Overview of Brain Tumors
The brain contains a network of nerves that carries messages. Some nerves go directly from the brain to parts of the head. Other nerves help to connect the rest of the body with the brain. The brain directs the things we choose to do (like walking and talking) and the things we do without thinking (like breathing). The brain is also in charge of our senses, memory, emotions and personality.
Brain TumorsTumors can be benign or malignant. The border or edge of a benign tumor can be clearly seen. While benign tumors do not invade tissue around them or spread into other parts of the body, they can press on sensitive areas of the brain and cause problems. Malignant tumors are generally more serious. They can grow rapidly and invade or crowd tissue around them. If the malignant tumor does not invade the surrounding healthy tissue, it is considered to be “encapsulated.”
Though the location of the tumor is determined through tests, a surgical biopsy is needed for a specific diagnosis. Grading may then be determined. Tumors are graded to facilitate communication, to plan treatment, and to predict outcome. Tumors can change classification (benign or malignant) or grade.
Tumor Grades
- Grade I - The least malignant. They grow slowly and are usually associated with long term survival.
- Grade II - They are relatively slow growing. Some can spread to nearby normal tissue.
- Grade III - These actively reproduce abnormal cells and can spread to nearby normal brain tissue.
- Grade IV - These are the most malignant. They reproduce rapidly and can easily grow into surrounding normal brain tissue.
More information on Tumors
Content provided by UW Medicine Neurological Surgery, Seattle, Washington
Symptoms of Brain Tumors
Symptoms caused by a tumor will depend on its location in the brain. Common symptoms include headaches, confusion, weakness, seizures, language troubles, double vision. However, tumors can be very large and cause no symptoms, or very small and cause major problems.
Because injuries to the brain are manifested by injury location, rather than injury type, strokes, head injuries, infections and other insults to the brain can have similar symptoms to brain tumors.
Causes of Brain Tumors
There are rare inherited (familial) syndromes that can be associated with brain tumors. Tumors in the brain are not known to be associated with foods, chemicals, cell phone use, or exposure to electrical wires. Primary brain tumors (those that start in the brain) occur in about 6 out of every 10,000 people in the United States each year. Secondary (metastatic) brain tumors (those that spread to the brain from other tumors) occur in about 20% of those with cancer. Some of these tumors have known associations, such as lung cancer and smoking. On the other hand, epilepsy can be due to any type of brain injury (tumor, infection, stroke, birth injury, high childhood fever, head trauma) and can run in families.
Diagnosis of Brain Tumors
The most important tests for brain tumors are MRI and/or CT scans. These show where the tumor is located, the size of the tumor, and often give hints about the type of tumor and its degree of malignancy.
All cases are presented at the multi-disciplinary Neuro-Oncology Tumor Board for management decisions. This team includes neurologists, neurosurgeons, neuropathologists, neuroradiologists, radiation oncologists, brain tumor researchers, nurses and social workers.
Figure 1: The “chemical signature” of tumor can be quite different from normal brain, stroke or infection. To view this, MRI spectroscopy is used to make a “chemical map” of the brain. These figures show an example of MRI multi-voxel spectroscopy demonstrating a brain tumor in the brainstem and corpus callosum.
Figure 2: Blood flow often increases in brain tumors. MRI perfusion studies can demonstrate this phenomenon. This Figure shows the increased blood flow in the tumor shown in Figure 1.