Tests and procedures used to diagnose oligodendroglioma include:

• Neurological exam. During a neurological exam, you're asked about signs and symptoms. Your vision, hearing, balance, coordination, strength and reflexes are checked. Problems in one or more of these areas may give clues about the part of the brain that could be affected by a brain tumor.
• Imaging tests. Imaging tests can help determine where the brain tumor is and its size. MRI is often used to diagnose brain tumors. It may be used with special types of MRI, such as functional MRI and magnetic resonance spectroscopy.

• Removing a sample of tissue for testing. A biopsy is a procedure to remove a small sample of tissue from the tumor for testing. When possible, the sample is removed during surgery to remove the tumor. If the tumor can't be removed with surgery, a sample might be collected with a needle. Which method is used depends on your situation and the location of the tumor.

  The tissue sample goes to a lab for testing. Tests can show what types of cells are involved. Special tests can show detailed information about the tumor cells. For example, a test may look at the changes in the tumor cells' genetic material, called DNA. The results tell your health care team about your prognosis. Your care team uses this information to create a treatment plan.

Oligodendroglioma treatments include:

• Surgery to remove the tumor. The goal of surgery is to remove as much of the oligodendroglioma as possible. The brain surgeon, who is also called a neurosurgeon, works to remove the tumor without harming healthy brain tissue. One way to do this is called awake brain surgery. During this type of surgery, you're awakened from a sleep-like state. The surgeon might ask questions and monitor the activity in your brain as you reply. This helps show the important parts of the brain so the surgeon can avoid them.

  Other treatments may be needed after surgery. Other treatments might be recommended if any tumor cells remain or if there's an increased risk that the tumor will come back.

• Chemotherapy. Chemotherapy uses strong medicines to kill tumor cells. Chemotherapy is often used after surgery to kill any tumor cells that might remain. It can be used at the same time as radiation therapy or after radiation therapy is finished.

• Radiation therapy. Radiation therapy uses powerful energy beams to kill tumor cells. The energy can come from X-rays, protons and other sources. During radiation therapy, you lie on a table while a machine moves around you. The machine sends beams to exact points in your brain.

  Radiation therapy is sometimes used after surgery and may be combined with chemotherapy.

• Clinical trials. Clinical trials are studies of new treatments. These studies give you a chance to try the latest treatment options. The risk of side effects may not be known. Ask a member of your health care team whether you can participate in a clinical trial.
• Supportive care. Supportive care, also called palliative care, focuses on providing relief from pain and other symptoms of a serious illness. Palliative care specialists work with you, your family and your other health care providers to provide extra support. Palliative care can be used at the same time as other treatments, such as surgery, chemotherapy or radiation therapy.