Astrocytoma is a primary intracerebral neuroepithelial (glial) tumor originating from stellate cells (astrocytes). Disease can have different degrees of malignancy. Its manifestations depend on the localization and are divided into general (weakness, loss of appetite, headaches) and focal (hemiparesis, hemihypesthesia, coordination disorders, hallucinations, speech disorders, behavior changes). Astrocytoma is diagnosed on the basis of clinical data, CT, MRI and histological examination of tumor tissues. Treatment of astrocytoma is usually a combination of several methods: surgical or radiosurgical, radiation and chemotherapeutic.
ICD 10
C71 Malignant neoplasm of the brain
General information
Astrocytoma is the most common type of glial tumors. Approximately half of all brain gliomas are represented by astrocytomas. Astrocytoma can occur at any age. Most often, astrocytoma is observed in men aged 20 to 50 years. In adults, the most characteristic localization of brain astrocytoma is the white matter of the hemispheres (brain hemisphere tumor), in children, damage to the cerebellum and brain stem is more common. Occasionally, children have optic nerve damage (chiasmal glioma and optic nerve glioma).
Etiology
Astrocytoma is the result of tumor degeneration of astrocytes – glial cells having the shape of a star, for which they are also called stellate cells. Until recently, it was believed that astrocytes perform an auxiliary supporting function in relation to the neurons of the central nervous system. However, recent research in the field of neurophysiology and neurology has shown that astrocytes perform a protective function, preventing injury to neurons and absorbing excess chemicals formed as a result of their vital activity. They provide neuronal nutrition, participate in the regulation of the functions of the blood-brain barrier and the state of cerebral blood flow.
Exact data on the factors provoking tumor transformation of astrocytes are not yet available. Presumably, the role of the trigger mechanism, as a result of which an astrocytoma develops, is played by: excessive radiation, chronic exposure to harmful chemicals, oncogenic viruses. A significant role is also assigned to the hereditary factor, since genetic breakdowns in the TR53 gene were found in patients with astrocytoma.
Classification
Depending on the structure of its constituent cells, an astrocytoma can be “ordinary” or “special”. The first group includes fibrillar, protoplasmic and hemistocytic astrocytoma. The “special” group includes pyelocytic (pilloid), subependimal (glomerular) and microcystic cerebellar astrocytoma.
According to the WHO classification, astrocytomas are divided according to the degree of malignancy. A “special” astrocytoma — pyelocytic belongs to the I degree of malignancy. Grade II malignancy is characteristic of “ordinary” benign astrocytomas, for example, fibrillar. Grade III malignancy includes anaplastic astrocytoma, grade IV — glioblastoma. Glioblastoma and anaplastic astrocytoma account for about 60% of brain tumors, while highly differentiated (benign) astrocytomas account for only 10%.
Symptoms
The clinical manifestations that accompany astrocytoma can be divided into general, observed at any location of the tumor, and local or focal, depending on the localization of the process.
Common symptoms are associated with an increase in intracranial pressure caused by it, irritative (irritating) effects and toxic effects of metabolic products of tumor cells. Common manifestations of astrocytoma include: constant headache, lack of appetite, nausea, vomiting, double vision and / or the appearance of fog in front of the eyes, dizziness, mood changes, asthenia, decreased ability to concentrate and memory impairment. Epileptic seizures are possible. Often, the first manifestations of astrocytoma are of a general nonspecific nature. Over time, depending on the degree of malignancy of the astrocytoma, there is a slow or rapid progression of symptoms with the appearance of a neurological deficit, indicating the focal nature of the pathological process.
Focal symptoms occur as a result of the destruction and compression of the cerebral structures located next to it by the tumor. Hemispheric astrocytomas of the brain are characterized by decreased sensitivity (hemihypesthesia) and muscle weakness (hemiparesis) in the arm and leg of the opposite side of the body to the affected hemisphere. Tumor lesion of the cerebellum is characterized by a violation of stability in the standing and walking position, problems with coordination of movements.
The location in the frontal lobe is characterized by inertia, pronounced general weakness, apathy, decreased motivation, bouts of mental excitement and aggressiveness, deterioration of memory and intellectual abilities. People surrounding such patients note changes and oddities in their behavior. When an astrocytoma is localized in the temporal lobe, speech disorders, memory disorders and hallucinations of various types occur: olfactory, auditory and gustatory. Visual hallucinations are characteristic of an astrocytoma located on the border of the temporal lobe with the occipital lobe. If the astrocytoma is localized in the occipital lobe, then along with visual hallucinations it is accompanied by various visual impairments. Parietal astrocytoma causes a disorder of writing and fine motor skills.
Diagnostics
Clinical examination of patients is carried out by a neurologist, neurosurgeon, ophthalmologist and otolaryngologist. It includes neurological examination, ophthalmological examination (determination of visual acuity, examination of visual fields, ophthalmoscopy), threshold audiometry, examination of the vestibular apparatus and mental status. Primary instrumental examination of patients with astrocytoma can reveal increased intracranial pressure according to Echo-EG data and the presence of paroxysmal activity according to electroencephalography. Detection of focal symptoms during neurological examination is an indication for CT and brain MRI.
Astrocytoma can also be detected by angiography. Histological examination allows to establish an accurate diagnosis and determine the degree of malignancy of the tumor. Histological material can be obtained during stereotactic biopsy or intraoperatively (to resolve the issue of the scope of surgical intervention).
Treatment
Depending on the degree of differentiation of the astrocytoma, its treatment is carried out by one or more of these methods: surgical, chemotherapeutic, radiosurgical, radiation.
Stereotactic radiosurgical removal is possible only with a small tumor size (up to 3 cm) and is carried out under tomographic control using a stereotactic frame placed on the patient’s head. With astrocytoma, this method can be used only in rare cases of benign course and limited tumor growth. The volume of surgical intervention performed by trepanation of the skull depends on the nature of astrocytoma growth. Often, due to the diffuse growth of the tumor into the surrounding brain tissue, its radical surgical treatment is impossible. In such cases, palliative surgery may be performed to reduce the size of the tumor or bypass surgery aimed at reducing hydrocephalus.
Radiation therapy of astrocytoma is carried out by repeated (from 10 to 30 sessions) external irradiation of the affected area. Chemotherapy is carried out by cytostatics using oral medications and intravenous injections. It is preferred in cases when an astrocytoma is observed in children. Recently, active developments have been underway to create new chemotherapeutic drugs that can selectively affect tumor cells without having a damaging effect on healthy ones.
Forecast
The unfavorable prognosis of astrocytoma is associated with its predominantly high degree of malignancy, the frequent transition of a less malignant form to a more malignant one and almost inevitable recurrence. In young people, there is a more common and malignant course of astrocytomas. The prognosis is most favorable if the astrocytoma has grade I malignancy, but even in this case, the patient’s life expectancy does not exceed 5 years. For astrocytomas of the III-IV degree, this time is on average 1 year.