How to Detect a Brain Tumor

Signs of brain tumors vary depending upon where in the brain they occur. Symptoms mimic those of other diseases, making brain cancer difficult to diagnose.

Brain tumors produce neurological deficits by destroying brain tissue, stealing nutrients from normal brain cells, or exerting pressure in the brain. This can cause a gradual loss of movement or sensation in an arm or leg, unsteadiness, vision or hearing loss, or the gradual onset of speech difficulties.

Increased pressure in the brain may cause headaches, vomiting, sleepiness, uncoordinated or clumsy movements and seizures, and eventually lead to death. A growing brain tumor may produce pressure within the bones that form the skull or block the fluid in the brain (cerebrospinal fluid). This is called hydrocephalus.

Abnormal nerve cell electrical activity can trigger seizures, and may signal a brain tumor.


Detecting brain tumors usually requires a combination of diagnostic procedures.

Neurological exams. Your physician will examine your vision, hearing, alertness, muscle strength, coordination and reflexes, and will check for swelling in your eyes.

Imaging. CT scans produce a series of detailed pictures of the brain or the spine. If your physician conducts an angiogram, he or she will inject a dye into your body that makes your blood vessels visible on an X-ray. Angiograms identify blood vessels that feed tumors. Similarly, brain scans rely on tiny amounts of injected radioactive material to highlight abnormalities on an X-ray. MRI (Magnetic Resonance Imaging), which also produces pictures of the brain, help physicians detect injuries to pathways in the brain or reveal metabolic activity in brain tumors.

Tissue sampling. Physicians collect samples of cerebrospinal fluid through a procedure called a spinal tap, or remove tissue samples (biopsy) to look for cancer cells. Biopsies are the only sure way to diagnose a brain tumor.

Electrical activity. Procedures such as the EEG (electroencephalogram) record electrical activity in the brain and can help identify abnormalities.

Absent symptoms, physicians don't have generally acceptable methods for brain cancer screening. The Brain Tumor Foundation advocates MRI brain scans for screening. They are non-invasive and don't subject people to radiation.