3D pCASL-perfusion in preoperative assessment of brain gliomas in large cohort of patients

The aim of the study was to evaluate the role of pseudocontinuous arterial spin labeling perfusion (pCASL-perfusion) in preoperative assessment of cerebral glioma grades. The study group consisted of 253 patients, aged 7-78 years with supratentorial gliomas (65 low-grade gliomas (LGG), 188 high-grade gliomas (HGG)). We used 3D pCASL-perfusion for each patient in order to calculate the tumor blood flow (TBF). We obtained maximal tumor blood flow (maxTBF) in small regions of interest (30 ± 10 mm²) and then normalized absolute maximum tumor blood flow (nTBF) to that of the contralateral normal-appearing white matter of the centrum semiovale. MaxTBF and nTBF values significantly differed between HGG and LGG groups (p < 0.001), as well as between patient groups separated by the grades (grade II vs. grade III) (p < 0.001). Moreover, we performed ROC-analysis which demonstrated high sensitivity and specificity in differentiating between HGG and LGG. We found significant differences for maxTBF and nTBF between grade III and IV gliomas, however, ROC-analysis showed low sensitivity and specificity. We did not observe a significant difference in TBF for astrocytomas and oligodendrogliomas. Our study demonstrates that 3D pCASL-perfusion as an effective diagnostic tool for preoperative differentiation of glioma grades.

[Intraoperative vascular fluorescence in cerebral glioblastomas and vascular histological features]

5-ALA intraoperative fluorescence is widely used in surgery of brain tumors for intraoperative demarcation of boundaries and more total resection because 5-ALA metabolites are not accumulated in the intact brain and vascular tissues. Given this fact, it was hypothesized that fluorescence of vessels in the immediate vicinity of a brain tumor may indicate their infiltration by tumor cells as a potential pathway for their dissemination and as a factor for continued tumor growth after surgery and adjuvant therapy.

PURPOSE

Identification of fluorescent vessels located near cerebral gliomas, with a histological description of their structure, relationships with the tumor, and potential invasion of the walls by tumor cells.

MATERIAL AND METHODS

A prospective cohort study included 14 patients with malignant supratentorial gliomas, aged 20 to 78 years. Five patients were operated on due to continued tumor growth. Two hours before surgery, all patients received 5-ALA orally. During surgery, a microscope (Carl Zeiss OPMI Pentero, Germany) with a fluorescent module (BLUE-400) was used. In all cases, molecular-genetic and immunohistochemical examinations of the tumor material were performed. During surgery, fluorescent vessels, after evaluating their functional significance, were also resected for histological examination.

RESULTS

Glioblastoma and anaplastic astrocytoma were verified in 10 and 4 patients, respectively. In 4 out of 10 glioblastoma cases, vessels with homogeneous or fragmentary fluorescent walls were detected in the tumor bed after resection of most of the tumor; in patients with anaplastic astrocytomas, vascular fluorescence was not observed. In the four vascular samples with intraoperatively detected wall fluorescence, tumor invasion into the vascular layers was revealed in all cases. These patients underwent an immunohistochemical examination with monoclonal antibodies to the glial GFAP marker, which clearly identified areas of ingrowth of tumor cells into the vascular wall.

CONCLUSION

5-ALA intraoperative fluorescence is a fundamentally new approach in the rapid diagnosis of tumor-infiltrated blood vessels. Invasion of tumor cells to intact vessels may be a mechanism of tumor progression and dissemination. Additional resection of fluorescent vessels may affect the radicalness of surgical treatment, but requires a mandatory assessment of their functional significance.

[Diffusion kurtosis imaging in diffuse axonal injury]

Diffuse axonal injury (DAI) is one of the most severe traumatic brain injuries. The availability of neuroimaging biomarkers for monitoring expansion of traumatic brain injury in vivo is a topical issue.

PURPOSE

To evaluate novel neuroimaging biomarkers for monitoring brain injury using diffusion kurtosis imaging (DKI) in patients with severe diffuse axonal injury.

