[Perifocal edema and glymphatic system dysfunction: quantitative assessment based on diffusion tensor magnetic resonance imaging]

BACKGROUND

Pathogenesis of peritumoral cerebral edema is unclear and potentially associated with glymphatic system dysfunction. Diffusion tensor MRI (DT-MRI) with analysis of ALPS (Analysis along the Perivascular Space) index may be valuable for assessment of edema. This approach visualizes fluid flow along perivascular spaces of deep cerebral veins.

OBJECTIVE

To assess glymphatic system function in supratentorial tumors and healthy volunteers using DT-MRI.

MATERIAL AND METHODS

There were 52 patients (59% men) aged 43 (28-64) years with supratentorial tumors (meningioma - 20, grade 3-4 glioma - 15, metastases - 9, lymphoma - 8). Tumors and perifocal edema did not involve deep cerebral veins. The control group included 6 healthy volunteers aged 34-66 years. MRI protocol (Signa HDxt, 3 T) contained standard T1, T2, T2FLAIR, DWI and post-contrast T1 (3D BRAVO). DT-MRI had the following parameters: TR=10 000 ms, TEmin=102 ms, FOV=240 mm, isotropic voxel size 3×3×3 mm3, 60 directions of diffusion gradients. Measurements were carried out at b-factor 0 and 1000 s/mm2. Analysis was carried out in the ReadyView software.

RESULTS

Right- and left-sided ALPS indices were similar in the control group (p=0.917). Perifocal edema (regardless of histological type of tumor) in the ipsilateral hemisphere was accompanied by significantly lower ALPS index (p<0.005), while these values in contralateral (intact) hemisphere were similar in both groups (p=0.7).

CONCLUSION

We found significantly lower ALPS index in deep parts of the affected hemisphere in patients with perifocal edema. These data can indicate the role of glymphatic system dysfunction in pathogenesis of this pathology.

[Factors influencing peritumoral edema in meningiomas: CT- and MRI-based quantitative assessment]

Background. Meningiomas may be accompanied by peritumoral edema. Incidence and pathogenesis of edema are nor clearly established. Prevalence and severity of edema vary significantly in patients with meningiomas similar in various parameters.

OBJECTIVE

To assess peritumoral edema in intracranial meningiomas and factors influencing incidence and severity of this process.

MATERIAL AND METHODS

There were 126 patients (69% women) aged 19-76 years (median 53), who were diagnosed with 142 meningiomas. Patients underwent surgery (n=111) and radiotherapy (n=15) in 2016-2018. The MRI protocol included T1, T2, T2-FLAIR, DWI and post-contrast T1-weighted images in three projections, diffusion tensor MRI in 27 cases and MR spectroscopy in 21 patients.

RESULTS

Peritumoral edema was detected in 46% (n=66) of cases including 21 (31%) patients with severe edema. The ALPS index was 1.510±0.1931 in meningiomas without edema and 1.308±0.19 in those with edema (p=0.014). There was positive correlation between edema, dimensions and uneven contours of meningioma, as well as negative correlation with CSF cleft sign. Blood flow velocity was higher in atypical and anaplastic meningiomas with edema (p=0.03). Other signs (localization, histological variant, malignancy grade, characteristics of MR signal, peaks of the main metabolites, diffusion and perfusion parameters of tumor) did not significantly affect peritumoral edema in patients with meningiomas (p>0.05).

CONCLUSION

Diffusion tensor tomography with ALPS index revealed significant effect of glymphatic system dysfunction on peritumoral edema. Large meningioma with uneven contours increased the risk of peritumoral edema, while CSF cleft sign reduced this risk. Other factors did not affect cerebral edema in meningiomas.

[Comparison of resting state and task-based functional MRI in preoperative mapping in patients with brain gliomas]

OBJECTIVE

To analyze and compare the results of cerebral cortex mapping with task-based (tb-fMRI) and resting-state functional MRI in patients with glioma of eloquent cortical areas.

