Glioma is the most common brain tumor originating from various glial cells. Clinical manifestations of glioma depend on its location and may include headache, nausea, vestibular ataxia, visual impairment, paresis and paralysis, dysarthria, sensitivity disorders, convulsive seizures, etc. Brain glioma is diagnosed based on the results of MRI of the brain and morphological examination of tumor tissues. Of auxiliary importance is the conduct of echo-EG, EEG, angiography of cerebral vessels, EEG, ophthalmoscopy, examination of cerebrospinal fluid, PET and scintigraphy. Conventional methods of treatment for brain glioma are surgical removal, radiation therapy, stereotactic radiosurgery and chemotherapy.
C71 Malignant neoplasm of the brain
Glioma occurs in 60% of cases of brain tumors. The name “glioma” is due to the fact that the tumor develops from the glial tissue surrounding the neurons of the brain and ensuring their normal functioning. Disease is basically a primary intracerebral tumor of the hemispheres of the brain. It has the appearance of a pinkish, grayish-white, less often a dark red node with indistinct outlines. Pathology can be localized in the wall of the ventricle of the brain or in the area of the chiasm (glioma of the chiasm). In rarer cases, glioma is located in nerve trunks (for example, optic nerve glioma). The germination of glioma into the meninges or bones of the skull is observed only in exceptional cases.
Disease often has a rounded or fusiform shape, its size ranges from 2-3 mm in diameter to the size of a large apple. In the vast majority of cases, glioma is characterized by slow growth and the absence of metastasis. However, at the same time, it is characterized by such pronounced infiltrative growth that the border of the tumor and healthy tissues cannot always be found even with the help of a microscope. As a rule, glioma is accompanied by degeneration of the surrounding nerve tissues, which often leads to a discrepancy in the severity of neurological deficit to the size of the tumor.
There are 3 main types of glial cells: astrocytes, oligodendrogliocytes and ependymocytes. In accordance with the type of cells from which the glioma originates, in neurology there are: astrocytoma, oligodendroglioma and ependyma. Astrocytoma accounts for about half of all brain gliomas. Oligodendrogliomas account for about 8-10% of gliomas, ependymomas of the brain — 5-8%. There are also mixed gliomas of the brain (for example, oligoastrocytomas), vascular plexus tumors and neuroepithelial tumors with unclear origin (astroblastomas).
According to the WHO classification, there are 4 degrees of malignancy of gliomas.
- I includes a benign slow-growing glioma (juvenile astrocytoma, pleomorphic xanthoastrocytoma, giant cell astrocytoma).
- II is considered “borderline”. It is characterized by slow growth and has only 1 sign of malignancy, mainly cellular atypia. However, such a glioma can transform into a grade III and IV glioma of malignancy.
- III has 2 of three signs: mitosis figures, nuclear atypia or endothelial microproliferation.
- IV is characterized by the presence of a necrosis area (glioblastoma multiforme).
By location, gliomas are classified into supratentorial and subtentorial, i.e. located above and below the cerebellar namet.
Like other volumetric formations, glioma can have a variety of clinical manifestations, depending on its location. Most often, patients have general cerebral symptoms: headaches that cannot be stopped by conventional means, accompanied by a feeling of heaviness in the eyeballs, nausea and vomiting, sometimes convulsive seizures. These manifestations are most pronounced if the glioma grows into the ventricles and liquor pathways. At the same time, it disrupts the circulation of cerebrospinal fluid and its outflow, leading to the development of hydrocephalus with increased intracranial pressure.
Among the focal symptoms of brain glioma, visual disturbances, vestibular ataxia (systemic dizziness, unsteadiness when walking), speech disorder, decreased muscle strength with the development of paresis and paralysis, decreased deep and superficial types of sensitivity, mental abnormalities (behavioral disorders, thinking disorders and various types of memory) can be observed.
The diagnostic process begins with interviewing the patient about his complaints and the sequence of their occurrence. Neurological examination for glioma allows you to identify existing sensitivity disorders and coordination disorders, assess muscle strength and tone, check the state of reflexes, etc. Special attention is paid to the analysis of the state of the patient’s mnestic and mental sphere.
Such instrumental research methods as electroneurography and electromyography help the neurologist to assess the state of the neuromuscular apparatus. Echoencephalography can be used to detect hydrocephalus and displacement of the mid-brain structures. If glioma is accompanied by visual disturbances, then an ophthalmologist’s consultation and a comprehensive ophthalmological examination, including visiometry, perimetry, ophthalmoscopy and a convergence study, are indicated. In the presence of convulsive syndrome, an EEG is performed.
Brain glioma needs to be differentiated from intracerebral hematoma, brain abscess, epilepsy, other CNS tumors (hemangioblastoma, medulloblastoma, germinoma, glomus tumor, ganglioneuroma, etc.), the consequences of an ischemic stroke.
The most acceptable way to diagnose brain glioma today is an MRI of the brain. If it is impossible to carry out it, MSCT or CT of the brain, contrast angiography of cerebral vessels, scintigraphy can be used. PET of the brain provides information about metabolic processes, which can be used to judge the growth rate and aggressiveness of the tumor. In addition, a lumbar puncture may be performed for diagnostic purposes. In glioma, the analysis of the obtained cerebrospinal fluid reveals the presence of atypical (tumor) cells.
The above-mentioned non-invasive methods of investigation allow to diagnose a tumor, however, an accurate diagnosis of brain glioma with determination of its type and degree of malignancy can be made only by the results of microscopic examination of the tissues of the tumor node obtained during surgery or stereotactic biopsy.
Complete removal of glioma is an almost impossible task for a neurosurgeon and is possible only if it is benign (grade I malignancy according to the WHO classification). This is due to the property of the brain glioma to significantly infiltrate and germinate the surrounding tissues. The development and application of new technologies during neurosurgical operations (microsurgery, intraoperative brain mapping, MRI scanning) has slightly improved the situation. However, until now, surgical treatment of glioma in most cases is essentially a tumor resection operation.
Contraindications to the implementation of the surgical method of treatment are the unstable state of the patient’s health, the presence of other malignant neoplasms, the spread of brain glioma in both hemispheres or its inoperable localization.
Brain glioma refers to radio- and chemosensitive tumors. Therefore, chemo- and radiotherapy are actively used both in the case of inoperable glioma, and as pre- and postoperative therapy. Preoperative radiation and chemotherapy can be performed only after the diagnosis is confirmed by the results of a biopsy. Along with traditional methods of radiotherapy, it is possible to use stereotactic radiosurgery, which allows to influence the tumor with minimal irradiation of surrounding tissues. It should be noted that radiation and chemotherapy cannot serve as a substitute for surgical treatment, since in the central part of the brain glioma there is often a site that is poorly susceptible to radiation and chemotherapy drugs.
Gliomas have a predominantly unfavorable prognosis. Incomplete removal of the tumor leads to its rapid recurrence and only prolongs the patient’s life. If the glioma has a high degree of malignancy, then in half of the cases patients die within 1 year and only a quarter of them live longer than 2 years. A more favorable prognosis has a grade I brain glioma of malignancy. In cases where it is possible to perform its complete removal with minimal postoperative neurological deficit, more than 80% of those operated on live longer than 5 years.