Primary Tumors Of Brain And Spinal Cord
Primary Tumors Of Brain And Spinal Cord- Definition
Primary Tumors Of Brain And Spinal Cord, Primary tumors of the brain and spinal cord are all the benign and malignant neoplasms which arise in the central nervous system, that is, those arising from the brain or spinal cord substance itself or the brain membranes surrounding it. Tumors, which originate from the cerebral nerves situated in the cranial nerve, or the nerve roots of the spinal cord lying in the vertebral column, are often added, but belong, from their origin, to the new formations of the peripheral nervous system.
Compared to other cancers, such as lung , breast , intestinal or prostate cancer, primary tumors of the brain and spinal cord are significantly less frequent. They account for only about 2% of all cancer cases. For the Federal Republic of Germany it is estimated that around 6,800 people are newly infected with a tumor of the brain or spinal cord every year. Primary tumors of the brain are much more common than primary tumors of the spinal cord. Men are generally slightly more affected than women.
There are, however, certain tumors, such as the meningiomas which emanate from the cerebral membranes, which occur more frequently in women. In principle, brain and spinal cord tumors can occur in every age. Most people are affected between 50 and 70 years of age. A second, much smaller frequency summit is found in the childhood. It is noteworthy that the tumors of the brain after the blood cancer ( leukemia ) rank second among the frequency statistics among the various cancer cases in childhood. The reason why brain tumors are more common in children compared to other forms of cancer is not yet known. Among the various types of brain tumors, benign gliomas and malignant medulloblastomas are found in childhood , while malignant gliomas and benign meningiomas predominate in the elderly.
Causes And Risk Factors
Despite intensive research efforts, the causes for the development of primary tumors of the nervous system remain largely unknown. In most patients, these tumors occur without any triggering factors being found. In this case the physician speaks of sporadic tumors and distinguishes them from the hereditary tumors. However, among the patients with a primary brain or spinal tumor, there is only a small percentage of a disease that promotes the development of tumors in the nervous system. These include, among others, neurofibromatoses, tuberous sclerosis, the Hippel-Lindau syndrome, or the very rare Li-Fraumeni syndrome.
Food and dietary habits , which are of great importance for the occurrence of other cancer diseases, such as smoking or excessive alcohol consumption, play no role in the development of primary tumors of the brain and spinal cord. Nor is there any convincing evidence that stress or unusual psychological stress causes these tumors. There is also no evidence of a possible interrelated relationship between brain injury and brain tumors.
The recent hypothesis that certain environmental influences, such as increased stress on the brain with electromagnetic fields in the area of high-voltage lines or the excessive use of mobile phones, lead to an increase in brain tumors, has not been documented. Only the direct radioactive irradiation of the nervous system, occasionally necessary for the treatment of other life-threatening diseases, eg acute leukemia, is associated with a slightly increased risk of tumors of the brain and brain membranes. Radioactive radiation is only important for a fraction of the patients with central nervous tumors.
Primary tumors of the brain and spinal cord comprise a wide variety of different types of tumors which originate from different cells of the nervous system and differ significantly in their growth behavior, response to treatment and prognosis. The exact classification (classification) of the different tumor types as well as the assessment of their biological value, ie the distinction between benign or malignant (grading), is carried out on the basis of fine tissue characteristics which are determined by means of microscope cutting preparations of the tumor tissue.
For this purpose, it is necessary to obtain tumor tissue samples either during an open operation or by a stereotactic biopsy .
Since the exact classification is the most important prerequisite for the estimation of the prognosis and the further treatment planning, the tumor tissue should always be examined by an experienced neuropathologist, ie a specialist specially trained for the delicate diagnosis of disorders of the nervous system. In its diagnosis, this is based on internationally recognized criteria, which are summarized in the classification of the tumors of the nervous system, published by the World Health Organization (WHO).
According to this WHO classification, a WHO “degree” is assigned to each tumor in addition to the type diagnosis. There are a total of four WHO degrees. The WHO grade I corresponds to a benign, slow-growing tumor with favorable prognosis and good healing potential by surgical tumor removal. In contrast, the WHO grade IV is given for malignant, very fast-growing tumors with unfavorable prognosis, which are mostly incurable with the currently available treatment methods (surgery, radiation therapy , chemotherapy ).
WHO Grading Of Tumors Of The Nerve Center
WHO grade I
Benign, slow tumor growth, very good prognosis
WHO grade II
Increased tendency to relapse, possible transition to malignant tumors
WHO grade III
Malignant, after the operation radiation and / or chemotherapy are necessary
WHO grade IV
Very malignant, rapid tumor growth, after the operation radiation and / or chemotherapy are necessary, poor prognosis
The WHO grading plays an important role not only for assessing the individual prognosis, but also serves as a guideline for further treatment. While tumors of the WHO grades I and II are often treated by a single operation, tumors of WHO grade III and IV receive additional radiation or chemotherapy after surgery.
The response to this additional therapy may vary greatly from tumor to tumor. Certain types of tumors, such as the anaplastic oligodendrogliomas , can be controlled very well and in the long term by a treatment, whereas others, such as the glioblastomas, have a tendency to grow again after an aggressive therapy.
The brain and the spinal cord contain, in addition to the nerve cells, various forms of support cells (glial cells), the most important of which are the astrocytes. In addition, the oligodendrocytes, which form the medullary nerve lancet in the central nervous system, and the ependym cells lining the inner brain chambers and forming the central canal of the spinal cord. In the inner brain chambers, there are also special structures, which are important for the formation of the brain water. These are called plexus choroid and have a special covering cell covering of plexus epithelial cells.
The meninges consist essentially of connective tissue cells and meningeal cover cells. Cranial nerves and spinal cord roots contain, in addition to nervous processes, Schwann cells, which have the important task of electrically isolating the nervous processes in the peripheral nerve from each other. Tumors can develop in principle from all the cell types mentioned. This is due to the great variety of different neoplasms of the nervous system. Interestingly, the fewest tumors are the nerve cells themselves, the neurons. The rarity of neuronal tumors is presumably due to the fact that most nerve cells do not divide in the mature brain tissue.
Brain tumors are the most common brain tumors from the different glial cells. These “gliomas” together account for about 60% of all primary tumors of the brain and spinal cord. According to the different glial cell types in the central nervous system, several subgroups of gliomas can be distinguished. The most common are the astrocytomas, among which glioblastoma is the most frequent and at the same time most malignant primary brain tumor. Other types of gliomas are oligodendrogliomas , mixed gliomas (oligoastrocytomas) and ependymomas . According to the gliomas, the meningiomas arising from the cerebral membranes form the second most common group among the primary tumors of the central nervous system. The most important malignant brain tumor of the child is the medulloblastoma of the cerebellum. The most common tumors of the cerebral nerves and spinal cord roots are called neurinomas or schwannomas. They proceed from the Schwann cells of the peripheral nervous system. The following list gives an overview of the most important primary tumors of the nervous system.