Medulloblastoma is a malignant intracranial tumor that develops from embryonic cells, most often( in 75% of the total number of patients with medulloblastoma) affecting children.
The prevalence of this ailment among children is two episodes per one hundred thousand peers. It accounts for one in five of all primary malignant neoplasms of the central nervous system in children. In adults, this figure is only 4%.
A typical age of detection of medulloblast in children is five to ten years. The number of detected by medulloblast for the tenth year of life of small patients is 70%.Boys suffer from them two to three times more often than girls. In adult patients, medulloblastoma is detected in the age range from 21 years to 40 years.
What is this tumor?
Medulloblastoma is a malignant neuroectodermal( developing from neuronal progenitor cells) tumor of the central nervous system( CNS). In medical literature medulloblastoma may be referred to as:
- by sarcomatous glioma;
- embryonic neuroglycytoma;
- isomorphous glioblastoma;
- by neurosporangioma;
- by neurospongioblastoma.
All of the above names are synonymous and are used for the name of the same disease.
The photo shows the medulloblastoma of the cerebellum
A distinctive feature of medulloblastom in comparison with other malignant tumors of the brain is their rapid metastasis along the liquor-conducting pathways( the paths of the constant circulation of cerebrospinal fluid - cerebrospinal fluid).
Rapid growth of the tumor, overlapping the channels of circulation of cerebrospinal fluid, leads to blockage of the flow of liquor. This results in a sharp increase in intracranial pressure in the patient and development of a syndrome of severe intracranial hypertension.
Histological examination of tumor tissues reveals the presence of many low-differentiated round embryonic cells that have a large hyperchromic nucleus and a thin cytoplasm.
Reasons for the appearance of
Most of the medulloblast is sporadic( irregular) in nature. Exception is made by patients suffering from a number of hereditary diseases characterized by a high probability of this malignant neoplasm. We are talking about patients with syndromes:
- of blue nevuses;
The true causes of development of medulloblastom have not been established to this day, however, a number of risk factors for this disease are known. These include:
- early( up to ten years) the age of the patient;
- exposure to ionizing radiation;
- effect of pathogenic viruses( herpes, human papilloma, cytomegalovirus, Epstein-Barr virus), causing damage to the cell genome;
- the presence of burdened heredity;
- harmful effects of carcinogens contained in food, household chemicals, paint and varnish products of chemical enterprises.
The germination of medulloblastoma in the brain stem leads to the development of bulbar syndrome, which manifests itself in the defeat of the cranial nerves, since their nuclei are located in the tissues of the medulla oblongata. The development of bulbar paralysis is characteristic of late stages of the disease.
80% of medulloblast is localized in the cerebellum worm, the rest - in the tissues of its hemispheres.
The histological structure of the tumor tissue divides the malignant tumor into the following species:
- Classical undifferentiated medulloblastoma;
- Tumor with neuronal differentiation;
- Neoplasm with glial differentiation;
- Desmoplastic medulloblastoma;
- Lipomatous medulloblastoma, containing fat cells. This type of tumors is the most benign.
To determine the individual clinical prognosis for each patient, most specialists use the Chang classification proposed by him in 1969.In full accordance with the principles of TNM, it takes into account the size of the malignant neoplasm, the degree of pathological infiltration and its metastasis.
Symptoms of granuloblastoma
The clinical course of granuloblast is largely determined by the location of the tumor, the severity of the brain syndrome caused by the rise in intracranial pressure and the localization of metastases.
- Given the cerebellar localization of medulloblastoma, most patients suffering from it develop a complex of symptoms called cerebellar ataxia. Its most striking manifestation is the presence of a "cerebellar gait," in which the patient walks, arranging legs and balancing with his hands, restoring balance and preventing a fall. Disturbed coordination of movements leads to frequent falls of the patient, strongly swinging from side to side.