MATERIAL AND METHODS

There were 55 patients (24 men and 31 women aged 24 - 74 years, median 39) with glial tumors. In 26 patients, the tumor was located in motor areas. Twenty-nine patients had lesions of Broca and Wernicke's areas. All patients underwent preoperative tb-fMRI and rs-fMRI. Then, resection of tumor was carried out in all cases.

RESULTS

Comparison of fMRI and rs-fMRI activation maps was assessed by calculating the Dice coefficient for inclusive speech and motor cortex masks and exclusive masks without brainstem, cerebellum, subcortical nuclei. Inclusive Dice coefficient for motor cortex ranged from 0.11 to 0.50, for speech cortex - from 0.006 to 0.240 (p<0.05). In case of exclusive masks, this value ranged from 0.15 to 0.55 for motor cortex and from 0.004 to 0.205 for speech cortex (p<0.05).

CONCLUSION

When comparing the results of cortical mapping in patients with glial tumors, the use of hemispheric exclusive and inclusive masks did not significantly increase activation maps matching. Probably, low degree of correspondence was associated with different genesis of activations, as well as with high variability of speech cortex.

[Endoscopic transnasal approach in surgical treatment of petrous temporal bone cholesteatoma extending towards the clivus. Three clinical observations and literature review]

Petrous temporal bone Cholesteatoma is widely described in the literature and accounts for up to 9% of all neoplasms of this localization. These cholesteatomas rarely spread towards the clivus. Isolated clival cholesteatomas are described only as single cases. There is currently no consensus on the choice of surgical approach for resection of similar neoplasms.

OBJECTIVE

To demonstrate the possibilities of endoscopic transnasal approach in surgery for clival and petrous cholesteatoma.

MATERIAL AND METHODS

This article presents 3 clinical cases: 2 patients with apical cholesteatoma of petrous part of temporal bone extending to the clivus and 1 patient with massive petrous temporal bone cholesteatoma extending towards the clivus according to the classification of Sanna M. All patients underwent endoscopic transnasal surgery.

RESULTS AND CONCLUSION

In our opinion, endoscopic transnasal approach is optimal for resection of similar neoplasms. Total and subtotal resection was performed in 2 and 1 case, respectively. However, there are certain limitations of this approach in accessing the most lateral parts of the neoplasm. Nevertheless, endoscopic transnasal approach ensures resection of petrous temporal bone cholesteatoma extending to the clivus without the risk of damage to acoustic-facial cranial nerves. It is especially significant in patients without their baseline dysfunction.

[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.

[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.

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.

[Breast cancer metastasis into a giant hormone-inactive pituitary adenoma adenoma. (Clinical case and literature review)]

Brain metastases of various types of cancer are diagnosed in 8-10% of all cancer patients. In the world literature, only 30 cases of cancer metastasis to the pituitary adenoma are described. This article presents yet another observation of a patient with breast cancer metastasis into the hormone-inactive pituitary adenoma at the Burdenko neurosurgical center, Russia The patient underwent endoscopic endonasal transsphenoid removal of the neoplasm. During microscopy and immunohistochemical studies of the biopsy, two types of tissue (pituitary adenoma and cancer metastasis) with different Ki-67 treated surgically (1% and over 40%) were found.

[Transsphenoid extirpation of pituitary adenomas in patients with McCune-Albright syndrome (two cases from practice and literature review)]

INTRODUCTION

McCune-Albright Syndrome is a rare genetic disease characterized by the formation of fibrous osteodysplasia foci of various localization, including the bones of skull base. Having a gross lesion of the main bone body and the simultaneous formation of the pituitary adenoma, its transnasal removal becomes very difficult.

MATERIAL AND METHODS

Two clinical observations are presented where at patients with the classic manifestation of McCune-Albright syndrome we were able to successfully remove somatotropinomas with endoextrasellar growth. In both cases the presence of visual disorder was the indication for surgery.

