Edema in case of brain cancer
- displacement, compression, change in the magnitude of the ventricles;
- blockade of cerebrospinal fluidways with development of occlusive hydrocephalus;
- narrowing, displacement, deformation of basal cisterns of the brain;
- edema of the brain, both near the tumor, and along the periphery.
- axial dislocation (estimated by deformation of the enclosing tank).
Density of the tumor can be increased bycompared with the density of the surrounding brain tissue as a result of hemorrhages or deposition of calcium salts in the tumor tissue. These changes are characteristic, first of all, for tumors of the meningo-vascular series. The decrease in density is observed because of the large amount of water or fat-like substances in the tumor. Heterogeneity of the structure of the tumor is characterized by alternating areas of density increase (hemorrhages and calcifications) against the background of low density of the tumor itself. Tumor density may not differ from the surrounding brain tissue.
Edema, an exciting white substance of the brain,characterized by a zone of reduced density around the tumor and manifests itself in different ways depending on the location of the tumor. In the temporal lobe the edema has a typical form of a shamrock, which is due to its spreading to the inner and outer capsule of the substance of the islet. Edema in the frontal lobe with spread to the inner capsule resembles a funnel in shape.
There are several forms of edema:
- local - occupies the white matter of the brain around the tumor at a distance of no more than 15 mm;
- generalized - captures no more than 2/3 of the hemisphere on the brain cut;
- total - with a uniform or heterogeneous decrease in density;
- periventricular - characterized bya decrease in density around the enlarged ventricles (or ventricle) of the brain, which is one of the important signs of the progressive course of hydrocephalus (VN Kornienko, 1993).
The perifocal zone is a productthe vital activity of tumor cells and at the same time serves as a kind of buffer that protects healthy brain tissue from direct contact with the focus of malignant growth, and plays the role of a kind of transformer that closes the anaplastic activity of tumor structures.
The morphologically perifocal zone, starting from the outbreak, includes:
Infiltration of tumor cells through the border of the focus;
· Proper perifocal edema;
Demyelinated white matter.
The main component of the perifocal zone, inwhich determines the clinical symptomatology, its dynamics and prognosis, is perifocal edema, which is based on the interaction of vascular and parenchymatous factors.
It is customary to distinguish between vasogenic and cytotoxictypes of cerebral edema that can be combined and change the quantitative relationships in the dynamics of development, depending on the cause that caused them. Perifocal edema in brain tumors is formed by increasing the volume of extracellular space as a result of the accumulation of fluid from damaged glial cells in it, and as a result of an increase in the permeability of the cell membrane of the capillary endothelium in the zone surrounding the lesion. Therefore, initially local and perifocal edema is intracellular. The prevalence of the perifocal edema zone is determined not only by the increase in the water content in it, but also by the degree of regional demyelination of the fibers of the white matter of the brain.
Vasogenous edema is more frequent and occursmost pronounced with rapidly growing, aggressive tumors, usually malignant (glioblastoma), while purely cytotoxic edema is more often traumatic or stroke origin and is associated with effusion into the gray matter of the brain.
As the volume of the tumor increasesprotein composition, both in the lesion focus and in the perifocal zone. These changes correlate with the degree of malignancy of the tumor. At the same time, regional impairments of the blood-brain barrier penetration develop, which increase cytotoxic edema.
An obligatory component of the tumor is the presenceiso-or hyper-solid solid node. With astrocytomas of the I-P degree of malignancy, it is almost always possible to clearly delineate the tumor node from the perifocal zone, which in this case is represented only by cytotoxic edema in the form of a narrow band of reduced density (25-23 NU) associated with effusion in the gray matter of the brain. With an increase in the degree of malignancy, the clearness of the visualization of the tumor node itself decreases, which is associated with pronounced diffuse infiltration of tumor cells. This increases the size of the perifocal zone, which is characterized by two types of edema: cytotoxic (density 24-22 NU), adjacent directly to the tumor node, and vasogenic (20-17 NU density) located distal. Between them there are no clear boundaries, they smoothly pass into each other. With an increase in the degree of malignancy, cytotoxic edema decreases and the volume of vasogenic edema increases, which captures the corresponding sections of the white matter. Vasogenic edema does not extend to the gray matter of the cortex and subcortical ganglia, but compresses and deforms them.
The image of edema on CT, as a rule, onstructure is homogeneous, but there is a complex set of factors, as a result of which the nutrition of brain tissue is disrupted, and axons are damaged. In this regard, CT can visualize the demyelinated sites, which causes the heterogeneity of the perifocal zone. This process is most typical for tumors of III-IV degree of malignancy.
The outer contours of the perifocal zone characterizevasogenic edema. Depending on the location of the tumor, the shape of the zone will be different. If the edema spreads to the convolutions of the hemisphere, then its zone acquires a fingerlike shape. With glioblastomas of the temporal lobe (due to the spread of the edema to the inner capsule and islet), it has the characteristic form of an irregular trefoil. For glial frontal lobe is characterized by a funnel-shaped form of edema, with the localization of the tumor in the parietal lobe - wedge-shaped. In gliomas of fronto-cullaceous localization, the edema extends to the contralateral hemisphere. Glial tumors, usually astrocytomas of the I-II degree of anaplasia, located in the region of middle structures, are accompanied by less pronounced edema than similar tumors localized in the white matter of the cerebral hemispheres.