico-cortical evoked potentials in a small sample confirmed its practical significance for analysis of cortical projections of effective speech communications between the frontal and temporal lobes. Further study of this method in large samples is required.

[Completeness of brain aneurysm exclusion according to CT angiography]

OBJECTIVE

To develop a classification of the completeness of brain aneurysm exclusion according to CT angiography for determining further diagnostic and curative strategy.

MATERIAL AND METHODS

The study included 138 patients who had 164 brain aneurysms. Clipping was carried out at the Burdenko Neurosurgery Center in 2013-2017. Titanium clips were used in 111 cases, cobalt clips - in 53 patients.

RESULTS

Completeness of brain aneurysm exclusion was assessed in 149 cases using CT angiography. In 15 cases, artifacts from cobalt clips impaired assessment. Total exclusion was achieved in 136 (91.3%) cases, subtotal (a remainder of residual neck) - in 10 (6.7%) cases, complete exclusion of the body and bottom (patent neck) - 2 (1.3%) patients, partial exclusion (partially patent bottom) - 1 patient (0.7%). In this series, a clip prevented complete contrast enhancement of brain aneurysm bottom in all cases.

CONCLUSION

CTA is a reliable method for assessing the quality of exclusion of brain aneurysm in patients with implanted titanium clips. In case of cobalt clips, stratification depending on severity of CT artifacts should be performed for data interpretation. In some cases, artifacts impair visualization of the vessels adjacent to the clips. In these patients, direct cerebral angiography or dual-energy computed tomography scanners with metal artifact suppression programs should be recommended.

Follow-up is recommended for patients with remnants of residual cervix. Redo surgery is indicated for completely patent neck, as well as partial or complete contrast enhancement of aneurysm bottom.

[Intracellular pH measurement in glioblastoma cells: the possibilities of phosphorus-31 MR spectroscopy]

OBJECTIVE

To analyze intracellular pH measurement with phosphorus-31 MR spectroscopy in glioblastoma cells and to compare these data with intracellular pH in healthy volunteers.

MATERIAL AND METHODS

There were 10 patients aged 41 - 67 years with supratentorial glioblastomas. Intracellular pH in glioblastoma cells was compared with pH in healthy persons.

RESULTS

We found a tendency to increased intracellular pH in glioblastoma cells in comparison with pH in intact brain tissue.

CONCLUSION

Intracellular pH in brain tissue can be used as a potential marker of early abnormalities which could not be detected by conventional MRI. Moreover, these data may be valuable to estimate the efficacy of chemotherapy. The study was supported by Russian Science Foundation (grant No. 18-15-00337).

[Comparative analysis of mono- and bipolar pyramidal tract mapping in patients with supratentorial tumors adjacent to motor areas: comparison of data at 64 stimulation points]

OBJECTIVE

To compare monopolar and bipolar mapping in point-by-point fashion by using of threshold amperage, frequency of positive motor responses and the number of muscles involved in response.

MATERIAL AND METHODS

A prospective non-randomized study included 14 patients with supratentorial tumors who underwent surgery in 2018-2019. All neoplasms were localized within 2 cm from the motor cortex and pyramidal tract. Age of patients ranged from 25 to 74 years. There were 9 women and 5 men. Eight patients had malignant glioma (grade III - 4, grade IV - 4), 6 patients - meningioma. Motor functions were assessed in all patients before and after surgery (1, 7 days and 3 months later) by using of a 5-point scale. In addition to routine neurophysiological monitoring, comparative mono- and bipolar mapping of the pyramidal tract within the bed of excised tumor was carried out at the end of surgery. The points of motor responses were marked. Comparative analysis of mono- and bipolar stimulation at identical points included threshold amperage, frequency of positive motor responses and the number of muscles involved in response (leg, forearm, hand, facial muscles). Brain MRI was performed in early postoperative period for assessment of resection quality.

RESULTS

There were 64 points of motor responses in 14 patients. The number of these points ranged from 2 to 8 per a patient (mean 5 points). Motor responses were recorded in 57 points during monopolar and bipolar stimulation, in other 7 points - only during monopolar stimulation. Amperage of monopolar stimulation was 3-15 mA, bipolar stimulation - 2.5-25 mA. Threshold amperage (7.37 mA for monopolar stimulation and 8.88 mA for bipolar stimulation; p=0.12), frequency of positive motor responses and the number of muscles involved in response (p=0.1 and p=0.73) were similar. Seven (50%) patients had neurological deterioration in early postoperative period (4 patients with glial tumors and 3 patients with meningiomas). At the same time, only 2 patients (14.3%) had persistent neurological deficit (both patients with infiltrative meningioma). According to postoperative MRI in T1+C mode, resection volume was 100% in 1 patient with contrast-enhanced glioma and 94% in another one. According to FLAIR MRI data, resection volume exceeded 70% in 2 patients with non-enhancing glioma and less than 70% in 2 patients. Meningioma resection volume was estimated according to postoperative T1+C MRI data and made up over 90% in 4 patients.

CONCLUSION

Monopolar stimulation is a reliable method of pyramidal tract identification in supratentorial brain tumor surgery.