Causes and Diagnoses

Causes and Diagnoses of Brain Tumors

The exact cause of brain tumors is unknown, but certain factors can contribute to your chances of developing these types of tumors. Risk factors include:

  • Radiation exposure: People who have received radiation to the head are at higher risk for brain tumors. Most often this exposure comes from radiation therapy used to treat another type of cancer, such as leukemia during childhood
  • Inherited syndromes: People who are born with certain syndromes, such as neurofibromatosis, von Hippel-Lindau disease, Li-Fraumeni syndrome, and tuberous sclerosis, have an increased risk of growing brain tumors
  • Family history: Most people with brain tumors don’t have a family history of the disease. But in rare cases, tumors can run in families
  • Weakened immune system: People who have a weakened immune system have a higher risk of developing a central nervous system (CNS) lymphoma. This includes people who have AIDS or who have had an organ transplant    
  • Prior history of cancer: Some cancers are more likely to spread to the brain, including breast, lung, prostate and multiple myeloma

Other possible causes of tumors

Researchers have also looked at other factors that might increase your risk of developing a brain tumor, including:

  • Contact with certain chemicals, such as vinyl chloride, pesticides, and petroleum products
  • Cell phone use
  • Living near power lines
  • Infection with certain viruses

While there isn't yet any strong evidence linking these other factors to brain tumors, research on these possible links remains ongoing.

When your symptoms suggest a brain tumor, your physician will obtain a detailed medical history in addition to diagnostic testing and other procedures, including:

  • Physical exam: This exam will have a strong focus on reflexes, muscle strength, sensation, eye and mouth movement, vision, coordination and alertness
  • Magnetic resonance imaging (MRI): An imaging technique that uses magnets and strong radio waves to take clear pictures of your brain to differentiate between a tumor and normal tissue
  • Computed tomography (CT) scan: A CT scan can be helpful to show detailed images of your brain
  • Positron emission tomography (PET) scans: PET scans allow your care team to identify an active, growing tumor in your brain
  • Magnetic resonance spectroscopy (MRS): An imaging scan that determines metabolites inside a tumor
  • Angiogram: A series of X-rays taken using a special dye, help your care team see your tumor and the blood vessels that lead to it
  • Magnetic resonance angiography (MRA): A special type of MRI that is a less invasive alternative to an angiogram
  • Skull X-ray: This X-ray can detect calcium deposits left by tumors and changes to the structure of the skull caused by tumors
  • Lumbar puncture (spinal tap): Removes a small amount of fluid that bathes your brain and spinal cord so it can be tested
  • Electroencephalogram (EEG): A non-invasive test that measures the electrical activity in your brain

Brain tumor biopsy

If other tests suggest that you have a brain tumor, your care team may recommend a biopsy of your brain to remove a small portion of tissue for testing. The sample of tissue from your tumor will allow your physicians to determine if your tumor is benign or malignant, as well as what type of brain tumor you have. An accurate diagnosis will help determine the best course of treatment. Two types of biopsies are used to diagnose brain tumors:

  • Stereotactic biopsy: This type of biopsy allows a neurosurgeon to use a thin, hollow needle to remove a piece of your tumor, while using CT or MRI imaging to carefully guide the procedure.
  • Open biopsy: This procedure is done through an opening in your skull, while you are sedated. During the procedure, your scalp is cut and a piece of skull bone is removed to provide access to brain. In most cases, the bone is put back in place after the biopsy. Often an early diagnosis is made while you are still in the operating room, so the neurosurgeon has information on how extensive the surgery will be.

If you are diagnosed with a brain, Northwestern Medicine is home to the very latest treatment options delivered by skilled cancer specialists. We take a multidisciplinary approach to diagnosing and treating these cancers. Together, we will develop a treatment plan, tailored to your specific condition, that offers the help and hope you need.

Related Resources

Lou and Jean Malnati Brain Tumor Institute at the Robert H. Lurie Comprehensive Cancer Center at Northwestern Memorial Hospital
Brain and Spine Tumor Center brochure: Learn about the Brain and Spine Tumor Center at Central DuPage Hospital and Delnor Hospital