A brain tumor is a mass of abnormal cells. It can be located inside your brain or next to it. Tumors can cause a wide range of problems throughout your body when they grow and press harmfully against the brain tissue. There are many types of tumors that can either originate in the brain itself, or come from another part of the body and travel to the brain (metastasize). Brain tumors may be classified as either benign (non-cancerous) or malignant (cancerous), depending on their behavior.
Meningiomas are the most common benign intracranial tumors, comprising 10 to 15 percent of all brain neoplasms. These tumors arise from the membrane-like structures (meninges) that surround the brain and spinal cord. Often, meningiomas cause no symptoms and require no immediate treatment.
Schwannomas are benign tumors in adults that arise along nerves. They account for about 8% of all brain tumors and commonly occur at the nerve of hearing (the 8th cranial nerve), which travels from the brain to the ear. Although these tumors are benign, they can cause serious complications and even death if they grow and exert pressure on nerves and eventually on the brain. Common symptoms include one-sided hearing loss and buzzing or ringing in the ears.
Gliomas are the most prevalent type of adult brain tumor, accounting for 78 percent of malignant brain tumors. They arise from the supporting cells of the brain, called the glia. The glia help to keep neurons in place and functioning well.
- Astrocytomas develop from astrocytes, star-shaped glial cells that make up the supportive tissue of the brain. They may occur in many parts of the brain, but most commonly in the cerebrum. Astrocytomas can appear in various parts of the brain and can develop in people of all ages, but they are more prevalent in adults, particularly middle-aged men. Symptoms vary, but headaches, seizures, memory loss, and behavior changes are common.
- Glioblastoma (GBM)also develop from astrocytes, but these aggressive tumors tend to grow rapidly and spread to other tissues. They are generally found in the cerebral hemispheres of the brain. GBM is more common in people ages 50 to 70, and more prevalent in men than women. Because they form and grow so rapidly, the increased pressure in the brain will create symptoms such as headache, nausea, vomiting, and drowsiness.
Causes and Risk Factors
Most brain tumors are caused by alterations in the genes, or by chromosome rearrangements which change the function of a gene. Patients with certain genetic conditions (i.e., neurofibromatosis, von Hippel-Lindau disease, Li-Fraumeni syndrome, and retinoblastoma) also have an increased risk to develop tumors of the central nervous system. Exposure to certain chemicals may also increase the risk of brain tumors. Patients who have received radiation therapy to the head are also at an increased risk for new brain tumors.
Brain tumors are complex and symptoms depend on the type and location of the tumor. Physical symptoms such as headache, nausea, loss of balance, weakness in one side of the body, vision or hearing changes, and seizures may occur. Behavioral changes may also be symptoms, such as confusion, impulsiveness, difficulty thinking, or personality changes.
Neurosurgeons use imaging techniques such as MRI or CT scans to help diagnose a tumor, and sometimes a biopsy is necessary. Brain tumors (whether primary or metastatic, benign or malignant) usually are treated with surgery, radiation, and/or chemotherapy. Decisions as to what treatment to use are made on a case-by-case basis and depend on a number of factors.