RESULTS

Despite pronounced deviations in the anatomy of the skull base bones in both cases we managed to access the Turkish saddle. Removal of the pituitary tumor did not differ from standard surgery. Improved vision after surgery was observed in two patients. Tumors were removed subtotally and clinical and biochemical remission of acromegaly was not achieved. In both cases, the tumors had morphological signs of atypia. Patients continued to receive therapy with somatostatin analogues and radiation.

CONCLUSION

The possibility of performing transnasal surgery in this category of patients using specific instruments and intraoperative navigation is shown.

DIFFUSION-KURTOSIS IMAGING IN ASSESMENT OF BRAIN MICROSTRUCTURE. HEALTHY VOLUNTEERS MEASURMENTS

Aim:discover quantitative and qualitative variance of diffusion parameters in white and gray matter of healthyvolunteers brain. Discover correlation between diffusion and kurtosis parameters, find out if there is correlation between the parameters and aging microstructural changes.Materials and methods.14 healthy volunteers were investigated (9 men, 5 women; age from 21 to 55 years, mean 34). The volunteers were classified into two groups by age: 7 subjects who younger 35 (6 men and 1 woman, mean age 25) and 7 subjects who older 35 years (3 men and 4 women, mean age 44). We used 3.0 Tesla MRI (3.0T SignaHDxt, General Electric, USA) with 8 channel head coil, gradient strength 50 mT/m, slew rate 150 T/m/s. Diffusion imaging was based on echo planar “spin echo” sequence (SE EPI), TR = 10000 ms, TEmin = 102 ms, FOV = 240 mm, voxel size 3 × 3 × 3 mm3, 60 non-coplanar diffusion directions and three b-values: 0, 1000, 2500 s/mm2. Acquisition time of diffusion kurtosis imaging was 22 minutes. We excluded extracerebral areas on diffusion and kurtosis parametric maps using semi-automatic approach. After that, brain images were transformed to MNI152 space using affine method. Masks of 9 anatomical structures were applied to the transformed images. Diffusion and kurtosis values were measured in these structures.Results.Fractional anisotropy (FA) changed from 0.06 in lateral occipital cortex to 0.25 in cerebral white matter, kurtosis anisotropy (KA) changed from 0.03 to 0.14 in the same cerebral structures. Axial (AK), radial (RK) and mean kurtosis (MK) were minimal in superior frontal gyrus and maximal in cerebral white matter. AK changed from 0.55 to 0.72, RK changed from 0.62 to 1.05, MK from 0.59 to 0.88. Axial(AxEAD) and radial extra axonal water diffusion (RadEAD) were minimal in putamen and maximal in superior frontal gyrus. AxEAD was changing from 1.38 • 10–3 to 2.57 • 10–3, RadEAD from 1.03 • 10–3 to 2.34 • 10–3. Axonal water fraction (AWF) had minimal value 0,18 in superior frontal gyrus and maximal value 0.29 in cerebral white matter. Tortuosity (TORT) changed from 1.06 in lateral occipital cortex to 1.43 in cerebral white matter. There was significant difference between age groups in AWF, RK, RadEAD in putamen and in KA in superior temporal gyrus. Maximal correlation with age was in MK in superior temporal gyrus, anterior division. It was equal to 0.562.Conclusions:Diffusion kurtosis imaging is highly sensitive method of brain tissue microstructure assessment, which detects age-related changes.

[Correlation of intracranial pressure and diameter of the sheath of the optic nerve by computed tomography in severe traumatic brain injury]

BACKGROUND

Noninvasive techniques to evaluate intracranial pressure (ICP) are important for everyday practice in intensive care and neurosurgery departments. CT data can be used to evaluate the optic nerve sheath diameter (ONSD) and, indirectly, the ICP value. The ONSD value is an additional criterion in deciding on invasive monitoring of ICP.

AIM

To analyze a correlation between CT-based ONSD and the results of invasive measurements of ICP in patients with severe traumatic brain injury.

MATERIAL AND METHODS

The study evaluated 41 patients with severe traumatic brain injury within the first 48 h after injury. Invasive monitoring of ICP (Codman & Shurtlett, MA, USA) was performed during 7±1.7 days. ONSD was measured using axial CT scans (CereTom, Neurologica Danvers, MA, USA) with a slice thickness of 2.5 mm. The ONSD value was measured at a distance of 3 mm from the posterior eyeball contour. The patients were allocated in a group with normal ICP (10 patients) and a group with high ICP (31 patients). ONSD served as an ICP classifier. The data were processed using ROC analysis.

RESULTS

According to the CT data, the optimal threshold ONSD value was 6.35 mm in patients in the acute TBI period. The sensitivity was 0.93 (95% СI 0.84-1.00), the specificity was 0.80 (95% СI 0.50-1.00), and AUC was 0.87 (95% СI 0.69-1.00).

CONCLUSION

We found a correlation between the CT-based ONSD and the median ICP (R=0.32, p<0.05). An ONSD value of 6.35 mm and more is one of the signs of previous or existing ICP.

Diffusion Kurtosis Imaging in the Assessment of Peritumoral Brain Edema in Glioblastomas and Brain Metastases

Aim: to explore the opportunities of application of diffusionkurtosis imaging (DKI) for assessment and estimation of diffusion scalar metrics in different locations of peritumoral edema for extra- and intracerebral tumors and in contralateral normal tissue.

Materials and methods. 38 patients with supratentorial brain tumors were investigated: 24 (63%) patients with primarily revealed glioblastomas (GB) and 14 (37%) patients with solitary cancer brain metastasis (MTS). MRI was performed on 3.0 T MR-scanner (Signa HDxt, General Electric, USA) with the standard protocols for brain tumor and additional protocol for DKI. The standard protocol for brain tumor included: T1-, T2-weighted images, T2-FLAIR, DWI,  T1 with contrast enhancement. Diffusion kurtosis MRI based on SE  EPI with TR = 10000 ms, TE = 102 ms, FOV = 240 mm, isotropic voxel size 3 × 3 × 3 mm3, 60 noncoplanar diffusion directions. We  used three b-values: 0, 1000 and 2500 s/mm2. Аcquisition time was 22 min. Total acquisition time was near 40 min. This study was approved by Ethical committee of Burdenko National Scientific  and Practical Center for Neurosurgery. Parametric maps were  constructed for the following diffusion coefficients: mean (MK),  transverse / radial (RK), longitudinal / axial (AK) kurtozis; medium  (MD), transverse / radial (RD) and longitudinal / axial (AD) diffusion; fractional anisotropy (FA) and a bi-exponential diffusion model  coefficients: axonal water fractions (AWF), axial (AxEAD) and radial  (RadEAD) extra-axonal water diffusion and the water molecules  trajectory tortuosity index (TORT). Normative quantitative indicators  were obtained for the six regions of the peritumoral zone as they  moved away from the tumor (region 2) to the edema periphery  (regions 4–5), as well as in the normal brain on the contralateral  hemisphere (C/L) (zone 7). A comparative analysis of these  indicators was conducted for cases with GB and MTS. DKI scalar metrics were estimated using Explore DTI (http://www.exploredti.com/).

Results. Anatomic MRI (T1 without/with contrast enhancement) for  all cases with GB and MTS visualized a contrast enhancement tumor.  The peritumoral edema, spreading mainly over the brain white  matter, was well visualized on T2-FLAIR. Diffusion kurtosis  coefficients decreased in the near peritumoral edema (regions 2–3)  and a gradually increased to the edema periphery (regions 5–6). In Region 2, MK in both GB and MTS groups were MKGB(2) = 0.637 ±  0.140 and MKMTS(2) = 0.550 ± 0.046; RK in this region were  RKGB(2) = 0.690 ± 0.154 and RKMTS (2) = 0.584 ± 0.051.  Differences both MK and RK coefficients in patients with GB and MTS of region 2 were significant (p < 0.001). There were no differences in AK values for GB and MTS in region 2 (p > 0.05), but in regions 3  and 4 differences were observed (p < 0.01). The minimum value of  AK in the central edema (regions 3–4) was AKMTS(3–4) = 0.433 ± 0.063 in patients with MTS. The values of MK and RK on the  contralateral side in patients with MTS were significantly higher than  in the GB group (p < 0.02); MKC/LMTC = 0.954 ± 0.140, RKC/LMTC  = 1.257 ± 0.308 and MKC/LGB = 0.829 ± 0.146, RKc/LGB = 0.989  ± 0.282. There was no significant difference for contralateral AK between the groups.

Conclusions. We found that DKI scalar metrics are the sensitive  tumor biomarkers. It allows us to perform a robust differentiation  between the infiltrating GB tumor and purely vasogenic edema of  МТS. The obtained results will allow further differential diagnosis of  extra- and intracerebral tumors and can be used to plan surgical /  radiosurgical treatment for brain tumors.

[The algorithm for surgical treatment of skull base tumors invading the craniovertebral junction]

Surgical treatment of skull base tumors invading the craniovertebral junction is a complex medical problem due to a high rate of adverse postoperative outcomes in these patients.

AIM

The study aim was to optimize surgical treatment in patients with skull base tumors invading the craniovertebral junction.

MATERIAL AND METHODS

A comparative analysis of 2 groups of patients was performed. The study group included 28 patients with skull base and craniovertebral junction chordomas who underwent single-stage surgery, including posterior occipitospondylodesis and tumour resection using the transoral and combined transoral and transnasal approaches, in the period between 2000 and 2015. The control group included 21 patients with the same pathology who underwent microsurgery using the transoral approach without occipitospondylodesis in the period between 1990 and 2009.

RESULTS

Most of the patients in both groups were operated on at late disease stages when they presented with gross clinical signs. The use of single-stage occipitospondylodesis and transoral skull base tumor removal significantly (compared to the control group) extends indications for surgical treatment of skull base tumors, which were previously considered unresectable, and provides better results.

CONCLUSION

New surgical techniques significantly increase the completeness of tumor resection, decrease the rate of postoperative complications, accelerate the rehabilitation process, and improve the patient's quality of life.

[SCT perfusion in the diagnosis of sellar and parasellar tumors]

The study is devoted to the use of a minimally invasive method of SCT perfusion for the differential diagnosis of sellar and pаrаsellar tumors. Given a wide differential diagnostic range of tumors occurring in this area, the tumor perfusion indicators were used as an auxiliary diagnostic criterion.

MATERIAL AND METHODS

The study analyzed outcomes in 115 patients with various tumors of the sellar area who underwent surgery or biopsy for histological verification of the diagnosis.

RESULTS

The statistically significant differences were obtained for certain groups of tumors based on the values of hemodynamic parameters (p<0.05) that enable, with a high confidence, making a conclusion on the histologic type of most tumors.

CONCLUSION

These findings demonstrated that SCT perfusion is a highly informative method of the preoperative differential diagnosis of these tumors. The sensitivity and specificity of SCT perfusion in the study were 100% and 81.2%, respectively.

3D-TOF MR-angiography with high spatial resolution for surgical planning in insular lobe gliomas

Despite the obvious progress in modern neurosurgery, surgery for glial tumors of the insular lobe is often associated with a high risk of postoperative neurological deficit, which is primarily caused by damage to perforating arteries of the M1 segment of the middle cerebral artery.

OBJECTIVE

The work is aimed at evaluating the effectiveness of high resolution time-of-flight (3D-TOF) MR angiography in imaging of medial and lateral lenticulostriate arteries and determining their relationship to tumor edge in patients with gliomas of the insula.