- Tumor germination in the brain stem leads to a sharp deterioration in the patient's condition, manifested in the disorder of hemodynamics( blood flow through the vessels) and respiration.
- Neurological symptoms include disorders such as paralysis of the eye, disturbance of the pharyngeal reflex, pathological nystagmus( involuntary rhythmic eye movements), disorder of friendly movements of the eyeballs( their convergence).
- Involvement in the tumor process of the brain leads to various impairments of sensitivity and paralysis of the lower limbs.
- Symptomatic of cerebral manifestations is expressed in excessive irritability, psychomotor agitation, loss of correct orientation in space, time and ideas about one's own personality.
- The patient often has seizures, morning headaches, persistent nausea and multiple vomiting-a characteristic symptom of intracranial( intracranial) hypertension.
This is why the medulloblastomas are detected after their germination not only in the hemisphere of the cerebellum and the fourth ventricle of the brain, but also in the structures of the bulbar department.
Another factor that significantly worsens the condition of patients is the presence of metastases. Their size and localization determine the nature of the clinical picture in each specific case.
The unusual feature of granuloblast is that they( unlike other brain tumors that do not metastasize beyond the central nervous system) are capable of producing metastases in the tissues of the lungs, liver and bones.
For the correct diagnosis, the neurologist sums up the data obtained as a result of the whole complex of studies:
- Magnetic resonance imaging or computed tomography of the brain. With the help of computer tomography, the localization and size of the tumor, as well as the level of infiltration of tumor tissues, are determined. MRI makes it possible to detect even minimal changes in the structure of the brain tissue.
- Positron emission tomography data allow to detect the presence of oncomarkers in the blood and to assess the course of the metastasis process.
- The procedure of neurosonography of infants with open fontanelles allows early diagnosis of medulloblastoma.
- The complex of laboratory tests includes: general blood and urine tests, biochemical blood analysis, histopathological analysis( biopsy) of tumor tissues.
In addition to laboratory and hardware studies, the patient passes through an examination procedure:
- by a Neurosurgeon.
- Ophthalmologist. The results of his ophthalmoscopy most often indicate the presence of intracranial hypertension.
Treatment with medulloblast is a complex, combining surgical removal of the tumor, radiation and chemical therapy.
- Total removal of a cancerous tumor is carried out using microsurgical methods and intraoperative magnetic resonance navigation.
- With complete removal of medulloblastoma and the absence of metastases, radiation therapy is prescribed in low doses: this avoids significant side effects. With incomplete removal of the tumor or the detection of metastases, the doses of radiation exposure significantly increase. If malignant formation has reached a significant size, radiation therapy is used before surgery. The purpose of radiation exposure is to reduce the tumor to an operative size. Radiation therapy is contraindicated in children under the age of three.
- The course of chemotherapy is used after the removal of the tumor and the course of radiotherapy. The most effective treatment is the treatment with procarbazine, vincristine and nitrosourea.
- A new method of treatment of medulloblastoma, proposed by American specialists, is the use of genetically modified measles virus. Laboratory tests performed on mice showed the ability of this virus to kill cancer cells for three days.
The most common complication of medulloblastoma is the occurrence of a dropsy of the brain( hydrocephalus).It is caused by a disturbance of the flow of liquor arising from the rapid growth of the tumor, overlapping either the opening of the Magendi and the Lushka, or a narrow canal called the aqueduct of the brain.
Prognosis with medulloblastoma in children and adults
The death rate and disability of patients with medulloblastoma is extremely high.
- Postoperative mortality is kept at 5%, and the five-year survival rate of operated patients is no more than 30%.
- The survival rate of boys over five years is no more than 24%, and girls - about 10%.
- Malignancy of the tumor is higher the younger the child, because the brain stem, responsible for vital functions, is involved in the tumor process extremely quickly.
- The prognosis for operated patients with a recurring tumor is most often disappointing.
A video about high-dosage chemotherapy for medulloblastoma in children older than 4 years: