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Gliomas are named according to the specific type of cell they derive from. The three main types of gliomas are astrocytomas, oligodendrogliomas, and ependymomas, which are named for astrocytes, oligodendrocytes, and ependymal cells, respectively. Mixed gliomas, such as oligoastrocytomas, contain cells from different types of glia.
Most gliomas are further categorized according to their grade, which is determined by pathologic evaluation of the tumor. Low grade gliomas are well-differentiated, slower growing, biologically less aggressive, and portend a better prognosis for the patient. High grade gliomas are undifferentiated or anaplastic , fast growing and can invade adjacent tissues, and carry a worse prognosis. There are numerous grading systems, but a commonly used system is the World Health Organization (or WHO) grading system for astrocytomas. The WHO system assigns astrocytomas a grade from 1 to 4, with 1 being the least aggressive and 4 being the most aggressive. Various types of astrocytomas are given corresponding WHO grades.
The prognosis is worst for Grade-4 gliomas, with an average survival time of 14-18 months. Overall, the five year survival rate is 5%.
The gliomas can also be roughly classified according to their location:
Symptoms of gliomas depend on which part of the central nervous system is affected. A brain glioma can cause headaches, nausea and vomiting, and cranial nerve disorders as a result of increased intracranial pressure. A glioma of the optic nerveThe optic nerve is the nerve that transmits visual information from the retina to the brain. Anatomy The nerve is the second of twelve paired cranial nerves but is usually considered to be part of the central nervous system as it is derived from an outpou can cause visual loss. Spinal cord gliomas can cause pain, weakness or numbness in the extremities. Gliomas do not metastasize by the bloodstream, but they can spread via the cerebrospinal fluid and cause "drop metastases" to the spinal cord.
High grade gliomas are highly vascular tumors and have a tendency to infiltrate. They have extensive areas of necrosis and hypoxia. Often tumor growth causes a breakdown of the blood-brain barrierThe blood-brain barrier is a physical barrier between the blood vessels in the central nervous system, and the central nervous system itself. The barrier stops many substances from travelling across it. The existence of such a barrier was first noticed in in the vicinity of the tumor. As a rule, high grade gliomas almost always grow back even after complete surgical excision.
On the other hand, low grade gliomas grow slowly, often over many years, and can be followed without treatment unless they grow and cause symptoms.
Treatment for brain gliomas depends on the location and the grade. Often, treatment is a combined approach, using surgery, radiation therapyRadiation therapy (or radiotherapy is the medical use of ionizing radiation as part of cancer treatment to control malignant cells (not to be confused with radiology, the use of radiation in medical imaging and diagnosis). Although radiotherapy is often u, and chemotherapyChemotherapy (pronounced keem-o-therapy is the use of certain drugs to treat disease, as distinct from other forms of treatment, such as surgery. Chemotherapy dates at least as far back as the use, by the Indians of Peru, of cinchona bark in the treatment. The radiation therapy is in the form of external beam radiation or the stereotacticStereotactic surgery is a minimally-invasive form of surgical intervention which makes use of a three-dimensional coordinates system to locate small targets inside the body and to perform on them some action such as ablation (removal), biopsy, lesion, inj approach using radiosurgeryRadiosurgery is a medical procedure which allows non-invasive brain surgery, i. without actually opening the skull), by means of directed beams of ionizing radiation. It is a relatively recent technique ( 1951), which is used to destroy, by means of a pre. Spinal cord tumors can be treated by surgery and radiation. Gene therapy using lytic viruses or prodrug converting retroviruses and adenoviruses is another new development for the treatment of gliomas. Temozolomide is a chemotherapeutic drug that is able to cross the blood-brain barrierThe blood-brain barrier is a physical barrier between the blood vessels in the central nervous system, and the central nervous system itself. The barrier stops many substances from travelling across it. The existence of such a barrier was first noticed in effectively and is being used in therapy.
NeurologyNeurology is a branch of medicine dealing with disorders of the central and peripheral nervous systems. Surgical operations on the nervous system are done by specialist neurosurgeons. Neurological disorders are disorders of the central nervous system ( br OncologyPlease refer to cancer for the biology of malignant disease, as well as a list of malignant diseases. Oncology is the medical study and treatment of cancer. A physician who practices oncology is an oncologist''. The term is from the Greek onkos meaning bu Neurosurgery