MATERIAL AND METHODS

3D-TOF MR angiography data were analyzed in 20 patients with primarily diagnosed cerebral gliomas involving the insula. All patients underwent non-contrast enhanced 3D-TOF MR angiography. In 6 cases, 3D-TOF MRA was performed before and after contrast enhancement.

RESULTS

3D-TOF angiography before intravenous contrast injection was capable of visualizing the medial lenticulostriate arteries in 19 patients (95% of all cases) and lateral lenticulostriate arteries in 18 patients (90% of all cases). Contrast-enhanced 3D-TOF angiography allows for better visualization of both the proximal and distal segments of lenticulostriate arteries. Three variants of relationship between the tumor and lenticulostriate arteries were identified. Variant I: the tumor grew over the arteries without their displacement in 2 cases (10% of the total number of observations); variant II: the tumor caused medial displacement of arteries without growing over them in 11 cases (55% of the total number of observations); variant III: the tumor partially grew over and displaced arteries in 2 cases (10%). In 25% of cases (5 patients), tumor was poorly visualized on 3D-TOF MR angiograms because their signal characteristics did not differ from those of the medulla (tumor tissue was T1 isointense). As a result, it was impossible to determine the relationship between the tumor and lenticulostriate arteries.

CONCLUSION

High spatial resolution time-of-flight MR angiography can be recommended for preoperative imaging of lenticulostriate arteries to plan the extent of neurosurgical resection in patients with glial tumors of the insular lobe.

Experience of surgical management of trigeminal schwannomas that simultaneously spread to the middle and posterior cranial fossae

INTRODUCTION

trigeminal schwannomas account for 0.07-0.36% of all intracranial tumors and 0.8-8% of all intracranial schwannomas. Different surgical approaches are used depending on the topographic anatomical variant of the tumor. Dumbbell-shaped tumors that spread both to the middle and posterior cranial fossae are the most challenging ones in terms of their resection.

MATERIAL AND METHODS

Five patients with dumbbell-shaped trigeminal schwannomas were operated on at the Burdenko Neurosurgical Institute in 2011-2013. In four cases, tumor resection comprised two stages using the retrosigmoid suboccipital approach (RSA) and lateral extended transsphenoidal endoscopic approach (LETEA); in one case, the tumor was resected in a single session through the LETEA. If there were pronounced symptoms affecting the brainstem and/or cerebellum, tumor resection from the posterior cranial fossa through RSA was resected at the first stage (3 cases). If no symptoms were observed, tumor resection from the middle cranial fossa through LETEA was used as the first stage (2 cases).

RESULTS

After two surgical stages, total, subtotal, and partial tumor resection was performed (one case each). Total tumor resection from the middle cranial fossa was achieved through LETEA in two cases. Aggravation of ipsilateral paresis of the craniocerebral nerve VI was observed after the surgery in two cases. No cases of nasal liquorrhea were observed after transnasal surgery. In one case, the cavernous segment of the internal carotid artery was damaged during LETEA, thus requiring endovascular occlusion of the damaged vessel to be performed.

CONCLUSION

LETEA is an effective approach that allows resection of tumors from the middle cranial fossa and the cavernous sinus. Combined with RSA, this approach can be used for two-stage resection of dumbbell-shaped trigeminal schwannomas.

Assessment of optic nerve decompression efficiency in resection of sellar region meningiomas via intradural subfrontal approach

