Brain tumour. Sectioned gross clinical specimen of a brain affected by a tumour (glioma, lower left). Glioma arises from uncontrolled division of glial cells, which provide the nerve cells with protection and electrical insulation. Glioma does not spread (metastasise) through the body, but it does invade surrounding brain tissue. This tumour is in one of the temporal lobes, which are involved in hearing, speech and memory. Symptoms of such a tumour could include seizures, language difficulties or loss of memory. Because glioma is not a well-defined tumour, it is hard to fully remove with surgery. Targetted radiation may be used as well as or instead of surgery.