Glioma is an umbrella term for a group of rare brain tumors in the central nervous system. They are derived from the cells of the glial tissue, the supporting and nourishing tissue for nerve cells.
Gliomas make up about 30-50% of all brain neoplasms and can be classified according to their cytogenetic origin and degree of malignancy. They are typical tumors of middle age, with an incidence peak between 40 and 65 years.
This includes about 50% of high grade glioblastomas (grade IV), about 25% of astrocytomas of grade I to III, 5 to 18% of oligodendrogliomas and 2 to 9% of ependymomas. Gliomas may be slow-growing and therefore more benign (low-grade gliomas, grade I and II) or fast-growing and malignant (high grade gliomas, grade III and IV).
Only the grade 1 tumors have a clear border to the brain tissue. All other gliomas infiltrate the surrounding tissue, which explains the relapse rate of these tumors after complete tumor removal. The exact reason for the genesis of gliomas is unknown. Depending on their location, gliomas can cause virtually any neurological disorder.
Local symptoms such as paresis, sensibility, vision or speech disorders can be differentiated from generalized intracranial signs such as headache, vomiting or changes in consciousness. Typical symptoms continue to be seizures, which are more common in low grade gliomas.
Due to its very good soft tissue resolution, magnetic resonance is the best method to make a diagnosis.