In this article we analyze results of the different variants of the optic nerve transcranial decompression in cases with different chiasmal region tumors. We operate 70 patient with different type meningioma (tuberculum sella, shenoid wings, anterior clinoid, optic canal), pituitary adenoma and one case with tuberculoma (we operate it thinking on meningioma, but histology was unexpected). Groups of the patients. Group1. 20 patients with pituitary adenoma with cavernous sinus invasion. It was our "pre-endoscopic" period when we frequently operated adenomas by transcranial approach. In this 20 patients we used intra-extradural Dolenc approach to cavernous sinus. In that cases we removed anterior clinoid process and decompressed optic canal. Here we use the results of surgery in this group for showing the possibility of using high speed drill for the optic canal decompression - for showing it safety. On our opinion this type of optic canal decompression is radical and safe but superfluous for the optic canal invasion by the meningioma. Group 2. 19 patients with meningioma. In that cases we partially unroofed optic canal by Kerrison and additionally we cut the falciform ligament. Group 3. 31 patients with meningioma. It's our "main" group. Here we made intradural wide unroofing the optic canal by high speed drill. Additionaly we cut the falciform ligament and open the dural sheet of the optic nerve. We propose this methodic like sufficient, safe and useful. In this cases we frequently saw the tumor spread inside the dural sheet of the optic nerve, without seeing it on the MRI. A lot of cases in this group was a recurrent after previous meningioma removal. Like a control groups we use two. Group 4. 11 cases with meningioma. In that cases we removed tumor from optic canal without any decompression. It was our archive group - we made this type of surgery before starting optic canal decompression. This group shows the risks of any manipulation with fixed optic nerves without optic canal decompression. Group 5. 31 case with meningioma. In this cases we saw the optic canal invasion by the tumor but we didn't try to decompress it. It was our archive group - we made this type of surgery before starting optic canal decompression. We use this group for found out the risks of canal decompression. This group shows the poor perspectives for the vision in optic canal invasion by the tumor without it decompression. We analyze the results of surgery on the day of discharge and on catamnesis - we decide that the optic nerves need time to recovery. We analyzed the results of surgery in patients with 3 types of the visual dysfunction: moderate (1.0-0.5), hard (0.5-0.1), decompensating (0.1-0). For showing the real risks and effectivety of any type of decompression and surgery without decompression we look for results in patients with decompensating of visual functions. For statistical analyses we use Fisher criteria which used in small series. We statistically showed that any attempts of tumor removal form the optic canal is more risky than decompression. Also we found a tendency that wide intradural decompresstion made by high speed drill with additional falciform ligament cutting and the dural sheet opening is more effective and safe than opening the optic canal by Kerrisson. This technique also could be used during the transcranial surgery for the other type of pathology particularly in cases with short optic nerves and prefixed chiasm - it gives the mobility for the nervesand decreased the nerve damaging.

[The use of three-dimensional reconstruction in neuroroentgenology]

The recent advent of spiral computed tomography (CT) and new fast impulse sequences in magnetic resonance imaging (MRI) into diagnostic practice has expanded the range of brain and spinal diseases detected by these techniques. This has also expanded the field of use of three-dimensional images obtained on the basis of mathematical algorithms for processing CT and MRI data. At present, not only neurotraumatology and maxillofacial surgery are the main areas in applying three-dimensional models. Spatial representation of bulky formations of the brain, their mutual location with the adjacent anatomic structures (with ventricles of the brain) may be useful in choosing a surgical access and in planning the scope of a surgical intervention. CT- and MR-angiographies that are now successfully used in diagnosing vascular pathology, providing high-solution angiograms not only can be competitive with direct angiography, but can replace this sophisticated study for vascular stenotic processes in the neck. Moreover, analyzing the internal surface of the vascular wall on the basis of virtual endoscopy may be useful in direct surgical and endovascular interventions. The purpose of this study was to pool long-term experience in using three-dimensional images in the qualitative improvement of diagnostic methods in examining neurosurgical patients and to define the most promising lines of their use in neurosurgery as a whole.