MATERIAL AND METHODS

DKI data of 12 patients with severe DAI (11 patients with a Glasgow Coma Scale (GCS) score of ≤ 8 and 1 patient with a GCS score of 9) and 8 healthy volunteers (control group) were compared. MRI examination was performed 5 to 19 days after injury; 7 of the 12 patients underwent repeated MRI examinations. We assessed the following parameters: mean, axial, and radial kurtosis (MK, AK, RK, respectively) and kurtosis anisotropy (KA) of the white and gray matter; fractional anisotropy (FA), axonal water fraction (AWF), axial and radial extra-axonal diffusion (AxEAD and RadEAD, respectively), and tortuosity (TORT) of the extra-axonal space) of the white matter. Regions of interest (ROIs) were set bilaterally in the centrum semiovale, genu and splenium of the corpus callosum, anterior and posterior limbs of the internal capsule, putamen, thalamus, midbrain, and pons.

RESULTS

A significant reduction in KA (p<0.05) in most of ROIs set on the white matter was revealed. AK was increased (p<0.05) not only in the white matter but also in the putamen and thalamus. A significant reduction in MK with time was observed when the first and second DKI data were compared. AWF was reduced in the centrum semiovale and peduncles. The TORT parameter was decreased (p<0.05) in the majority of ROIs in the white matter, with the most pronounced changes occurring in the genu and splenium of the corpus callosum.

CONCLUSION

DKI provides novel data about microstructural injury in DAI and improves our knowledge of brain trauma pathophysiology. DKI parameters should be considered as potential biomarkers of brain injury and potential predictors of the outcome.

[Intraoperative fluorescence diagnostics in surgery of intracranial meningiomas: analysis of 101 cases]

Fluorescence diagnostics has been extensively applied in surgery of malignant brain gliomas. However, the use of this technique in surgery of intracranial meningiomas has remained controversial.

OBJECTIVE

The study objective was to assess the sensitivity of 5-aminolevulinic acid-based (5-ALA) fluorescence diagnostics in surgery of brain meningiomas and to clarify the clinical and biological factors that may influence the fluorescent effect.

MATERIAL AND METHODS

The study consistently included 101 patients with intracranial meningiomas of various locations who were operated on using 5-ALA. There were 28 (27.72%) males and 73 (72.27%) females (median age, 54 years). In all patients, surgery was performed using an operating microscope equipped with a fluorescent module; in 24 of these, laser spectroscopy was used. For comparison of chances to observe the fluorescent effect of 5-ALA in patients having meningiomas with different WHO histological grades (Grade I vs Grade II-III), we performed a meta-analysis that included 10 studies (the largest series) on outcomes of surgical treatment of meningiomas using intraoperative fluorescence diagnostics.

RESULTS

Of 101 patients included in this series, observable fluorescence was detected in 95 (94.1%) patients: weak fluorescence in 12 (11.9%), moderate fluorescence in 23 (22.8%) cases, and strong fluorescence in 60 (59.4%) patients. There was no statistically significant relationship (p>0.05) between the rate and intensity of observable fluorescence and the tumor growth pattern (primary/continued), location, WHO grade of malignancy, and histological subtype. In the absence of intraoperative bleeding, tumor fluorescence was statistically significantly brighter (p=0.02). Of 26 patients with hyperostosis, bone fluorescence was observed in 11 (42.3%) cases. There was no statistically significant relationship between administration of dexamethasone, its dose, administration of anticonvulsants, gastrointestinal tract diseases, as well as diabetes mellitus and the fluorescence intensity. There was also no significant relationship between the extent of tumor resection (Simpson scale) and the presence of fluorescence as well as its intensity. Comparison of the observable fluorescence intensity and the laser spectroscopy indicators revealed a significant correlation (r=0.75; p=0.005).

CONCLUSION

Meningioma is a well fluorescent tumor, with the technique sensitivity being 94.1%. In some cases, the use of fluorescence diagnostics in surgery of meningiomas improves identification of residual tumor fragments and enables correction of a surgical approach. To assess the effect of fluorescence diagnostics on the recurrence rate and disease-free duration, further research is required.

[Intraoperative mapping of long association fibers in surgery of gliomas of the speech-dominant frontal lobe]

Surgery of intracerebral tumors involving long association fibers is a challenge. In this study, we analyze the results of intraoperative mapping of the superior longitudinal, arcuate, and frontal aslant tracts in surgery of brain gliomas.

PURPOSE

The study purpose was to compare the results of intraoperative mapping and the postoperative speech function in patients with gliomas of the premotor area of the speech-dominant frontal lobe, which involved the superior longitudinal, arcuate, and frontal aslant tracts, who were operated on using awake craniotomy.

MATERIAL AND METHODS

Twelve patients with left frontal lobe gliomas were operated on: 11 patients were right-handed, and one patient was a left-hander retrained at an early age. Histological types of tumors were represented by Grade II diffuse astrocytomas (6 patients), Grade III anaplastic astrocytomas (1 patient), Grade IV glioblastoma (1 patient), Grade II oligodendroglioma (1 patient), and Grade III anaplastic oligodendrogliomas (3 patients). The mean age of patients was 45 (29-67) years; there were 6 males and 6 females. All patients underwent preoperative and postoperative MRI with reconstruction of the long association fibers and determination of the topographic anatomical relationships between the fibers and the tumor. Surgery was performed using the asleep-awake-asleep protocol with intraoperative awakening of patients. All patients underwent cortical and subcortical electrophysiological stimulation to control the localization of eloquent structures and to clarify the safe limits of resection. For intraoperative speech monitoring, a computerized naming test was used with naming of nouns or verbs, and automatic speech was evaluated (counting from 1 to 10, enumeration of months and days of the week), which was complemented by a talk with the patient. Speech disorders before, during, and after surgery were evaluated by a neuropsychologist. The mean current strength during direct electrical stimulation was 3 (1.9-6.5) mA.

RESULTS

The association fibers were intraoperatively identified in all patients (SLF/AF in 11 patients; FAT in one patient). In 4 patients, the cortical motor speech area was intraoperatively mapped; in three cases, tumor resection was accompanied by speech disturbances outside the stimulation. During direct electrical stimulation, speech disturbances developed in 7 of 12 cases. All patients underwent control MRI within the first 48-72 h: total resection (more than 90% of the tumor) was performed in 7 cases; subtotal resection was achieved in two patients; partial resection was performed in two cases. According to postoperative MR tractography, the resected tumor bed was adjacent to the SLF/AF complex in 7 cases, located near the SLF/AF complex in three cases, and adjacent to the FAT in two cases. Postoperatively, 11 out of 12 patients had worsening of neurological symptoms in the form of various speech disturbances. In one patient, speech disturbances developed 2 days after surgery, which was associated with an increase in edema. On examination 3 months after surgery, severe speech disturbances remained in 1 patient.

CONCLUSION

Resection of frontal lobe tumors in the speech-dominant hemisphere using early postoperative awakening is associated with a high rate of complex speech disorders due to injury to the SLF/AF complex and FAT. In these cases, intraoperative speech mapping with allowance for the course of long association fibers is an essential procedure. Preoperative tractography in combination with intraoperative speech mapping enables identification of association fibers of the SLF/AF complex and FAT, which may help to avoid severe conduction aphasia with poor speech recovery after tumor resection.

[Li-Fraumeni syndrome in a patient with multiple anaplastic oligodendrogliomas of the brain (a case report and literature review)]

Li-Fraumeni syndrome (LFS) is a clinically and genetically heterogeneous hereditary syndrome with predominantly oncological manifestations, which is associated with mutations in the TP53, MDM2, and CHEK2 genes. The most common variant is a TP53 mutation.

OBJECTIVE

To analyze the literature and present a clinical case of a patient with Li-Fraumeni syndrome and multiple anaplastic oligodendrogliomas of the brain.

CLINICAL CASE

A 42-year-old male patient presented with complaints of headaches, word finding difficulty, memory loss, right hemianopsia, and generalized convulsive attacks. For 10 years, he underwent multiple interventions and chemotherapy courses for colon adenocarcinoma and recurrent B-cell lymphoma. MRI revealed multiple space-occupying lesions of the cerebraln hemispheres, which were located in the left temporo-occipital and right frontal regions.

RESULTS

The patient underwent resection of multiple space-occupying lesions of the left temporo-occipital and right frontal regions. The postoperative period proceeded without complications. The histological diagnosis was WHO grade III anaplastic oligodendroglioma. The patient and one of his sons were detected with a R248W missense mutation in the TP53 gene. The patient underwent six courses of temozolomide chemotherapy. At a follow-up examination 20 months after surgery and chemotherapy, the patient's condition was satisfactory; he returned to work. Control MRI of the brain revealed no signs of continued tumor growth.

CONCLUSION

An analysis of the literature and the clinical case indicate the success of multiple surgical interventions and chemotherapy courses performed for a long time in the patient with Li-Fraumeni syndrome manifested by colon adenocarcinoma, recurrent B-cell lymphoma, and multiple anaplastic oligodendroglioma of the brain. The patient had a good quality of life and returned to professional activity.

[Dynamics of functional MRI and speech function in patients after resection of frontal and temporal lobe tumors]

RATIONALE

There are no studies on application of functional MRI (fMRI) for long-term monitoring of the condition of patients after resection of frontal and temporal lobe tumors.

PURPOSE

The study purpose was to correlate, using fMRI, reorganization of the speech system and dynamics of speech disorders in patients with left hemisphere gliomas before surgery and in the early and late postoperative periods.

MATERIAL AND METHODS

A total of 20 patients with left hemisphere gliomas were dynamically monitored using fMRI and comprehensive neuropsychological testing. The tumor was located in the frontal lobe in 12 patients and in the temporal lobe in 8 patients. Fifteen patients underwent primary surgery; 5 patients had repeated surgery. Sixteen patients had WHO Grade II and Grade III gliomas; the others had WHO Grade IV gliomas. Nineteen patients were examined preoperatively; 20 patients were examined at different times after surgery. Speech functions were assessed by a Luria's test; the dominant hand was determined using the Annette questionnaire; a family history of left-handedness was investigated. Functional MRI was performed on an HDtx 3.0 T scanner using BrainWavePA 2.0, Z software for fMRI data processing program for all calculations >7, p<0.001.

RESULTS

In patients with extensive tumors and recurrent tumors, activation of right-sided homologues of the speech areas cold be detected even before surgery; but in most patients, the activation was detected 3 months or more after surgery. Therefore, reorganization of the speech system took time. Activation of right-sided homologues of the speech areas remained in all patients for up to a year. Simultaneous activation of right-sided homologues of both speech areas, the Broca's and Wernicke's areas, was detected more often in patients with frontal lobe tumors than in those with temporal lobe tumors. No additional activation foci in the left hemisphere were found at the thresholds used to process fMRI data. Recovery of the speech function, to a certain degree, occurred in all patients, but no clear correlation with fMRI data was found.

CONCLUSION

Complex fMRI and neuropsychological studies in 20 patients after resection of frontal and temporal lobe tumors revealed individual features of speech system reorganization within one year follow-up. Probably, activation of right-sided homologues of the speech areas in the presence of left hemisphere tumors depends not only on the severity of speech disorder but also reflects individual involvement of the right hemisphere in enabling speech function. This is confirmed by right-sided activation, according to the fMRI data, in right-sided patients without aphasia and, conversely, the lack of activation of right-sided homologues of the speech areas in several patients with severe postoperative speech disorders during the entire follow-up period.

[Non-contrast ASL perfusion in preoperative diagnosis of supratentorial gliomas]

The purpose of this study was to investigate the potential of pseudocontinuous arterial spin labeling perfusion (pCASL) in assessing the degree of malignancy of brain gliomas at the preoperative stage. MATERIAL AND METHODS: The study included 126 patients aged 12-75 years with supratentorial gliomas of different malignancy (35 low-grade gliomas and 91 high-grade gliomas). The maximum tumor blood flow (TBF) was measured, and the normalized tumor blood flow (nTBF) was calculated relative to the intact semiovale white matter of the contralateral hemisphere. The TBF and nTBF indicators differed significantly between low-grade and high-grade glioma groups (p<0.001). When using TBF and nTBF in the differential diagnosis of low-grade and high-grade gliomas, the area under the ROC curve was 0.96 in both cases. Our findings suggest that 3D pCASL perfusion is an effective technique for preoperative differential diagnosis of low-grade and high-grade gliomas. The study was supported by the Russian Foundation for Basic Research (grant #18-315-00384).

[Evaluation of vascular reactivity to overcome limitations of neurovascular uncoupling in BOLD fMRI of malignant brain tumors]

The sensitivity of fMRI in identification of eloquent cortical centers in the case of large infiltrative growing tumors and pronounced peritumoral edema may be reduced or significantly limited in some cases. The main cause is an attenuated Blood-Oxygen-Level-Dependent response (BOLD) caused by pathological vascular reactivity and subsequent neurovascular uncoupling of fMRI. In our study, we attempted to overcome these limitations and increase the sensitivity of this technique in identification of eloquent cortical areas adjacent to brain tumors by using vasoreactivity features of a breath-holding test and including these data in the BOLD analysis. Local vasoreactivity using a breath-holding paradigm with the same block design of both motor and speech tests was determined in 5 healthy volunteers and 3 patients in the preoperative period (two patients with high grade gliomas and one patient with single metastasis). A coherence-based model was developed for analysis of BOLD fMRI, which took into account altered hemodynamics in peritumoral zones. Obtained coherence maps demonstrated clinically more significant activation zones that were not seen with standard methods of fMRI processing. Thus, neurovascular uncoupling that is known to affect the accuracy of the BOLD fMRI response adjacent to brain tumors may be partially overcome by including an independent measurement of vasoreactivity using a breath-holding test in the BOLD analysis.

[Application of intraoperative electromagnetic frameless navigation in transcranial and endoscopic neurosurgical interventions]

The paper summarizes the experience in using a system of electromagnetic intraoperative frameless navigation in various neurosurgical pathologies of the brain. The electromagnetic navigation technique was used for 102 operations in 98 patients, including 36 transnasal endoscopic interventions. There were no intraoprtative and postoperative complications associated with the use of the system. In the process of using the system, factors influencing the accuracy of navigation and requiring additional control by the surgeon were identified.

PURPOSE

The study purpose was to evaluate the use of electromagnetic navigation in surgical treatment of patients with various brain lesions.

MATERIAL AND METHODS

The system of electromagnetic navigation was used for 102 operations in 98 patients (42 males and 56 females, including 18 children; median age, 34.8 years (min, 2.2 years; max, 69 years)) in the period from December 2012 to December 2016. In 36 patients, the system was used for endoscopic interventions. In 19 patients, electromagnetic navigation was used in combination with neurophysiological monitoring.

RESULTS

In our series of cases, the frameless electromagnetic navigation system was used in 66 transcranial operations. The mean error of navigation was 1.9±0.5 mm. In 5 cases, we used the data of preoperative functional MRI (fMRI) and tractography for navigation. At the same time, in all 7 operations with simultaneous direct stimulation of the cortex, there was interference and significant high-frequency noise, which distorted the electrophysiological data. A navigation error of more than 3 mm was associated with the use of neuroimaging data with an increment of more than 3 mm, image artifacts from the head locks, high rate of patient registration, inconsequence of touching points on the patient's head, and unsatisfactory fixation to the skin or subsequent displacement of a non-invasive localizer of the patient. In none of the cases, there was a significant effect of standard metal surgical tools (clamps, tweezers, aspirators) located near the patient's head on the navigation system. In two cases, the use of massive retractors located near the patient's localizer caused noise in the localizer and navigation errors of more than 10 mm due to significant distortions of the electromagnetic field. Thirty-six transnasal endoscopic interventions were performed using the electromagnetic frameless navigation system. The mean navigation error was 2.5±0.8 mm.

CONCLUSION

In general, electromagnetic navigation is an accurate, safe, and effective technique that can be used in surgical treatment of patients with various brain lesions. The mean navigation error in our series of cases was 1.9±0.5 mm for transcranial surgery and 2.5±0.8 mm for endoscopic surgery. Electromagnetic navigation can be used for different, both transcranial and endoscopic, neurosurgical interventions. Electromagnetic navigation is most convenient for interventions that do not require fixation of the patient's head, in particular for CSF shunting procedures, drainage of various space-occupying lesions (cysts, hematomas, and abscesses), and optimization of the size and selection of options for craniotomy. In repeated interventions, disruption of the normal anatomical relationships and landmarks necessitates application of neuronavigation systems in almost mandatory manner. The use of electromagnetic navigation does not limit application of the entire range of necessary intraoperative neurophysiological examinations at appropriate surgical stages. Succession in application of neuronavigation should be used to get adequate test results.

[The phenomenon of long-term survival in glioblastoma patients. Part I: the role of clinical and demographic factors and an IDH1 mutation (R 132 H)]

The median overall survival of glioblastoma patients is about 15 months. Only a small number of patients survive 3 years. The factors of a favorable prognosis for the 'longevity phenomenon' in glioblastoma patients are not fully understood.

OBJECTIVE

to determine the occurrence rate of long-living patients with glioblastomas, identify clinical predictors of a favorable prognosis, and identify the presence and prognostic significance of an IDH1 mutation.

MATERIAL AND METHODS

Among 1494 patients operated on for glioblastoma at the Burdenko Neurosurgical Institute from 2007 to 2012, there were 84 (5.6%) patients who lived more than 3 years after primary surgery. In all the cases, histological specimens were reviewed, and immunohistochemical detection of a mutant IDH1 protein was performed. Overall survival was calculated from the time of first surgery to the date of the last consultation or death, and the recurrence-free period was calculated from the time of first surgery to MRI-verified tumor progression.

RESULTS

The median age of long-living patients with glioblastoma was 45 years (19-65 years). All tumors were located supratentorially. The median Karnofsky performance status score at the time of surgery was 80 (range, 70-100). All patients underwent microsurgical resection of the tumor, followed by chemoradiotherapy. The median recurrence-free period was 36 months (5-98 months). Overall survival of 48, 60, and 84 months was achieved in 23, 15 and 6% of patients, respectively. Among 49 specimens available for the IDH1 analysis, 14 (28.6%) specimens had a mutant protein. There was no significant difference in survival rates in patients with positive and negative results for IDH1 (44.1 vs. 40.8 months; p>0.05).

CONCLUSION

The significance of various factors that may be predictors of a favorable course of the disease is discussed in the literature. This work is the first part of analysis of prognostically significant factors positively affecting overall survival of glioblastoma patients. In our series, the predictors of a favorable prognosis for long-living patients with the verified diagnosis of glioblastoma were as follows: young age, the supratentorial location of the tumor, a high Karnofsky score before surgery, and tumor resection. In our series, we used immunohistochemical tests and found no prognostic significance of the IDH1 gene mutation; further analysis will require application of direct sequencing. We plan to study other morphological and molecular genetic features of tumors, which explain prolonged survival of glioblastoma patients, as well as the role of various types of combined chemoradiation treatment.

[Awake craniotomy]

Awake craniotomy is a neurosurgical intervention aimed at identifying and preserving the eloquent functional brain areas during resection of tumors located near the cortical and subcortical language centers. This article provides a review of the modern literature devoted to the issue. The anatomical rationale and data of preoperative functional neuroimaging, intraoperative electrophysiological monitoring, and neuropsychological tests as well as the strategy of active surgical intervention are presented. Awake craniotomy is a rapidly developing technique aimed at both preserving speech and motor functions and improving our knowledge in the field of speech psychophysiology.

