Glioma symptoms depend on the tumor's size and location. Although people with small gliomas may not experience symptoms, large glioma tumors can cause:

Glioma tumors get their names from the type of glial cells they start in.

• Astrocytomas start in astrocyte cells and make up 20% of all brain tumors. Glioblastoma is a type of astrocytoma and the most common—and most aggressive—cancerous brain tumor in adults.
• Ependymomas start in the ependymal cells and account for 2% of brain tumors.
• Oligodendrogliomas begin in the oligodendrocytes cells and are rare, representing 1% to 2% of brain tumors.

Doctors further classify gliomas by grade, depending on how fast the tumor grows and how likely it is to spread.

• Low-grade (grade 1 or 2) tumors typically grow slowly and are less likely to invade surrounding tissues.
• High-grade (grade 3 or 4) tumors grow and spread quickly. 

In most cases, we don't know what causes glioma. However, some factors may increase your risk, including:

• Age
• Prior radiation therapy
• A family history of certain inherited genetic disorders

Your doctor wants to learn about your medical history, including any previous radiation therapy, and your habits and lifestyle. Sharing your family’s medical history also helps doctors understand your situation and alert them to possible inherited genetic disorders.

Doctors use a neurological exam to help diagnose glioma. During this exam, your doctor looks for changes in your vision, hearing, balance, coordination, strength, and reflexes. These changes can be signs of a tumor and may help determine its location.

Imaging tests that take pictures of your brain and the areas around it also help diagnose glioma. Doctors use various imaging technologies, each offering different insights to confirm a tumor's presence and location.

• MRI: Our doctors prefer to use magnetic resonance imaging (MRI) to confirm the presence of glioma. This test uses radio waves and powerful magnets to create images of brain structures. A technologist or nurse may perform this scan by injecting contrast dye into your arm to highlight the tumor's location.
• CT scan: Some people cannot have an MRI because the magnets interfere with implanted medical devices such as pacemakers and cochlear implants (hearing devices). Computed tomography (CT) scans combine multiple X-rays into 3D images and provide doctors with another way to see structures in the brain.

Your doctor may perform a biopsy to diagnose glioma. During a biopsy, your doctor uses a small needle to remove cells from the tumor.

Doctors look at the cells under a microscope to determine if the tumor is cancerous. They also evaluate the glioma tumor's type, genetic features, and grade, which help determine how quickly it may grow or spread. 

Genetic testing is a medical test that identifies changes in genes, chromosomes, or proteins. For brain tumors, genetic testing can show whether you have inherited mutations in genes related to the disease.

Before and during treatment, your doctor will ask you to have your blood drawn and tested at a lab. Blood tests can provide a variety of information, helping to establish your diagnosis and plan your course of brain tumors treatment.