[The contrast enhancement of brain and spinal cord tumors using Gd-DTPA in magnetic resonance tomography with an extra-low magnetic-field intensity]

The contrasting agent Gd-DTPA (Magnevist, Schering AG, Germany) was tested when used in magnetic resonance tomography using extra-low (0.04 T) magnetic field intensity in 68 patients with various brain and spine tumors. The agent was injected intravenously in a dose of 0.1 mmol/kg. No complications were found. The tests showed its high efficiency in the diagnosis of brain neoplasms (particularly in malignant intracerebral disorders, meningiomas and neurinomas). Benign astrocytomas induced no noticeable signal intensification on post-contrasting T1-weighed tomograms. In all cases of spinal tumors, the application of Gd-DTPA could specify the extent of tumor invasions, the presence of cysts and identify accessory tumor nodes in one case.

[The dynamics of brain edema in severe craniocerebral trauma (computed tomographic and magnetic resonance studies)]

The dynamics of vasogenic brain edema were studied with comparison of the results of CT and MRT in 17 patients with severe craniocerebral trauma (CCT). It was established that edema fluid clearance in vasogenic edema in the early stages of CCT occurs through various parts of the ventricular system, which is confirmed by the hypodensity "path" on the CT and the "path" of increased activity on the MRT. The authors revealed a phenomenon of "interruption" (cessation) of the sanogenous "path" connecting the foci of contusions and/or intracerebral hematoma with the ventricular system. The formation of a more or less marked mass-effect is evidently needed for the occurrence of pressure gradient which would be sufficient enough to move the edema fluid and disintegration products from the traumatic substrate into the ventricular system.

[Magnetic resonance tomography of malignant tumors of the maxilla]

The authors discussed their experience in investigating 20 patients with maxillary malignant tumors using routine x-ray studies and MR-tomography, and 13 patients, investigated in the same way plus CT. MRT permitted defining a topical localization of a tumor and its spreading to adjacent anatomical regions (the pterygopalatine and infratemporal fossae, pharynx and peripharyngeal space, orbit, buccal soft tissues, and the cranial cavity). MRT was used to differentiate between tumor tissue and inflammation even within the sinus. As to the detection of osseous destruction, CT seemed much more superior than MRT. It was only in one patient that x-ray findings brought about better results than MRT because of artefacts resulting from metal crowns on the affected side.

[Magnetic resonance tomography in the diagnosis of paranasal sinusitis]

The potentialities of a new method--magnetic resonance tomography (MRT)--as applied to the diagnosis of paranasal sinusitis are discussed. The method permits detection of inflammation in the paranasal sinuses identified as a significant enhancement of a signal in the projection of the affected sinus. This paper presents two cases: patients with rhinosinusogenic cerebral arachnoiditis and arachnoencephalitis in whom paranasal pathologies which had no clinical manifestations were diagnosed by MRT. This helped to choose adequate therapy. In contrast to X-ray methods, MRT causes no unnecessary irradiation which allows repeated examinations.

[NMR tomography in the diagnosis of neoformations of the nasal cavity and paranasal sinuses]

Magnetic and resonance characteristics have been obtained for nasal and paranasal tumors in two groups of patients. Advantages and disadvantages of the NMR--tomography versus computed x-ray tomography are outlined.

[Magnetic resonance tomography in the diagnosis of juvenile nasopharyngeal angiofibromas]

This work is based upon the experience in the diagnosis of juvenile nasopharyngeal angiofibromas (JAF) in 14 patients using MR-tomography and routine x-ray examination. In all the patients MR-tomography made it possible to assess the topical position of a tumor, its spreading to the cranial, nasal, accessory sinusal and orbital cavities, and the pterygopalatine and infratemporal spaces. MR-tomographic diagnosis made it possible to differentiate between tumor invasion and inflammatory processes detecting JAF attending tubotitides. However MR-tomography cannot be used alone to assess the status of osseous tissue.

[Magnetic resonance tomography in the diagnosis of chronic intracranial hematomas]

The authors set forth a method of magnetic resonance tomography with superlow field intensity which is used for identifying chronic intracranial hematomas. They describe the magnetic resonance tomographic syndromes of chronic subdural and epidural hematomas and the possibility of their differentiation from hygromas of the meninges.