[The structure of activation of the language zone in patients with intracerebral tumors according to fMRI with respect to tumor location and the functional asymmetry profile]

MATERIAL AND METHODS

A total of 50 patients were examined prior to surgical resection of intracranial tumors of the temporal and frontal lobes. Left-sided tumors were observed in 33 patients and right-sided tumors were observed in 17 patients. The functional asymmetry profile was determined using self-assessment, the Annet questionnaire, and the dichotic listening task. Twelve patients were left-handers or retrained left-handers and the remaining 38 patients were right-handers. FMRI examination was carried out on a 3.0 T SignaHDxt magnetic resonance tomograph (GE). The standard language block design paradigm was used in the study. We used the following tests: 1) recitation of months in reverse order; 2) generation of nouns according to the initial letters shown on the screen (K, M, L, N, P, C); 3) generation of verbs according to simple actions shown on the screen; 4) producing sentences using nouns shown on the screen; 5) listening to text through headphones. Data were processed using the standard BrainWave PA software (General Electric). Z-test was used in the range from 6 to 9. In all the studies, p<0.001. Statistical data processing included the nonparametric Spearman's test to determine the correlation between lateralization of the detected activation zone under speech load and tumor location (tumor is adjacent to the language zone, invades the language zone, or is located far from the language zone), as well as left- or right-handedness.

RESULTS

Among 16 patients (right-handers and 2 left-handers) the activation of language zones was observed only on the left side; in one left-handed patient, Broca's area was detected only on the right side. In other patients (including right-handers with right-sided tumors), lateralization of language zones was different, including bilateral. Statistical processing revealed that bilateral activation of both Broca's and Wernicke's areas was more frequently observed in left-handers. Broca's area was more frequently detected on the left side in the presence of a distant tumor, while this trend did not apply for Wernicke's area.

CONCLUSION

Localization of activation of Broca's area is more dependent on tumor location, while it depends on personal characteristics of an individual in the case of Wernicke's area.

[Clinical guidelines for the use of intraoperative fluorescence diagnosis in brain tumor surgery]

In this paper, we present a review of current literature on the application of intraoperative fluorescence diagnosis and fluorescence spectroscopy using 5-aminolevulinic acid in surgery for various types of brain tumors, both alone and in combination with other neuroimaging methods. Authors' extensive experience with these methods allowed them to develop a set of clinical guidelines for the use of intraoperative fluorescence diagnosis and fluorescence spectroscopy in surgery of brain tumors.

Diffusion tensor imaging tractography and intraoperative neurophysiological monitoring in surgery of intracranial tumors located near the pyramidal tract

BACKGROUND

Practical application of methods for intravital examination of the brain pathways, such as preoperative diffusion tensor imaging (DTI) tractography and intraoperative neurophysiological monitoring, facilitates safer resection of intracranial tumors located near the pyramidal tracts (PTs).

PURPOSE

The study purpose was to investigate the relationships between intracerebral tumors of different histological nature and the pyramidal tract based on preoperative DTI tractography and various methods of intraoperative neurophysiological monitoring for intraoperative identification of the pyramidal tract, depending on different variants of the topographo-anatomic relationships between the pyramidal fascicle and the tumor.

MATERIAL AND METHODS

The study included 29 patients with supratentorial tumors of a different histological structure. Of these, 2 patients had grade I tumors, 8 patients had grade II tumors, 4 patients had grade III tumors, 11 patients grade IV tumors, and 4 patients had brain metastases. The patients underwent preoperative DTI tractography with PT reconstruction and evaluation of the topographo-anatomic relationships between the pyramidal tract and the tumor (tract: intact, infiltrated, displaced). Neurophysiological monitoring (direct electrical stimulation in 24 patients and transcranial motor evoked potentials in 26 patients) was used during surgery. The strength of stimulating current for direct stimulation was varied from 10 to 30 mA. Postoperatively, the motor function was evaluated by using a 5-score scale, and the data were compared to the preoperative data.

RESULTS

According to preoperative DTI tractography in patients with grade I-II gliomas, the corticospinal tracts were infiltrated in 2 cases, displaced in 3 cases, and intact in 5 cases. In patients with grade III-IV gliomas and metastases, the tracts were infiltrated in 8 cases, displaced in 4 cases, and intact in 7 cases. Motor responses evoked by direct electrical stimulation were obtained in 5 out of 6 patients with the pyramidal tract displaced by the tumor and in 7 out of 8 patients with the tract infiltrated by the tumor. In the case of the intact tract, the PT to tumor distance and the stimulus strength play an important role: responses were obtained in 4 out of 10 patients. In the case of transcranial motor evoked potentials (TCMEPs), no dynamics of the potential amplitude was detected in 17 out of 26 patients during surgery; a reduced TCMEP amplitude was detected in 9 patients.

CONCLUSION

1. Patients with an infiltrated or displaced pyramidal tract had significantly more often hemiparesis before surgery and aggravation of hemiparesis after the surgery compared to patients with an intact tract. 2. In the case of direct electrical stimulation of the PT, motor responses (according to preoperative DTI tractography) were significantly more often observed for the pyramidal tract infiltrated and displaced by the tumor. 3. A reduction in the motor neurologic deficit in the postoperative period was significantly more often observed for application of a larger current strength during direct electrical stimulation. 4. Persistence of the TCMEP amplitude during surgery is a reliable predictor for no aggravation of the motor neurological deficit after surgery. Postoperative aggravation of hemiparesis was significantly more often observed when TC MEPs decreased during surgery.

[Blood-brain barrier permeability in healthy rats and rats with experimental C6 glioma after fractionated radiotherapy of the brain]

OBJECTIVE

To evaluate the effect of fractionated radiotherapy on permeability of the blood-brain barrier in healthy rats and rats with C6 glioma in vivo.

MATERIAL AND METHODS

An increase in BBB permeability in C6 glioma was assessed by dynamic MRI monitoring (glioma size before and after radiation therapy in combination with immunotherapy, n=30) and confocal microscopy (fluorescence imaging of tumor invasion boundaries in a dose-dependent experiment for the amount of injected antibodies). In healthy rats, BBB permeability to macromolecular substances (MMS) was assessed by ELISA (n=23, 192 plasma samples) and confocal microscopy (n=7).

RESULTS

It was shown that BBB permeability to biological macromolecules in blood-brain and brain-blood directions was increased after fractionated radiotherapy.

CONCLUSION

Drug delivery to the brain can be improved using therapeutic doses of radiation treatment that affects the BBB and minimizes the risk of serious side effects that are often associated with the drug dose.

[Glioblastoma metastases: a literature review and a description of six clinical observations]

INTRODUCTION

since the 1990s, the literature has described cases of glioblastoma metastases with the development of foci located at a distance from the primary tumor. However, the pathogenesis of this process remains unclear until the end. This focus is believed to result, on the one hand, from tumor metastasis from the primary site and, on the other hand, from multifocal growth. This article presents a literature review and a description of clinical observations of patients with glioblastoma metastases.

MATERIAL AND METHODS

The study included 6 patients (1 female and 5 males) with brain glioblastomas who received treatment at the Burdenko Neurosurgical Institute (5 patients) and the Department of Neurosurgery of the Research Center of Neurology (1 patient) in the period from 2010 to 2014. Neurophysiological control was used if the tumor was localized near the eloquent cortical areas and pathways; 4 of 6 patients were operated on using the methods of intraoperative fluorescence diagnosis (5-ALA agent--Alasens).

RESULTS

Four patients had metastases within one hemisphere, two had metastases in the contralateral hemisphere in the period of 5 to 18 months after the first operation. The primary tumor site was located near the ventricular system in two patients. In one patient, the lateral ventricle was opened during the first operation. In another patient, the prepontine cistern was opened during the first operation. In two patients, the primary tumor site was located at a distance from the lateral ventricles, however, the tumor was located near them during recurrence. Based on metabolic navigation, fluorescence of the tumor was observed in the four patients during both the first and repeated operations.

CONCLUSIONS

The close relationship between primary glioblastomas and metastases and the cerebrospinal fluid circulation pathways may confirm the fact of dissemination of tumor cells with cerebrospinal fluid flow. In our opinion, there should be an increased suspicion of the possibility for metastases of glioblastomas that are closely associated with the cerebrospinal fluid circulation pathways. Metabolic navigation with 5-ALA is effective both during primary surgery in patients with glioblastomas and during resection of glioblastoma metastases.